TABLE OF CONTENTS · The necklace is composed of 12.5 mm turquoise beads sep-arated by diamond...

ABOUT THE COVER: For thousands of years, turquoise has been used in jewelryand other items of adornment. In recent times, much of this material has beentreated to improve its appearance and wearability. In particular, a relatively new,proprietary treatment has been used to enhance millions of carats of turquoise forthe last decade. Referred to here as the “Zachery treatment,” it cannot be detectedby standard gemological techniques. The lead article in this issue describes theproperties of this treated turquoise and discusses methods to identify it. All of theturquoise shown here, which is from the Sleeping Beauty mine in Arizona, has beentreated by this method. The necklace is composed of 12.5 mm turquoise beads sep-arated by diamond rondelles, with a white gold clasp containing 1.65 ct of dia-monds. The carving measures 30 × 60 mm. Courtesy of Roben Hagobian, Glendale,California.

Photo © Harold & Erica Van Pelt––Photographers, Los Angeles, California.

Color separations for Gems & Gemology are by Pacific Color, Carlsbad, California.Printing is by Fry Communications, Inc., Mechanicsburg, Pennsylvania.

© 1999 Gemological Institute of America All rights reserved. ISSN 0016-626X

T A B L E O F C O N T E N T S

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SPRING 1999 VOLUME 35 NO. 1

EDITORIALS11 Symposium ‘99—You Can’t Afford to Miss It!

Alice S. Keller

22 The Dr. Edward J. Gübelin Most Valuable Article Award

FEATURE ARTICLES44 The Identification of Zachery-Treated Turquoise

Emmanuel Fritsch, Shane F. McClure, MikhailOstrooumov, Yves Andres, Thomas Moses, John I. Koivula, and Robert C. Kammerling

1177 Some Diagnostic Features of Russian HydrothermalSynthetic Rubies and Sapphires

Karl Schmetzer and Adolf Peretti

3300 The Separation of Natural from SyntheticColorless Sapphire

Shane Elen and Emmanuel Fritsch

REGULAR FEATURES4422 Gem Trade Lab Notes4477 Gem News6611 Gems & Gemology Challenge6633 Book Reviews6655 Gemological Abstracts7777 Guidelines for Authors

or months now, GIA has been talking aboutthe Third International GemologicalSymposium. You’ve received a brochure.

You’ve seen ads in this and other publications.You’ve read the articles and heard about it from yourfriends. San Diego, June 21-24, 1999, ‘Meeting theMillennium.’ What is it really, and why am I, as editor ofGems & Gemology,urging you to go?

To answer the latter question first: for your own good.GIA has held only two other international symposia inthe last 17 years. Each brought together the most impor-tant people in the international gem and jewelry commu-nity both as participants and attendees. Manyof the topics introduced at the 1991Symposium set the stage for tackling thegemological challenges of the 1990s,such as fracture-filled and syntheticdiamonds, jade identification, pearlresearch, and emerald treatments.The technological advances of thepast decade have been mindboggling—and, as a jeweler or gemol-ogist, you are accountable to your cus-tomers to know how to address new syn-thetics, treatments, and deceptive practices assoon as they appear in the market. You also need toknow the new marketing practices that work in the U.S.and worldwide, must be able to anticipate periods of eco-nomic instability in the diamond and colored stone mar-kets, and must be aware of new and declining localitiesfor gem materials. The 1999 Symposium will give youmore of the tools you musthave to operate successfully inour industry.

So, exactly what is Symposium? The core of the programis a series of concurrent speaker and panelist sessions thatwill address such topics as sources, production, and eco-nomics and manufacturing for both diamonds and col-ored stones. Also included are sessions on pearls, jewelrydesign, and estate jewelry, as well as—of course—the

identification of new treatments, synthetics, and simu-lants. Entering the 21st century, suppliers and retailersalike are looking for new marketing opportunities, bothvia conventional retail channels and through such elec-tronic media as television and the Internet; all of thesewill be addressed. New to Symposium this year are thefour War Rooms—on appraisals, disclosure, branding,and diamond cut—where attendees and panelists willinteract to find solutions to such pressing issues as cutgrading and the new L.K.I.-G.E. ‘processed’ diamonds.

But Symposium offers even more. It offers 70-plus postersessions with in-depth introductions to specific new tech-

niques, instruments, localities, and the like. It offers the insight of four prominent nonin-

dustry experts in the areas of marketing,technology, the economy, and ethics forthe new millennium. It offers powerfuladvice from world business leaders suchas Peter Ueberroth and the senior states-man of the diamond industry, MauriceTempelsman.

And Symposium is not just about learning.Symposium is also about meeting old friends

and making new ones, while enjoying superb foodand entertainment in one of the world’s most beautiful

settings: the Hyatt Regency, on San Diego Bay. Theopening reception is at Embarcadero park, right on thewater; Tuesday follows with a visit to the ‘Nature ofDiamonds’ exhibit at the San Diego Natural HistoryMuseum, and a buffet under the stars. On Wednesday,there will be a pearl reception and fashion show.Symposium closes with Italian cuisine and a uniquesalute to the history of the Italian jewelry industry, ‘Artein Oro.’

Please, take my word for it. There is nothing like it. Andthere will be nothing like it for many years to come. TheJune 1999 International Gemological Symposium is oneevent you truly can’t afford to miss.

Editorial GEMS & GEMOLOGY Spring 1999 1

Symposium ‘99You Can’t Afford to Miss It!

F

2 Gübelin Most Valuable Article Award GEMS & GEMOLOGY Spring 1999

First PlaceModeling the Appearance of the Round Brilliant Cut Diamond: An Analysis of BrillianceT. Scott Hemphill, Ilene M. Reinitz, Mary L. Johnson, and James E. Shigley

SSccootttt HHeemmpphhiillll,, a GIA research associate, has been programming com-puters for the past 30 years. Mr. Hemphill received a B.Sc. in engineer-ing and an M.Sc. in computer science from the California Institute ofTechnology. IIlleennee RReeiinniittzz is manager of Research and Develop-ment atthe GIA Gem Trade Laboratory (GIA GTL), New York, and an editorof Gem Trade Lab Notes. Dr. Reinitz, who has co-authored many arti-cles for G&G and other publications, received her Ph.D. in geochemistryfrom Yale University. MMaarryy JJoohhnnssoonn is manager of Research andDevelopment at GIA GTL, Carlsbad, and editor of the Gem News sec-tion. A frequent contributor to G&G, she received her Ph.D. in mineral-ogy and crystallography from Harvard University. JJaammeess SShhiigglleeyy is direc-tor of GIA Research in Carlsbad. Dr. Shigley, who has been with GIAsince 1982, received his Ph.D. in geology from Stanford University. Hehas written numerous articles on natural, treated, and synthetic gems.

T he readers of Gems&Gemology have voted, and your choices for the Dr. Edward J. Gübelin Most ValuableArticle Award for best article published in 1998 reflect the increasing importance of advanced research in thepractice of gemology. Receiving first place is “Modeling the Appearance of the Round Brilliant Cut Diamond:

An Analysis of Brilliance” (Fall 1998), in which the authors used computer modeling to tackle one of the most com-plex and controversial issues in the trade, the evaluation of diamond cut. Second place goes to “Characterizing Natural-Color Type IIb Blue Diamonds” (Winter 1998), a comprehensive study of blue diamonds and their color classification.The third-place winner, “Separating Natural and Synthetic Rubies on the Basis of Trace-Element Chemistry”(Summer 1998), used semi-quantitative chemical analysis to address a critical gem identification problem.

The authors of these three articles will share cash prizes of $1,000, $500, and $300, respectively. Following are pho-tographs and brief biographies of the winning authors.

Congratulations also to Ron Lotan of Ramat Gan, Israel, whose ballot was randomly chosen from the many entriesto win a five-year subscription to Gems& Gemology.

Scott Hemphill

The Dr. Edward J. Gübelin Most Valuable Article Award

Ilene M. Reinitz

James E. ShigleyMary L. Johnson

Second PlaceCharacterizing Natural-Color Type IIb Blue DiamondsJohn M. King, Thomas M. Moses, James E. Shigley, Christopher M.Welbourn, Simon C. Lawson, and Martin Cooper

JJoohhnn KKiinngg is laboratory projects officer at GIA GTL, New York. Mr. Kingreceived his M.F.A. from Hunter College, City University of New York.With 20 years of laboratory experience, he frequently lectures on coloreddiamonds and laboratory grading procedures. TThhoommaass MMoosseess,, vice presi-dent of Identification Services at GIA GTL, New York, attended BowlingGreen University in Ohio before he entered the jewelry trade more than 20years ago. He is a prolific author and an editor of the Gem Trade LabNotes section. Please see the first-place entry for biographical informationon JJaammeess SShhiigglleeyy.. CChhrriissttoopphheerr WWeellbboouurrnn is head of the Physics andPatents Departments at De Beers DTC Research Centre in Maidenhead,United Kingdom. Dr. Welbourn, who joined the De Beers ResearchCentre in 1978, holds a Ph.D. in solid state physics from the University ofReading. SSiimmoonn LLaawwssoonn is a research scientist in the Physics Departmentof the De Beers DTC Research Centre. He obtained his Ph.D. in opticalspectroscopy of diamond at King’s College London and has publishednumerous papers on this topic. MMaarrttiinn CCooooppeerr,, who also joined De Beersmore than 20 years ago, is research director at the De Beers DTC ResearchCentre. Mr. Cooper received his B.Sc. in physics from the University ofLondon and his M.Sc. in materials science from Bristol University.

Third PlaceSeparating Natural and Synthetic Rubies on the Basis of Trace-Element ChemistrySam Muhlmeister, Emmanuel Fritsch, James E. Shigley, Bertrand Devouard, and Brendan M. Laurs.

SSaamm MMuuhhllmmeeiisstteerr is a research associate with GIA GTL, Carlsbad.Born in Germany, Mr. Muhlmeister received bachelor’s degrees inphysics and mathematics from the University of California at Berkeley.EEmmmmaannuueell FFrriittsscchh is professor of physics at Nantes University, France.Dr. Fritsch, who received his Ph.D. from the Sorbonne in Paris, haspublished numerous articles in G&G. JJaammeess SShhiigglleeyy is profiled in thefirst-place entry. BBeerrttrraanndd DDeevvoouuaarrdd is assistant professor of mineralogyat Blaise Pascal University in Clermont-Ferrand, France. Dr. Devouardhas a Ph.D. in mineralogy and crystallography from Aix-MarseilleUniversity. His research specialties are microstructures and high spatial-resolution analytical techniques in minerals. BBrreennddaann LLaauurrss,, senior editorof Gems & Gemology, holds a B.Sc. in geology from the University ofCalifornia at Santa Barbara and an M.Sc. in geology from Oregon StateUniversity. Prior to joining GIA, Mr. Laurs was an exploration geologistspecializing in colored gems.

John M. King

C.M. Welbourn Simon C. Lawson

Martin Cooper

Brendan M. Laurs and Sam Muhlmeister

Emmanuel Fritsch Bertrand Devouard

Thomas M. Moses

Gübelin Most Valuable Article Award GEMS & GEMOLOGY Spring 1999 3

Over the last 10 years, millions of carats ofturquoise have been enhanced by a propri-etary process called the Zachery treatment.Tests show that this process effectivelyimproves a stone’s ability to take a good pol-ish and may or may not improve a stone’scolor. It also decreases the material’s porosity,limiting its tendency to absorb discoloringagents such as skin oils. Examination ofnumerous samples known to be treated bythis process revealed that Zachery-treatedturquoise has gemological properties that aresimilar to those of untreated naturalturquoise, and that the treatment does notinvolve impregnation with a polymer. MostZachery-treated turquoise can be identifiedonly through chemical analysis—most effi-ciently, by EDXRF spectroscopy—as it con-tains significantly more potassium than itsuntreated counterpart.

4 Zachery-Treated Turquoise GEMS & GEMOLOGY Spring 1999

THE IDENTIFICATION OFZACHERY-TREATED TURQUOISE

By Emmanuel Fritsch, Shane F. McClure, Mikhail Ostrooumov, Yves Andres, Thomas Moses,John I. Koivula, and Robert C. Kammerling

urquoise is one of the oldest gem materials known.Its use in jewelry and for personal adornment can betraced back 70 centuries, to ancient Egypt (Branson,

1975). Today it is popular in fine jewelry worldwide (seecover and figure 1) as well as in various cultures, mostnotably among Native American groups of the southwest-ern United States (figure 2). However, because the supply ofhigh-quality turquoise is limited, and because this materialreadily accepts many treatments, most turquoise is adulter-ated (Liddicoat, 1987). Cervelle (1985) even states thatturquoise must be treated, to avoid the change in colorcaused by absorption of substances such as cosmetics,sweat, or grease into this typically porous material. Themost common type of turquoise treatment is impregnationwith an organic material. Such treatment can be readilydetected by observation with a microscope, use of a hotpoint (Liddicoat, 1987), or infrared spectroscopy(Dontenville et al., 1986). However, there is a relatively new,proprietary turquoise treatment, commonly known in thetrade as “enhanced turquoise” (again, see figures 1 and 2),which cannot be detected by any of these classical methods.The purpose of this article is to describe the properties ofthis treated turquoise, with the specific intent of offering amethod for its identification.

BACKGROUNDAt the 1988 Tucson show, one of the authors (RCK) wastold that a new type of treated turquoise had been marketedfor at least six months under the name “Zacharia-treatedturquoise.” This enhancement was reportedly done withchemicals such as copper sulfate (letter from Pat Troutmanto RCK, February 24, 1988). Some of the material was beingsold through R. H. & Co. Inc. in Glendale, California.Inquiries to R. H. & Co. were answered by Roben Hagobian.He stated that US$1.5 million had been spent on developingthis process, and that the treatment could not be detected.He also specified that it was not called “Zacharia treat-

ABOUT THE AUTHORS

Dr. Fritsch ([email protected]) is professor ofPhysics at the University of Nantes, France. Mr.Moses is vice president for Research andIdentification at the GIA Gem Trade Laboratory inNew York. The late Mr. Kammerling was vice-president for Research and Identification, Mr.McClure is manager of Identification Services,and Mr. Koivula is chief research gemologist atthe GIA Gem Trade Laboratory in Carlsbad. Dr.Ostrooumov is professor at the St. PetersburgSchool of Mines, Russia, and currently professorat the Universidad de Michoacán de San Nicolásde Hidalgo, Michoacán, Mexico. Dr. Andres isassistant professor at the Nantes School ofMines, in Nantes.

Please see acknowledgments at end of article.

Gems & Gemology, Vol. 35, No. 1, pp. 4–16© 1999 Gemological Institute of America

T

Zachery-Treated Turquoise GEMS & GEMOLOGY Spring 1999 5

Figure 1. These pieces illus-trate some of the fine

turquoise jewelry and fash-ioned goods that are cur-

rently in the marketplace.All of these pieces have

been fashioned fromZachery-treated turquoisefrom the Sleeping Beauty

mine. The beads in the topnecklace are 13 mm in

diameter; the heart-shapedpendant is 35 mm wide; the

cabochons in the earringseach measure 15 × 20 mm;

and the larger stones in therings are about 12 mm in

largest dimension. Courtesyof Roben Hagobian; photo ©

Harold & Erica Van Pelt.

ment;” rather, that name probably referred to a sci-entist named Zachery who actually developed theprocedure. Mr. Hagobian could not provide anydetails on the method himself, as he only providedthe stones to be treated and got them backenhanced. At that time, we were also informed(through a letter dated June 23, 1989, from PatTroutman to Loretta Bauchiero of GIA) thatturquoise that was color-enhanced by this treat-ment might fade over time. No other informationwas made available to us, however, and our effortsto obtain additional samples and data were unsuc-cessful until recently.

At the end of 1996, we inadvertently encoun-tered new information about the treatment in thecourse of another investigation. While researchingpolymer-impregnated turquoise, we were told of acompany that was treating turquoise by a methodthat could not be detected. We subsequently learnedthat the material was being treated and marketed bySterling Foutz of Sterling Products, Phoenix,Arizona. At the 1997 Tucson show, two of theauthors (SFM and EF) met with Mr. Foutz, whoagreed to supply a large number of treated samplesfrom known turquoise mines around the world, aswell as some untreated natural material from a

number of these localities. Mr. Foutz told us thatthe process was invented by James E. Zachery, anentrepreneurial electrical engineer who “grew up”in the turquoise trade. It stemmed from a desire toimprove the properties of turquoise without usingartificial additives such as plastic. The key advan-tages of this treatment, according to Mr. Foutz, arethat the treated stones take a better polish and aremore resistant to “oxidation” or discoloration overtime, apparently due to a significant decrease in theporosity of the turquoise. They can also apply thesame process to produce a greater depth of color inthe turquoise. More than 10 million carats ofturquoise have been treated by this process since itwas first invented in the late 1980s; RobenHagobian (pers. comm., 1999) noted that in 1998alone he had 1.2 million carats of turquoiseenhanced by the Zachery process.

Mr. Foutz reported that the treatment processtakes approximately three to six weeks, and that noorganic or inorganic colorants or organic impregna-tions are used. Because the process is proprietary,Mr. Foutz did not provide specifics of the actualtechnique and asked us not to use the samples hesupplied to research the precise technique. He didadd, though, that the process only works on medi-


TABLE 1. Turquoise samples studied by gemological testing and EDXRF analysis.a

Description No. of Sample Year Color Zachery FTIR Size Commentssamples no. acquired treated? data? (weight or

max. dim.)

Sample Sets"Emerald Valley"b 2 220a-b 1998 Whitish No – 1 No 21 mm Rough, sawn in half;

green; Yes – 1 30 mm cabochons also madegreen

2 221a-b 1998 Green No – 1 No 34 mm Rough, sawn in half; Yes – 1 20 mm cabochons also made

2 222a-b 1998 Green No – 1 No 40 mm Rough, sawn in half; Yes – 1 34 mm cabochons also made

Sleeping Beauty, AZc 4 225a-d 1998 Blue Yes – 4 No 11.22-18.28 ct Cabochons, sawn in half: surface treated only (a),throughout (b,c),throughout + surface (d)

Sleeping Beauty, AZd 4 231a-d 1998 Blue No - 1 No 18-34 mm Rough, polished slabs: Yes - 3 untreated (a); treated

throughout (b), surfacetreated (c), throughoutand surface (d)

Other Samples"Blue Bird"e 3 164-166 1997 Med. blue All samples All 18-24 mm Rough w/ matrix, polished;

samples 166 had a partial blue rimChina 4 362 GIA Blue No – 1 No – 1 13 mm Rough, sawn and polished

155-157 1997 Yes – 3 Yes – 3 21-23 mm Rough w/ matrix, polished"Emerald Valley" 4 158-160 1997 Green All samples; All samples 23-36 mm Rough w/ matrix, polished;

170 2 with rough, sawn and polishedno evidenceg

Mexico 3 152-154 1997 Blue, All samples All samples 16-22 mm Flat fragment w/ matrix, sl. gr. blue polished; rough, polished

Nevada (unspecified) 1 TQE4B CRG Greenish blue No Yes 11 mm Rough, polishedNevada Fox, NV 3 161-163 1997 Green-blue All samples All samples 17-21 mm Rough w/ matrix, polished;

rough, polishedNevada Smith, NV 3 149-151 1997 Blue All samples All samples 22-24 mm Rough w/ matrix, polished;

rough, polishedPersia 1 13925 GIA Blue No No 28.78 ct Oval cabochonSleeping Beauty, AZ 5 141-145 1997 Blue No – 2 All samples 15-21 mm Rough, sawn and polished–

Yes – 3 All samples all with blue rim, lesspronounced on untreated

Sleeping Beauty, AZ 2 229-230 1998 Blue No No 5.67, 5.86 ct Beads"Thunder Blue" f (China) 3 167-169 1997 Blue All samples All samples 22-23 mm Rough w/ matrix, polishedTurquoise Mtn., AZ 3 146-148 1997 Sl. gr. All samples All samples 21-27 mm Rough ± matrix, broken;

blue 1 polished, 2 unpolishedU.S. (unspecified) 1 172 EF Blue No Yes 19 mm Rough, sawn and polishedUtah (unspecified) 1 171 EF Blue No Yes 22 mm Rough w/ matrix, polishedUzbekistan 1 OST1 EF Blue No Yes 20 mm Flat slab w/ matrix, polishedUnspecified locality 6 ZTT1-6 1988-89 Blue All samples; Yes – 4 0.49-4.39 ct Cabochons – 5 (1 w/ matrix);

1 showed No – 2 bead – 1no evidence

a All samples were tested for refractive index (by the spot method), specific gravity (except Uzbekistan sample OST1, which had too much matrix), long- and short-wave UV radiation, visible spectrum (as seen with a hand-held spectroscope), and response to a thermal reaction tester. EDXRF chemical analysis also was performed on all samples. Abbreviations: max. dim. = maximum dimension, CRG = Centre de Recherches Gemmologiques Jean-Pierre Chenet (University of Nantes) collection, GIA = GIA collection, EF = Emmanuel Fritsch collection, gr. = greenish, sl. = slightly, med. = medium, w/ = with.

b Refers to distinctly green turquoise from China, Mexico (Baja California), or the U.S. (New Mexico or CrescentValley, Nevada).

c One surface-treated cabochon was analyzed by electron microprobe, before and after exposure to oxalic acid solution.d All four slabs were analyzed by electron microprobe.e Refers to medium blue turquoise from Mexico or the U.S. (Nevada or Arizona–Sleeping Beauty mine).f The name given to turquoise from China by a particular supplier.g These samples were represented as treated, but they showed no K peak with EDXRF.


um- to high-grade material; low-quality, chalkyturquoise will not enhance successfully. Also, sev-eral different results are possible with the samebasic treatment process, with some adjustments formaterial from different mines. One is the treatmentof the stone throughout without affecting the colorof the original material. This approach is usuallyused on rough, and it is done to decrease the porosi-ty of the turquoise and improve its ability to take agood polish. After a stone has been cut from suchrough, it can be treated again to improve its color.This second treatment, which has a relatively shal-low penetration, produces a darker, more saturatedhue. A third scenario is to treat a previouslyuntreated cut turquoise with the near-surface pro-cess both to improve its color and decrease itsporosity.

In 1998, we received a letter from Mr. Zachery,who provided additional information regarding thenature of the treatment. According to his letter,“the enhancement process evolved from serious sci-entific attempts to duplicate the environment thatallowed the famous Kingman high-grade turquoiseto be deposited amid large potassium feldspar beds. . . . Although wholesale deposition of magnifi-cent specimens did not occur, the microcrystallinestructure of almost any specimen could be perfect-ed. . . .” He wrote that “no dyes of any kind, eitherorganic or inorganic, have been used; . . . the normalcolor producing metallic ions found in naturalturquoise, such as copper or iron, have not beenadded. . . . ” and that “any environments wet or drythat may have facilitated the enhancement proce-dure have not contained any of the aforementionedcoloring ions, nor have any electrodes which con-tain these elements been employed.” Moreover, hewrote that this material “has not been impregnatedwith plastic” or “with any wax, oil or lacquerwhether natural or synthetic.” He added his beliefthat “the principles involved in the Zachery processare widely applicable to other porous or penetrablegems such as beryls and opals.”

Mr. Zachery recommended the phrase “micro-crystalline structurally enhanced by the Zacheryprocess” to describe material treated in this fashion.For the sake of simplicity, we will refer to this prod-uct as “Zachery-treated turquoise.” For the remain-der of this article, this term and the term treatedturquoise will be used interchangeably to refer tothis process.

MATERIALS AND METHODSWe performed comprehensive testing on a total of58 samples (see table 1): 16 cabochons (four untreat-ed, 12 treated), three beads (two untreated, onetreated), two unpolished pieces of rough (both treat-ed), and 37 slabs or polished pieces of rough (eightuntreated, 29 treated). The fashioned samplesranged from 0.49 ct to 28.78 ct, and the rough sam-ples ranged up to 4 cm in maximum dimension.The polished surface on the rough samples was flator slightly rounded.

The samples in table 1 are designated by theirgeographic origin or color variety (as represented byMr. Foutz). Untreated samples were from China,Persia, Uzbekistan, and the U.S. (Arizona—SleepingBeauty mine, Nevada, Utah, and an unspecifiedlocality). Treated samples were from China (includ-ing material represented as “Thunder Blue”),Mexico, and the U.S. (Arizona—Sleeping Beautymine and the Turquoise Mountain mine nearKingman; Nevada—Nevada Fox and Nevada Smithveins at the Fox mine in Crescent Valley). Six treat-

Figure 2. Turquoise jewelry has long been popularwith Native Americans from the Southwesternstates. Today, much of this turquoise is also treat-ed by the proprietary Zachery process. Courtesy ofSterling Foutz; photo by Maha DeMaggio.


ed samples were from unspecified localities. Thecolor varieties were designated as “Blue Bird” (threetreated samples) and “Emerald Valley” (threeuntreated and seven treated samples). “Blue Bird”refers to medium blue turquoise; these samplescould be from Mexico or the U.S. (Nevada orArizona—Sleeping Beauty mine). “Emerald Valley”refers to turquoise with a distinctly green color;these samples could originate from China, Mexico(Baja California), or the U.S. (New Mexico orCrescent Valley, Nevada).

To test the durability and cutting performance ofthe treated material, we obtained from Mr. Foutzthree rough samples that represented different qual-ities of “Emerald Valley” turquoise. Each samplewas cut in half; one half was treated by the Zacheryprocess (the precise treatment was not specified, butthe same type was used on all), and the other wasleft untreated (figure 3). Subsequently, we had acabochon fashioned from each half to compare bothhow well the treated and untreated materialsresponded to the cutting wheel and the relativequality of their polish. To test the effectiveness ofthe treatment in decreasing the porosity of thematerial, we cut fragments of the treated anduntreated samples in half, and immersed one half ofeach in Johnson’s® baby oil for a total of six days.The samples were removed from the oil and exam-ined regularly during this period.

To characterize turquoise with different treat-ment types, we asked Mr. Foutz to treat a series ofslabs from the same piece of rough. A nodule fromthe Sleeping Beauty mine was cut into four slabs(figure 4), and the following samples were prepared:(1) untreated, (2) surface treated only with the color

enhanced,(3) treated throughout and left naturalcolor, and (4) treated throughout and then surfacetreated to improve the color. This sample suiteallowed us to make direct comparisons between thesamples—before and after treatment, and betweenthe different treatments—on a single piece of rough.

Also at our request, Mr. Foutz supplied fourcabochons of treated Sleeping Beauty turquoise thatwe cut in half to observe changes in coloration.Two of these cabochons were treated throughout,one was surface treated only (with the colorenhanced), and one was treated throughout andthen surface treated to improve the color.

To investigate the color stability of the treatedmaterial, we took the three cabochons we had cutfrom the treated halves of the Emerald Valley treat-ed-and-untreated specimens described above andsawed them in half. We placed one half of each sam-ple in an Oriel 81150 solar simulator with a 300-watt xenon light source. This instrument creates anoutput emission that approximates the daylightspectrum at two times its normal intensity. We leftthe cabochons in the solar simulator for 164 hours,checking them at approximately 24 hour intervals.This is equivalent to approximately 328 hours ofnoon sunlight exposure. The second half of eachcabochon was kept in the dark as a control.

All of the samples were tested by the followingmethods, with the exception of the one untreatedturquoise from Uzbekistan, for which specific-gravi-ty testing would have been meaningless because itcontained so much matrix material. Indices ofrefraction were measured by the spot method witha GIA Gem Instruments Duplex II refractometer.Specific gravity was determined by the hydrostatic

Figure 3. These samples (nos. 220–222a,b; 20–40 mm long) of rough “Emerald Valley” turquoise illus-trate the results of treatment on different qualities of material. Half of each sample was treated by theZachery process, and the other half was left untreated for comparison. Little change is visible in thetreated half (top) of the high-quality (low-porosity) material in A. The medium-quality turquoise in Bshows distinctly higher color saturation in the treated half (right sample), as does the low-qualitymaterial in C (also right). Photos by Maha DeMaggio.

A B C


method. We also observed the samples with a Beckprism spectroscope, and a long-wave (366 nm) andshort-wave (254 nm) ultraviolet lamp unit (in adarkened room). We applied a standard thermalreaction tester (TRT) to check for the presence of apolymer.

We performed Fourier-transform infrared spec-troscopy (FTIR) on most of the samples (see table 1)using a Nicolet 20 SXC instrument in the specularreflectance mode, at a resolution of 4 cm−1, in themid-infrared range 4000–400 cm−1. Semi-quantita-tive chemical analyses by energy-dispersive X-rayfluorescence (EDXRF) were obtained on all thestudy samples on either of two instruments: aTracor Spectrace 5000 at GIA or an OxfordInstruments ED2000 at Nantes. The Spectrace 5000had a rhodium anticathode, whereas the ED2000had a silver anticathode. Instrumental artifactscaused by the machines, in particular the silveranticathode, were visible in the spectra collected;these could conceal the presence of small amountsof silicon or chlorine. The conditions were chosento be appropriate for the simultaneous measure-ment of peaks for light elements (such as alu-minum) through the end of the first series of transi-tion elements (copper and zinc). For the Spectrace5000, the analyses were performed in a vacuum,with no filter, and with a tube voltage of 15 kV anda livetime of 100 seconds. The same conditionswere used for the ED2000, except for a tube voltageof 10 kV and a livetime of 120 seconds.

Dr. F. C. Hawthorne at the University ofManitoba, Canada, performed electron microprobeanalyses on (1) all four slabs from the Sleeping

Beauty mine and (2) one of the color-treatedSleeping Beauty cabochons that had been cut in halfand one half immersed in oxalic acid. Cross-sec-tions of the slabs were analyzed to provide quantita-tive chemical data near the surface and within thecore of each sample. The analyses were performedusing a Cameca SX-50 microprobe with an acceler-ating voltage of 15 kV, sample current of 20 nA, anda beam spot size of 20 microns. Dr. Hawthorne alsoperformed X-ray diffraction analysis, using trans-mission geometry, on one untreated and two of thetreated slabs.

RESULTSEffectiveness of the Treatment. The three green“Emerald Valley” samples for which one half wastreated and the other half was left in its originalstate illustrate the potential influence of the processon various aspects of appearance, cuttability, anddurability. Two of the treated halves were muchmore saturated than their untreated counterparts,and some areas of matrix were a darker brown. Thesomewhat chalky appearance of these pieces beforetreatment disappeared after treatment. The color ofthe third sample was unaffected by treatment.

As noted above, one of the advantages claimedfor Zachery-treated turquoise is that it is easier tocut and takes a better polish. According to the cut-ter of the six cabochons fashioned from these treat-ed and untreated halves of “Emerald Valley” rough,all of the treated material was easier to work in thatit gave a cleaner cut that did not crumble or splinteralong the sawn edge. Indeed, the cutter had difficul-ty keeping the lowest-quality untreated material

Figure 4. These four slabs(nos. 231a–d; 18–34 mmwide) were cut from the

same piece of SleepingBeauty mine rough. Three

of the slabs were treatedby the Zachery process to

obtain different results.From left to right: (1)untreated, (2) surface

treated only to enhancecolor, (3) treated through-out and left natural color,

and (4) treated through-out and then surface

treated to improve thecolor. Photo by Maha

DeMaggio


from breaking up during sawing. The three Zachery-treated turquoise cabochons also took a better pol-ish than the untreated material, with the lowest-quality turquoise showing the most pronounced dif-ference (figure 5). In fact, the unusually high lusterwas somewhat superior to what one would normal-ly expect from high-quality untreated turquoise.

Another advantage claimed for Zachery treat-ment is that it reduces the tendency of turquoise toabsorb oil and/or grease (by decreasing the porosity).We tested this claim by immersing fragments ofthese same samples in baby oil (while retaining por-tions of these fragments as controls). Within a fewminutes, we observed that more air bubbles wereescaping from the untreated fragments, which indi-cates that they were more porous than their treatedcounterparts. After six days of immersion, the threetreated fragments did not show any change inappearance, but their untreated counterpartsbecame noticeably to dramatically darker than thecontrol samples. This illustrates that the treatedturquoise has little or no tendency to absorb oil andgrease, which would cause it to discolor over time,as does natural turquoise (Bariand and Poirot, 1985).

As noted earlier, some concern was expressed inthe trade that Zachery-treated turquoise might fadeover time. After exposure for 164 hours in a solarsimulator, however, the three treated “EmeraldValley” cabochon halves did not show any fading orother change of appearance when compared to thecontrol samples.

Gemological Properties. The samples ranged fromblue through greenish blue to green (again, see table1). The vast majority were the typical greenish bluecolor associated with turquoise. However, all of thesamples labeled “Emerald Valley” were whitishgreen to green, as were two samples from NevadaFox. Most of the rough samples showed variousamounts of matrix admixture. On their natural,

unpolished surfaces, the rough samples alsorevealed the botryoidal morphology typical ofturquoise.

In general, the treated samples had darker, moresaturated colors than their untreated counterparts.These colors are slightly unnatural in appearance andcan be used as an indication of treatment, eventhough the difference is subtle and would requiresome experience to discern. Of the four SleepingBeauty slabs cut from the same piece of rough, theone that was not color treated remained the samecolor as the untreated slab, whereas the surfaces ofthe two color-treated samples were darker and slight-ly more saturated than the underlying material.

To determine if there was a visible penetrationof color in the treated material, we sawed in half(and polished the sawn edges) of the four SleepingBeauty cabochons of known treatment type. Thecolor-treated cabochons showed a layer of darkercolor that was subtle but clearly visible (figure 6).The penetration depth ranged from approximately0.2 to 0.5 mm in these specimens.

For all samples—both untreated and treated—the refractive index ranged from 1.60 to 1.62 (spotmethod). The specific gravity ranged from 2.61 to2.74. These values are well within those reportedfor natural, untreated turquoise.

When examined with the hand spectroscope, allsamples—again, both treated and untreated—showed the band at about 430 nm that is character-istic of turquoise. In addition, all samples lumi-nesced a weak to moderate whitish blue to long-wave UV radiation and were inert to short-waveUV. None of the samples, whether natural orZachery treated, showed any response to the ther-mal reaction tester.

When viewed with the gemological microscope,all samples revealed a typical turquoise structurewith minor cavities and occasional pyrite and cal-cite inclusions. The treated samples did not reveal

Figure 5. Cabochons were fashioned from the treated and untreated rough photographed in figure 3 so that wecould compare the cuttability of the material. In each photo, the half fashioned from the treated piece of roughis shown on the right. Note especially the distinct improvement in luster in the treated stones, with the mostpronounced difference seen in the lower-quality material (B and C). Photos by Maha DeMaggio.

A CB


any of the characteristics that are common toturquoise treated by more traditional methods (suchas evidence of filler materials in surface-reachingfractures and cavities). We did not observe fillers inany of the Zachery-treated samples we examined.

In fact, there was only one distinctive differencevisible in any of the treated samples—concentra-tions of color along fractures—and it was only visi-ble in some of them. This was best illustrated in thetreated slabs from Sleeping Beauty that were cutfrom the same piece of rough and then processeddifferently. We did not see any color concentrationsalong fractures in the untreated slab or two of thetreated slabs. However, the slab that was first treat-ed all the way through and then surface treated toimprove its color showed distinct concentrations ofdark blue along fractures (figure 7). The color con-centrations were not confined to the fracture itself,but rather they also penetrated the turquoise oneither side of the break. This is an important obser-vation, since low-quality turquoise that is impreg-nated and dyed will often show concentrations ofcolor along fractures, but those concentrations con-sist of a colored filler material and are confined tothe fracture itself (figure 8). Either type of color con-centration is unnatural and, in our experience, doesnot occur in untreated turquoise.

Infrared Spectroscopy. Reflectance infrared spec-troscopy of natural and treated samples in the mid-infrared range produced similar spectra for bothgroups. Both showed major peaks at approximately1125, 1050, and 1000 cm−1, which represent vibra-tions of the PO4 units; they did not show the peaksexpected for polymer impregnation or organic com-pounds (for details, see Dontenville et al., 1986).These spectra also confirm that the samples testedwere indeed natural, and not synthetic turquoise.The width of the peak, which was similar for boththe untreated and Zachery-treated turquoise,

demonstrates that the crystallite size is within thesame range for both products (see Fritsch andStockton, 1987).

Energy-Dispersive X-ray Fluorescence Spectrometry.EDXRF analyses of all the untreated and treatedsamples demonstrated, as expected, the presence ofall the major constituents of turquoise[CuAl6(PO4)4(OH)8 •5H2O] that could be detectedwith our instruments (figure 9): aluminum (Al),phosphorus (P), and copper (Cu). Iron (Fe), a com-mon impurity in turquoise, was also detected in allsamples. The height of the Fe peak correlated to thegreen component of the color (in pyrite- and iron-oxide-free samples); that is, the green samplesshowed the most intense Fe peaks. This is consis-tent with the report by Cervelle et al. (1985) thatFe3+ produces the yellow component of greenturquoise. Sulfur (S) was occasionally detected; itssignal was stronger in pieces with pyrite (FeS) inclu-sions. Traces of the common transition elementstitanium, chromium, and vanadium were also pre-

Figure 6. This cross section of a cabochon that wassurface treated to improve color shows a narrowrim of more saturated color. The depth of this rimranged from 0.2 to 0.5 mm in the samples weexamined. Photomicrograph by Shane F. McClure;magnified 14×.

Figure 7. Blue color concentrations alongfractures were seen in some of the color-treated samples. In these two slabsshown in figure 4, the sample that wastreated but not color enhanced (left)shows no change in coloration along thefracture. However, the same fracture inthe adjacent slab, which was colorenhanced, shows an obvious color con-centration (right). Photomicrographs byShane F. McClure; magnified 10×.


sent in some samples (both natural and treated). Asmall calcium (Ca) signal was present in all the nat-ural, untreated samples; this Ca peak was some-times accompanied by a separate potassium (K)peak, which was always smaller.

In general, the EDXRF spectra of the treated anduntreated samples were similar, with one importantexception: The potassium peak was much strongerin most of the treated samples than in the untreatedones, when this peak was compared to that of anelement that is intrinsic to turquoise (such as phos-phorus; figure 10). Although the height of the potas-sium peak varied from one treated piece to the next,in the vast majority of instances the amount ofpotassium in the treated turquoise was significantlygreater than that recorded in the untreated samples.

EDXRF analyses of the four slabs cut from thesame piece of Sleeping Beauty rough gave particu-larly interesting results in this regard. As originallyrecorded, the potassium contents of the untreatedsample as well as the two samples that had beencolor treated were strong when compared to thephosphorus peak. Yet the slab that had been treatedwithout changing its color did not show elevatedpotassium. Closer inspection of the untreated sam-ple revealed a cavity in the center of the slab, whichmust have contained some potassium-bearing com-pound. When the untreated sample was analyzed inan area away from the cavity, the potassium con-tent was much smaller. Electron microprobe analy-ses of these four slabs were consistent with the laterEDXRF results. In addition, systematic variations inthe total wt.% oxides measured by microprobeanalysis in these four slabs indicated a decrease inporosity with increasing intensity of treatment.

EDXRF analyses were also performed on the fourSleeping Beauty cabochons that were cut in half,with one half treated for a specific result and theother half left untreated. As was the case with theslabs, the two stones that were color treated showedelevated potassium, and the two cabochons that

were treated without producing any effect on theircolor did not.

Because the three non-color-treated samplesdescribed above (the slab and the two cabochons)lacked elevated potassium contents, we decided totest some additional samples that we knew weresimilarly treated (i.e., for durability only, not forcolor) to determine if the increase in potassiumoccurred only in color-treated stones. Mr. Foutzloaned us 13 samples of irregular slabs from China,Mexico, and Arizona that he had treated specificallyfor durability/porosity but not for color. These irreg-ular slabs ranged from green to blue to very lightblue (a color the turquoise trade sometimes calls“white” turquoise) and had various amounts ofmatrix present. We specifically requested specimensof varying qualities and localities different fromthose of the three stones described earlier, whichwere all high-quality material from the SleepingBeauty mine. Of these 13 treated samples, 10showed significantly elevated potassium levels. Theother three showed much smaller K peaks, butthese peaks were still slightly stronger than those inthe untreated turquoise we have tested. Theseresults suggest that the porosity of the startingmaterial helps determine whether or not a piece oftreated turquoise will show elevated potassiumwith EDXRF. It was primarily the high-qualitytreated material that lacked elevated potassium lev-els, possibly because such material is less porous.

Three of the treated samples in table 1 (one highquality, and the other two medium quality) alsolacked the K peak in their EDXRF spectra.

X-Ray Diffraction. Analyses of the one untreatedand two of the treated Sleeping Beauty slabsrevealed no significant differences among the threesamples. This proves that no new minerals (otherthan, possibly, turquoise) were precipitated in thetreated turquoise, and the cell dimensions remainedunchanged.

Figure 8. Color concentrations inZachery-treated material look verydifferent from those seen in turquoiseimpregnated with colored polymers.The color concentrations in the blue-polymer-filled stone (left) are restrict-ed to the fractures. In the Zachery-treated stone (right) the color concen-trations appear to diffuse into thestone adjacent to the fractures.Photomicrographs by Shane F.McClure; magnified 35×.


Oxalic Acid. Mr. Foutz (pers. comm., 1998) told usabout a simple—but destructive—test that may dis-tinguish untreated from Zachery-treated turquoise.A small amount of oxalic acid solution is applied tothe sample; if the material has been Zachery treat-ed, a white skin usually will form on the surface.Mr. Foutz noted that this test works best on stonesthat have received color treatment and may notshow on stones that have been treated for durabili-ty/porosity only.

To investigate this, we prepared a 20% solutionof oxalic acid, into which we immersed one half ofeach of the three Sleeping Beauty cabochons treatedby the different methods. We also tested an untreat-

Figure 9. The EDXRF spectra for untreatedturquoise from various deposits were very similar;those shown here (left) are from the Nevada Smithmine (top) and the Sleeping Beauty mine (bottom).A small potassium peak is sometimes present inthe untreated material, but it is always smallerthan the calcium (Ca) peak. In contrast, theZachery-treated turquoise (right) usually showspotassium peaks, which are much higher than inthe untreated turquoise. The highest and lowestpotassium peaks that we detected in the treatedmaterial are shown at the top and bottom, respec-tively. Note: The shaded peaks are artifacts of theinstrumentation, and should be ignored.

Figure 10. These EDXRF spectra of the “EmeraldValley” samples shown in figure 3 demonstrate thepotassium enrichment in the treated halves (redline) compared to their untreated counterparts(black line). To facilitate comparison, the spectrahave been normalized according to the height oftheir phosphorus (P) peaks. For the treated sam-ples, the potassium (K) peak is small in the high-quality sample (A), and becomes progressivelylarger in the medium- (B) and low-quality (C) sam-ples. Note: The shaded peaks are artifacts of theinstrumentation, and should be ignored.


ed turquoise bead. For comparison purposes, weretained the other half of each cabochon and setaside another untreated bead of like color. After thestones had been in the solution for four hours, werinsed them off and allowed them to dry. Theuntreated bead showed no apparent change, and thestone that was treated throughout but not colortreated showed only a very slight whitishness.However, the stone that was treated throughoutand then color treated showed a definite lighteningof the blue color, and the stone that was only colortreated showed a dramatic change to pale blue (fig-ure 11). The porosity of all of the treated stones wasalso increased, proportional to the amount of visiblereaction to the acid. This was evidenced by the factthat the stones were now sticky to the touch. Theseresults are consistent with the information wereceived from Mr. Foutz. Microprobe analyses per-formed on one of the color-treated Sleeping Beautycabochons revealed that the enriched potassium atthe surface of the treated control half was absentfrom the half that was immersed in oxalic acid.They also confirmed that the immersed halfshowed an increase in porosity.

We performed another variation of this test byplacing a small drop of solution on several polishedslabs of treated turquoise. Minutes to hours wererequired for a reaction, and the acid left a mark thatwas considerably larger than the original spot ofacid applied because the liquid spread on the surfaceof the sample. Note that it is very difficult to per-form this test on curved surfaces, since the acidruns off before it has time to react with theturquoise. The white film that forms as a result ofthis procedure does not wipe off, and repolishing isrequired to return the stone to its original condition.Therefore, this test is destructive and should beused only with that limitation in mind.

DISCUSSION Identification by Gemological Tests. Zachery-treat-ed turquoise cannot be identified using classicalgemological methods. Its gemological propertiescompletely overlap those of natural turquoise.

The only gemological clues to the presence ofthis treatment are visual in nature and quite subtle.These include a slightly unnatural color (in thosestones that have been color treated) and a very high-quality polish. These clues are not proof of treat-ment, but they are indications that the averagegemologist might see in the course of a visual exam-ination. The presence of blue color concentrations

along fractures and into the adjacent turquoise isanother indication of Zachery treatment.

Identification by Advanced Testing. The mid-infrared spectra of untreated and Zachery-treatedturquoise showed no significant differences. Themost effective method of identifying Zachery-treat-ed turquoise is chemical analysis. Specifically,EDXRF revealed that the vast majority of theZachery-treated samples in this study contained sig-nificantly more potassium than natural, untreatedturquoise (again, see figure 10). These results con-firm observations made by the senior author (EF)after examining the original samples in 1990. Onlysix of the 55 Zachery-treated stones tested byEDXRF (including the 13 samples not shown intable 1 because they were not fully characterized)did not show a higher potassium content than thatseen in the untreated turquoise. We know from Mr.Foutz that three of these exceptions were treatedwithout improving their color. We do not know theintended effect of the treatment on the other threesamples. What is most important is that all thestones that revealed a high potassium content wereindeed Zachery treated.

Porosity and the Treatment Process. In his 1998 let-ter to the authors, Mr. Zachery stated that the treat-ed material “has not been impregnated with anywax, oil or lacquer.” Our studies support this state-ment. However, this does not exclude the possibili-ty that the treatment might be adding other compo-nents, which affect the porosity of the turquoise.

To understand how the filling of pores in a min-eral can affect its appearance, it is necessary tounderstand how light reflects off materials of differ-ing porosities. The visual appearance of porosity inmaterials such as turquoise is equivalent to that of amaterial containing small bubbles of air (of muchlower R.I.) scattering light. If the voids are largerthan the wavelength of visible light (i.e., a micron ormore on average), then the white light that is scat-tered will recombine, giving a white, cloudy, ormilky cast to the stone (Fritsch and Rossman,1988). This is indeed what we observe in all natural,untreated turquoise. The same phenomenon givesrise to the white color in milky quartz (scattering bymicroscopic fluid inclusions). Even if the material isstrongly colored, scattering will produce a lightercolor. Hence, a dark brown beer has a very light-col-ored foam, because the myriad microscopic air bub-bles scatter light efficiently, and the walls of the


bubbles are very thin. Conversely, if the voids arefilled, a significantly darker and more saturatedcolor will be observed. A similar phenomenon isseen when a piece of colored fabric is partiallyimmersed in water: The wet area becomes muchdarker and more saturated than the dry area,because the voids in the weave (its “porosity”) arefilled with water, thus considerably reducing thelight scattering. This is what we believe we are see-ing in Zachery-treated turquoise, and what isknown to happen in polymer-impregnatedturquoise.

One scenario that would be consistent with ourobservations is that turquoise is being grown in situwithin the porous areas during treatment, withpotassium being an aid to or by-product of the pro-cess. Alternately, the treatment may use the naturalporosity of untreated turquoise to introduce a sub-stance that helps make the material more cohesive.These scenarios would reduce the porosity of theturquoise and thus might improve the color insome specimens, much in the same way that thefilling of porous chalky turquoise with polymersimproves its color. These theories are best support-ed by the fact that the treated turquoise no longeraccepts contaminants such as oils, and that thequality of the polish is improved.

The lack of potassium in some treated samplesmay be due to the low porosity of the starting mate-rial. If the turquoise has little or no porosity beforetreatment, then it will be more difficult to intro-duce a foreign substance. Hence, even if such apiece has undergone the full treatment process, itmay not show the presence of potassium.

Another explanation is that turquoise that isnonporous or only slightly porous will not allow thepotassium to penetrate until the treatment is con-centrated enough to improve the stone’s color. Thiswould be consistent with the fact that three of thestones that did not show an increased potassiumcontent were known to have been treated withoutimproving their color. These stones were all high-quality material and demonstrated the reducedporosity characteristic of this treatment.

Gemological Nomenclature. This type of treatmentpresents some nomenclature problems for gemolo-gists. In the colored stone trade, treatments thataffect color are often perceived more negativelythan those that affect clarity or other characteris-tics. The problem with material treated by theZachery process is that, while in the vast majority

of cases we can tell by chemical analysis that astone has been treated, at this time there is nodefinitive way to determine whether its color hasbeen affected. One can usually assume that stonesthat show blue concentrations in and near fractureshave been color treated, but not all of the turquoisethat has been color treated by the Zachery processshows these concentrations.

Mr. Foutz sells his material as “enhanced”turquoise, to differentiate it from treated materialthat is referred to as “stabilized.” Unfortunately, asdiscussed above, we do not know exactly what ishappening to the turquoise when it is treated bythis process. In fact, Mr. Foutz admits that he andMr. Zachery do not know the exact mechanismthat is taking place. This creates a nomenclatureproblem for gemological laboratories, where concisedescriptions of treatments are essential. Until moreis known about the process involved, the GIA GemTrade Laboratory will continue to call this material“Treated Natural Turquoise.”

CONCLUSIONZachery-treated turquoise cannot be detected bystandard gemological techniques, although a slight-ly unnatural color and blue color concentrations inand around fractures are indications. Bleaching after

Figure 11. An oxalic acid solution can be used todetect some of the Zachery-treated turquoise. Foreach pair, the sample on the right was immersedin oxalic acid for four hours. Shown clockwisefrom the lower left, the samples are: untreated(beads); treated throughout and left natural color;treated throughout and then color treated; andcolor treated only. Photo by Maha DeMaggio.


exposure to oxalic acid may also indicate treatment,but this is a destructive test. On the basis of thelarge number of samples we tested from variouslocalities, we have demonstrated that the vastmajority of Zachery-treated turquoise can be identi-fied by relatively high potassium levels. However,chemical analysis requires access to advanced tech-nology such as EDXRF spectrometry or microprobeanalysis; such instrumentation is available in onlythe most sophisticated gemological laboratories.The presence of potassium as the only detectableadditive is unique among gem treatments.

Acknowledgments: The authors thank the late PatTroutman of the Hope Franklin company, Prescott,Arizona, for first bringing this material to their atten-tion. Special thanks go to Sterling Foutz([email protected]) of Sterling Products, Prescott,for providing numerous samples and valuable infor-mation. We are also grateful to Phil Owens, of theGIA Gem Trade Laboratory in Carlsbad, for hisassistance and information regarding the cutting andpolishing of this material; and to Shane Elen, of GIA

Research, for gathering EDXRF data. Dr. FrankHawthorne, at the University of Manitoba, kindlyprovided electron microprobe analyses and X-raydiffraction data.

This article is dedicated to the memory of the lateBob Kammerling, our friend and colleague.

REFERENCESBariand P., Poirot J.-P. (1985) Larousse des Pierres Précieuses.

Larousse, Paris, France, pp. 242–249.Branson O. (1975) Turquoise, the Gem of the Centuries. Treasure

Chest Publications, Santa Fe, NM.Cervelle B. (1985) Turquoises: les bonnes, les brutes et les

traitées. La Recherche, No. 163, pp. 244–247.Dontenville S., Calas G., Cervelle B. (1986) Etude spectro-

scopique des turquoises naturelles et traitées. Revue deGemmologie a.f.g., No. 85, pp. 8–10; No. 86, pp. 3–4.

Fritsch E. (1990) “Zacharia” treated turquoise. Internal GIAResearch memo, April 19, 1990.

Fritsch E., Stockton C.M. (1987) Infrared spectroscopy in gemidentification. Gems & Gemology, Vol. 23, No. 1, pp. 18–26.

Fritsch E., Rossman G.R. (1988) An update on color in gems. Part3: Colors caused by band gaps and physical phenomena.Gems & Gemology, Vol. 24, No. 2, pp. 81–102.

Liddicoat R.T. Jr. (1987) Handbook of Gem Identification, 12thed. Gemological Institute of America, Santa Monica, CA.

Russian Synthetic Rubies and Sapphires GEMS & GEMOLOGY Spring 1999 17

ydrothermal synthetic ruby of Russian produc-tion first appeared on the international marketin 1993 (Peretti and Smith, 1993, 1994).

Subsequently, in 1995, yellow, orange, blue-green, and bluesynthetic sapphires from Novosibirsk became available (fig-ure 1). Recently, these sapphires were described in detail(Peretti et al., 1997; Thomas et al., 1997). As those authorsreported, infrared and visible-range spectroscopy, as well astrace-element chemistry, are useful to separate these syn-thetic sapphires from their natural counterparts.Microscopic examination has also revealed features of diag-nostic value, such as copper-bearing particles and flake-likeaggregates, as well as various types of fluid and multi-phaseinclusions. However, the gemologist does not always haveaccess to sophisticated analytical equipment, and character-istic inclusions are not always present. Therefore theauthors decided to investigate the internal growth patternsof this material in an effort to identify distinctive character-istics that might be readily seen in most samples.

Growth patterns in hydrothermal synthetic emeralds,such as those of Russian production, generally are known togemologists (see Schmetzer, 1988), and irregular growth fea-tures in Russian hydrothermal synthetic rubies and sap-phires also have been mentioned briefly (Sechos, 1997;Thomas et al., 1997). However, these publications describedno specific orientation of the synthetic rubies and sapphiresduring examination for these features. In the experience ofthe present authors, the observation of growth features inunoriented samples is sufficient to identify only somehydrothermally grown samples; that is, only heavily dis-turbed, strongly roiled growth patterns can be observedwithout a specific orientation (figure 2; see also figure 16 inThomas et al., 1997, p. 200). These patterns can also be mis-taken for growth features seen in natural rubies and sap-phires. For oriented samples, however, a diagnostic growth

SOME DIAGNOSTIC FEATURES OFRUSSIAN HYDROTHERMAL SYNTHETIC

RUBIES AND SAPPHIRESBy Karl Schmetzer and Adolf Peretti

ABOUT THE AUTHORS

Dr. Schmetzer is a research scientist residing inPetershausen, near Munich, Germany. Dr.Peretti ([email protected]) is director ofGRS Gemresearch Swisslab AG, Lucerne,Switzerland.

Acknowledgments: The authors are grateful tothe following people for supplying some of thesamples used in this study: Fred Mouawad,Bangkok, Thailand; Christopher P. Smith andDr. Dietmar Schwarz, both of the GübelinGemmological Laboratory, Lucerne,Switzerland; Dr. James E. Shigley, GIAResearch, Carlsbad, California; and the SiberianGemological Center, the United Institute ofGeology, Geophysics and Mineralogy, and thejoint venture Tairus, all of Novosibirsk, Russia.


Most Russian hydrothermal synthetic rubiesand pink, orange, green, blue, and violet sap-phires—colored by chromium and/or nickel—reveal diagnostic zigzag or mosaic-like growthstructures associated with color zoning. Whenthe samples are properly oriented, these internalpatterns are easily recognized using a standardgemological microscope in conjunction withimmersion or fiber-optic illumination.Pleochroism is also useful to separate chromi-um-free blue-to-green synthetic sapphires fromtheir natural counterparts. Samples colored by acombination of chromium, nickel, and iron arealso described.

H

18 Russian Synthetic Rubies and Sapphires GEMS & GEMOLOGY Spring 1999

pattern can be seen in most of the synthetic rubies,as well as in a major portion of the synthetic sap-phires. Yet few of these growth patterns have beenillustrated to date. The present study gives adetailed description of the diagnostic growth fea-tures, and describes a method to position a sampleso that these features can be readily seen in com-mercially available Russian hydrothermal syntheticrubies and sapphires (i.e., those colored by chromi-um and/or nickel).

Differences in pleochroism have been men-tioned as being useful to separate some Tairusgreenish blue synthetic sapphires from their naturalcounterparts (Thomas et al., 1997). A pleochroismof weak to strong green-blue to blue was indicatedfor some of the Tairus samples; however, this is alsofound in basaltic-type bluish green to blue naturalsapphire (see, e.g., Schmetzer and Bank, 1980, 1981).Consequently, we also re-evaluated the applicabili-ty of pleochroism to the identification of syntheticRussian hydrothermal rubies and sapphires.

MATERIALS AND METHODSThe 83 samples studied were reportedly producedeither at the United Institute of Geology,Geophysics and Mineralogy, Novosibirsk, Russia,or at the hydrothermal growth facilities of TairusCo., also in Novosibirsk. Forty-two samples wereacquired between 1993 and 1996 by one of theauthors (AP) during various stays in Bangkok andNovosibirsk (see Peretti et al., 1997). Two addition-al synthetic rubies were purchased in 1998 at TairusCo., Bangkok, Thailand; and a collection of 17 sam-ples, loaned by C. P. Smith, contained hydrothermal

synthetic rubies and sapphires obtained from 1993to 1998 in Novosibirsk and Bangkok. A set of 22faceted samples from the GIA research collectionoriginated directly from Tairus Co., Novosibirsk; 18of these were used in the report by Thomas et al.(1997).

The samples included six complete syntheticruby (2) and synthetic sapphire (4) crystals grown ontabular seeds (see, e.g., figure 3), as well as two crys-tals that were grown on spherical (Verneuil) seedsspecifically for the study of crystal growth. Theeight crystals ranged from about 6 to 59 ct. Twenty-two of the samples were irregular pieces that hadbeen sawn from larger crystals, and 12 samples wereplates that had been polished on both sides. Most ofthese 34 irregular pieces and plates contained a por-tion of a colorless tabular seed. A polished windowwas prepared on about 15 of the crystal fragments(the largest of which was 41 ct) for microscopicexamination. The remaining 41 synthetic rubiesand sapphires of various colors were faceted andranged from 0.22 to 4.72 ct (see, e.g., figure 1).

To characterize the samples according to theircause of color and trace-element contents, weobtained ultraviolet-visible (UV-Vis) spectra forabout half the 41 synthetic rubies and pink sap-phires, and all the 42 synthetic sapphires, by meansof a Leitz-Unicam SP 800 UV-Vis spectrophotome-ter. We performed trace-element analysis by energy-dispersive X-ray fluorescence (EDXRF), using aTracor Northern TN 5000 system, for 32 samplesthat included each color variety and/or each type ofabsorption spectrum.

Figure 1. Russian crystal-growth laboratories arenow producing hydrothermal synthetic ruby aswell as sapphires in a range of colors. The blue-green sapphire in the center (9.2 × 7.0 mm) weighs2.65 ct. Photo by Maha DeMaggio.

Figure 2. If a hydrothermal synthetic sapphire orruby is not oriented in a specific direction when itis examined with magnification and fiber-opticillumination, as seen in this Russian synthetic sap-phire, the growth patterns are difficult to resolveand may mimic those seen occasionally in naturalcorundum. Magnified 40×.


To document a possible color change by gamma-irradiation, we exposed one intense blue-green syn-thetic sapphire to 60Co in a commercial irradiationfacility.

Morphological characteristics of the completecrystals were measured with a goniometer. Theexternal faces of the smaller sawn pieces, the pol-ished plates, and the internal growth patterns of all83 samples were examined with a Schneider hori-zontal (immersion) microscope with a speciallydesigned sample holder and specially designed eye-pieces (to measure angles: Schmetzer, 1986, andKiefert and Schmetzer, 1991; see also Smith, 1996).We also examined many of the samples with anEickhorst gemological microscope (without immer-sion) using fiber-optic illumination.

Most of the faceted samples were cut with theirtable facets at various oblique angles to the c-axis ofthe original crystal. Consequently, we determinedthe pleochroism of all the faceted samples in immer-sion with the following three-step procedure: (1)using crossed polarizers, we oriented the c-axis paral-lel to the direction of view by observation of the vari-ation in interference rings as the sample was rotated(see Kiefert and Schmetzer, 1991); (2) we rotated thesample through 90° about the vertical axis of thesample holder to orient the c-axis in the east-westdirection of the microscope, and then removed onepolarizer; and (3) we determined both pleochroic col-ors by rotating the remaining polarizer.

RESULTS AND DISCUSSION Characterization of Samples According to Color andCause of Color. On the basis of color, absorption

Figure 3. These three samples are representative ofthe Russian hydrothermal synthetic ruby and sap-phire crystals grown on tabular seeds. Two stan-dard seed orientations are used: The 31 × 13 mmsynthetic ruby on the bottom was grown with aseed parallel to a prism b {101

_0}, whereas the

orange synthetic sapphire (40 × 18 mm) and thesynthetic ruby in the inset (35 × 18 mm) weregrown with seeds parallel to a negative rhombohe-dron −r {011

_1}. The rough, uneven faces of two of

the crystals are oriented parallel to the seed; bycontrast, the crystal in the inset reveals alternatinghexagonal dipyramids n {224

_3}. Photo © GIA and

Tino Hammid; inset by M. Glas.

TABLE 1. Properties of Russian hydrothermal synthetic ruby and sapphire samples colored by chromium and/or nickel.

Color Cause of color Pleochroism || c-axis Pleochroism ⊥ c-axis Samplesa

Ruby and pink sapphire Cr3+ Yellowish red to orange Red to purplish red 15 pieces, 14 faceted,8 plates, 2 crystals,

2 crystals with sphericalseeds

Reddish orange to Cr3+, Ni3+ Light reddish yellow Intense reddish orange 5 facetedorange-pink sapphireOrange sapphire Cr3+, Ni3+ Light yellowish orange Intense orange 2 crystals, 1 facetedYellow sapphire Ni3+ Yellow Yellow 4 facetedGreen sapphire Ni2+, Ni3+ Yellowish orange Yellowish green 1 piece, 1 facetedBluish green sapphire Ni2+, Ni3+ Orange Green 2 facetedBlue-green sapphire Ni2+, Ni3+ Reddish orange Bluish green 1 piece, 2 facetedBlue sapphire Ni2+ Reddish violet Blue-green 1 plate, 3 facetedBlue-violet sapphire Ni2+, Cr3+ Reddish violet Blue 1 piece, 2 facetedBluish violet sapphire Ni2+, Cr3+ Violetish red Bluish violet 3 facetedViolet sapphire Ni2+, Cr3+ Violetish red Violet 1 faceted

a “Crystals” were complete, and grown on tabular seeds; rough “pieces” were sawn from crystals grown on tabular seeds; and thin “plates” were polished onboth sides.


spectroscopy, and trace-element analysis, we foundthat 71 of the 83 samples were colored predomi-nantly by chromium and/or nickel (table 1).Synthetic ruby and sapphires containing these ele-ments are now commercially produced by TairusCo. at Novosibirsk. Three of the remaining 12 sam-ples are described in Box A; these samples are col-ored by chromium, nickel, and iron. The remainingnine synthetic sapphires did not contain chromiumand/or nickel as color-causing trace elements.Therefore, these samples are not described here.

On the basis of their color, absorption spectra,and trace-element contents, we separated the 71commercially available samples into six color “vari-eties:” ruby–pink sapphire and reddish orange toorange, yellow, green to blue-green, blue, and blue-

violet to violet sapphire (again, see table 1).Although traces of iron were detected by EDXRF inthese samples, no Fe3+ absorption bands wereobserved. Consequently, the influence of iron ontheir color is negligible. EDXRF analyses revealedvarious amounts of chromium—but no nickel—inthe synthetic rubies and pink sapphires. In the yel-low, green, blue-green, and blue samples, traces ofnickel only were present as color-causing elements,whereas the blue-violet to violet and the orange toreddish orange synthetic sapphires contained tracesof both chromium and nickel. These chemical prop-erties are comparable to analytical data publishedby Thomas et al. (1997).

The absorption spectra were consistent with ourchemical data as well as with the interpretation of

The three synthetic corundum samples that werefound to contain a combination of chromium, nick-el, and iron consisted of two color-change syntheticsapphires (one rough and one faceted) and onebluish violet synthetic sapphire crystal.

Color-Change Samples. The seed in this crystalwas oriented differently from those in the crystalsfrom the main sample. This crystal showed anuneven face that was oriented perpendicular to alarge r face; consequently, the seed must have beencut perpendicular to r. The internal growth patternsof the faceted color-change sample indicate thesame seed orientation. Such a seed orientation hasnot been observed in other chromium- and/or nick-el-bearing Russian synthetic rubies or sapphires.

The color-change synthetic sapphires (figure A-1) were bluish green in day (or fluorescent) light andreddish violet in incandescent light. There was onlya weak change in these colors when the samples

BOX A: CHARACTERIZATION OF RUSSIAN HYDROTHERMAL

SYNTHETIC SAPPHIRES COLORED BY CHROMIUM, NICKEL, AND IRON

Figure A-1. These color-change synthetic sap-phires are colored byiron, chromium, andnickel. The facetedsample weighs 2.89 ct.Incandescent light;photo by M. Glas.

Figure A-2. The absorption spectrum of thiscolor-change hydrothermal synthetic sapphire(A) is very similar to the spectra (B and C) ofnatural color-change sapphires (in this case,from Mercaderes, Colombia). The syntheticsapphire reveals absorption bands of Fe3+,Cr 3+, and Ni2+, whereas the natural samplesare colored by Fe3+, Cr 3+, and Fe2+/Ti4+ pairs.The maximum caused by Cr 3+ and Ni2+ (A) isslightly shifted to higher wavelengths com-pared to the peak caused by Cr3+ and Fe2+/Ti4+

(B and C).


color causes by Thomas et al. (1997).* Our samplesare represented in a triangular diagram (figure 4),with basic colors caused predominantly by Cr3+

(rubies and pink sapphires), Ni3+ (yellow sapphires),and Ni2+ (blue sapphires). Intermediate syntheticsapphires colored by a combination of Cr3+ and Ni3+

(reddish orange to orange), Ni3+ and Ni2+ (green toblue-green), and Ni2+ and Cr3+ (blue-violet to violet)are arranged along the edges of the triangle. Thomaset al. (1997) described all samples of the Ni2+-Cr3+

series as greenish blue. However, we feel that sam-ples of this series are better described as blue, blue-violet, bluish violet, and violet (see figure 4 andtable 1). Intermediate samples with high chromiumand small Ni2+ contents, as well as samples withhigh amounts of Ni3+ and smaller Ni2+ contents,

were not observed in this study. An intense blue-green sample, however, turned intense yellowishgreen on γ-irradiation, which can be explained byconversion of part of the Ni2+ to Ni3+ (see Thomas etal., 1997).

For comparison, the natural counterparts ofthese synthetic rubies and sapphires are representedin another triangular diagram, with red to pink, yel-low, and blue to blue-violet in the three corners (fig-ure 5). This diagram is based on several thousandabsorption spectra recorded over a 25 year period byone of the authors (KS; mostly unpublished), from

were viewed parallel and perpendicular to the c-axis; that is, the colors were more intense parallelto c. These samples were found to be heavily iron-doped members of the chromium-nickel series.Their absorption spectra showed the dominant Ni2+

absorption band of blue synthetic sapphire superim-posed on minor Cr3+ and Fe3+ absorption bands (fig-ure A-2). With an absorption maximum in the yel-low and minima in the red and blue-green areas ofthe visible region, this spectrum reveals all the fea-tures associated with color change in a mineral (see,e.g., Schmetzer et al., 1980; Hänni, 1983). In naturalcolor-change sapphire (e.g., from Mercaderes,Colombia), this particular spectrum is caused byFe2+/Ti4+ absorption bands of blue sapphire super-imposed on Cr3+ and Fe3+ absorption bands (figureA-2; Schmetzer et al., 1980; see also Keller et al.,1985). In the authors’ experience, natural color-change samples from Sri Lanka and Tanzania(Umba and Tunduru-Songea areas) have almostidentical spectra.

The growth patterns of both samples (figure A-3) were comparable to the patterns seen in samples

of the chromium-nickel series (see, e.g., figures 13and 15), with subparallel striations and subgrainboundaries between microcrystals observed in both.However, unlike the color zoning seen in samplesgrown with one of the two standard seed orienta-tions (see, e.g., figure 8), these two samples revealedcolor zoning at an inclination to the dominant sub-grain boundaries.

Bluish Violet Sample. This crystal consists of a thinovergrowth of synthetic corundum over a tabularseed with an orientation parallel to −r. Typical irreg-ular surface features representing subindividualswere seen on both −r faces parallel to the seed plate.The pleochroic colors were violet perpendicular tothe c-axis, and yellow parallel to the c-axis. Thecolor of the crystal is a complex function of super-imposed Cr3+, Ni2+, and Fe3+ absorption bands; theabsorption spectrum is comparable to that of bluishviolet sapphires of the chromium-nickel series, withadditional subordinate Fe3+ absorption bands. Thissample was higher in chromium than the two color-change synthetic sapphires.

Figure A-3. The growth patterns in the color-change synthetic sapphires were similar tothose seen in the synthetic samples of theseries. Subparallel striations (left) wereobserved in the faceted sample at 70 × magni-fication. A zigzag pattern (right) was visible inthe crystal in a view parallel to the striationsat 50× magnification (both with immersion).

*The polarization of the spectrum of a greenish blue syntheticsapphire is erroneously reversed in figure 5A in the Thomas etal. (1997) article.


Figure 4. This triangular dia-gram shows the varieties ofRussian hydrothermal syn-thetic corundum that arecolored by chromium andnickel. The three basic chro-mophores are labeled at thecorners of the triangle, name-ly Cr3+ (red to pink), Ni3+

(yellow), and Ni 2+ (blue).Solid lines represent interme-diate color varieties observedby the authors, and brokenlines represent possible inter-mediate samples which werenot available for this investi-gation. Samples containingNi 3+and Ni2+ are green toblue-green; Cr 3+ with Ni3+

produces reddish orange toorange; and Ni2+ with Cr3+

causes blue-violet to violet.The yellow sample (1.09 ct)measures 7.1 × 5.2 mm, andthe blue sample (2.70 ct)measures 9.5 × 6.8 mm.Photos by M. Glas.

Figure 5. This triangular diagramshows the colors of natural ruby andsapphires that are equivalent to the

synthetic samples illustrated in figure4. The three principal causes of color in

natural corundum are Cr3+ (red topink), color centers or Fe3+ (yellow),

and Fe2+/Ti4+ ion pairs with or withoutadditional Fe2+/Fe3+ pairs (blue to blue-

violet). All intermediate colors areseen in natural corundum. Adapted

from Schmetzer and Bank (1981).

all major commercial sources of natural ruby andsapphire. There are two basic types of natural yel-low sapphire, which are caused predominantly bycolor centers or by Fe3+. Intermediate between redand yellow are chromium-bearing “padparadscha”sapphires. Blue to blue-violet natural sapphires arecolored predominantly by Fe2+/Ti4+ ion pairs (meta-morphic type) or by Fe2+/Ti4+ and Fe2+/Fe3+ ion pairs(basaltic type). Sapphires with intermediate colorsexist in the blue-to-yellow (Fe3+) and blue-to-red(Cr3+) series (again, see figure 5).

Pleochroism. The pleochroism of both natural andsynthetic corundum is identical for samples in theyellow-orange-red color range, including “padparad-


scha.” Likewise, natural and synthetic reddish vio-let to bluish violet sapphires cannot be separatedroutinely by their pleochroism. However, pleochro-ism is a diagnostic feature of blue-to-green naturaland synthetic sapphires.

Natural blue sapphire is predominantly coloredby ion pairs of Fe2+ and Ti4+, with additional influ-ence from Fe3+ or Fe2+/Fe3+ (or both) absorptions. Allnatural blue to blue-violet sapphires colored by theFe2+/Ti4+ ion pair reveal distinct pleochroism: lightblue or greenish blue, green, and yellowish greenparallel to the c-axis, and intense blue, bluish violet,or violet perpendicular to the c-axis (Schmetzer andBank, 1980, 1981; Schmetzer, 1987; Kiefert andSchmetzer, 1987).

The blue hydrothermal synthetic sapphires inthe chromium-nickel series are colored predomi-nantly by Ni2+. These sapphires revealed a distinctpleochroism of reddish violet parallel to the c-axisand blue-green perpendicular to the c-axis (figure6)—the opposite of that seen in natural blue sap-phire. Consequently, this difference in pleochro-ism is useful to separate natural and synthetic bluesapphire.

The pleochroism of the Ni2+- and Ni3+-bearingblue-green to green synthetic sapphires (table 1)also differs from that of natural blue-green, bluishgreen, or green sapphires. Natural samples of thisseries contain relatively high amounts of Fe3+

(again, see figure 5); their pleochroism is yellowishgreen, green, or bluish green parallel to the c-axisand bluish green to blue perpendicular to the c-axis(Schmetzer and Bank, 1980, 1981; Schmetzer, 1987;Kiefert and Schmetzer, 1987). Using the techniquesdescribed above, we observed in their hydrothermalsynthetic counterparts reddish orange to yellowishorange parallel to the c-axis and bluish green to yel-lowish green perpendicular to the c-axis (figure7).** Consequently, pleochroism is also useful todistinguish hydrothermal synthetic sapphires inthe blue-green to green series from their naturalcounterparts.

Orientation of Seeds and Morphology of the Rough.The morphology of the two rubies that were grownon spherical seeds is consistent with the descriptionin Thomas et al. (1997).

As reported by Thomas et al. (1997) for the Tairushydrothermal synthetic sapphires, the seed plates inthe samples we examined were cut fromCzochralski-grown colorless synthetic sapphire. Inthe complete crystals, the seed plates measured30–40 mm in their longest dimension. Examinationof these complete crystals, as well as of the sawnpieces, polished plates, and faceted stones that con-tained residual parts of the seed, revealed that theseed plates were cut in two different standard orien-tations: (1) parallel to the c-axis, that is, parallel to afirst-order hexagonal prism b {101

_0} (figure 8); and (2)

at an inclination of about 32° to the c-axis, that is,parallel to a negative rhombohedron −r {011

_1} (figure

9). Seed plates cut in the latter orientation were notmentioned by Thomas et al. (1997), but they wereseen in about half the samples we examined.

The crystals grown with seeds cut parallel to theprism b revealed two large rough, uneven faces (see,e.g., figure 10) parallel to the seed, and two elongat-ed faces each of the following forms: basal pinacoidc {0001}, positive rhombohedron r {101

_1}, and posi-

tive rhombohedron φ {101_4} (figure 11A). In addi-

tion, these samples showed six smaller second-orderhexagonal prism faces a {112

_0}. Occasionally, small-

er r faces and hexagonal dipyramids n {224_3} were

also observed (figure 11B).

Figure 6. The blue synthetic sap-phires showed diagnostic pleochro-

ism that is the opposite of that seenin natural blue sapphire. In the

Russian hydrothermal synthetics,we saw reddish violet parallel to thec-axis and blue-green perpendicular

to it. Immersion, polarized light,magnified 40×.

**Note that Thomas et al. (1997, p. 196) reported a strong vio-letish blue to blue-green pleochroism in the Ni2+/Ni3+-dopedsamples that they describe as blue-green. According to S. Z.Smirnov (pers. comm., 1999), the dichroism given in theThomas et al. (1997) article represents colors seen in daylight insamples that were not crystallographically oriented. These col-ors are not identical to those determined parallel and perpen-dicular to the c-axis for oriented samples (see also table 1 of thepresent article). Note also that a small color shift is alwaysobserved between daylight and incandescent light with theimmersion microscope (see the Materials and Methods section).


Most of the crystals grown with 30–40 mmseeds cut parallel to the negative rhombohedron −r{011–1} showed two large uneven faces parallel to −r,two relatively large, elongated faces parallel to apositive rhombohedron r, and striated, somewhatcurved faces parallel to the basal pinacoid c (figure11C). In some samples, another elongated positiverhombohedron φ was also present (figures 11C andD). Adjacent to the uneven −r faces were two largehexagonal dipyramids n; two smaller n faces weredeveloped adjacent to the positive rhombohedron r.In most cases, two smaller faces of the prism a wereobserved perpendicular to the seed plane (figure11D). Occasionally, smaller r, φ, and n faces alsowere present (figure 11C).

We do not know of any natural ruby or sapphirecrystals with this morphology, especially with dom-inant b or −r faces. Consequently, crystals with this

morphology can be easily recognized as synthetic.In those samples grown with seed plates 30–40

mm long, the two large uneven faces parallel to theseed dominated the morphology of the crystals (see,e.g., figures 3 and 11). In one relatively thick crystal,instead of an uneven face parallel to −r, alternatingn faces were seen (see figure 3, inset). Where smallerseeds (i.e., 10–15 mm long) were used for the crystalgrowth, no external faces parallel to the seed wereobserved (figure 9). Therefore, crystals grown onsmaller seed plates may not have either b or −rfaces; synthetic crystals with such a morphologycould be confused with natural ruby or sapphire.

Internal Growth Structures. Color Zoning. A differ-ence in color from one growth sector to another, orin subsequent growth regions, was observed insome of the polished plates (see, e.g., figure 9). A

Figure 8. This thin plate (approximately 1.2 mmthick) of a hydrothermal synthetic ruby crystalhas been cut perpendicular to the colorless seed(visible at the bottom of the photo) to show char-acteristic growth zoning. The seed is oriented par-allel to the c-axis. Three generations of syntheticruby are revealed by the irregular boundaries thatparallel the surface of the seed, which is orientedparallel to a hexagonal prism b {101

_0}. Numerous

subindividuals—long, thin microcrystals—arealso visible; color zoning is seen between differentgrowth sectors of adjacent subindividuals.Immersion, magnified 30×.

rnn

n -r

Figure 9. This 11.5 × 6.5 mm plate (0.8 mm thick)of a hydrothermal synthetic ruby, cut at an incli-nation of 30° to the optic axis, shows the relation-ship of the crystal faces to the seed. The colorlessseed is oriented parallel to a negative rhombohe-dron −r {011

_1}. The synthetic ruby shows three

hexagonal dipyramids n {224_3} and one face of the

positive rhombohedron r {101_1}. A color zoning is

also seen between subsequent growth regions.

Figure 7. The pleochroismobserved in the Ni 2+- and Ni3+-bearing blue-green to green syn-thetic sapphires also appears to bedistinctive: reddish orange parallelto the c-axis, and yellowish greenperpendicular to it. Immersion,polarized light, magnified 50×.


similar color distribution is frequently seen on amacroscopic scale in natural as well as flux-grownsynthetic ruby and sapphire crystals. In the roughand faceted Russian hydrothermal synthetic rubiesand sapphires, we did not observe any macroscopiccolor distribution in different growth sectors orregions that could be useful to distinguish thesesamples.

Growth Boundaries. Tairus hydrothermal syntheticcorundum is routinely grown in a single autoclaverun, rather than in several successive runs (S. Z.Smirnov, pers. comm., 1998). However, some of oursamples revealed one or more distinct growthplanes parallel to the seed (again, see figure 8). Theseplanes represent boundaries between layers of syn-thetic corundum and indicate that these specimensgrew in several intervals. They suggest that therewere “interruptions” during the formation of theseparticular crystals, probably due to unintentionalbrief fluctuations in the power supply of the growthfacility.

Specific boundaries were also noted in all eightfaceted samples (two synthetic rubies and six vari-ously colored synthetic sapphires) that containedparts of the seed (see, e.g., figure 12). In general,these boundaries were associated with tiny copper-bearing particles, as previously described by Perettiand Smith (1993) and Peretti et al. (1997). The cop-

Figure 10. The rough surface texture of this orangehydrothermal synthetic sapphire crystal is formed bya distinct microstructure consisting of numerouslong, thin microcrystals, as illustrated in figure 8.Magnified 20×.

Figure 11. The morphology of the synthetic ruby and sapphire crystals is controlled by the orientation oftheir seed plates. Crystals A and B were grown with tabular seeds cut parallel to a prism b {101

_0}. On

these crystals, uneven faces are developed parallel to b; also present are the basal pinacoid c {0001}, theprism a {112

_0}, positive rhombohedra r {101

_1} and φ {101

_4}, and (in some cases) the hexagonal dipyramid

n {224_3}. Crystals C and D were grown with tabular seeds cut parallel to a negative rhombohedron −r

{011_1}. Uneven faces are developed parallel to −r; also shown are the basal pinacoid c {0001}, the prism a

{112_0} (in D), positive rhombohedra r {101

_1} and φ {101

_4}, and the hexagonal dipyramid n {224

_3}.


per in these inclusions originates from the wiresused to mount the seed plates, from the seals of theautoclave, and/or from the buffers used during crys-tal growth (see also Thomas et al., 1997). In some ofthese faceted samples, the boundaries between seedand overgrowth were oriented parallel to a prismface; in the others, they were parallel to a rhombo-hedral face. Consequently, the two types of seed ori-entation in these faceted samples were consistentwith those found in the rough samples.

Subgrain Boundaries and Color Zoning. TheRussian hydrothermal synthetic corundum crystalsconsist of numerous long, thin microcrystals thatare observed at a specific inclination to the seedplate, depending on its orientation. The termina-tions of these microcrystals form the rough, uneven

surfaces that are parallel to the seed plate on thecrystals (again, see figures 8 and 10). This growthpattern has been described by Voitsekhovskii et al.(1970) for hydrothermally grown synthetic corun-dum as a “microblock” structure that consists of anassemblage of fine (0.05 to 0.5 mm in diameter)elongated crystals that are disoriented relative toone another by not more than 1–3 minutes of arc.

These long, thin microcrystals form a diagnosticgrowth pattern that is associated with a distincttype of fine-scale color zoning observable in immer-sion. In thin (1–2 mm) plates cut perpendicular tothe seed, the variable intensity in color betweengrowth sectors of adjacent subindividuals is clearlyvisible (figure 8). In thicker plates, or in faceted sam-ples, in the same orientation, only the boundariesbetween the differently colored growth sectors canbe seen, in the form of subparallel (i.e., not perfectlyparallel) striations (figure 13). The use of crossedpolarizers often can enhance the contrast betweengrowth sectors (figures 13 and 14).

An even more characteristic internal growth pat-tern is seen in a view parallel to these striations. Tofind the best—that is, most diagnostic—direction ofview in faceted samples, search first for the presenceof the subparallel striations, then turn the facetedstone to a direction in which the striations are paral-lel to the direction of view. Only in this orientationis it possible to see the zigzag or mosaic-like growthpattern that is most distinctive of this material (fig-ure 15). Although this growth pattern sometimesmay be seen without immersion (see Sechos, 1997),the use of an immersion liquid or at least the use ofplane polarized light in combination with fiber-optic illumination (if an immersion microscope isnot available) is strongly recommended.

When properly oriented, almost all of theintensely colored samples of the chromium-nickelseries revealed this zigzag or mosaic-like growthpattern. Depending on the diameter of the subindi-

Figure 12. A portion of the seed is present along thetable facet (flat lower surface) of this yellowhydrothermal synthetic sapphire. Adjacent to theseed are tiny copper-bearing particles. The faintstriations oriented nearly perpendicular to the seedrepresent subgrain boundaries between long, thinmicrocrystals within the larger crystal. (The areaaround the table facet appears green because ofdispersion.) Immersion, magnified 50×.

Figure 13. The subparallel stri-ations within this facetedhydrothermal synthetic ruby(left) are enhanced by the useof crossed polarizers (right).Immersion; magnified 40×(left) and 35× (right).


viduals that form the synthetic corundum crystal,the color zoning may vary from fine to coarse intexture. With training, however, the gemologist canrecognize the striations and zigzag or mosaic-likepatterns in synthetic rubies and sapphires that havesufficient color saturation, with the exception ofyellow synthetic sapphires colored by Ni3+ alone. Inonly one of the four yellow samples with no evi-dence of Cr3+ in the absorption spectrum did weobserve extremely weak striations (figure 12). Inaddition, no diagnostic growth pattern was found intwo light blue, almost colorless, samples in whichNi2+ was the predominant cause of color as provedby absorption spectroscopy and EDXRF analysis.

Although growth patterns associated with colorzoning are also observed frequently in natural rubiesand sapphires (figure 16), these patterns are very dif-ferent from those seen in the synthetic samples. Ingeneral, natural rubies and sapphires are not com-posed of numerous long, thin microcrystals withslightly different orientations. Thus, growth pat-terns in natural samples are mainly caused by colorzoning due to growth fluctuations within a singlecrystal. The mosaic-like pattern in hydrothermalsynthetic rubies and sapphires is strongly diagnos-tic, and no chemical or spectroscopic examinationis necessary when it is present. However, UV-Vis orinfrared spectroscopy in combination with trace-ele-ment analysis may be necessary to identify the yel-low synthetic sapphires, as well as extremely palesamples of other hues.

CONCLUSIONThe hydrothermally grown nickel- and/or chromi-um-doped Russian synthetic rubies and sapphiresexamined revealed an external morphology andinternal growth features that reflect their formationconditions. The identification of characteristicgrowth patterns is a relatively straightforwardmethod to distinguish most of these syntheticsfrom their natural counterparts. A horizontal micro-scope with immersion or a standard gemologicalmicroscope with fiber-optic illumination in combi-nation with polarizing filters is all that is needed tocarry out this investigation.

Figure 14. In this faceted blue-green synthetic sap-phire, as in the synthetic ruby in figure 13, one cansee striations representing oriented subgrainboundaries between the long, thin microcrystals.Immersion, crossed polarizers, magnified 70×.

Figure 15. When the facetedhydrothermal synthetic ruby andsapphire samples are oriented so

that the subparallel striations areparallel to the direction of view,distinctive zigzag (A and B) and

mosaic-like (C and D) growth pat-terns can be seen. All of these pho-

tomicrographs were taken withimmersion and polarized light. A

and B = synthetic ruby, magnified50× and 60×, respectively; C = pinksynthetic sapphire, magnified 40×;D = blue-green synthetic sapphire,

magnified 45×.

A

DC

B


The characteristic internal features of thesehydrothermal synthetic rubies and sapphires are: (1)subparallel striations; and (2) a distinct zigzag ormosaic-like growth structure, associated with colorzoning between different growth sectors of adjacentsubindividuals. The latter can be seen only whenthe sample is viewed in a direction parallel to thestriations. Only the yellow hydrothermal syntheticsapphires and extremely light blue samples did notshow any of these diagnostic internal growth char-acteristics. In the absence of other distinctive inclu-sions, such corundums will require additional test-ing by spectroscopic or analytical techniques suchas UV-visible absorption spectroscopy or EDXRF.

Pleochroism is also useful to identify somehydrothermal synthetic sapphires, particularly todistinguish chromium-free samples of the blue-to-green series from their natural counterparts. To per-form this test, the orientation of the optic axis in afaceted sample must first be determined.

Figure 16. Growth patterns are frequently seen innatural rubies and sapphires, as in this blue sap-phire from Andranondambo, Madagascar. Thispattern is not related to microstructures consist-ing of subindividuals that reveal color zoningbetween various growth sectors. In this case, thepattern consists of growth planes parallel to one rand two n faces. Adjacent growth sectors showchanges in size and color intensity. Immersion,magnified 50×.

REFERENCES Hänni H.A. (1983) Weitere Untersuchungen an einigen farbwech-

selnden Edelsteinen. Zeitschrift der DeutschenGemmologischen Gesellschaft, Vol. 32, No. 2/3, pp. 99–106.

Keller P.C., Koivula J.I., Jara G. (1985) Sapphire from theMercaderes-Río Maya area, Cauca, Colombia. Gems &Gemology, Vol. 21, No. 1, pp. 20–25.

Kiefert L., Schmetzer K. (1987) Blue and yellow sapphire fromKaduna Province, Nigeria. Journal of Gemmology, Vol. 20,No. 7/8, pp. 427–442.

Kiefert L., Schmetzer K. (1991) The microscopic determination ofstructural properties for the characterization of optical uniaxi-al natural and synthetic gemstones, part 1: General considera-tions and description of the methods. Journal of Gemmology,Vol. 22, No. 6, pp. 344–354.

Peretti A., Mullis J., Mouawad F., Guggenheim R. (1997)Inclusions in synthetic rubies and synthetic sapphires pro-duced by hydrothermal methods (TAIRUS, Novosibirsk,Russia). Journal of Gemmology, Vol. 25, No. 8, pp. 540–561.

Peretti A., Smith C.P. (1993) A new type of synthetic ruby on themarket: Offered as hydrothermal rubies from Novosibirsk.Australian Gemmologist, Vol. 18, No. 5, pp. 149–157.

Peretti A., Smith C.P. (1994) Letter to the Editor. Journal ofGemmology, Vol. 24, No. 1, pp. 61–63.

Schmetzer K. (1986) An improved sample holder and its use inthe distinction of natural and synthetic ruby as well as natu-ral and synthetic amethyst. Journal of Gemmology, Vol. 20,No. 1, pp. 20–33.

Schmetzer K. (1987) Zur Deutung der Farbursache blauer

Saphire—eine Diskussion. Neues Jahrbuch für MineralogieMonatshefte, Vol. 1987, No. 8, pp. 337–343.

Schmetzer K. (1988) Characterization of Russian hydrothermally-grown synthetic emeralds. Journal of Gemmology, Vol. 21,No. 3, pp. 145–164.

Schmetzer K., Bank H. (1980) Explanations of the absorptionspectra of natural and synthetic Fe- and Ti-containing corun-dums. Neues Jahrbuch für Mineralogie Abhandlungen, Vol.139, No. 2, pp. 216–225.

Schmetzer K., Bank H. (1981) The colour of natural corundum.Neues Jahrbuch für Mineralogie Monatshefte, Vol. 1981, No.2, pp. 59–68.

Schmetzer K., Bank H., Gübelin E. (1980) The alexandrite effectin minerals: Chrysoberyl, garnet, corundum, fluorite. NeuesJahrbuch für Mineralogie Abhandlungen, Vol. 138, No. 2, pp.147–164.

Sechos B. (1997) Identifying characteristics of hydrothermal syn-thetics. Australian Gemmologist, Vol. 19, No. 9, pp. 383–388.

Smith C.P. (1996) Introduction to analyzing internal growthstructures: Identification of the negative d plane in naturalruby. Gems & Gemology, Vol. 32, No. 3, pp. 170–184.

Thomas V.G., Mashkovtsev R.I., Smirnov S.Z., Maltsev V.S.(1997) Tairus hydrothermal synthetic sapphires doped withnickel and chromium. Gems & Gemology, Vol. 33, No. 3, pp.188–202.

Voitsekhovskii V.N., Nikitichev P.I., Smirnova Z.F., FurmakovaL.N. (1970) The microblock structure of hydrothermal crys-tals of corundum. Soviet Physics-Crystallography, Vol. 14,No. 5, pp. 733–735.

ABOUT THE AUTHORS

Mr. Elen ([email protected]) is a research gemologistat GIA Research, Carlsbad, California, and Dr.Fritsch is professor of physics at NantesUniversity, France.

The authors thank Sam Muhlmeister and DinoDeGhionno of the GIA Gem Trade Laboratory inCarlsbad for recording some of the EDXRF spec-tra and measuring gemological properties,respectively. Some of the samples were loanedby Dave Ward of Optimagem, San Luis Obispo,California; Michael Schramm of MichaelSchramm Imports, Boulder, Colorado; and ShaneF. McClure of the GIA Gem Trade Laboratory inCarlsbad. Dr. James E. Shigley of GIA Researchprovided constructive review of the manuscript.


30 Colorless Sapphire GEMS & GEMOLOGY Spring 1999

undreds of millions of carats of colorless syn-thetic sapphire are manufactured annually (allgrowth techniques combined), according to B.

Mudry of Djevahirdjian in Monthey, Switzerland, a leadingproducer of Verneuil synthetics (pers. comm., 1997). He esti-mates that about 5%–10% of this production (50–100 mil-lion carats) is used by the jewelry industry. Distinguishingnatural from synthetic colorless sapphire can often, but notalways, be accomplished by standard gemological testing(see below). However, this distinction is time consuming forlarge parcels, and it is difficult to impossible for melee-sizestones.

As first described more than 50 years ago (Wild andBiegel, 1947), natural colorless corundum can be separatedfrom flame-fusion synthetic colorless corundum (onlyVerneuil material was being produced at that time) by a dif-ference in transparency to short-wave ultraviolet (SWUV)radiation. The present study shows that the difference inSWUV transparency is a result of the difference in trace-ele-ment chemistry between natural and synthetic colorlesssapphire. We also demonstrate that SWUV transparencytesting is valid for Czochralski-grown synthetic colorlesssapphire, too. Therefore, this technique can help meet theneed for a simple, cost-effective method to mass screen thisrelatively inexpensive gem material.

BACKGROUNDNatural Colorless Sapphire. Colorless sapphire is a relativelypure form of aluminum oxide (Al2O3); it is often inaccurate-ly called “white sapphire.” Truly colorless sapphire is quiteuncommon, and most “colorless” sapphire is actually near-colorless, with traces of gray, yellow, brown, or blue. For thepurposes of this article, both colorless and near-colorlesssapphires will be referred to as “colorless.” The primarysource for this material has been, and remains, Sri Lanka.

Colorless sapphire was a common diamond simulant in

THE SEPARATION OFNATURAL FROM SYNTHETIC

COLORLESS SAPPHIREBy Shane Elen and Emmanuel Fritsch

Greater amounts of colorless sapphire—promot-ed primarily as diamond substitutes, but also asnatural gemstones—have been seen in the gemmarket during the past decade. In the absence ofinclusions or readily identifiable growth struc-tures, natural colorless sapphires can be separat-ed from their synthetic counterparts by theirtrace-element composition and short-waveultraviolet (SWUV) transparency. Energy-disper-sive X-ray fluorescence (EDXRF) analysis showshigher concentrations of trace elements (i.e., Fe,Ti, Ca, and Ga) in natural sapphires. Theseimpurities cause a reduction in SWUV trans-parency that can be detected by UV-visible spec-trophotometry (i.e., a total absorption in the UVregion below 280–300 nm, which is not seen intheir synthetic counterparts). This articledescribes a SWUV transparency tester that canrapidly identify parcels of colorless sapphires.

H

Colorless Sapphire GEMS & GEMOLOGY Spring 1999 31

the late 19th and early 20th centuries. In the early1970s, it first began to be used as an inexpensivestarting material for blue diffusion-treated sapphires(Kane et al., 1990). At around the same time, largequantities of colorless sapphire were heat treated toproduce yellow sapphire (Keller, 1982). The demandfor colorless sapphire increased significantly in thelate 1980s to early 1990s. This was a result of thegreater interest in blue diffusion-treated sapphires(Koivula et al., 1992), and colorless sapphire’sincreasing popularity in jewelry as an affordablealternative to diamond that could be used as melee,for tennis bracelets, or attractively set as a centerstone (Federman, 1994).

From 1993 through the first half of 1994, asteady demand for faceted colorless sapphire causedthe per-carat price to almost double, to US$70 percarat retail (“White sapphire sales up 172%,” 1994).Colorless sapphire jewelry (figure 1) has remained

popular (“Demand strong for white sapphires,”1996; M. Schramm, pers. comm., 1999), and hasfueled a market for synthetic colorless sapphire.

Synthetic Colorless Sapphire. Synthetic sapphirehas been produced by several growth techniques—in particular, flux, hydrothermal, flame-fusion, andCzochralski. However, because of manufacturingcosts, only two types of synthetic colorless sapphireare typically used as gems: flame-fusion (Verneuil,1904) and Czochralski “pulled” (Rubin and VanUitert, 1966). Early in the 20th century, flame-fusion synthetic colorless sapphire was the first syn-thetic gem material to be used as a diamond simu-lant (Nassau, 1980, p. 210). However, other synthet-ic gem materials have since surpassed colorless syn-thetic sapphire for this purpose because of the sig-nificantly lower refractive index and dispersion ofcorundum as compared to diamond.

Figure 1. Colorless sapphire con-tinues to be popular in jewelry,

especially for items such as tennisbracelets, but also as single

stones. The larger loose sapphireis 4.44 ct; the tennis bracelet con-tains a total weight of 4.33 ct; the

stone in the pendant is 8.56 ctand the sapphire in the ring is5.17 ct. Courtesy of Sapphire

Gallery, Philipsburg, Montana;photo © Harold & Erica Van Pelt.


Early synthetic sapphire produced by theVerneuil method often contained characteristicgrowth defects, such as striations and inclusions.These defects were unacceptable to the industrialmarket, which required extremely high (“optical”)quality synthetic sapphire. This led to the develop-ment of several new growth techniques, includingthe Czochralski method, which provides the high-est-quality single crystals for application in high-performance optics, sapphire semiconductor sub-strates, watches, and bearings (Nassau, 1980, p. 84).With these refinements, the characteristics thatwere previously used to separate natural from syn-thetic colorless sapphire became less obvious orwere eliminated, and the separation became consid-erably more difficult.

Review of Identification Techniques. In manyinstances, larger natural and synthetic colorless sap-phires (see, e.g., figure 2) can be separated by stan-dard gemological methods, such as microscopy (forthe identification of inclusions and the study ofgrowth structures visible with immersion) or UV-induced fluorescence (see below). However, smaller,

melee-size sapphires may not exhibit any character-istic inclusions or growth structures. R.I. and S.G.values are of no help, as they are identical for syn-thetic and natural stones (Liddicoat, 1987, p. 338).

Inclusions. Natural colorless sapphire contains thesame distinctive inclusions encountered in othercolor varieties of corundum: silk (fine, needle-likerutile or boehmite crystals), groups of rutile needlesintersecting in three directions at 60° to one anoth-er, zircon crystals surrounded by stress fractures,and well-defined “fingerprint” inclusions (figure 3)that consist of large networks of irregular fluid-filledcavities (Gübelin, 1942a and b, 1943; Kane, 1990).Two- and three-phase inclusions may be encoun-tered, as well as small crystals of spinel, uraninite,mica, pyrite, apatite, plagioclase, albite, anddolomite (Gübelin and Koivula, 1992; Schmetzerand Medenbach, 1988).

Colorless synthetic sapphire may exhibitgrowth-induced inclusions, typically small gas bub-bles (figure 4) or unmelted aluminum oxide parti-cles that occur individually, in strings, or in“clouds.” Gas bubbles may appear round or elongat-ed in a flask or tadpole shape (figure 5). The gas bub-bles may follow curved trajectories, allowing indi-rect observation of the curved striae that are other-wise invisible in colorless synthetic sapphire(Webster, 1994).

The irregularly shaped gas bubbles in syntheticcorundum could be mistaken for natural crystalinclusions with partially dissolved crystal faces.Occasionally, undissolved alumina may take on theappearance of a natural inclusion (Webster, 1994).As noted above, however, recent production tech-

Figure 2. These stones (0.32 ct to 3.08 ct) formedpart of the sample set used in this study. The col-orless sapphires on the left are synthetic, andthose on the right are natural. Photo © TinoHammid and GIA.

Figure 3. This “fingerprint” is actually a partiallyhealed fracture that exhibits a network of fluidinclusions; it is typical of natural colorless sapphire.Photomicrograph by Shane Elen; magnified 20×.


niques have almost entirely eliminated any charac-teristic inclusions, especially in the case ofCzochralski-grown synthetic corundum, which hasa strictly controlled growth environment.

Growth Structures. Immersion microscopy oftencan reveal internal growth features such as twin-ning or growth planes in corundum (Smith, 1996).The detection of Plato lines (Plato, 1952; figure 6)may identify Verneuil synthetic sapphire, whichdoes not always exhibit visible growth features.However, heat treatment of colorless flame-fusionsynthetic sapphire can make growth structureseven less apparent (Kammerling and Koivula, 1995),and we have never observed Plato lines in colorlesssynthetic sapphire grown by the Czochralskimethod. Furthermore, observation of growth struc-tures by immersion microscopy is not easy, andrequires some practice and understanding of crystal-lography.

Other Techniques. Energy-dispersive X-ray fluores-cence (EDXRF) spectrometry has been used for thechemical analysis of many different gemstones(Stern and Hänni, 1982), most recently for the sepa-ration of natural from synthetic ruby (Muhlmeisteret al., 1998). This semi-quantitative method used toidentify trace elements is particularly suited forgemstones such as colorless sapphire that may notexhibit inclusions or growth features. However, thetechnique requires expensive equipment and atrained operator, and it can test only one stone at atime.

In addition, natural and synthetic colorless sap-phires may exhibit different luminescence reactionsto UV radiation, cathode rays (electron beam), andX-rays (Anderson, 1990; Webster, 1994). Somegemologists have used UV luminescence (figure 7)

as a first step in separating batches of natural andsynthetic colorless sapphire: Stones that showchalky blue fluorescence to SWUV radiation areconsidered synthetic, but those that are inert couldbe either natural or synthetic, so they must be indi-vidually evaluated for other distinguishing charac-teristics (C. Carmona, pers. comm., 1999). However,because the intensity and color of the luminescenceis not consistent within each group (i.e., natural orsynthetic), luminescence is not a conclusive test.UV fluorescence or cathodoluminescence can beused for positive identification of colorless sapphireonly when characteristic growth features—such asthe angular growth zoning typical of natural stones

Figure 4. This group of gas bubbles is typical ofVerneuil synthetic sapphire. Photomicrograph byShane Elen; magnified 20×.

Figure 5. Although bubbles are uncommon inCzochralski-grown synthetic sapphires, this flask-shaped bubble was noted in one of the samples.Photomicrograph by Shane Elen; magnified 20×.

Figure 6. Plato lines may be observed in someVerneuil synthetic sapphire by viewing the sample(while it is immersed in methylene iodide) down theoptic axis with cross-polarized light. Photomicrographby Shane Elen; magnified 3×.


(figure 8) and the curved striae seen in synthetic sap-phires (figure 9)—are observed in the luminescencepatterns (Ponahlo, 1995; Kammerling et al., 1994).However, these features may be difficult to resolve,and magnification is frequently required.

More than 50 years ago, Wild and Biegel (1947)noted that natural and synthetic (Verneuil) colorlesssapphires differed in their transparency to short-wave UV radiation (again, see figure 7). Colorlesssynthetic corundum subsequently was found toexhibit transparency down to 224 nm, whereas col-orless natural corundum did not transmit below288 nm (Anderson and Payne, 1948). Theoretically,pure corundum is extremely transparent to short-wave UV because of its lack of impurities, andshould exhibit transparency down to 141 nm(French, 1990). As the level of impurities increases,the transparency to SWUV decreases. Althoughtransparency to SWUV may be decreased in stonesthat are heavily flawed, the colorless sapphire in thejewelry market is typically “eye clean.”

Yu and Healey (1980) applied these SWUV trans-parency differences to the separation of natural fromsynthetic colored corundum by means of an instru-ment called a phosphoroscope (Yu and Healey,1980). Its use for this purpose was limited, though,because colored synthetic corundum grown by thehydrothermal and flux methods often exhibitedSWUV absorption similar to that of natural corun-dum of comparable color. However, hydrothermal

and flux synthetic sapphires are not commerciallyavailable in colorless form, so we felt this techniquecould be useful for this separation.

MATERIALS AND METHODSA total of 112 colorless natural and synthetic sap-phires were characterized for this study. The 72 nat-ural samples were all faceted stones. They ranged

Figure 7. These six samples of natural(two on the far right) and synthetic (theCzochralski, the two in the middle;Verneuil, the two on the far left) sap-phires range from 0.78 to 2.75 ct. Theywere photographed with: (A) naturallight, (B) long-wave (LW) UV, (C) SWUV,and (D) in the SWUV transparency tester.Here, the synthetic samples are inert toLWUV, while the natural stones fluo-resce strongly yellow and orange; all thesynthetics fluoresce chalky blue toSWUV, but the natural stones are inert(the slight blue is due to reflection fromthe synthetics). Although these fluores-cence colors are typical, they are not con-sistent. The natural sapphires appeardark in the SWUV transparency testerbecause they absorb SWUV; the synthet-ic sapphires appear transparent. Photo Aby Maha DeMaggio; B–D by Shane Elen.

Figure 8. Although cathodoluminescence hasbeen used to reveal the characteristic straightgrowth bands in this natural colorless sapphire,these bands often can be observed with long-wave UV radiation or immersion microscopy.Photomicrograph by Shane Elen; magnified 3.5×.

A

DC

B


from 0.05 to 3.08 ct (2.0–8.4 mm) and originatedfrom Sri Lanka (66), Montana (1), Myanmar (1),Umba (1), and unknown sources (3). The syntheticsapphires consisted of 39 faceted samples (0.05–3.82ct, 2.0–9.5 mm) and one Verneuil-grown half boule(18.3 ct). The faceted synthetic sapphires includedfive flame-fusion and four Czochralski-grown sam-ples of known growth method. The 30 remainingfaceted synthetic samples were of unknown growthmethod. In addition, a single 8 mm round brillianthydrothermal colorless sapphire, which had beengrown for experimental purposes (Walter Barshai,pers. comm., 1997), was obtained from Tairus.

Of the 112 samples, the origin of 43 natural and22 synthetic faceted sapphires was confirmed by thepresence of characteristic inclusions or growthstructures observed using immersion microscopy orluminescence patterns. The remainder, generallythe smaller samples, exhibited no readily identifi-able features, so we accepted their origins as repre-sented by the reliable sources who supplied them.

We performed EDXRF analysis on 26 natural and19 synthetic samples of known origin with a TracorSpectrace 5000 X-ray system, using conditionsestablished for ruby analysis (see Muhlmeister et al.,1998). The purpose was twofold: to determine theusefulness of this technique to separate naturalfrom synthetic colorless sapphires, and to providemore information about how trace-element contentaffects the SWUV transparency. EDXRF analysiswas restricted to samples greater than 4 mm indiameter (approximately 0.3 ct) because of limita-tions imposed by the X-ray spot size of this equip-ment. Absorption spectra were obtained on all 112samples at room temperature with a Hitachi U4001spectrophotometer. Spectra for a few of the sampleswere collected from 250 nm to 750 nm; however,since data above 350 nm were not important forthis study, the remaining analyses were collected inthe UV range from 250 nm to 350 nm.

At the request of GIA, John Schnurer of PhysicsEngineering (Yellow Springs, Ohio) constructed aSWUV transparency instrument for the separationof natural from synthetic colorless sapphire (see BoxA). This instrument was based on the phosphoro-scope originally proposed by Yu and Healey (1980),and was constructed to provide a relatively simple,rapid, and cost-effective means of separation.

RESULTSChemical Composition. The natural sapphire sam-ples typically contained three or more trace ele-

ments (table 1; figure 10). The most significant wasiron (Fe); other elements recorded include titanium(Ti), calcium (Ca), and gallium (Ga). Vanadium (V)and chromium (Cr) were only detected at concen-trations just exceeding the detection limit of theinstrument. In general, no trace elements weredetected in the flame-fusion and Czochralski-grownsynthetic sapphires, although some samplesshowed very small amounts of Ca, Ti, and Fe—again, just exceeding the detection limit. The ironcontent was much greater in the natural sapphires(0.021–0.748 wt.% FeO) than in the synthetic sap-phires (up to 0.007 wt.% FeO; table 1). Qualitativeanalyses of the hydrothermal synthetic sapphireshowed significant amounts of Fe, Ga, cobalt (Co),and copper (Cu).

UV-Visible Spectrophotometry. Table 1 lists thewavelengths for the absorption cutoff of all the sam-ples analyzed by EDXRF. The natural colorless sap-phires typically showed a sharp absorption cutoff(i.e., complete absorption) below 280–300 nm,whereas the synthetic sapphires showed at mostonly a slight increase in absorption at around 250nm (see, e.g., figure 11). Note that three of the small(about 2 mm) colorless natural sapphires exhibited agentle increase in absorption, only slightly greaterthan that of the synthetic samples. The hydrother-mal synthetic sapphire exhibited a sharp absorptioncutoff at 280 nm, similar to natural sapphire.

SWUV Transparency. All 72 natural colorless sap-phires tested with the modified phosphoroscopewere opaque to SWUV, and all 40 flame-fusion andCzochralski-grown synthetics were transparent toSWUV. The single hydrothermal synthetic sapphire

Figure 9. Curved striae cannot be detected in colorlesssynthetic sapphires with standard visible lighting.However, some flame-fusion synthetic sapphires mayreveal this feature when exposed to SWUV radiation.Photomicrograph by Shane Elen; magnified 6×.


appeared opaque to SWUV. Some of the natural andsynthetic colorless sapphires acquired a slightbrown bodycolor as a result of their exposure toSWUV radiation. However, they returned to theiroriginal color after gentle heating under the bulb ofan incandescent desk lamp (Kammerling andMcClure, 1995).

DISCUSSIONThe higher concentrations of Fe, Ti, and Ga aid indistinguishing natural colorless sapphire from thesynthetic material. However, Fe is the dominantimpurity in natural colorless sapphire, where it ispresent in quantities typically 10 to 100 timesgreater than in its synthetic counterpart. The

The modified phosphoroscope (after Yu and Healey,1980; figures A-1 and A-2) we constructed for thisstudy consists of a glass plate that has been coatedwith a specially selected (proprietary) nontoxicphosphor, an overhead short-wave ultraviolet(SWUV) lamp, and a mirror positioned at a 45°angle below the glass plate. To reduce glare, theglass plate and mirror were placed inside a box,with the UV lamp mounted externally. The phos-phor-coated glass plate fluoresces when exposed toSWUV radiation (254 nm wavelength), creating abrightfield background.

For testing, we placed the samples table-downon the glass plate, one or more at a time, andobserved their transparency to SWUV in the mirror(figure A-3). Samples that are opaque to SWUV (i.e.,natural colorless sapphires) do not allow the radia-tion to pass through the stone to the phosphor-coat-ed plate, so there is no fluorescence where the stonecontacts the plate. Consequently, natural colorless

sapphires appear in the mirror as dark spots on abrightfield background. Conversely, samples thatare transparent to SWUV (such as melt-grownsynthetic colorless sapphires) allow UV radiationto pass through the stone to the phosphor-coatedplate. So the Verneuil- and Czochralski-grown syn-thetic colorless sapphires typically appear in the

Figure A-1. The SWUV transparency tester wasconstructed with simple materials: wood, a mir-

ror, a glass plate, and drafting vellum. A GemInstruments long-wave/short-wave UV lamp is

positioned over an opening at the top of the box.The samples are loaded into the upper part of

the unit through a door on the back. The num-ber of stones that can be tested depends on the

size of the fluorescent plate, which in turn isgoverned by the size and intensity of the SWUV

source; 100 melee-size stones can easily beaccommodated in this particular unit. Photo by

Maha DeMaggio.

BOX A: THE MODIFIED PHOSPHOROSCOPE

TO TEST SHORT-WAVE UV TRANSPARENCY


hydrothermal synthetic sapphire also contained Feand Ga, but it showed distinctive Co and Cu, too—neither of which was detected in any of the othersamples. The impurities detected in natural sap-phires (i.e., Fe, Ti, Ca, and Ga) are present essential-ly as transition metal ions, so their absorptionsaffect the ultraviolet transparency of the colorlesssapphires as measured by UV-visible spectropho-

tometry. The absorption is due to charge-transferprocesses, as well as to electronic transitions of iso-lated metal ions (McClure, 1962). Although all thetransition impurities induce absorption in the UV,iron is the primary cause because its absorptionis situated closer to the visible range and it is thedominant impurity in the natural material.Consequently, we plotted the relationship between

mirror as light spots, each of which is surroundedby a dark perimeter, imposed on the brightfieldbackground. The dark perimeter results from totalinternal reflection of the incident radiation as itpasses through the pavilion and strikes the bezelfacets. Therefore, it is important when testing thetransparency to observe only the response in thecentral part of the gem (Yu and Healey, 1980).

Following the lead provided by Yu and Healey(1980), one of the authors (SE) subsequently modi-fied this unit by replacing the proprietary phosphorwith a readily available translucent paper product(drafting vellum) that has all the necessary fluores-cence characteristics described above. This product

is more uniform than the proprietary phosphor, andit has brighter fluorescence characteristics; it is alsoinexpensive, clean, and nontoxic.

The modified phosphoroscope is simple to con-struct from inexpensive materials (about $30excluding the UV source). Those interested in con-structing a SWUV transparency tester shouldreview the limitations listed in the Discussion andnote the following recommendations: 1. Wear UV-protective glasses, and take precautions

not to expose unprotected skin to the SWUVradiation when the gems are sorted by hand.

2. Use known samples of natural and synthetic col-orless sapphires as standards for evaluating thereactions of the unknown stones. These “con-trol” samples should be 3 to 4 mm in diameterand free from abundant eye-visible inclusions.These may also be useful in selecting the appro-priate paper product for the luminescent screenwhen constructing a phosphoroscope.

Figure A-3. When viewed with the SWUVtransparency tester, the natural colorless sap-phires appear opaque, while the synthetic sam-ples are transparent, resulting in a bright spotin their central regions. These samples rangefrom 0.20 to 2.12 ct. Photo by Shane Elen.

Figure A-2. This schematic diagram of theSWUV transparency unit shows how theimage of the samples that have been illumi-nated by the UV lamp is reflected towardthe viewer. This also illustrates the appear-ance, observed in the mirror, of a naturalsapphire (right) as compared to its syntheticcounterpart (left).


TABLE 1. Semi-quantitative EDXRF data and UV absorption maxima for natural and synthetic colorless sapphires.

Oxide (wt.%)

no. (ct) CaO TiO2 V2O3 Cr2O3 FeO Ga2O3 (nm)

Natural1433 3.08 bdlb 0.006 bdl bdl 0.066 0.033 2921447c 2.10 0.061 0.030 bdl bdl 0.090 0.055 3002190 0.78 0.047 0.036 0.003 bdl 0.116 0.012 2922191 1.10 bdl 0.032 0.004 0.002 0.246 0.019 2982336 1.84 bdl 0.018 bdl bdl 0.117 0.003 2932348c 0.33 0.045 0.048 0.004 bdl 0.099 0.005 2932349c 0.19 0.069 0.049 bdl bdl 0.091 0.008 2902885 0.84 0.021 0.016 0.005 0.015 0.748 bdl 3102886 2.75 bdl 0.018 0.002 bdl 0.058 0.013 2904009 0.98 0.011 0.033 0.005 0.002 0.046 0.018 2904010 0.94 bdl 0.018 bdl bdl 0.079 0.005 2924011 0.59 0.029 0.031 bdl bdl 0.097 0.014 2904012 0.64 0.039 0.026 bdl bdl 0.122 0.011 2924013 0.76 0.016 0.022 0.003 0.006 0.096 0.014 2884014 0.75 bdl 0.013 bdl bdl 0.042 0.005 2844015 0.49 0.039 0.065 bdl bdl 0.048 0.016 2824016 0.42 0.041 0.028 bdl bdl 0.134 0.015 2914017 0.60 0.039 0.024 bdl bdl 0.021 0.014 2804018 0.33 0.048 0.043 0.004 bdl 0.091 0.011 2904019 0.33 0.029 0.028 bdl bdl 0.148 0.013 2924020 0.47 0.037 0.011 bdl bdl 0.179 0.013 2914021 0.42 0.060 0.010 bdl 0.003 0.108 0.012 2924022 0.32 0.066 0.017 bdl bdl 0.276 bdl 2964023 0.61 0.029 0.028 0.005 bdl 0.055 0.023 2884024 0.74 0.017 0.036 0.006 bdl 0.059 0.020 2914025 0.57 0.017 0.024 0.004 bdl 0.070 0.017 292Synthetic – Czochralski1635 0.89 0.022 bdl bdl bdl bdl bdl <2502334 0.91 0.017 bdl bdl bdl 0.003 bdl <2502352 0.98 0.027 0.009 bdl 0.003 0.004 bdl <2502353 1.01 0.024 bdl bdl 0.004 0.002 bdl <250Synthetic – Flame Fusion2335 2.81 bdl 0.005 bdl bdl bdl bdl <2502509 18.30 bdl bdl bdl bdl bdl bdl <2502887 2.44 0.016 0.009 bdl bdl 0.002 bdl <2502888 2.12 bdl 0.005 bdl bdl 0.002 bdl <2502889 2.49 bdl bdl bdl bdl bdl bdl <2502890 1.45 bdl bdl bdl 0.003 0.002 bdl <250Synthetic – Unspecified Method of Synthesis3931a 1.12 0.019 0.009 bdl bdl 0.003 bdl <2503931b 1.06 0.028 bdl bdl bdl 0.005 bdl <2503931c 0.99 0.015 bdl bdl bdl 0.002 bdl <2503931d 1.06 0.018 0.006 0.003 bdl 0.004 bdl <2503932a 0.66 bdl 0.006 bdl bdl 0.003 bdl <2503932b 0.64 0.024 bdl bdl bdl bdl bdl <2503932c 0.61 0.038 bdl bdl bdl 0.007 bdl <2503933 3.82 bdl bdl bdl bdl bdl bdl <2503934 1.10 0.014 bdl bdl bdl 0.003 bdl <250Detection Limitsd

0.3 0.019 0.009 0.004 0.004 0.004 0.0050.6 0.013 0.005 0.003 0.003 0.003 0.0031.0 0.009 0.005 0.003 0.002 0.002 0.002

aFor the synthetic samples, the absorption cutoff did not occur in the measured region above 250 nm, so we infer <250 nm.bbdl = below detection limit. MnO was looked for, but not detected in any of the samples.cThree samples also contained traces of Si, probably due to the presence of silicate inclusions: 1447 = 0.251 wt.% SiO2 ,2348 = 0.396 wt.% SiO2 , and 2349 = 0.428 wt.% SiO2 .

dDetection limits vary according to the weight of the sample. Calculated after Jenkins (1980).

Sample Weight UV abs.a


the Fe content and the UV absorption cutoff for nat-ural, flame-fusion, and Czochralski-grown syntheticcolorless sapphires (figure 12). The UV cutoff for allthe synthetic colorless sapphire samples can be seenat the intersection of the two axes, in the bottomleft corner of the plot (at 250 nm). In reality, thispoint only represents a slight increase in absorption,and the true cutoff occurs below 250 nm (i.e., belowthe wavelength range of the UV-Vis spectropho-tometer used for this study). Together, the EDXRFand the UV-Vis data illustrate the effect of trace-metal impurity concentrations on SWUV trans-parency; in particular, they show how the increasein iron content results in a decrease in SWUV trans-parency.

For the natural colorless sapphires, the sharpincrease (or cutoff) in SWUV absorption below

280–300 nm indicates complete absorption, andtherefore the point at which they become opaque toSWUV radiation. With the exception of thehydrothermal sample—which showed an absorp-tion cutoff at 280 nm, and therefore could not beseparated from natural sapphire using UV-Vis spec-trophotometry—the synthetic colorless sapphiresexhibited only a slight increase in SWUV absorptionaround 250 nm, which indicates that they are rela-tively transparent to SWUV. Although most of thesmall (2 mm) natural sapphires exhibited a sharpabsorption edge, a few did not. Certainly, some nat-ural colorless sapphires with low impurity concen-trations may be thin enough to allow some trans-mission of SWUV. In our sample, this appeared tobe the case particularly for the few melee stones

Figure 10. The EDXRF spectra typical of natural(A) and synthetic (B) colorless sapphires are dis-tinct. The natural sapphires exhibit more trace-ele-ment peaks (e.g., Fe, Ti, and Ga) than the syntheticsapphires.

Figure 11. These UV-Vis spectra are representativeof natural (A) and synthetic (B) colorless sap-phires. The natural samples show a sharp absorp-tion cutoff below 280–300 nm, whereas no cutoffis evident in this region for the synthetic sap-phires. Therefore, the natural sapphires wereopaque to SWUV radiation (at 254 nm), but thesynthetic samples were transparent.


that were cut with shallow pavilions. Nevertheless,these samples appeared opaque in the SWUV trans-parency tester, perhaps because of the lower “reso-lution” as compared to UV-Vis spectrophotometry.The hydrothermal colorless sapphire, however,exhibited the same opaque reaction to SWUV as thenatural samples, so it could not be effectivelyscreened out using the transparency tester.

On the basis of this study, it appears that theSWUV transparency tester is useful for separatingmost synthetic colorless sapphires currently on themarket (i.e., flame-fusion and Czochralski grown)from their natural counterparts. However, the fol-lowing limitations should be considered with regardto the SWUV transparency tester:1. It can be used only for unmounted gems, which

must be placed table down on the fluorescentscreen. Most mountings would screen the stonefrom the SWUV radiation, so the test resultswould not be meaningful.

2. Samples must be colorless (or near-colorless) andshould be at least 2 mm in diameter (based onUV-Vis spectrophotometry observations).

3. Hydrothermal synthetic sapphires cannot be sep-arated from natural sapphires by their SWUVtransparency. We do not know the reaction offlux-grown synthetic colorless sapphire, because

this has not been reported in the literature andwe were not able to obtain samples for thisstudy. However, because of the relatively highcost of manufacturing colorless synthetic sap-phire by either of these methods, it is unlikelythat this material will be encountered in themarketplace.

4. Some colorless sapphires, both natural and syn-thetic, may turn light brown after only brief expo-sure to SWUV radiation. This can be removed bygentle heating, such as with the bulb of an incan-descent desk lamp.

5. Heavily included or fractured material shouldnot be tested by this technique, as the inclusionsand/or fractures might affect the transparency ofthe material. Thus, a synthetic sapphire might bemisidentified as natural. The natural or syntheticorigin of heavily included material can be identi-fied by microscopy. This is generally not a prob-lem in today’s marketplace, as most of the syn-thetic colorless sapphire typically has very fewinclusions or visible fractures.

6. Although no such samples were encounteredduring this study, it is recommended that sam-ples with extremely strong fluorescence toSWUV not be tested by this method, as thebrightness of the fluorescence may influence the“apparent” opacity of the sample and result in anincorrect identification.

CONCLUSIONWith standard gemological techniques, only onecolorless sapphire at a time can be investigated. Inaddition, it is usually more difficult to identifysmaller stones, because they commonly do notshow any diagnostic features. The advanced tech-niques of EDXRF analysis and UV-Vis spectropho-tometry are also useful to separate most natural andsynthetic colorless sapphires. Our trace-elementdata illustrate that, in general, natural colorless sap-phires contain greater amounts of Fe, Ti, Ca, and Gathan do their synthetic counterparts. UV-Vis data fur-ther confirm that synthetic colorless sapphires aremore transparent to SWUV, because they exhibitonly a small increase in absorption at approximately250 nm. By comparison, natural colorless sapphirestypically exhibit total absorption below 280–300 nm.

However, EDXRF and UV-Vis spectrophotome-try are not readily available to most gemologists;nor are they economical for testing large quantities

Figure 12. Iron is the primary cause of absorptionin colorless sapphire. In general, the natural sap-phires analyzed in this study showed higher UVabsorption values with increasing iron content.The synthetic sapphires (19 represented here) allshowed very low iron contents (<0.007 wt.% FeO),and had UV cutoffs below the wavelength forSWUV radiation (~250 nm).


of stones. Our modified phosphoroscope provedmost effective for rapidly separating unmountedsamples of natural colorless sapphires (which areopaque to SWUV) from flame-fusion andCzochralski-grown synthetic colorless sapphires(which are transparent to SWUV), in sizes 2 mm orlarger. This simple gemological instrument can beinexpensively manufactured by the gemologist(again, see box A).

The SWUV transparency tester cannot be usedto separate natural sapphire from hydrothermal syn-thetic sapphire. However, the relatively high cost ofproducing colorless hydrothermal synthetic sap-phire (Walter Barshai, pers. comm., 1997) precludesits widespread use by the jewelry industry. If neces-sary, in most cases results from the SWUV trans-parency test can be confirmed with a gemologicalmicroscope.

REFERENCESAnderson B.W. (1990) Gem Testing, 10th ed. Rev. by E.A.

Jobbins, Butterworth & Co., London.Anderson B.W., Payne C.J. (1948) Absorption of visible and ultra-

violet light in natural and artificial corundum. TheGemmologist, Vol. 17, No. 207, pp. 243–247.

Demand strong for white sapphires (1996) Jewellery News Asia,No. 147, p. 84.

Federman D. (1994) Gem profile: Colorless sapphire—The greatwhite hope. Modern Jeweler, Vol. 93, No. 8, p. 44.

French R.H. (1990) Electronic band structure of Al2O3 with com-parison to AlON and AlN. Journal of the Ceramic Society,Vol. 73, No. 3, pp. 477–489.

Gübelin E.J. (1942a) Local peculiarities of sapphires. Gems &Gemology, Vol. 4, No. 3, pp. 34–39.

Gübelin E.J. (1942b) Local peculiarities of sapphires. Gems &Gemology, Vol. 4, No. 4, pp. 50–54.

Gübelin E.J. (1943) Local peculiarities of sapphires. Gems &Gemology, Vol. 4, No. 5, pp. 66–69.

Gübelin E.J., Koivula J.I. (1992) Photoatlas of Inclusions inGemstones. ABC Edition, Zurich, Switzerland.

Jenkins R. (1980) An Introduction to X-ray Spectrometry.Heyden, Philadelphia.

Kammerling R.C., DeGhionno D., Madison P. (1994) Gem TradeLab notes: Synthetic sapphire, another striae resolution tech-nique. Gems & Gemology, Vol. 30, No. 4, p. 270.

Kammerling R.C., Koivula J.I. (1995) Microscope lighting tech-niques for identifying melt-grown synthetics. Bangkok Gemsand Jewellery, Vol. 8, No. 7, pp. 88–94.

Kammerling R.C., McClure S.F. (1995) Gem Trade Lab notes:Synthetic sapphire, with color changed by UV radiation.Gems & Gemology, Vol. 31, No. 4, p. 271.

Kane R.E., Kammerling R.C., Koivula J.I, Shigley J.E., Fritsch E.(1990) The identification of blue diffusion-treated sapphires.Gems & Gemology, Vol. 26, No. 2, pp. 115–133.

Kane R.E. (1990) Gem Trade Lab notes: Sapphire—Large color-less. Gems & Gemology, Vol. 26, No. 3, pp. 225–226.

Keller P.C. (1982) The Chanthaburi-Trat gem field, Thailand.Gems & Gemology, Vol. 18, No. 4, pp. 186–196.

Koivula J.I., Kammerling R.C., Fritsch E. (1992) Gem news:Update on diffusion-treated sapphires. Gems & Gemology,

Vol. 28, No. 1, pp. 62–63.Liddicoat R.T. Jr. (1987) Handbook of Gem Identification, 12th

ed. Gemological Institute of America, Santa Monica, CA.McClure D.S. (1962) Optical spectra of transition-metal ions in

corundum. Journal of Chemical Physics, Vol. 36, No. 10, pp.2757–2779.

Muhlmeister S., Fritsch E., Shigley J.E., Devouard B., Laurs B.M.(1998) Separating natural and synthetic rubies on the basis oftrace element chemistry. Gems & Gemology, Vol. 34, No. 2,pp. 80–101.

Nassau K. (1980) Gems Made By Man. Chilton Book Co.,Radnor, PA.

Plato W. (1952) Oriented lines in synthetic corundum. Gems &Gemology, Vol. 7, No. 7, pp. 223–224.

Ponahlo J. (1995) Cathodoluminescence (CL) of gemstones andornamental stones. Analusis, Vol. 23, No. 1, pp. M30–M33.

Rubin J.J., Van Uitert L.G. (1966) Growth of sapphire and ruby bythe Czochralski technique. Materials Research Bulletin, Vol.1, pp. 211–214.

Schmetzer K., Medenbach O. (1988) Examination of three-phaseinclusions in colorless, yellow, and blue sapphires from SriLanka. Gems & Gemology, Vol. 24, No. 2, pp. 107–111.

Smith C.P. (1996) Introduction to analyzing internal growthstructures: Identification of the negative d plane in naturalruby. Gems & Gemology, Vol. 32, No. 3, pp. 170–184.

Stern W.B., Hänni H.A. (1982) Energy dispersive X-ray spectrom-etry: A non-destructive tool in gemmology. Journal ofGemmology, Vol. 18, No. 4, pp. 285–296.

Verneuil A. (1904) Memoire sur la reproduction du rubis parfusion. Annales de Chimie et de Physique, Ser. 8, No. 3, pp.20–48.

Webster R., Read P.G. (1994) Gems: Their Sources, Descriptionsand Identification, 5th ed. Butterworth-Heinemann GemBooks, Oxford, England, pp. 851, 931–933.

White sapphire sales up 172% (1994) Jewellery News Asia, No.120, pp. 92–94.

Wild G.O., Biegel H. (1947) Absorption of sapphire in the ultra-violet region. The Gemmologist, Vol. 16, No. 195, pp.279–280.

Yu R.M., Healey D. (1980) A phosphoroscope. Journal ofGemmology, Vol. 17, No. 4, p. 250.

42 Lab Notes GEMS & GEMOLOGY Spring 1999

ALEXANDRITE, With a Fish-Eye Effect

The West Coast Gem Trade Laboratoryrecently examined an oval mixed cutthat proved to be somewhat unusual.We identified the 2.93 ct stone as anatural alexandrite chrysoberyl; itappeared red-brown in incandescentlight, with a slight change of colortoward green in fluorescent light.

The identification as chrysoberylwas a relatively routine gemologicalmatter. However, while looking for abiaxial interference figure using asmall glass ball as a condensing lensand cross-polarized light, we noted afish-eye type of optical effect (figure1). Further examination of the stoneat different levels of magnificationrevealed a slightly milky cloud thatappeared to be composed of extremelyfine, submicroscopic particles.

The “fish-eye” could only beresolved in one particular direction

through the stone. Since this did notcoincide with an optic axis in thechrysoberyl, we did not suspect that itwas an odd interference phenomenon.

A similar optical effect—althoughnot as well defined—can be seenwhen cat’s-eye imitations made fromfiber-optic glass are examined with acondensing lens down the length oftheir fibers. If the submicroscopicinclusions in the natural chrysoberylare aligned in the same manner as theglass fibers in the imitation cat’s-eyes,the effect shown might be due to atunneling of light through the lens. Ifthis is indeed the cause of the opticaleffect shown in figure 1, then animportant question remains unan-swered: Why is cross-polarized lightnecessary to resolve the “fish-eye”?This is the first time that we haveseen such an optical effect in any nat-ural gemstone, and we have manyquestions. More detailed opticalexamination, probably including thestudy of a thin section under highmagnification, would be required tofind a more complete answer.

John I. Koivula

DIAMOND, with a Stellate Cloud

During the course of diamond qualitygrading, graders occasionally encounterunusual internal features. Eventhough such features can reduce theoverall clarity of their host, and con-sequently the assigned clarity grade,they can be interesting from a scien-tific standpoint. Such was the casewith the stellate “cloud” in a near-colorless round-brilliant-cut dia-mond shown in figure 2.

Because of the extent and translu-cency of this cloud, together with itsprominent position centered underthe table facet, the assigned claritygrade was understandably low.Nevertheless, the exotic hexagonal,star-like appearance of this cloud gavethe interior of the diamond an attrac-tive geometric character. While geo-metric clouds are occasionally seen indiamonds, most of these are cubic oroctahedral in shape; a hexagonal formis considerably rarer.

The cloud shown here appears tobe a phantom of either a hextetrahe-dron or hexoctahedron diamond crys-tal. In these two crystal forms, the tri-angular faces are divided into six sec-tions each. As shown in figure 3, thisdivision changes a four-sided tetrahe-dron to a 24-sided hextetrahedron, oran eight-sided octahedron to a 48-sided hexoctahedron.

When one looks perpendicular toa hextetrahedral or hexoctahedralcrystal face, one sees a form com-posed of six pie-shaped faces dividedby six interfacial ridges. This gives theappearance of a six-rayed star. A phan-tom formed in a diamond crystal withthis habit might show a stellate cloudin a cut stone. If the cutter orientedthe rough so that a hextetrahedral orhexoctahedral face was nearly parallelto the plane of the table facet, thenthe star-shaped cloud would be readi-ly visible through the table facet.

Editors’ note:The initials at the end of each itemidentify the editor(s) or contributing editor(s) whoprovided that item.Gems & Gemology, Vol. 35, No. 1, pp. 42–46©1999 Gemological Institute of America

Figure 1. This unusual fish-eyeeffect was noted in a 2.93 ctalexandrite when it wasobserved in one particular direc-tion through a condensing lenswith cross-polarized light.

Lab Notes GEMS & GEMOLOGY Spring 1999 43

The view of this cloud was dis-torted by reflection and refractionfrom the facets, so no firm conclusioncould be drawn as to which crystalform it represented. Suffice it to saythat this is a most unusual inclusionin a diamond, and in this writer’sopinion it is also quite beautiful.

John I. Koivula

EMERALD, The Case of the Invisible Filler

The use of organic compounds to fillsurface-reaching fractures and fracturesystems in emeralds has been a stan-dard practice for many years. It isoften said that virtually all emeraldstoday are “oiled,” and this generaliza-tion has been borne out by our experi-ence in the laboratory. The visibilityof surface-reaching fractures isreduced by replacing the air that nor-mally fills those openings with anorganic compound that has a refrac-tive index similar to that of the hostemerald. The treatment effectivelyreduces the mirror-like reflectivequality of any cracks and, in the pro-cess, improves the apparent colorintensity of the emerald. This methodof emerald enhancement was thor-oughly addressed by R. Ringsrud inthe Fall 1983 issue of Gems &Gemology (“The oil treatment ofemeralds in Bogotá, Colombia,” pp.149–156), and by R. Kammerling et al.

in the Summer 1991 issue (“Fracturefilling of emeralds: Opticon and tradi-tional ‘oils,’” pp. 70–85).

Occasionally, a surface-reachingfracture will intersect an includedcrystal or a larger primary fluid-inclu-sion chamber (a negative crystal),thereby exposing the inclusion to thesurface. Some of these mineral inclu-sions are very vulnerable to attack byacidic solutions. Most notable are car-bonates, such as calcite and dolomite.If exposed to the surface, these inclu-sions are often dissolved away, some-times during the cleaning processesused on rough crystals to remove ironoxide and hydroxide stains and otherundesirable debris. This leaves a com-paratively large void, with the shapeof the original mineral inclusion, inthe emerald. Fluid inclusions simplydrain out once they have been inter-sected by a fracture, also leaving a void.

When such voids are filled withan organic compound, the result isnever perfect. The refractive indicesof the fillers we have encountered todate do not exactly match that of thesurrounding emerald. (In particular,they cannot match both refractiveindices of an emerald.) The reliefcaused by this difference in refractiveindices makes the filled voids visible.Gas bubbles trapped in the filler with-in these relatively large voids oftenmake the treatment even more obvi-ous (see, e.g., figure 4). As a result,

such voids often provide the first indi-cations of treatment when the emer-ald is examined with magnification.

Therefore, staff members in theWest Coast lab were somewhat sur-prised to encounter a treated naturalemerald with a filled void that wasessentially invisible. This lack ofrelief indicated that the R.I. of thefilling agent was nearly identical tothose of the emerald—more so thanany other filler we had previouslyexamined. The only reason this voidwas recognized at all was because itcontained three gas bubbles. As canbe seen in figure 5, the bubblesappear to be enclosed within theemerald itself; the chamber surround-ing them is virtually invisible. Noform of microscopic manipulation orcreative illumination, including anattempt at the Becke line test, ade-quately resolved the complete out-line of the void. Nor did we see anyflash-effect colors in the “invisible”fractures that must have been inter-secting it. The refractive index of theemerald was 1.576–1.581, so the fillermust have had an R.I. between thosetwo readings.

Although there is no doubt that afiller was present, the combined limi-tations of nondestructive testing andthe short time available for examina-tion prevented us from determining

Figure 2. The hexagonal star-shaped cloud in this diamondappears to represent a phantomwith a rare crystal form. The riblike extensions possibly fol-low previous growth steps.Magnified 10×.

Figure 3. These line drawingsillustrate two rare forms foundamong isometric crystals suchas diamond. The hextetrahedronat left has 24 faces, formed bydividing each of the four trian-gular faces of a tetrahedron intosix parts. The hexoctahedron atright exhibits 48 faces.

Figure 4. Note the prominent gasbubble and yellowish liquid fill-ing in this rhombohedral void. Asis typical of most large voids insuch treated emeralds, the cham-ber is readily visible because therefractive index of the filler issufficiently different from one orboth of those of the surroundingemerald. Magnified 15×.


its precise nature. We did observe thatthe filling material was either solid orhighly viscous. It is possible that amixture of substances yielded thevery close match in optical propertiesthat made this filling invisible.However, because natural emeraldsexhibit a range of refractive indices,we think it unlikely that such “invisi-ble” treatment will become the norm.

John I. Koivula

GLASS Imitation of Peridot

Two green oval faceted gems wererecently sent to the West Coast labo-ratory (figure 6). An identification wasrequested for the larger of the two(26.28 ct). When they were examinedface up, both looked very much likethe peridot that has been coming outof Pakistan for the last several years.

Once we started testing, however, itimmediately became apparent thatthey were not peridot at all.

The R.I. of the larger “stone” wasover the limits of the refractometer.The polariscope showed that it wassingly refractive, and we measured itsS.G. at 4.43 using the hydrostaticmethod. These properties indicate ahigh-property glass. Microscopicexamination revealed parallel flowlines, confirming this conclusion.

We subsequently learned that thesetwo samples had been purchased atthe 1998 Tucson gem show as Chineseperidot by renowned American gemcutter Arthur Anderson. He acquired afew of these pieces in their facetedshape, intending to recut them intosome of his own designs. As he start-ed to cut the first one (figure 7), henoticed that the material did not reactto the cutting wheel like peridot, atwhich point he sent the two pieces tothe GIA Gem Trade Laboratory foridentification.

Glass has been used to imitate amultitude of gemstones for centuries.In recent years, it has been found insalted parcels of amethyst, aquama-rine, and Mexican fire opal, to namejust a few examples. Careful manipu-lation of the color makes it impossi-ble to distinguish these glasses fromthe stones they imitate by visualappearance alone. Of course, anynumber of gemological tests (e.g.,optic character) can separate these

imitations quickly in most instances,but it is easy to forget that any stonecould potentially be glass.

This is the first instance we haveencountered of material sold asChinese peridot turning out to beglass. This should, however, serve asa warning for anyone in the marketfor such peridot to be wary of thisimitation. SFM and IR

JADEITE with UnusualEvidence of Enhancement

The identification of treated jadeitehas been a persistent problem forgemologists and jewelers for manyyears. The methods of treatmentmost commonly used historically,such as dyeing and waxing, areintended to enhance the outwardappearance of lower-quality, or poorlypolished, material. More recently,there has been a proliferation ofjadeite objects treated throughout by amulti-step process that involves heat-ing, acid “bleaching,” and impregna-tion with an organic polymer (see, e.g.,E. Fritsch et al., “Identification ofbleached and polymer-impregnatedjadeite,” Gems & Gemology, Fall1992, pp. 176–187). The jadeite gems,jewelry, and carvings enhanced bythis process are widely known as“bleached jade” or “B-jade.”

Because the vast majority of thesurface-reaching fissures filled by thisprocess are extremely fine, there isusually no visible evidence of treat-ment even with a microscope. Today,most laboratory gemologists rely pri-marily on Fourier-transform infraredspectrometry (FTIR) to detect B-jade.So, while it is relatively easy for agemologist to identify a material asjadeite, detection of bleaching andimpregnation almost always requiresadvanced testing with FTIR.

On rare occasions, however, alarge surface pit or wider fissure willcontain visual evidence of this treat-ment in the form of polymer residueand/or trapped gas bubbles. Such wasthe case for a mottled bright green-and-white jadeite bangle that wasrecently submitted to the West

Figure 6. These green ovals looklike peridot, but they were iden-tified as glass. The sample onthe right weighs 26.82 ct.

Figure 7. The behavior duringcarving of a third sample, simi-lar to those shown in figure 6,made the cutter suspicious thatthe material was not peridot.This glass imitation weighs18.81 ct.

Figure 5. These three trapped gasbubbles provide the only evi-dence of a filled void in thisemerald; the filler itself is virtu-ally invisible, probably becauseits refractive index is very closeto both those of the host emer-ald. Magnified 30×.

Lab Notes GEMS & GEMOLOGY Spring 1999 45

Coast laboratory for identificationand testing for possible enhance-ment. Without magnification, thisbracelet looked like many otherjadeite objects we receive in the labo-ratory. When we examined it with amicroscope at even 10× magnifica-tion, however, numerous small gasbubbles (figure 8) were easily seen.Some of the bubbles were almost per-

fectly spherical, while others werequite distorted. They were individual-ly contained in small voids in thejadeite that we speculated must havebeen formed during the acid bleaching.

It is possible that acid-dissolvableinclusions of some mineral, such as acarbonate, may have been removedfrom the jadeite by the acid treat-ment. The resulting voids were thenonly partially filled with the polymerduring the impregnation step, leavinga gas bubble as proof of enhancement.

John I. Koivula

CULTURED PEARLS

Black, Surface EnhancedSuspecting that a strand of 11 mmblack circled pearls had been treatedto enhance their appearance, a clientsubmitted them to our West Coastlab for identification. All the pearlshad an extremely high luster andshowed pronounced purplish pinkand green overtones. While handlingthem, the client had noticed a pecu-liar smoothness on the pearls’ surfaceand that they were somewhat stickyto the touch.

Gemological tests verified thatthey were indeed cultured pearls ofnatural color, and microscopic exami-nation with reflected overhead illumi-nation showed a highly reflective sur-face, with a top nacre layer that wasvery transparent. Pearls (both naturaland cultured) normally show a pat-tern of fine lines (figure 9), calledsuture lines, that are a characteristicgrowth feature in the nacre. However,

the suture lines in these black cul-tured pearls were barely visible (figure10). We did see some fine polishinglines, but they appeared to be locatedslightly underneath the surface ratherthan on it. The needle probe left asmooth indentation, similar to thatleft on plastic-coated materials, whichraised more doubts regarding the sur-face condition. Without using destruc-tive testing methods, though, wecould not verify the type of treatment.Therefore, we obtained the client’spermission to remove one culturedpearl (figure 11) for further testing.

We checked this sample with athermal reaction tester. The hot nee-dle initially left only a chalkedgroove, as would be expected for asoft carbonate. However, with contin-ued application of heat, the chalkedmaterial began to coagulate. Thischange proved that some foreignmaterial was present on the surface.We sent the cultured pearl to a labora-tory that specializes in polymer analy-sis to identify the surface material.The laboratory reported that this for-eign material was a poly-dimethylsiloxane, a form of silicone that isoccasionally applied to pearls toenhance their appearance. KH

Imitation Tahitian PearlsThe occurrence of gray-to-black natu-ral pearls is rare (see, e.g., M. Goebeland D. M. Dirlam, “Polynesian blackpearls,” Gems & Gemology, Fall1989, pp. 130 –148). Throughout thetrade, dark-colored pearls are pre-sumed to be cultured, but a laboratory

Figure 8. Subsurface bubblesprovide evidence of enhance-ment in a bangle bracelet of “B-jade.” Some of the bubbles arebadly distorted, while othersare nearly spherical. Theirreduced visibility is caused bythe translucency of the overly-ing jadeite. Magnified 40×.

Figure 9. The suture lines in thisnatural-color black culturedpearl are readily visible withmagnification and reflectedlight. Magnified 30×.

Figure 10. Suture lines are muchmore difficult to resolve in thiscoated black cultured pearl.Magnified 30×.

Figure 11. The coating on thisblack cultured pearl greatlyenhances all aspects of itsappearance.


report is often desired to determinewhether the color is natural or theresult of treatment. Less frequent isthe need to determine whether thematerial itself is genuine (that is, nat-ural/cultured or imitation). A recentexample of such a submission, exam-ined in the West Coast lab, are the earstuds shown in figure 12.

To the unaided eye, these grayishgreen spheres (which measured10.15–10.25 mm in diameter) havethe appearance of “pistachio” coloredTahitian cultured pearls. However,magnification revealed several sub-surface features that were typical forglass or plastic, but unlike any wehave ever seen in a pearl: swirl marks,flow lines, and gas bubbles beneath asmooth, transparent coating (figure13). We obtained a refractive index of

1.50 by the spot method, and deter-mined that the optic character wasisotropic. We saw no lines with adesk-model spectroscope, and weobserved weak, chalky green fluores-cence to both long- and short-waveUV radiation. These properties provedthese items to be imitation pearls.

A strand of silvery gray to blackimitation pearls was seen in the WestCoast lab a few years ago (Fall 1995Gem Trade Lab Notes, pp. 202–203).Those beads had an odd, rubbery sur-face texture, and a layered construc-tion was visible at the drill holes. Wedetermined that one of the layers wasbismoclite (a bismuth oxide chlorideused as a coating material), whichgave those imitation pearls their color.Unfortunately, the mounting of eachof the recently examined ear studs

prevented observation of a drill hole ordetermination of their composition.

CYW and IR

Cat’s-Eye TAAFFEITE

Some gems commonly exhibit phenom-ena, such as change of color (alexan-drite), chatoyancy (chrysoberyl), andasterism (sapphire). Occasionally weare reminded that any gem materialpotentially can show a phenomenon,even if such a phenomenon was notseen in that material before.

Such was the case with a 1.44 ctchatoyant cabochon recently submit-ted to the West Coast lab for identifi-cation. The purplish brown stone hada fairly well developed “eye” (figure14). We determined an R.I. of 1.72 bythe spot method, and an S.G. of 3.68by the hydrostatic method. The stoneshowed a uniaxial optic figure, weakpleochroism, and was inert to bothlong- and short-wave ultraviolet radia-tion. These properties all pointed tothe rare gem mineral taaffeite as theidentity of the cabochon. However,we had never seen a cat’s-eye taaffeitebefore. Since we could only get a spotR.I., and thus no estimate of the bire-fringence, we decided to analyze thestone on the Raman spectrometer.The Raman spectrum confirmed thatthe stone was indeed taaffeite.

Microscopic examination did notreveal the parallel needles or growthtubes normally found in a chatoyantstone. Instead, there were parallelreflective planar inclusions with stria-tions (figure 15). These striations,along with the reflectivity of the inclu-sions, caused the chatoyancy. We haveseen similar reflective inclusions as acause of chatoyancy on at least oneother occasion (see “Cat’s-eye sap-phire,” Summer 1995 Gem Trade LabNotes, pp. 126–127). SFM

PHOTO CREDITSMaha DeMaggio photographed figures 6, 7, 11,12, and 14. John Koivula was the photographerfor figures 1, 2, 4, 5, 8, 9, 10, and 13. ShaneMcClure provided figure 15.

Figure 12. The grayish greenspheres (10.15–10.25 mm indiameter) in these ear studsmake convincing imitations ofTahitian black pearls.

Figure 13. With 10× magnifica-tion, the imitation pearls shownin figure 12 exhibit gas bubblesand swirl marks below a smoothcoating.

Figure 14. This 1.44 ct chatoyantpurplish brown cabochon wasidentified as the rare mineraltaaffeite.

Figure 15. A group of parallelreflective planar inclusions withstriations was responsible forthe cat’s-eye effect in this taaf-feite. Magnified 30×.

Gem News GEMS & GEMOLOGY Spring 1999 47

The 1990s ended with a quietly productive season at thevarious Tucson gem and mineral shows, where manynew items were brought to our attention. The editorialteam spent two weeks visiting almost all of the 27shows. Information was also gathered by GIA GemTrade Laboratory staff members Philip Owens, CherylWentzell, Dr. Ilene Reinitz, Karin Hurwit, MahaDeMaggio, and contributing editors Dino DeGhionnoand Shane McClure, as well as by Phil York and WendiMayerson of GIA Education, collection curator Jo EllenCole, and G&G senior editor Brendan Laurs. Highlightsof the information we gathered, and some of the manyitems seen, are presented here. Additional reports fromTucson ‘99 will appear in future Gem News sections.

DIAMONDSFashioned diamonds from the Ekati mine, NorthwestTerritories, Canada. Faceted diamonds from Canada’sfirst diamond mine, Ekati (see, e.g., Winter 1998 GemNews, pp. 290–292), were available in the United Statesfor the first time, at the AGTA show. Craig de Gruchy ofSirius Diamonds (at the booth of Barker & Co.,Scottsdale, Arizona) showed Dr. Ilene Reinitz severalround brilliants. Six of the diamonds, which weighedfrom 0.75 to 1.01 ct, had been graded by the GIA GemTrade Laboratory; they ranged in color from E to J, and inclarity from VVS1 to VS1 (figure 1). All had been cut bySirius Diamonds, Vancouver, British Columbia, which isone of the first companies to manufacture Canadian dia-monds in that country. According to Mr. de Gruchy,each Ekati diamond faceted by Sirius is laser inscribedwith a polar bear logo (figure 2).

Synthetic diamonds widely available. Alex Grizenko ofthe Russian Colored Stone Co. (RCS), Golden, Colorado,reported that scientists working for RCS have improvedtheir growth processes and quality control over the lastyear. They can now grow synthetic diamonds with few

inclusions in relatively large sizes—up to 5.5 ct rough. Avariety of colors are being produced: yellow, blue, andtreated pink, red, orange, and color-change (figure 3), aswell as near-colorless material. Yields for fancy shapes,especially rectangles, can be quite high, resulting in fash-ioned synthetic diamonds up to about 4.5 ct. Facetedgoods are sold under the trademark “Ultimate CreatedDiamonds.” The company currently produces 300–400carats of crystals per month. However, they are poised toincrease production at least 10-fold, in about equalamounts of near-colorless and saturated colors.

According to Mr. Grizenko, these synthetic diamondshave the same properties as those GIA has examined inthe past (see, e.g., J. E. Shigley et al., “A chart for the sep-

TUCSON 1999

Figure 1. These six diamonds (0.75–1.01 ct) representsome of the early production from the newly openedEkati mine, Northwest Territories, Canada. Theywere fashioned in Canada as well. Courtesy of SiriusDiamonds; photo by Maha DeMaggio.

aration of natural and synthetic diamonds,” Winter 1995Gems & Gemology, pp. 256–264; Spring 1995 GemTrade Lab Notes, pp. 53–54; and Winter 1998 Gem TradeLab Notes, pp. 286–287). Dr. Ilene Reinitz, who spokewith Mr. Grizenko at Tucson, confirmed the reportedproperties. In particular, all of the RCS near-colorlesssynthetic crystals show phosphorescence after exposureto SWUV, although the strength of the reaction variesgreatly from one sample to another.

Dr. Reinitz also spoke to another purveyor of synthet-ic diamonds, Dr. Leonid Pride of the Morion Co.,Brighton, Massachusetts. This company works withcrystal growers in the eastern Ukraine. Dr. Pride showedher (predominantly rough) yellow, blue, treated red, andheavily included near-colorless synthetic diamonds,ranging from 0.18 to 1.24 ct.

In addition, Gem News editor John I. Koivula saw ayellow synthetic diamond crystal at the GJX show thathad triangular growth hillocks (resembling etchedtrigons, but raised above the surface of the crystal) on theoctahedral faces. These hillocks showed a positive orien-tation to the host face—that is, the triangles were paral-lel to the triangular sides of the octahedral crystal face—instead of the negative orientation seen for the etched

trigons on natural diamond crystals (a photograph of sim-ilar triangular growth hillocks on a synthetic diamond isshown as figure 5 on p. 48 of the Spring 1997 issue ofGems & Gemology). In conversations with dealers offer-ing both materials at the show, Mr. Koivula was amusedto note that synthetic moissanite was more expensivethan synthetic diamond.

COLORED STONES AND ORGANIC MATERIALSCat’s-eye andradite from San Benito County, California.Although this material is not new (see T. Payne, “Theandradites of San Benito County, California,” Fall 1981Gems & Gemology, pp. 157–160), recently a lease wasactivated in the area by Steve Perry Minerals, Davis,California. Mr. Perry was marketing rough and cut mate-rial that had been mined at the Yellow Cat claim sinceNovember 1998 (figure 4). The deposit is located about12 km northwest of the Benitoite Gem mine, within thesame serpentinite body. The andradite occurs in fracturescutting the serpentinite, together with dark green chlo-rite (ripidolite) and traces of black perovskite and whiteapatite.

The deposit produces mineral specimens and limitedamounts of cutting rough of the yellow-green to brown-ish orange variety of andradite. So far, about 300 grams ofcat’s-eye rough have been extracted, with cutting yieldsof about 10%–15%. Smaller quantities of facet-graderough are recovered: Mr. Perry estimates that the year’sproduction will yield about 50 carats of faceted material(see, e.g., figure 5). Of this, about 75% is “honey col-ored,” 10% is orange, and 10% is yellow (all of thesehues are sometimes called “topazolite” in the trade);

48 Gem News GEMS & GEMOLOGY Spring 1999

Figure 2. Sirius Diamonds laser inscribes a styl-izedpolar bear on the girdle of each Ekati diamondthey facet. This stone weighs about 1 ct; photo ©Anthony de Goutière.

Figure 4. Small amounts of cat’s-eye andradite(shown here, 0.65 and 6.09 ct) are being mined againin San Benito County, California. Courtesy of StevePerry; photo by Maha DeMaggio.

Figure 3. These 0.04–1.07 ct round brilliant syntheticdiamonds illustrate some of the as-grown and treatedcolors available this year. Courtesy of Alex Grizenko;photo by Maha DeMaggio.


another 5% is greenish yellow. Eye-clean finished stonesare usually smaller than 0.5 ct, and faceted andraditelarger than 1 ct from San Benito County is rare. Mr. Perryprojects that small amounts of material will continue tobe produced.

An “enhydro” emerald from Colombia. Although quartzcrystals and agates are the usual hosts for large fluidinclusions with movable gas bubbles—”enhydros”—thisrare feature can occur in other materials as well. Forinstance, enhydro gypsum crystals were seen at Tucsonthis year, and we reported previously on an enhydro tan-zanite crystal (Spring 1997 Gem News, p. 66). At the1999 AGTA show, Ray Zajicek of Equatorian Imports,Dallas, Texas, loaned us for examination a 20.95 ct dou-bly terminated emerald crystal (figure 6) he had acquiredin Colombia that contained a large fluid inclusion with amovable gas bubble (figure 7). The fluid-and-gas-filledinclusion in the emerald was so large that the specificgravity of the stone was only 2.62 (rather than a moretypical 2.72). Additional properties were: refractiveindices—1.573–1.580; “Chelsea” color filter reaction—red; and inert to both long- and short-wave UV radiation.The inclusion appeared natural, and we saw no evidenceof clarity enhancement in this emerald crystal.

Abundant eudialyte. Eudialyte is an uncommon mineralfound in alkali- and zirconium-rich intrusive rocks, suchas in Canada, Greenland, and the Kola Peninsula ofRussia; it is rarely seen in gem quality. (The gemologicalproperties of a faceted 0.36 ct eudialyte from southwest-ern Quebec, Canada, were reported in the Winter 1993Gem News, pp. 287–288.) This year, Bill Gangi of BillGangi Multisensory Arts, Tucson, had unusually largequantities of fashioned eudialyte, which he showed con-tributing editor Shane McClure. Mr. Gangi has pur-chased the entire mine run of more than 45 kg of brightlycolored eudialyte-rich rock from a mine in eastern

Canada. The eudialyte was fashioned into free-formcabochons that incorporated portions of the matrix (fig-ure 8). Other minerals present in this material werefeldspar, tourmaline, fluorite, and galena.

New cuts for Oregon sunstone. Although not a newmaterial, Oregon sunstone continues to intrigue cuttersand carvers (see, for example, the “watermelon” sun-stone carving in Summer 1997 Gem News, p. 145). KlausSchäfer of Idar-Oberstein, Germany (who was in Tucsonat the booth of Bernhard Edelsteinschleiferei, Idar-Oberstein), has faceted this material in a manner thathighlights the copper inclusions (figure 9). Schäferincludes matte-finished facets in his fashioned sunstonesto direct light through the stone so that some inclusionlayers are prominent and others recede. To produce thematte facets, he uses silicon carbide applied with a brushto an iron lap wheel.

Near-colorless forsterite. K. K. Malhotra of K&KInternational, Falls Church, Virginia, loaned contributingeditor Shane McClure a near-colorless 6.20 ct cushion-cut stone (figure 10) from Sri Lanka. The stone appeared

Figure 6. This Colombian emerald crystal (20.39 ×11.62 × 8.76 mm) contains a large fluid inclusion witha movable gas bubble. Specimen courtesy of RayZajicek; photo by Maha DeMaggio.

Figure 5. These faceted andradites (0.07–1.10 ct) illus-trate the range of color in which the San BenitoCounty material occurs. The greenish yellow stonesare typically smaller than those with warmer yellowto-orange hues. Courtesy of Steve Perry and LenPisciotta; photo by Maha DeMaggio.

pale green when viewed table-down, but it was essential-ly colorless when viewed table-up. It had R.I. values of1.639–1.670 and an S.G. of 3.25. Its absorption spectrumshowed only a weak, sharp peak at 495 nm. The stonewas inert to both long- and short-wave UV radiation.Microscopic examination revealed numerous parallelstrings of whitish clouds. A Raman spectrum had majorpeaks at 857 and 825 cm−1, and smaller peaks at 968, 919,608, 434, and 306 cm−1. All of these properties were con-sistent with olivine that contains little or no iron (i.e.,end-member forsterite). EDXRF analysis of the forsteriteby GIA Gem Trade Laboratory research associate SamMuhlmeister revealed major amounts of magnesium andsilicon, some iron, minor manganese, and traces of zincand calcium. The trace elements suggested a natural ori-gin for the stone (see, e.g., K. Nassau, “Syntheticforsterite and synthetic peridot,” Summer 1994 Gems &Gemology, pp. 102–108).

The most common series in the olivine mineralgroup is that between forsterite (Mg2SiO4) and fayalite(Fe2SiO4). The common gem variety of olivine, peridot, isforsterite with about 12 atom percent iron substitutingfor magnesium (see, e.g., W. A. Deer et al., 1974, AnIntroduction to the Rock-Forming Minerals, LongmanGroup Ltd., London, pp. 1–7) and R.I. values of1.654–1.690. This sample of colorless gem-qualityforsterite contained only about one-third as much iron astypical peridot (as estimated from the EDXRF data),which would account for its colorless appearance. It was

surprising to see a natural gem forsterite—not a peridot—of this large size.

“Watermelon Garnet.” The variety of elbaite tourmalinethat has a pink center and green rind is familiar to mostpeople in the gem trade as “watermelon” tourmaline.This form of tourmaline is routinely cut perpendicular tothe length of the crystal and sold as polished slices forjewelry applications. Recently, Bill Heher of Rare EarthMining Co., Trumbull, Connecticut, sent one of theGem News editors (MLJ) a polished slab and a polished,tapered cabochon that were reminiscent of watermelontourmaline in color but not pattern (figure 11). Accordingto Mr. Heher, the material was mined in the 1940s inSouth Africa, and was represented to him as“hydrogrossular garnet” (commonly referred to as“Transvaal Jade”). He was also told that the material had“high concentrations of chromium and manganese.”

Refractive index (spot) values of 1.712 were obtainedfor both the green and pink areas of the cabochon. We didnot determine specific gravity because the samples con-tained a significant amount of matrix. Both the pink andgreen portions were inert to long- and short-wave UVradiation, but some areas of the matrix showed whitefluorescence to long-wave UV.

The absorption spectrum (as seen with a handheldspectroscope) was interesting in that the green end of thecabochon showed a strong single line at 466 nm; howev-


Figure 8. These five cabochons of eudialyte-rich rockmeasure about 2–3 cm each. Courtesy of Bill Gangi;photo by Maha DeMaggio.

Figure 9. This Oregon sunstone (about 2 cm across)has been fashioned with some matte-finished facetsto bring out the appearance of the copper inclusions.Courtesy of Klaus Schäfer; photo by Maha DeMaggio.

Figure 7. As the emerald istilted (left, right), the gasbubble moves in the 2.4-mm-long fluid-filled cavi-ty. Photomicrographs byJohn I. Koivula.


er, as the stone was moved from the green to pink por-tion across the spectroscope, this absorption line gradual-ly became fainter. It completely disappeared in the pinkarea that was farthest from the green end.

Another interesting characteristic was noted whenthe cabochon was analyzed along its length with a laserRaman microspectrometer. By comparison with refer-ence spectra, we identified the green end as vesuvianiteand the pink end as hydrogrossular, which was consis-tent with the gemological properties. Raman spectraobtained at spots intermediate between the two endsindicated a mixture of these phases. This gradation in theRaman spectra down the length of the stone supports theobservations of the visible-light absorption spectra, sincea line at about 466 nm is characteristic of vesuvianite. Asthe hydrogrossular became the major phase in the mix-ture, toward the pink end of the cabochon, the 466 nmline faded out.

Because Mr. Heher had been told that the materialcontained high concentrations of chromium and man-ganese, we asked Sam Muhlmeister to measure thechemistry using EDXRF spectrometry. An analysisacross the entire sample revealed no evidence of Cr. Thechemical elements detected were aluminum, calcium,iron, manganese, silicon, strontium, and titanium.

This material presents an interesting nomenclaturedilemma. The primary mineral in the green area, vesu-vianite, is more familiar to gemologists as idocrase. Thepink material is hydroxyl-rich garnet—hibschite, katoite,or hydrous grossular—and usually simply referred to ashydrogrossular. In the samples we saw, there appeared tobe a dominance of hydrogrossular (pink) over idocrase(green), so that “hydrogrossular-idocrase” would be anappropriate name to apply to these bicolored, mixed-min-eral gemstones. Mr. Heher had several hundred stones in

Tucson. Because brightly colored bicolored gems arealways popular, a consistent supply of good-quality mate-rial would create its own market in the areas of designerjewelry and small carvings.

New deposits in India and Nepal. Anil Dohlakia of AnilDohlakia, Inc., Franklin, North Carolina, had severalinteresting gems that were recently mined from newdeposits in Asia. These included kyanite from Nepal;apatite from Rajasthan, India; and chrysoberyl fromAndhra Pradesh, India.

The kyanite (figure 12) was found shortly before theTucson show. Approximately 500 carats have beenfaceted from the 5% of the rough that was gem quality.The resulting fashioned stones are somewhat large (tomore than 10 ct) and range from medium to dark in tone.

The apatite is also notable for the large pieces recov-ered; the largest fashioned stone Mr. Dohlakia had(which weighed more than 50 ct) is shown in figure 13.He reported that about 200 kg of apatite were available.

About 500 carats of fashioned cat’s-eye chrysoberylFigure 10. This 6.20 ct cushion-cut near-colorlessstone, reportedly from Sri Lanka, is natural forsterite.Courtesy of K. K. Malhotra; photo by Maha DeMaggio.

Figure 11. This 8.5 cm polished slab and 25.52 ctcabochon were both cut from hydrogrossular-idocraserock that was mined in South Africa in the 1940s.Courtesy of Bill Heher; photo by Maha DeMaggio.

Figure 12. These kyanite ovals from Nepal weigh 6.07,7.74, and 10.12 ct. Courtesy of Anil Dohlakia; photoby Maha DeMaggio.

were available from the new find near Vishakhapatnam,Andhra Pradesh State. The cabochons ranged up to 20 ct.

Iolite and other gems from Canada. Canadian miningcompany Anglo Swiss Resources (Vancouver, British

Columbia) is developing deposits of several colored gemminerals in the Slocan Valley of southeastern BritishColumbia. The company’s claims cover an area of meta-morphic host rock that measures 13,000 acres (about 45km2). The following information is based on discussionswith Anglo Swiss president Len Danard—who was show-ing rough and cut material in Tucson—and informationprovided by geologist James Laird.

The company began by examining their sapphireprospects, particularly at the Blu Moon and Blu Starrgroups of claims (figure 14). Gray-to-black sapphires withgood asterism (figure 15) were found in the host rock; Mr.Danard estimates grades of 30 carats of finished cabo-chons per ton of rock. Heat-treatment experiments pro-duced some improvement in the color, but at theexpense of the asterism. Mr. Danard hopes to recovermore-profitable goods when they start mining their 1,853acres of newly permitted placer deposits in the Slocanand Little Slocan Rivers this spring. Bright pinkish redpyrope-almandine garnets (again, see figure 15) were alsofound in the host rock at the Blu Starr claim. The garnetcrystals can exceed 10 cm in diameter, but because theyare often highly fractured, the largest stone fashioned todate weighs 3 ct. About 250,000 carats of rough garnetwere collected during the 1998 mining season, and yieldsof 46% were realized from pre-trimmed ore.

In November 1998, iolite (again, see figure 15) wasfound in the host rock at two separate workings, thenknown as the Rainbow North and Rainbow South zones.These are believed to be part of one continuous rock unitthat extends for more than 2 km along the surface. Thelargest crystal recovered weighed more than 1,500 ct.However, much of this material is also heavily fractured,so the largest iolite faceted thus far weighs only 0.64 ct.Nevertheless, the material shown to one of the GemNews editors (MLJ) was an attractive deep bluish violet,even in small sizes. The company estimates that aboutone billion carats can be recovered from the surface lay-ers of the deposit.

Amethyst, light blue beryl, moonstone, titanite, andzircon have also been recovered by Anglo Swiss from theSlocan Valley; as of February 1999, all but the zircon hadbeen faceted. Several varieties of quartz (e.g., smoky, star,rock crystal, and rose) have been recovered, as haveJapan-law-twinned quartz crystals for use as mineralspecimens. Clearly, this area has the potential to producea large variety of gem materials.

Jasper “planets.” One of the pleasures of the Tucsonexperience is finding materials that are reminiscent ofother materials. Many of the resulting Gem Newsentries are cautionary tales, of the “Don’t be fooled bythis!” variety. Here is a case where the resemblance isunlikely to cause confusion, however. Two spheres ofMexican jasper (figure 16) were shown to one of the GemNews editors (MLJ) by Jorge A. Vizcarra of OK. Rock’s &Minerals Whole, El Paso, Texas. The spheres are unlikely


Figure 13. Rajasthan, India, is the source of thisfaceted apatite, which weighs more than 50 ct andmeasures 29 × 24 mm. Courtesy of Anil Dohlakia;photo by Maha DeMaggio.

Figure 14. The Slocan Valley in British Columbia isbeing explored and mined for several gem minerals byAnglo Swiss Resources. Bulk sampling at the BluMoon claim is shown here; the Blu Starr claims arevisible on the hillside in the background. Photo cour-tesy of Anglo Swiss Resources.


to be confused with giant planets in the outer solar sys-tem, but their colors and markings greatly resemblethose of Jupiter and Saturn.

Opal in matrix from Brazil. Carlos Vasconcelos ofVasconcelos Brasil, Governador Valadares, had a fewsamples of opal with good play-of-color (figure 17) from anew deposit near Tranqueira in Piauí State, northernBrazil. The area lies about 200 km south of previouslyknown opal deposits in Piauí, and was discovered about 5km southwest of another locality that is being mined for

orange opal. The deposit was first found about threeyears ago, but organized mining is just beginning. About200 carats of rough have been produced thus far.

White and pastel Chinese freshwater cultured pearls. Atthe AGTA show, Hussain Rezayee of Freiburg, Germany,and Tetsu Maruyama of C. Link International, Tokyo,showed the G&G editors several strands and loose sam-ples of freshwater cultured pearls (figure 18) grown onfarms in China. This material has been available in abun-dance lately, in much larger sizes and far better qualitythan the “rice pearls” of several years ago. The colorsinclude orange, “lavender,” pink, and white.

According to a company brochure supplied by Mr.Maruyama, the C. Link farms in China have nearly500,000 pearl oysters each, and the pearls are tissue

Figure 15. Among the gems recovered from the SlocanValley are star sapphires (upper left; largest stone 18 ×12 mm), pyrope-almandine garnets (upper right;rough 9 mm in diameter), and iolite (left; rough 17mm long). Courtesy of Len Danard; photos by JeffScovil, © Anglo Swiss Resources, Inc.

Figure 16. These are not planets visible in the clearskies of Tucson, but jasper spheres (62.8 and 75.3 mmin diameter) from Mexico. Photo by Maha DeMaggio.

Figure 17. This 6 × 5.5 × 2 cm piece of opal in matrixcomes from a new deposit in Brazil. Photo courtesy ofCarlos Vasconcelos.

nucleated rather than bead nucleated. A 9 mm round cul-tured pearl takes about four years to grow, and those larg-er than 10 mm require five to seven years. However, 600tons of 8 mm cultured pearls have been produced (froman unspecified number of farms and an unknown timeperiod). Round tissue-nucleated cultured pearls are rela-

tively rare: Only 3% of the production of 8 mm pearls areconsidered round by C. Link, and only 5% of this smallgroup are considered top quality.

The largest cultured pearls in this sample measured12.5 mm in diameter (for rounds) and slightly larger than15 mm (for button shapes).

Drusy quartz “leaves.” At the booth of Rare EarthMining Co., Trumbull, Connecticut, Dr. Ilene Reinitzsaw many colors of drusy agate that had been carved intoleaf shapes by Greg Genovese of Cape May, New Jersey(figure 19). We found these shapes to be an interestingand attractive use of geode material—which was, in thiscase, reportedly from Rio Grande do Sul, Brazil. Theleaves ranged from about 10 × 16 mm to over 7 cm long;Mr. Genovese carved 1,000 such pieces during the fivemonths preceding the show. Colors in the rough werechosen for their resemblance to natural leaves, althoughsome material was dyed blue or black.

Twelve-rayed star quartz from Sri Lanka. Star quartz wasreported in Gems & Gemology several times in the1980s. These entries included white and brown stoneswith six-rayed stars, a blue-gray stone with a 12-rayedstar, quartz with one strong band (a cat’s-eye) as well asless prominent rays, and Sri Lankan samples with multi-ple centers of asterism (see, e.g., Gem Trade Lab Notes:Winter 1982, p. 231; Summer 1984, pp. 110–111; Spring1985, pp. 45–46; and Spring 1987, pp. 47–48). This yearin Tucson, Michael Schramm of Michael SchrammImports, Boulder, Colorado, showed Dr. Ilene Reinitz a31.37 ct star quartz from Sri Lanka (figure 20) that had


Figure 18. These tissue-nucleated freshwater culturedpearls are typical of the better-quality material recentlyproduced in China. The white circled pearls are 11 mm(and larger) in diameter, and the cultured pearls in theother strands range from 9.5 to 11 mm. Courtesy ofHussain Rezayee; photo by Maha DeMaggio.

Figure 19. These five leafshapes were carved fromdrusy quartz by GregGenovese; the large “oakleaf” on the lower rightmeasures 7.2 × 2.8 cm.Courtesy of Rare EarthMining Co.; photo byMaha DeMaggio.


many of these optical effects. This stone contained a 12-rayed star, additional off-axis stars, and a bright centralband that had the appearance of a cat’s-eye when viewedwith low-intensity illumination. As mentioned in theSummer 1984 Lab Note, Dr. Edward Gübelin had con-cluded that sillimanite was responsible for the asterismin Sri Lankan star quartz.

New finds of spessartine in Brazil. At least three dealershad Brazilian spessartines that were reportedly from newsources. James Dzurus of Franklin, North Carolina, hadsome spectacular orange spessartines from a deposit inMinas Gerais. He showed contributing editor ShaneMcClure and editor MLJ a 29 gram piece of rough (withdodecahedral and trapezohedral crystal faces), as well asfashioned stones ranging from 9 to 38.58 ct. The roughwas mined during the last two years at an unspecifiednew pegmatite deposit. We hope to have more informa-tion about spessartine from this source in a future GemNews item.

Carlos Vasconcelos had mineral specimens of gem-quality spessartine from a new find at Barra de Cuieté,Minas Gerais. Mining of the pegmatite began about twoyears ago, initially for ceramic-grade feldspar and gemtourmaline. Since October 1998, about 50 kg of spessartinehave been recovered, with 2,000 carats fashioned so far.The largest cut stones reportedly weigh more than 20 ct.

Brian Cook (Nature’s Geometry, Graton, California)had samples and photos of a new spessartine find innortheastern Brazil that he is mining with partner DeanWebb (Pan-Geo Minerals, Sebastopol, California). Thematerial was recovered from a granitic pegmatite at the

Mirador mine in Rio Grande do Norte State. About 5 kgof gem rough have been recovered from this pegmatitesince January 1999 (figure 21). The find was so recent thatonly rough was available; however, a 2.66 ct stone wasfaceted by gem cutter Jacques Vireo (Precision Cutters ofLos Angeles, California) while at the Tucson show.Limited amounts of gem-quality gahnite showing a lightgreen color were also recovered with the spessartine.

TREATMENTS “Blatant” dyed pearls. With the increasing availability oflarge freshwater cultured pearls, we saw large quantitiesof inexpensive cultured pearls that were obviously dyed.The strand in figure 22, acquired in Tucson by contribut-ing editor Dino DeGhionno, consists of 71 drilled cul-tured pearls with a bright, light green color that is onlyvaguely similar to a color seen in untreated culturedpearls. Dye concentrations were readily apparent with a

Figure 20. This 31.37 ct star quartz from Sri Lankashows many optical effects, including a 12-rayed star,multiple centers of asterism, and one bright band thatlooked like a cat’s eye when the stone was viewedwith low-intensity illumination. Courtesy of MichaelSchramm; photo by Maha DeMaggio.

Figure 21. A number of new localities in Brazil haveproduced fine-quality gem spessartine. These samples,from northeastern Brazil, weigh 70.90 and 5.45 ct(rough) and 2.66 ct (faceted). Courtesy of Brian Cook;photo by Maha DeMaggio.

Figure 22. Large quantities of dyed freshwater cul-tured pearls were seen in Tucson this year. The cul-tured pearls in this strand range from 7 × 5.5 mm to 8× 6 mm in diameter. Photo by Maha DeMaggio.

microscope. According to David Federman, in the March1999 issue of Modern Jeweler (“Triple Crown,” p. 38),Chinese freshwater cultured pearls are commonlybleached during processing. The “rejects” from thebleaching process are dyed “silver” or “pistachio.”

SYNTHETICS AND SIMULANTSFused silica glass, sold as “cultured snow quartz.” Fine-grained quartzite is sometimes tumbled or even fash-ioned into cabochons, but it is not a gem material thatwe would expect to see imitated. Nevertheless, GemsGalore of Mountain View, California, was marketingmatte-finished tumbled pieces of so-called “snowquartz” (figure 23). According to their literature, thematerial was produced by “fusing quartz” and then rapid-ly cooling it to a “quasi-amorphous state.” The samplewe acquired was composed of two eye-visible layers.Magnification revealed that both layers contained dense

concentrations of round bubbles of various sizes, and theboundary between the layers was simply a demarcationbetween different densities of bubbles. The sample hadan R.I. of 1.46, and EDXRF analysis revealed only silicon.Although we could not discern any individual grains, thesample gave an aggregate reaction in the polariscope,probably because of scattering of light by the gas bubbles.On the basis of these properties, especially the low R.I.value and characteristic inclusions, we concluded thatthis material was silica glass.

Blue slag glass from Sweden, resembling opal. Slag glassis a material that seems to be particularly confusing tothe amateur field collector. Over the past five years, wehave seen several misidentifications of slag as mete-orites, emeralds, and obsidian (see, e.g., “Obsidian imita-tion,” Winter 1998 Gem News, p. 301). Still another con-troversial identity was claimed for a probable slag (manu-factured) glass available at Tucson this year: CSD, or“Crash Site Debris,” which supposedly had come fromthe site of a UFO impact at St. Joseph, Missouri, in 1947(“UFO tale is rocky but rare: ‘Alien’ debris is just slag,skeptic says,” Arizona Daily Star, February 5, 1999, pp.1A, 6A).

It was, therefore, a pleasure to observe a dealer repre-senting slag glass for what it actually is. We acquired a17.48 × 13.46 × 4.75 mm (8.92 ct) cabochon and a 338.6ct chunk of rough (figure 24) from Gun Kemperyd Olsonof Ingeborgs Stenar AB, Stockholm, Sweden. Accordingto Ms. Olson, this manufactured glass came from theBergslogen region in central Sweden, where iron has beenmined and processed since the 1600s. The cabochon wastransparent yellowish green in transmitted light, butappeared milky blue in reflected light. With the micro-scope, we saw round gas bubbles, linear flow banding,and fluffy-looking aggregates of opaque particles with ametallic luster. The chunk of rough was opaque lightblue and showed conchoidal fracture; the fractured sur-face cut through some of the gas bubbles. Although atfirst glance this material resembles blue opal (such as thatmined in Peru), its microscopic features are distinctive.

The Materials Handbook (G.S. Brady and H.R.Clauser, McGraw-Hill, New York, 1986) defines slag as“molten material that is drawn from the surface of ironin the blast furnace. Slag is formed from the earthy mate-rials in the ore and from the flux. Slags are produced fromthe melting of other metals, but iron blast-furnace slag isusually meant by the term.” The Handbook gives a com-position of 32[wt.]% SiO2 , 14% Al2O3, 47% CaO, 2%MgO, and small amounts of other elements, althoughthere is considerable variation depending on the ore.

Imitation “Chinese freshwater” cultured pearls. JackLynch of Sea Hunt Pearls, San Francisco, California,loaned us four samples (figure 25) that had been repre-sented to him as Chinese freshwater cultured pearls. Thebeads were purchased at a pearl farm about six hours’drive from Shanghai, China; they were supposedly natu-


Figure 23. This 99.90 ct free-form promoted as “cul-tured snow quartz” is actually fused silica glass witha high density of gas bubbles. It makes a convincingimitation of quartzite. Photo by Maha DeMaggio.

Figure 24. This 338.6 ct piece of rough and 8.92 ctcabochon are manufactured slag glass from centralSweden. Photo by Maha DeMaggio.


ral-color freshwater cultured pearls that had been pro-cessed to make them round after extraction, and all inthe parcel shown to Mr. Lynch were the same color.

The greater availability and wide range of colors offreshwater cultured pearls from China were described inG&G in Fall 1998, in both the Gem Trade Lab Notes (pp.216–217) and Gem News (pp. 224–225) sections. The for-mer entry noted sizes up to 13 × 15 mm for oval culturedfreshwater pearls; the latter mentioned treated-colorblue-to-gray Chinese freshwater cultured pearls (similarto Tahitian products), as well as “pink, orange, and pur-ple” color varieties. So on that basis, these 12.5-mm-diameter grayish purple round beads were somewhatplausible.

However, microscopic examination revealed a surfacetexture of many small, flattened bubbles on a uniformbackground (figure 26), resembling the effects of aerosolpainting on a smooth surface, and very unlike the appear-ance of actual cultured pearls. The perfectly round shapeof these undrilled samples was also suspicious. Mr.Lynch kindly gave us permission to slice one open. Thisrevealed a painted shell over a featureless white bead.

Synthetic zincite possibly represented as sphalerite.Although we cannot confirm or refute every rumor thatwe hear in Tucson, one that came to us from two sourcesseems worth a comment. At Tucson this year, David andMaria Atkinson of Terra in Sedona, Arizona, mentioneda bright orange material that was being represented assphalerite from northern Pakistan. They suspected thatthis material was Polish synthetic zincite, which is beingdistributed through Russia. Another dealer showed us afaceted oval of synthetic zincite, which was from a parcelof “collector” gems acquired in Sri Lanka.

Synthetic zincite was abundant at Tucson this year, asit has been in recent years, so there is quite a lot of mate-rial available for deceptive purposes. To prevent possiblemisidentifications in the trade, we felt it worthwhile tomention the properties that distinguish orange syntheticzincite from natural sphalerite. The simplest distinctionsare: the singly refractive (sphalerite) versus doubly refrac-

tive (zincite) optic character; inclusions (fluid inclusionsand sulfide crystals in sphalerite; dislocations, clouds ofsmall particles, and small acicular crystals in syntheticzincite); and S.G. (4.09 for sphalerite, 5.70 ± 0.02 for syn-thetic zincite, although both are heavier than typicalheavy liquids). For more on synthetic zincite, see theSpring 1995 Gem News, pp. 70–71, and R. C. Kammerlingand M. L. Johnson, “An examination of ‘serendipitous’synthetic zincite,” Journal of Gemmology, Vol. 24, No. 8,1995, pp. 563–568.

MISCELLANEOUSDrill holes as design elements: Michael M. Dyber and“Luminaires.” American gem carver Michael M. Dyber

Figure 25. This grayish purple bead (12.5 mm in diam-eter) resembles certain Chinese freshwater culturedpearls currently in the marketplace, but it proved tobe an imitation consisting of a coated round bead.Photo by Maha DeMaggio.

Figure 26. The surface texture of the imitation pearlsshown in figure 25 did not resemble that of either nat-ural or cultured pearls. Photomicrograph by John I.Koivula; magnified 15×.

Figure 27. This 22.20 ct bicolored African tourma-line was carved by Michael M. Dyber. The carvedlight tubes, or “luminaires,” reflect the stone’scolor in interesting ways. Photo by Robert Weldon,© Michael M. Dyber.

of Rumney, New Hampshire, has been winning awardsfor his innovative designs for more than a decade. In thepast, he has developed carved gems with “optic dish-es”—concave polished curved facets—that reflect andrefract light into interesting patterns. This year atTucson, he introduced gems fashioned with polishedcylindrical channels, for which he has trademarked thename “Luminaire.” These particular manufactured“inclusions” (figure 27) might be mistaken at first glancefor natural etch tubes, or even prismatic mineral inclu-sions; however, their polished cylindrical shape demon-strates their manufactured nature.

Using mineralogical techniques to solve gemologicalproblems, part 1: Internal “Becke lines” in spinel. In theWinter 1998 Gem Trade Lab Notes section (pp.288–289), Gem News editor John Koivula reported on aparcel of spinels from Myanmar that contained coreswith higher refractive indices than the surrounding crys-tal. The relative R.I. values were observed using theBecke line method. The Becke line is a narrow band or

rim of light that is visible along the boundary betweenmaterials with different refractive indices when they areexamined with intermediate to high magnification (typi-cally, at least 40×). As the distance between the sampleand the objective lens of the microscope is increased (i.e.,by raising the microscope objective), the Becke linemoves into the region with the higher R.I. The Beckeline can sometimes be enhanced by shadowing or othertechniques (see, e.g., J. I. Koivula, “Shadowing: A newmethod of image enhancement for gemologicalmicroscopy,” Fall 1982 Gems & Gemology, pp.160–164).

The relative R.I. values in the zoned spinel crystalswere determined by first focusing sharply on the darkercore portion (figure 28, left), and then raising the micro-scope objective while watching the movement of theBecke line. In both of the samples examined, the Beckeline moved into the darker red core (figure 28, right), thusproving that the core had a higher R.I. than the surround-ing crystal.

Using mineralogical techniques to solve gemologicalproblems, part 2: “Plato lines” and growth structures insynthetic corundum. During the recent examination of arectangular block of flame-fusion pink synthetic sapphirebelonging to contributing editor Dino DeGhionno, weobserved a most unusual anomaly in polarized light. The60.49 ct block (15.83 × 14.90 × 13.60 mm), which he had


Figure 28. In shadowed transmittedlight, a bright Becke line appeared likea halo surrounding the darker red 0.3mm core (left) in this 0.19 ct spineloctahedron from Myanmar. As theobjective was raised (right), the Beckeline moved into the core, proving thatit has a higher R.I. than the surround-ing crystal. Photomicrographs by John I. Koivula.

Figure 29. This 60.49 ct block of pink flame-fusionsynthetic sapphire was cut to emphasize dichroism.Photo by Maha DeMaggio.

Figure 30. Colorful “Plato lines” are observed in thesynthetic sapphire block when it is viewed down theoptic-axis direction in cross-polarized light.Photomicrograph by John I. Koivula; magnified 10× .


purchased for classroom demonstrations, was oriented todisplay dichroism dramatically (figure 29). However, italso shows the colorful, strain-related “Plato lines”(Sandmeier-Plato striations; figure 30) that are oftenobserved in flame-fusion synthetic corundum when it isviewed nearly parallel to the optic axis in cross-polarizedlight (see, e.g., W. F. Eppler, “Polysynthetic twinning insynthetic corundum” Summer 1964 Gems & Gemology,pp. 169–174, 191).

What was curious about this piece, however, is thatin addition to the characteristic Plato lines, it shows avery distinctive, yet subtle, form of structurally inducedoptical activity. In polarized light, this activity appears asrelatively thick, interconnected blocks with rectangularedges that, in some areas, give the appearance of a jigsawpuzzle (figure 31, left). When the analyzer of the micro-scope is rotated, some of the structural blocks in this pat-tern visibly darken, while others get lighter (figure 31,right). This puzzle-like pattern is crystallographically ori-ented at about 90° to the optic-axis direction and thePlato lines. Because the pattern is in direct rotationalalignment with the long direction of the much more visi-ble Plato lines, when the Plato lines are located—and theblock is turned in the direction that they “point”—thenext polished face that comes into view is the face thatdisplays the more subtle puzzle-like pattern (figure 32).

This puzzle-like pattern is probably a form of what isknown in X-ray crystallography as a mosaic structure;crystals containing such individual “pieces” are referredto as mosaic crystals. As explained by A. Taylor in X-RayMetallography (John Wiley & Sons, New York, 1961, p.233), mosaic crystals develop when “the lattice takes onthe character of a mosaic, in which, without destroyingthe essential continuity, the mosaic blocks are tilted afew seconds or minutes of arc with respect to eachother.” This structural misalignment produces strain inthe host crystal. In the case of the synthetic corundum,this strain is easily visible with cross-polarized light asthe bright interference colors seen in the optic-axis direc-tion, that is, the Plato lines. It therefore appears that themosaic structure is the actual cause of Plato lines inflame-fusion synthetic corundum. This relationship wasoverlooked in the past because the visual effect is quitesubtle, and gemologists do not usually work with orient-ed, polished blocks.

ANNOUNCEMENTSNature of Diamonds at the San Diego Natural HistoryMuseum. The Nature of Diamonds exhibit, whichdebuted in New York at the American Museum ofNatural History in 1997, is now in San Diego, California,through September 7, 1999. The comprehensive exhibitdemonstrates many aspects of diamond, from its geologicorigins to its place in history, art, and adornment, and itsvarious uses in modern technology. Visitors will find avariety of displays ranging from world-famous gems andjewelry to unusual specimens and diamonds in theirnatural state. A walk-through mine tunnel, a dramaticwalk-in vault, and computer animation enhance the interactive experience. Attendees of GIA’s 3rd International Gemological Symposium will enjoy a spe-cial gala evening viewing at the museum Tuesday,June 22. Contact the San Diego Natural HistoryMuseum at 619-232-3821, or visit their Web site athttp://www.sdnhm.org, for more information.

Figure 31. The subtle mosaic structurebecomes visible when the syntheticsapphire block is rotated 90° from theoptic-axis direction (left). As themicroscope’s analyzer is rotated, someof the blocks in the mosaic patternbecome dark, while others appearlighter (right). Photomicrographs byJohn I. Koivula; magnified 10×.

Figure 32. This drawing shows the orientation betweenthe mosaic structure in the synthetic sapphire blockand the strain-related Plato lines. The optic axis is per-pendicular to the top of the cube.

New exhibit at the Royal Ontario Museum. The IncoGallery of Earth Sciences, an interactive exhibit thatexplores the Earth’s evolution and processes, is sched-uled to open May 30, 1999, at the Royal OntarioMuseum in Toronto, Canada. One of the exhibit’s fourmain sections is Treasures of the Earth, which explainsthe formation and characteristics of minerals. This sec-tion will include the S. R. Perren Gem and Gold Room,which originally opened in 1993 and contains over 1,000gems. For more details, contact Nikki Mitchell at 416-586-5565, or e-mail [email protected].

International Colored Gemstone Association Congress.ICA will hold its next Congress on May 16–19, 1999, inAbano Therme, Italy. Presentations, panels, and work-shops will be complemented by a variety of social events.Contact the ICA office in New York at 212-688-8452 formore details.

International Gemological Symposium. The 3rdInternational Gemological Symposium (hosted by GIA)will take place June 21–24, 1999, at the Hyatt RegencyHotel in San Diego, California. The event, which is heldonly once every 8–10 years, is known as the “world sum-mit” for the gem and jewelry industry. A distinguishedlineup of trade and scientific leaders will speak on themajor issues in the industry. Panel discussions, all-new“War Room” sessions, and dozens of poster presenta-tions round out the academic portion of Symposium. Toregister, contact GIA’s Symposium Office at 760-603-4406 (toll-free in the U.S. and Canada, call 800-421-7250,ext. 4406), or register online at http://www.gia.edu.

International Society of Appraisers conference. ISA willhold its 20th annual International Conference onPersonal Property Appraising on May 2–5, 1999, in Troy,Michigan. There will be a wide array of lectures, semi-nars (including “Gemstone Enhancement: Effects onPricing”), panel discussions, and social activities. Foradditional information, contact the ISA headquarters attheir Web site at http://www.isa-appraisers.org, or callthem at 888-472-4732.

Gemstones in upcoming scientific meetings. Special sec-tions on diamonds and/or colored stones will be incorpo-rated into several upcoming meetings on geology, miner-al exploration, and advanced analytical techniques:● The theme of the 4th Annual Penn State Mineral

Symposium (May 21–23, 1999) will be The Mineralogy ofGems and Precious Metals. For more information, callAndrew Sicree at 814-865-6427, or write Penn StateMineral Museum, 122 Steidle Building, University Park,PA 16802.

● The Joint Annual Meeting of the Geological Associ-ation of Canada and the Mineralogical Association of

Canada (GAC-MAC) will occur May 26–28, 1999, inSudbury, Ontario, Canada. Special sessions will focuson the genesis of gemstone deposits and diamondexploration using kimberlite indicator minerals. A one-day short course for nonspecialists will review geo-physical exploration techniques for several resources,including gold and diamonds. A separate field trip tothe Wawa area in Ontario will focus on exploring forrare-element pegmatites and kimberlites using glacialtill and modern alluvium. For more information, con-tact Laurentian University at 705-673-6572 (phone),705-673-6508 (fax), or you can visit their Web site athttp://www.laurentian.ca/www/geology/1STCIRC.htm.

● GEORAMAN’99: The 4th International Conference onRaman Spectroscopy Applied to the Earth Sciences will beheld June 9–11, 1999, in Valladolid, Spain. Applications ofRaman spectroscopy to gemology (and other disciplines)will be discussed. Further information can be accessed athttp://www.iq.cie.uva.es/~javier/georaman/geoeng.html.

ERRATA:

1. In the Fall 1998 Gem News item “Rossmanite, a newvariety of tourmaline” (p. 230), rossmanite should havebeen described as a new species of the tourmaline group.

2. On page 274 of the Sunagawa et al. article“Fingerprinting of Two Diamonds Cut from the SameRough” (Winter 1998), figures 6 and 7 are mislabeled.The labels for the a1 and a2 directions in the right-hand photo of each figure should be reversed.

3. On pages 264– 265 of the Nassau et al. article“Synthetic moissanite: A new diamond substitute”(Winter 1997), the thermal inertia data were printedincorrectly. The sentence at the bottom of page 264should read: “Because the thermal conductivity rangesof diamond (1.6–4.8 cal/cm °C sec) and moissanite(0.55–1.17 cal/cm °C sec) nearly overlap. . . .” The tablebelow presents the correct data for both thermal conduc-tivity and thermal inertia of diamond and moissanite.

4. The announcement on page 302 of the Winter 1998Gem News that the synthetic moissanite article hadreceived an ASAE award should have mentioned ShaneElen as one of the authors.


Thermal conductivity Thermal inertia(cal/cm °C sec) (W/cm K) (cal/cm2 °C sec1/2)

Diamond 1.6 – 4.8 6.6 –20.0 0.82 – 1.42Moissanite-6H 0.55– 1.17 2.3 – 4.9 0.30 – 0.63

Gems & Gemology Challenge GEMS & GEMOLOGY Spring 1999 61

1. When using laser Raman microspec-trometry to identify gem materials, theoperator must be aware that the spec-trum can vary according to

A. the size of the sample.B. the orientation of the sample.C. the fragility of the sample.D. the metal in which the sample is

set.

2. Russian synthetic pink quartz cansometimes be distinguished from natu-ral pink quartz on the basis of its

A. microscopic features.B. UV-visible absorption spectrum.C. refractive index.D. birefringence.

3. In GIA’s diamond cut model, weightedlight return (WLR)

A. is calculated using the two-dimen-sional path of light rays.

B. excludes the dispersion of lightrays as they move through the vir-tual diamond.

C. places equal emphasis on all lightreturned from the diamond’scrown.

D. places the greatest emphasis onlight rays that emerge straight upfrom the crown.

4. To manufacture a blue diamond with astronger, more evenly colored face-upappearance, a cutter could use

A. a French culet.B. no culet.C. 24 pavilion facets.D. a thick girdle.

5. The Raman identification of inclusionsin fluorite as barite was further support-ed by the

A. blocky form of the barite.B. color change of the barite.C. presence of barite in the Illinois

fluorite deposits.D. decrepitation halos in the fluorite

host.

6. The model developed for GIA’s dia-mond brilliance study

The following 25 questions are based on informationfrom the four 1998 issues of Gems&Gemology. Refer tothe feature articles and “Notes and New Techniques” inthose issues to find the single best answer for each ques-tion; then mark your choice on the response card provid-ed between pages 46 and 47 of this issue (sorry, no pho-tocopies or facsimiles will be accepted; contact theSubscriptions Department if you wish to purchase addi-tional copies of the issue). Mail the card so that we receiveit no later than Monday, July 12, 1999. Please includeyour name and address. All entries will be acknowledgedafter that date with a letter and an answer key.

Score 75% or better, and you will receive a GIAContinuing Education Certificate. If you are a memberof GIA Alumni and Associates, you will earn 5 CaratPoints toward GIA’s new Alumni Circle of Achievement.(Be sure to include your GIA Alumni membership num-ber on your answer card and submit your Carat card forcredit.) Earn a perfect score, and your name will also befeatured in the Fall 1999 issue of Gems & Gemology.Good luck!

NNoottee:: Questions are taken from the four 1998 issues.Choose the single bbeesstt answer for each question.

GemsGemology&

hallengeC

62 Gems & Gemology Challenge GEMS & GEMOLOGY Spring 1999

A. can only be used to evaluate dia-monds weighing more than 1 ct.

B. assumed that the diamond isperfectly symmetrical and per-fectly polished.

C. used a focused light source thatoriginated above the diamond.

D. took into account minor inclu-sions and cavities.

7. The following bonding agent was usedby the creator of “Leigha” because ofits strength and transparency:

A. cyanoacrylate adhesive.B. epoxy.C. UV-curing cement.D. natural resin.

8. EDXRF can be used most reliably toA. determine the manufacturer of a

synthetic ruby.B. determine the locality of a ruby.C. separate natural from synthetic

rubies.D. measure the R.I. of faceted

rubies.

9. In estimating the weights of mountedcolored gemstones, the greatest chal-lenge lies in correcting for

A. specific gravity.B. measurement precision.C. rounding errors.D. proportion variations.

10.The yield (percentage of originalweight retained after cutting) for dia-monds cut in India

A. is about 45%, the same as forwell-formed diamonds cut else-where.

B. has been approximately15%–23% since 1980.

C. averages only about 4%.D. cannot be estimated because of

the absence of official statistics.

11.The identification of two diamonds ascoming from the same rough is basedon their

A. mineral inclusions.B. color and clarity grades.C. growth histories.D. infrared absorption spectra.

12.Some of the world’s largest rubydeposits, such as those found inCambodia and Thailand, are

A. metasomatic.B. marble-hosted.C. metamorphic.D. basalt-hosted.

13.The topaz recovered from KleinSpitzkoppe, Namibia, is usually

A. colorless.B. brown.C. pale blue.D. pale yellow.

14.The preferred nucleus for the cultureof abalone blister pearls is in the formof a

A. sphere.B. marquise shape.C. flattened hemisphere.D. high-domed hemisphere.

15.Images obtained by X-ray topographyare distorted according to the

A. size of the sample.B. density of the sample.C. intensity of the X-ray beam.D. direction of reflection of the X-

ray beam.

16.Most diamonds cut in India areA. smaller than 7 pts and of low

quality.B. between 2 and 7 pts and of SI2

or better clarity.C. comparable in size and quality to

those cut in Antwerp and Israel.D. variable in size but always of

good clarity (SI2 or better).

17. Rubies formed in marble generallycontain relatively

A. low amounts of vanadium.B. low amounts of iron.C. high amounts of iron.D. high amounts of manganese.

18. Which one of the following materialswas not identified in the two historicalobjects from the Basel Cathedral?

A. DoubletsB. RubiesC. GlassD. Quartz

19.The vivid color and iridescence of thenacre of abalone “mabés” from NewZealand is enhanced by

A. the orientation of microscopicaragonite crystals.

B. a thick conchiolin layer under-neath the nacre.

C. the presence of a blue polymercoating.

D. organic dyes.

20.The fact that blue diamonds generallyhave high clarity is related to their

A. diamond type.B. color.C. size.D. facet style.

21.Today the percentage of the world’sdiamonds that are cut in India isabout

A. 70% by weight/70% by whole-sale value.

B. 70% by weight/35% by whole-sale value.

C. 50% by weight/35% by retailvalue.

D.50% by weight/20% by retailvalue.

22.The coloration of synthetic pinkquartz is probably related to the pres-ence of

A. aluminum.B. iron.C. phosphorus.D. manganese.

23.Which of the following materials can-not be studied by Raman analysis?

A. Synthetic gem materialsB. Fluorescent mineralsC. Metals and alloysD. Crystalline inclusions in gems

24.In the GIA analysis of brilliance forround brilliant diamonds, moderatelyhigh to high WLR values were calculat-ed

A. for only one particular pavilionangle.

B. for many combinations of crownangle, pavilion angle, and tablesize.

C. only for table sizes up to 58%.D. only for star facets longer than

50%.

25.With respect to the color appearance oftype IIb blue diamonds,

A. each hue transitions smoothly intothe neighboring color hues.

B. the saturation range is compressedcompared to yellow diamonds.

C. subtle hue shifts are seen through-out their color range.

D. there is little variation in tone.

Book Reviews GEMS & GEMOLOGY Spring 1999 63

ARAB ROOTS OFGEMOLOGY—Ahmad ibnYusuf al Tifaschi’s BestThoughts on the Best of StonesTranslated with comments bySamar Najm Abul Huda, 271 pp.,illus., publ. by Scarecrow Press,Lanham, MD, 1998. US$45.00.

One important aspect of gemology isthe history of gemstones. Unfor-tunately, a wealth of early workshave been lost to modern gemolo-gists, as evidenced by the number ofgem references cited in Pliny’s first-century encyclopedia that have disap-peared without a trace. Althoughmuch of the knowledge possessed byancient Greece and Rome was pre-served by Arabic writers, for the mostpart such works have remained inac-cessible to all but the very few west-ern scholars who have learnedArabic.

This compilation offers a fascinat-ing glimpse at ancient gemology,according to the book Best Thoughtson the Best of Stones, by Ahmad ibnYusuf al Tifaschi (1184–1254). Itstranslation marks the first time thatearly Arab gemological literature hasbeen studied by a modern Arabgemologist. Mrs. Huda is a compe-tent translator who has endeavoredto make the contents of this pioneer-ing work easily accessible to English-speaking readers. She aimed the bookat “all readers interested in geology,gemology, mineralogy, jewelry, histo-ry, Arab heritage, Islamic art, and thehistory of science.” In the reviewers’opinion, she has accomplished hergoals with great success. The book isclearly written in a straightforwardmanner that is easily understood,even by those readers for whomEnglish is a second language.

After an introduction by Dr. JohnSinkankas and a foreword by EricBruton, the book opens with a gener-al introductory chapter that brieflydiscusses early Arabic works on gem-stones. This part includes a glossaryof gem names in English with theirancient and modern Arabic namesand phonetic (English) equivalents.Mrs. Huda places al Tifaschi’s workin context by describing the era inwhich he wrote and the nature of theArabic literature on gems from theeighth to the 13th centuries. She pro-vides a two-page table of the gemo-logical terms used in the 13th centu-ry and explains the monetary terms,weights, and measures employed atthat time.

Next, a photocopy of the manu-script in Arabic is provided, followedby Mrs. Huda’s English translation ofal Tifaschi’s survey of 25 gemstones.The organization is very consistentthroughout. For each gemstone, alTifaschi briefly describes how thegem is formed; its localities, quali-ties, characteristics, benefits (mostlymedicinal and talismanic), andprices; and, in some cases, its lap-idary treatment. Each section closeswith a discussion by Mrs. Huda,which makes al Tifaschi’s text under-standable for the nongemologist andprovides rich grazing for the seriousgemologist.

The book is sturdy, measures 14 ×22 cm (51/2 × 81/2 inches), and is clearlyprinted on good-quality paper. Thereare only two illustrations: black-and-white photos of a turquoise Mamlukring and an almandine garnet mount-ed in gold. Neither is vital to the use-fulness of the book.

The book is remarkably free oftypos or errors. After diligent search,we found only one specific error,

probably a typo. On page 229, azur-malachite is defined by Mrs. Huda as“malachite intergrown with lazu-rite.” The term azurmalachite wascoined by George F. Kunz in 1907 fora banded mixture of azurite andmalachite.

The reviewers consider this animportant and unique addition to thegemological literature that deserves aplace on the shelf of every seriousgemologist.

SI and ANN FRAZIERLapidary Journal Correspondents

El Cerrito, California

L’EMERAUDE: CONNAIS-SANCES ACTUELLES ETPROSPECTIVES[The Emerald: Current andProspective Knowledge]Edited by Didier Giard, 235 pp.,illus., publ. by AssociationFrançaise de Gemmologie[[email protected]], Paris, 1998(softbound; in French, with partialEnglish translations). 350.00 FF(about US$57.00).

This attractive, lavishly illustratedvolume is a collection of 35 articlesand essays from 52 authors world-wide. Emphasized are developmentsin the study of emerald in the closingyears of the millennium. The book’seditor has collected articles on histo-ry/culture (8), geochemistry (1), inclu-sions (2), enhancement (3), synthesis(2), geology/mineralogy (3), specificdeposits (10—including Afghanistan,Australia, Brazil, Colombia, India,

Susan B. Johnson & Jana E. Miyahira, Editors

*This book is available for purchase throughthe GIA Bookstore, 5345 Armada Drive,Carlsbad, CA 92008. Telephone: (800)421-7250, ext. 4200; outside the U.S. (760)603-4200. Fax: (760) 603-4266.

BBooookk RReevviieewwss

64 Book Reviews GEMS & GEMOLOGY Spring 1999

Madagascar, Pakistan, Zambia, andZimbabwe), optics (1), and lapidary/jewelry (2), along with a bibliographyof 1990s works and abstracts of recentcontributions. An extensive table giv-ing the gemological properties ofemeralds from various deposits andthe principal types of synthetic emer-ald completes the text. There is nooverall index.

Of particular value are articles onthe use of infrared spectroscopy andlaser Raman microspectrometry, andthe use of oxygen isotopes for charac-terizing emeralds from specificsources. Also useful are articles onthe common practice of “oiling” orotherwise filling fractures with liq-uids or polymers. Other valuable arti-cles provide updated information onthe geology and origin, and mining,of the world’s major deposits. Manyother articles make for highly inter-esting and informative reading.Unfortunately, those on cuttingemeralds and setting them into jew-elry offer little of value, having beencovered already in far more thoroughpublications.

A “retrospective bibliography”for the years 1990–1997 appears nearthe end of the book but erroneouslylists the GIA Bookstore as the pub-lisher for several books (see, forexample, the listing for Bowersox andChamberlin, 1995). The bibliographyis apparently intended to provide anupdate on recent works. However,this reviewer would have liked to seesuch valuable sources of informationon the emerald and its literature as R.A. Dominguez’s Historia de lasEsmeraldas de Colombia (1965), I. A.Mumme’s The Emerald (1982), G. O.Muñoz and A. M. Barriga Villalba’sEsmeralda de Colombia (1948), A.Santos Munsuri’s La Esmeralda, LasGemas, y Otras Materias Preciosas(1868), and J. Sinkankas’s Emeraldand Other Beryls (1981) mentionedin some sort of preliminary bibliogra-phy.

As is often the case with booksassembled from articles by a numberof contributors, there is someunevenness in presentation. Also,

several articles on geochemistry,advanced identification techniques,and geology are beyond the compre-hension of readers not formally edu-cated in those sciences. Nevertheless,the whole hangs together very well,and provides a wealth of up-to-dateinformation that is not readily avail-able in any other single current publi-cation.

As a final note concerning thisimportant and valuable compilation,the addition of English summariesand translations of most of the arti-cles is a welcome feature, but a finalinspection by an English-languageeditor could have prevented certainawkward phrasings and spellings.

L’Emeraude is made from high-quality materials. Although a hard-cover version is not available, thebook is encased in a stiff papercover, with a matching black dustjacket.

JOHN SINKANKASPeri Lithon Books

San Diego, California

OTHER BOOKS RECEIVEDThe Great Encyclopedia of Preciousand Decorative Stones, by NikodemSobczak and Tomasz Sobczak, 422pp., illus., publ. by National SciencePublishers, Warsaw, 1998 (inPolish), US$20. This reference textdescribes “precious” and decorativestones, their imitations and synthet-ic counterparts, as well as artificialproducts that are used in decorativearts and jewelry. The opening sec-tion provides a 56-page backgroundon crystallography and the gemologi-cal and physical properties of gemmaterials. Next, nearly 350 pagescover specific gems and decorativematerials in alphabetical order.Complete listings of characteristicsare provided for the most importantstones, along with localities of ori-gin. The authors used academic thesesand periodicals published throughthe end of 1996 to write this ency-clopedia, which contains 264 color

photographs. They plan to publish anEnglish edition.

STUART D. OVERLINGemological Institute of America

Carlsbad, California

Larousse des Pierres Précieuses, byPierre Bariand and Jean-Paul Poirot,287 pp., illus., publ. by Larousse-Bordas, Paris, 1998 (in French), 250.00FF (about US$42.00).* Updated andexpanded (see the Spring 1986 Gems& Gemology, pp. 65–66, for a reviewof the first edition), this Larousse isintended for a general audience. Itsopening section, History and Qualitiesof Gems, is a 60-page overview of gemhistory, symbolism, origins, sources,properties, imitations and synthetics,identification techniques, and classifi-cation. At the heart of this Larousse isits Dictionary section, where the read-er will find more than 200 entries ongemstones and other gem materials,in different levels of detail, accompa-nied by dozens of excellent color pho-tographs by Nelly Bariand. Theremaining portion is an Appendix thatcontains a glossary, a comprehensivebibliography, a listing of museumswith major gem collections, and atable of gem characteristics. SDO

Standards & Applications for DiamondReport/Gemstone Report/Test Report,by SSEF Swiss Gemmological Insti-tute, 118 pp., illus., publ. by SSEF,Basel, Switzerland, 1998, US$65.00.This monograph was written to clari-fy the SSEF Swiss GemmologicalInstitute’s full gem treatment disclo-sure policy. It provides several exam-ples of the Institute’s various testreports and describes how differentgem treatments are evaluated. Thefirst section, an overall statement ofthe laboratory’s policy and standards,is followed by two chapters devotedto colorless and colored diamonds,respectively. Subsequent chapterssummarize ruby, sapphire, and emer-ald individually, while chapter 8 dis-cusses other gemstones. The manualcloses with a chapter on pearls andcultured pearls. SDO

Gemological Abstracts GEMS & GEMOLOGY Spring 1999 65

COLORED STONES AND ORGANIC MATERIALSBlack is beautiful. A. Lohr, Hawaii Business, Vol. 43, No.

9, March 1998, pp. 68–69.Several Hawaiian jewelry companies are reaping the ben-efits of the current upswing in U.S. consumer demand forTahitian black pearl jewelry. According to many in thetrade, this demand is fueled by the successful advertisingcampaign for Elizabeth Taylor’s “Black Pearls” perfume.

One company, Steven Lee Designs, struggled toincrease market share until the company’s namesakebegan incorporating black pearls into his jewelry designs.The first year after this change, the company’s sales morethan doubled. Now, Lee says, about 80% of his company’sbusiness is black pearl jewelry.

Another company that has experienced a dramaticsales increase is Tahitian Midnight Pearls. Although thiswholesale pearl supply company is based in Tahiti, itssales office is located in Hawaii. The president of the U.S.division states that his company experienced a 13-foldincrease in pearl sales between 1995 and 1997. The com-pany currently sells about 70% of its pearl inventory tothe U.S. market.

This same story is repeated for many successfulHawaiian jewelry companies that have turned to blackpearls to expand their market and attract new customers.

SW

This section is designed to provide as complete a record as prac-tical of the recent literature on gems and gemology. Articles areselected for abstracting solely at the discretion of the section edi-tor and his reviewers, and space limitations may require that weinclude only those articles that we feel will be of greatest interest to our readership.

Requests for reprints of articles abstracted must be addressed tothe author or publisher of the original material.

The reviewer of each article is identified by his or her initials at theend of each abstract. Guest reviewers are identified by their fullnames. Opinions expressed in an abstract belong to the abstrac-ter and in no way reflect the position of Gems & Gemology or GIA.

© 1999 Gemological Institute of America

AbstractsGemological

EDITORA. A. Levinson

University of Calgary, Calgary,Alberta, Canada

REVIEW BOARD

Anne M. BlumerBloomington, Illinois

Peter R. BuerkiGIA Research. Carlsbad

Jo Ellen ColeGIA Museum Services, Carlsbad

Maha DeMaggioGIA Gem Trade Laboratory, Carlsbad

Michael GrayCoast to Coast, Missoula, Montana

R. A. HowieRoyal Holloway, University of London

Mary L. JohnsonGIA Gem Trade Laboratory, Carlsbad

Jeff LewisGIA Gem Trade Laboratory, Carlsbad

Margot McLarenRichard T. Liddicoat Library, Carlsbad

Elise MisiorowskiLos Angeles, California

Jana E. Miyahira-SmithGIA Education, Carlsbad

Carol M. StocktonAlexandria, Virginia

Rolf Tatje Duisburg University, Germany

Sharon WakefieldNorthwest Gem Lab, Boise, Idaho

June YorkGIA Gem Trade Laboratory, Carlsbad

66 Gemological Abstracts GEMS & GEMOLOGY Spring 1999

Emerald chemistry from different deposits: An electronmicroprobe study. I. I. Moroz and I. Z. Eliezri,Australian Gemmologist, Vol. 20, No. 2, 1998, pp.64–69.

Twenty-six natural emeralds—from 11 mining districtsin nine countries—and three hydrothermally grown syn-thetic emeralds were analyzed nondestructively with anelectron microprobe. Multiple analyses were obtained,particularly for color-zoned crystals, resulting in a total of219 analyses for 16 elements.

The emeralds from “schist-type” occurrences inAustralia, Brazil, Mozambique, Russia, Tanzania, andZambia showed relatively high concentrations of magne-sium (0.7–3.1 wt.% MgO), iron (0.3–1.8 wt.% FeO), andsodium (0.2–2.8 wt.% Na2O). In contrast, Colombian andNigerian emeralds showed low contents of magnesium(<0.76 wt.% MgO) and sodium (<0.67 wt.% Na2O). Thesynthetic emeralds had chemical characteristics similarto those of natural stones from Colombia and Nigeria.

Kyaw Soe Moe

Indonesian Pearl Report. Jewellery News Asia, No. 171,November 1998, pp. 50–68 passim.

This compilation of seven short articles concerns thestate of pearl production in Indonesia. It provides insightinto the country that may challenge Australia’s positionin the global South Seas pearl market in the new millen-nium. Indonesia produced about 200–220 kan—equal toapproximately 30% of the world’s white South Seapearls—in 1998 [1 momme = 3.75 g; 1000 momme = 1kan]. The expected annual growth is about 15%.

Currently, the Indonesian pearl industry is profitingfrom low labor costs for unskilled workers, which areabout one-tenth of those in Australia (skilled employeesare paid salaries comparable to those in other countries).Also aiding the Indonesian expansion is the fact thatthere are few restrictions on investing in the pearl indus-try. This has encouraged pearl companies from othercountries to invest, and set up farms, in Indonesia. Withsuch rapid growth, the Indonesian Pearl CultureAssociation has suggested a system to regulate newpearling licenses to prevent overcrowding and pollution.The report includes overviews on several companies thatare currently culturing pearls in Indonesia. JEM-S

Opal report. C. Dang, Jewellery News Asia, No. 171,November 1998, pp. 74, 76–77, 80, 82–86.

The three articles in this report are based on interviewswith several opal manufacturers and suppliers, and pre-sent a picture of the global market for loose opals and opaljewelry; information on manufacturing of Peruvian opalis also supplied.

According to opal suppliers, sales of calibrated opalunder $300 have increased in the U.S., where demand ishigh for black opal and boulder opal with blue and greenplay-of-color. This type of opal sells best in the 3–10 ct

category, for stones under $100 each. Also popular is fireopal, which wholesales for $10 to $20 per carat, and cali-brated white opal, which wholesales for under $300 percarat. Demand in Europe is mostly for black and boulderopal in ovals and freeforms from 1 to 5 ct, priced between$100 and $300 each. In Asia, demand is mainly fromJapan, Taiwan, and Singapore for calibrated stones pricedbetween $2 and $5 per carat; there is also some demand,mainly in Japan, for top-quality stones up to $90,000each. The Olympic Games scheduled for 2000 in Sydney,Australia, are expected to increase sales of opal in thatcountry, because the Australian government is promot-ing opal as the national gemstone.

Opal jewelry suppliers report that sales of opal jewel-ry are growing in the U.S., Europe, and Asia. In the U.S.,demand is strong for 9–18K gold earrings, rings, bracelets,and pendants that are set with black opal or boulder opal;wholesale prices for these items range from $200 to$2,000. In Europe, most popular are black opal and boul-der opal (in oval and freeform shapes), set in yellow andwhite gold and platinum; prices range from $200 to$10,000 depending on size and quality. The largest mar-ket for opal jewelry in Asia remains Japan, even after anapproximately 40% drop in sales in 1998 compared with1997. Leading the demand are pieces with black, boulder,white, or fire opal in prices under $500, as well as muchmore expensive pieces from $50,000 to $60,000. Somemanufacturers report increased sales of opal doublets andtriplets. For example, demand is high in the U.S. for pen-dants, earrings, rings, and bracelets in 14K gold with 1–4ct doublets, particularly with a green play of color, atprices below $100.

Peruvian opal has recently been introduced by GallantGems, Hong Kong, and is being marketed in the U.S.,Germany, Switzerland, and Japan. Polished stones infreeform shapes, cabochons, and beads of various sizeswholesale from $0.50 to $3,000 per carat depending onquality. Gallant, which supplies Peruvian opal in pink,green, or blue, has developed a special cutting techniquefor the material, which has a different hardness from opalmined elsewhere. MD

Pearl identification. S. J. Kennedy, Australian Gemmologist,Vol. 20, No. 1, 1998, pp. 2–19.

Pearl identification and testing is a specialized disciplinethat requires sophisticated instrumentation and consid-erable experience. This well-illustrated article describesthe equipment and procedures used at the Gem TestingLaboratory of Great Britain in London. After providingdefinitions of many pearl terms (e.g., natural pearls,nacre, conchiolin, orient, nucleated cultured pearls, non-nucleated cultured pearls), the author describes the labo-ratory’s pearl-testing procedures. Visual examination isused to determine external features (e.g., color, luster,shape, and surface characteristics), as well as internal fea-tures seen within drill holes. When examined with 10×

magnification, imitations are easily detected by theirgrainy surface texture. All pearls (including necklaces)submitted to the laboratory are also checked with X-radi-ography for details of their internal structure (e.g., thepresence or absence of a bead nucleus) that, when com-bined with visual observations, are necessary for deter-mining whether a pearl is natural or cultured. X-ray lumi-nescence and X-ray diffraction techniques are employedfor special situations.

The article contains much useful information. Forexample, natural pearl necklaces are almost always grad-uated; if a cultured pearl necklace is graduated, the colormatch between pearls is usually much better than in anatural pearl necklace. The greatest challenge in pearltesting is differentiating natural pearls from tissue-nucle-ated cultured pearls. When this situation arises, two X-radiographs are taken in mutually perpendicular direc-tions. If growth lines are present within the gray area inthe center of the sample, the pearl is probably natural. Aneven, or somewhat patchy, center that is a slightly darkergray indicates the presence of a cavity. If that cavity isirregular in shape and relatively small, then the sample isa tissue-nucleated cultured pearl; however, if the outlineof the cavity roughly follows the contours of the externalshape of the sample, it is probably a natural pearl.

MD

Pearls in the making. A. Mercier and J.-F. Hamel, IslandsBusiness, Vol. 24, No. 4, April 1998, pp. 16–17.

A pearl project was recently established in the SolomonIslands (South Pacific Ocean), to (1) assess the potentialfor pearl culturing in this venue and (2) study the biolo-gy of the blacklip pearl oyster (Pinctada margaritifera) inorder to protect the remaining natural stocks. The pro-ject is a collaborative venture between the InternationalCentre for Living Aquatic Resources Management(ICLARM) and the Solomon Islands Fisheries Division.

The center of this intensive study was the seeding ofnearly 2,000 blacklip oysters in September 1997 at aresearch facility located on the small island of Nusa Tupe.Harvesting of this first batch of cultured pearls was sched-uled for March 1999.

Researchers indicate that prospects for establishing aprofitable pearl-culturing industry in the WesternProvince of the Solomon Islands are promising. SW

Rossmanite, (LiAl2)Al6(Si6O18)(BO3)3(OH)4, a new alkali-deficient tourmaline: Description and crystal struc-ture. J. B. Selway, M. Novák, F. C. Hawthorne, P.Cerny , L. Ottolini, and T. K. Kyser, AmericanMineralogist, Vol. 83, No. 7–8, 1998, pp. 896–900.

Rossmanite is a new tourmaline species, the type locali-ty being the Hradisko quarry of the Rozná pegmatite,western Moravia, Czech Republic. This is also the typelocality for lepidolite, which was first discovered over 200years ago, in 1792. Chemically, rossmanite is classified as

a lithium-aluminum tourmaline, along with elbaite andliddicoatite. The distinction between the three species isbased on the element occupancy in the “X” site: sodiumfor elbaite, calcium for liddicoatite, and predominantlyvacant (i.e., alkali-deficient, represented by “ ” in thechemical formula) for rossmanite. It occurs as pinkcolumnar crystals with striations on the prism faces par-allel to the c-axis. Indices of refraction are ω = 1.645 andε = 1.624, and the specific gravity is 3.06.

Rossmanite is indistinguishable from elbaite, themost important gem tourmaline species, by standardgemological techniques; it can be identified only bychemical analysis. The species is named after ProfessorGeorge R. Rossman of the California Institute ofTechnology, Pasadena, in recognition of his wide-rangingcontributions to mineralogy in general, and to the tour-maline group of minerals in particular. [Abstracter’s note:Rossmanite is now known from other pegmatites in theCzech Republic, Canada, Italy, and Sweden; see GemNews, Fall 1998 Gems & Gemology, p. 230.] AAL

Special emerald report. W. Lau, Jewellery News Asia, No.167, July 1998, pp. 43–52 passim; No. 168, August1998, pp. 56–70 passim; No. 169, September 1998,pp. 157–168 passim.

The worldwide emerald industry is suffering primarily fortwo reasons: a slowdown in the Asian economy and con-fusion over emerald treatments. About 60%–65% of theworld’s emerald rough comes from Colombia. In June1998, a new organization, PSICEJ (Promotional Societyfor the International Center for Emeralds and Jewelry)was established by the Colombian government and tradegroups to revitalize exports and improve the image ofemeralds to the trade. The description of this organiza-tion, its objectives, and its support for a proposed “emer-ald center” in Bogotá (which would include a bourse, agemological laboratory, lapidaries, and educational andconference facilities) sets the stage for this three-part col-lection of articles covering the entire industry from min-ing to retailing. Most of the emphasis is on the industryas seen from the Colombian perspective, but some atten-tion is also paid to new deposits in Brazil and to the pos-itive implications of Zambia’s recent liberalization ofmining regulations.

The various articles contain a wealth of information(but with some inconsistencies from one entry to thenext) about the Colombian industry. For example, anestimated 500,000 workers are employed in all aspects ofthe industry; the finest gem material comes from Muzoand Chivor, but Cosquez presently has the greatest (77%by weight) production; and of the total 1997 exports,rough emeralds accounted for 85% by weight but only1.7% by value, whereas polished emeralds accounted for15% by weight and 98.3% by value.

Emerald wholesalers from several countries giveinsight into their businesses, including the qualities andsizes in which they specialize, the efforts they use to


restore consumer confidence, and the latest markettrends for the countries in which they deal. Another high-light is the nature of emerald fillings (e.g., resins, Opticon,and cedarwood oil), and the advanced analytical methodsby which these fillings are identified by the SSEF SwissGemmological Institute in Basel. Overall, these articlesare realistic with respect to the present state of theworld’s emerald trade and decidedly positive about thefuture. MM

Sweet Home rhodochrosite—What makes it so cherryred? K. J. Wenrich, Mineralogical Record, Vol. 29,No. 4, 1998, pp. 123–127.

Rhodochrosite (MnCO3) crystals from the Sweet Homemine, Colorado, were analyzed to ascertain the differ-ences between the pink rims and the “gemmy” red cores.Microscopic observation revealed that the red cores aretransparent, while the pink rims contain numerous solidand fluid inclusions. Crystal and inclusion relationshipssuggest that the transparent red core formed first, at ahigher temperature than the pink rim that subsequentlyovergrew it.

Electron microprobe analyses were conducted on 127specimens to measure 28 chemical elements. The resultsfor Fe+Mg+Ca, which can substitute for Mn in the crystalstructure of rhodochrosite, are most important. Fe+Mg+Camake up <1 atomic percent in the red (transparent)rhodochrosite, compared to 2–7 atomic percent in the pinkrims. Relatively high Fe contents are responsible for thecoloration of lower-quality pink rhodochrosite. Gem-qual-ity red rhodochrosite from the Sweet Home mine is chem-ically the “purest” on record. These results will help nar-row the search for gem quality crystals to those areas in themine with low Fe+Mg+Ca geochemical signatures.[Editor’s note: For more information on rhodochrosite fromthis locality, see K. Knox and B. K. Lees, “Gemrhodochrosite from the Sweet Home mine, Colorado,”Summer 1997 Gems & Gemology, pp. 122–133.] JL

Troubled waters. D. Ladra, Colored Stone, Vol. 11, No. 4,July-August 1998, pp. 14–19.

Analysis of trade figures for the period 1992–1996 indi-cates that there is a healthy consumer demand for pearls,as the value of world consumption was US$3.7 billionover this five-year period. However, world productionduring this time amounted to US$2.5 billion, so supply isnot keeping up with demand. This is due to the dwin-dling supply of natural pearls, as well as to the decline incultured pearl production in Japan (where widespreadoyster deaths are being attributed to a parasitic infectionor virus). Although there are pearl fisheries throughoutthe world, Asian countries supplied 96.1% of theunworked cultured pearls, 78.6% of the worked culturedpearls, and 53.7% of the natural pearls that entered theworld markets in the 1992–1996 period; cultured pearlsaccounted for at least 90% of the total production. Of the

Asian producers, Japan, Australia, China, and Indonesiawere the biggest suppliers of cultured pearls, while Indiaprovided 15% of the world’s natural pearls. Interestingdetails, including statistics, are given for the industries inJapan, China, and the South Seas (mainly Australia andthe Philippines).

Projections to the year 2001 indicate dramatic increas-es (on the order of 150% in US$ terms) in the worldwideproduction of cultured pearls over 1997, but a decline of40% for natural pearls. Nevertheless, the imbalancebetween supply and demand is expected to grow, creatingample opportunity for investment in pearl culture. AMB

Turquoise: Blue sky . . . Blue stone. B. Jones, Rock &Gem, Vol. 28, No. 6, June 1998, pp. 13–15.

This article is concerned primarily with turquoise fromthe Southwestern United States, where it has beenrevered since ancient times by Native Americans, as evi-denced by the large amounts found at diggings at ChacoCanyon (New Mexico) and elsewhere. It is found ingravesites and is known to have been traded with coastaltribes. Today, it has worldwide appeal.

Geologically, turquoise is a secondary mineral thatforms in a weathering environment; its occurrence is dueto the availability of essential aluminum (from feldspars)and phosphorus (from apatite), and it is commonly asso-ciated with weathered copper deposits. The beautiful sky-blue color is modified toward a less desirable green colorwith the incorporation of iron into the crystal structure.However, when iron occurs as black-to-red infillings ofiron oxide, the popular “spiderweb” pattern results.

As gem-grade turquoise supplies have dwindled, theprice for the finest material has sharply increased. Also,lower-quality material has been routinely treated toenhance its durability and/or color. One stabilizationprocess, developed by Colbaugh Processing Co. in the1950s, brings out the natural color of lower-gradeturquoise while giving it sufficient hardness and strengthto survive lapidary treatment. The turquoise is dried byintense and prolonged heating, infused under pressurewith epoxy, sealed in small metal containers, and cooledvery slowly; the entire process takes months.

Turquoise was once easily obtained from copperdeposits by amateurs, since it had no ore value. Today,however, most turquoise mined in the U.S. is obtained bycontractors who have arrangements with the large coppercompanies operating open pit mines in Arizona. Rarelycan an individual collect good rough on his or her own.

MD

DIAMONDSArgyle’s tale: The making of a mine. M. Hart, Rapaport

Diamond Report, Vol. 21, No. 30, August 7, 1998,pp. 30, 32.

Although a few alluvial diamonds were found in the


Pilbara district of Western Australia in the 1890s, it wasnot until October 2, 1979, that the huge AK1 pipe, whichwould become the Argyle mine, was discovered in the farnorth region of Western Australia. The AK1 pipe mea-sures 2 km long, ranges from 150 to 500 m in width, andcovers 45 hectares (about 111 acres). The mine is ownedand operated by Argyle Diamond Mines Pty. Ltd. (owned57% by Rio Tinto plc of London, 38% by Ashton MiningLtd., and 5% by WA Diamond Trust). Although thedeposit is massive, its diamonds are generally small andof low value (average about $7 per carat), but these factorsare offset by its high grade (6 carats/ton of ore when pro-duction started in 1986); it currently produces about 40million carats annually. Future production will dependon the grade of the ore and the mine’s ability to maintainefficient production. Argyle operates an in-house dia-mond-sorting facility, and nonunion work is farmed outto subcontractors, thus avoiding the characteristic laborpitfalls of many mines. MM

Argyle extends open pit. Diamond International, No. 54,July-August 1998, pp. 15–16.

Rio Tinto and Ashton Mining, the owners (together withthe Australian government) of the Argyle diamond minein Western Australia, have approved the expansion of theAK1 open pit mine, and the work has already begun. Toaccess an additional 17.6 million tonnes of open-pit ore atan average grade of 2.58 carats per tonne, pre-stripping ofaround 100 million tonnes of waste is required. The min-ing reserve at AK1 is estimated at 64 million tonnes.Underground development of the mine still remains apossibility at a later date. MM

Argyle succeeds selling full annual production: No inven-tory growth. Mazal U’Bracha, Vol. 15, No. 197,November-December 1998, pp. 48–49.

Whereas the world market for more-expensive diamondjewelry has been hampered by the present state of theAsian economies, the demand for cheaper polished goodscut in India has remained steady. Australia’s Argyle mine,a major supplier of rough to the Indian cutting centers,sees a continuing trend to “trade down” as consumerssearch for value. With the greater demand for jewelrywith diamonds of lower quality, the Argyle product con-stitutes a growing market niche. For the first half of 1998,Argyle saw stronger prices and record sales for its rough;there was no growth in inventory. The alliance betweenArgyle and the Indian diamond industry is pivotal toArgyle’s success. Argyle supports all efforts, includingsigned agreements with its Indian customers, to preventthe use of child labor in diamond manufacturing.

The United States and Japan are the major consumermarkets for Argyle-type (i.e., low-quality “Indian goods”)diamonds. On a weight basis, such diamonds account for62% and 68%, respectively, of these countries’ sales ofstones smaller than 0.17 ct. AAL

The diamond pipeline into the third millennium: Amulti-channel system from the mine to the con-sumer. M. Sevdermish, A. R. Miciak, and A. A.Levinson, Geoscience Canada, Vol. 25, No. 2,1998, pp. 71–84.

Canada is poised to become one of the world’s significantproducers of gem-quality diamonds. It is anticipated that,by 2002, Canada will produce about 10% (by weight) ofthe world’s rough diamonds. This new resource requiresthat Canada develop expertise in various economicaspects of the diamond industry, particularly in market-ing the rough. This article explores the dynamics of the“diamond pipeline” for distributing and marketing dia-monds in the late 1990s.

Historically, the majority of diamond rough proceededfrom mine to consumer via a single-channel pipeline con-trolled by the Central Selling Organisation (CSO), a whol-ly owned company of De Beers Consolidated Mines, Ltd.The CSO’s mission is to maintain equilibrium betweensupply and demand, which then translates to price stabil-ity. Two recent events significantly affected this balance.After the dissolution of the Soviet Union in the early1990s, the Russians began selling significant quantities oftheir diamond rough outside the CSO pipeline. Then, in1996, the Argyle mine in Australia did not renew its con-tract with De Beers and began marketing all of its pro-duction independently.

These departures from the traditional distribution andmarketing strategy have led to the current multi-channeldiamond pipeline, which consists of three parallel chan-nels for distribution and marketing: the Traditional GemChannel, the Indian Channel, and the emerging RussianChannel. The Traditional Gem Channel consists of thegenerally higher-value production that remains in the for-mer single-channel system. The authors estimate thatabout 50% of the world’s retail diamond jewelry salesresult from this channel. The Indian Channel is the con-duit for small and low-quality diamonds. Production thatenters this channel originates both with the CSO and fromthe open market, including Argyle and Russian stones.About 50% of the diamond jewelry sold at retail world-wide contains stones that have traversed this channel.

The authors also postulate the existence of a dis-cernible Russian Channel. This channel, though, is stillevolving through conflicting economic and politicalinterests. Approximately 25% of the world’s diamondsare mined in Russia, but at present only a small portionof these stones are routed through the Russian Channel.The impact of these changes on the traditional marketingof rough diamonds provides additional options forCanada’s emerging diamond industry. SW

A gem of a mine. South African Mining, Coal, Gold &Base Minerals, May 1, 1998, pp. 10, 15, 17.

This relatively short article gives a good general overviewof the De Beers Finsch diamond mine in the northern part


of Cape Province, South Africa, from the original prospec-tors looking for asbestos in 1957 through plans for blockcaving in 2003.

Finsch Diamonds was established in 1961, and miningbegan soon after. In 1978, after bench mining in the openpit to a depth of 423 m, underground mining commenced.By 1990, work in the open pit had stopped completely. Todate, the plant has treated more than 95 million tons ofore, yielding about 78 million carats of diamonds. Themine had a recovered grade of 58 carats per hundred tonsin 1997. Among South African diamond mines, theFinsch pipe—at about 500 m in diameter and 18 hectares(44 acres) in surface area—is second in size only to thePremier pipe.

The kimberlite is mined using a modified blast hole,open stoping method. At the treatment plant, the ore getsscrubbed, crushed, washed, and screened to size the mate-rial. A dense media separation is followed by X-ray sepa-ration of the diamonds, which are then sent to a sortingfacility. The article is illustrated with an informative flowchart of the treatment plant and a graphic model thatexplains block caving. Thomas Gelb

India bounces back. Diamond International, No. 55,September-November 1998, pp. 57–60, 62.

After two years of decline, Indian exports of cut and pol-ished diamonds for 1997-98 (financial year ending March31) jumped 6% over the previous year in terms of bothvalue (to $4.493 billion) and weight (to 20.6 millioncarats). Thus, India’s share of the global trade in polisheddiamonds is 40% in terms of value and 80% in terms ofweight, the highest ever. Much of this is a reflection ofreduced sales of better-quality rough by De Beers and thusa decline in more-expensive diamonds on the world mar-ket. Import of diamond rough amounted to a staggering115 million carats—about equal to the total currentworld rough production. The euphoria is not without itspressures, however. For example, the average price real-ized for Indian-cut diamonds (i.e., predominantly near-gems) has declined 31% from its 1990–91 peak (the aver-age was $218 per carat in 1997-98). There is also concernabout a steady supply for rough diamonds in the currentmulti-channel pipeline. Extended credit demands (up to150–160 days) by overseas buyers, meanwhile, have haddetrimental effects on cash flow.

Nevertheless, the Indian diamond industry is opti-mistic. It feels that new technology, continued govern-ment cooperation (e.g., simplified customs and bankingprocedures), and increased exports of diamond-set jewel-ry (which already accounts for 15% of the country’s gemand jewelry exports) will enable the industry to continueits expansion. Government estimates show a 12%increase in exports per annum through 2002. This is con-sistent with the prediction by one diamantaire that with-in 10 years India—in addition to its monopoly in near-gem stones—will process 50%–75% of the goods in the

“medium” range and 10%–20% of gem-quality dia-monds. At this level, India would command 60% (byvalue) of the global trade in polished diamonds.

AAL

India’s GJEPC claims negligible level of child labor inIndian diamond industry. Mazal U’Bracha, Vol. 15,No. 106, October-November 1998, pp. 67–70.

The illegal use of child labor in underdeveloped countriesis a highly sensitive and significant issue; in the past,some components of India’s diamond industry have beenimplicated in this tragedy. India’s Gem and JewelleryExport Promotion Council (GJEPC) is concerned aboutthis matter, not only from a humanitarian perspective,but also because of the negative effects of what it consid-ers adverse and exaggerated press reports. Since 1995,GJEPC has been intensifying its anti-child-labor cam-paign with success.

An independent survey conducted in June 1998showed that the incidence of child labor (i.e., workersyounger than 14 years old) in the Indian diamond indus-try has declined significantly from 1994–95, when thelast survey was conducted. Presently, child labor repre-sents 0.16% of the work force in the “organized sector”(i.e., larger, better-equipped factories, and generally goodworking conditions), and 1.47% in the “semi-organizedsector” (i.e., medium to low technology, and satisfactoryto poor working conditions). The wages for these cate-gories are US$59–$95 per month and $35–$71 per month,respectively. On the basis of statistics from 659,550 work-ers, the child labor rate for the entire diamond industry inIndia is 0.89% (compared to 3.18% during 1994–95).GJEPC’s goal is to bring this down to zero. AAL

Nucleation environment of diamonds from Yakutiankimberlites. G. P. Bulanova, W. L. Griffin, and C. G.Ryan, Mineralogical Magazine, Vol. 62, No. 3,1998, pp. 409–419.

A detailed study of mineral inclusions in the genetic cen-ter [nucleation point] of single crystals of Yakutian dia-monds, which was undertaken to gain insight into thegrowth environment of diamond crystals, shows thatmost of the diamonds nucleated on mineral “seeds.” Inperidotitic diamonds, the most common central inclu-sion is Mg-rich olivine; in eclogitic diamonds, pyrrhotiteand omphacite (a clinopyroxene) are most abundant. Theminerals identified as the central inclusions of Yakutiandiamonds indicate that the diamonds grew in a reducedenvironment, with ƒO2 [oxygen fugacity] controlled bythe iron-wüstite equilibrium. The data imply that dia-mond nucleation took place in the presence of a fluid,possibly a volatile-rich silicate melt, that was highlyenriched in large-ion lithophile elements (e.g., K, Ba, Rb,and Sr) and high field-strength elements (e.g., Nb, Ti, andZr). This fluid also carried immiscible Fe-Ni-sulfidemelts, and possibly a carbonatitic component. RAH


An oscillating visible light optical center in some naturalgreen to yellow diamonds. I. M. Reinitz, E. Fritsch,and J. E. Shigley, Diamonds and Related Materials,Vol. 7, 1998, pp. 313–316.

Most natural- and treated-color green diamonds are col-ored by exposure to ionizing radiation, which manifestsitself as an absorption peak at 741 nm (associated withthe GR1 center). Of the [approximately 3,000] colored dia-monds seen by GIA researchers in the last decade, 10green-to-yellow stones—which would be expected toproduce a GR1-related absorption spectrum—insteadshowed many peaks in their UV-visible absorption spec-trum when chilled to liquid nitrogen temperatures. Theauthors list 38 peaks between 543 and 761 nm, which canbe divided into two series: one centered around 620 nmwith 202 cm−1 spacing between the peaks, and the othercentered around 700 nm with 169 cm−1 spacing.

All 10 stones showed weak nitrogen-related featuresin the mid-infrared, including those related to single sub-stitutional nitrogen, as well as features related to hydro-gen impurities in the diamonds. The authors believe thatthe unique structure of the UV-visible absorption patternis related to a molecule or molecular ion impurity, withmore than one energetically accessible state at liquidnitrogen temperature. However, the absorption peaks donot match those for any known simple molecule (or ion)containing carbon, nitrogen, and/or hydrogen. This low-temperature absorption spectrum has only been seen innatural-color diamonds. MLJ

Trace element composition and cathodoluminescenceproperties of southern African kimberlitic zircons.E. A. Belousova, W. L. Griffin, and N. J. Pearson,Mineralogical Magazine, Vol. 62, No. 3, 1998, pp.355–366.

Zircon (ZrSiO4) commonly occurs in felsic granitoidcrustal rocks, and more rarely in mafic rocks such as kim-berlite pipes (which are of mantle origin). Individual zir-con crystals are geologically long-lived in alluvial envi-ronments. This study assesses whether or not kimberliticzircons exhibit unique characteristics that can aidprospectors in the search for diamondiferous pipes. Fifty-one zircons (0.5–6 mm) were taken from 12 southernAfrican pipes. The authors used cathodoluminescence(CL) to observe the crystal structure and laser ablationinductively coupled plasma-source mass spectrometry(ICPMS) to examine the chemistry of the zircons. WithCL, the kimberlitic zircons appeared dominantly blue, incontrast to crustal zircons, which (in the authors’ experi-ence) are yellow. The authors suggest that higher concen-trations of trace elements in crustal zircons lead to morecrystal lattice defects, which cause the dominance of yel-low CL hues. This hypothesis is supported by the ICPMSdata, which showed a concentration difference betweenyellow and blue CL zircons of up to two or three orders ofmagnitude for some trace elements. When the zircons are

plotted on trace-element discrimination diagrams, thekimberlite and crustal zircons each plot in their own dis-tinct groups. The authors conclude that the distinctiveCL and geochemical characteristics of the kimberlite zir-cons allow their use as prospecting tools. JL

GEM LOCALITIESApplication of graphite as a geothermometer in

hydrothermally altered metamorphic rocks of theMerelani-Lelatema area, Mozambique Belt, north-eastern Tanzania. E. P. Malisa, Journal of AfricanEarth Sciences, Vol. 26, No. 2, 1998, pp. 313–316.

In the Merelani-Lelatema tanzanite and green garnetmining area in Tanzania, the graphite-bearing host rocksunderwent regional high-temperature metamorphism,followed by hydrothermal alteration. Since the formationof graphite in metamorphic rocks is mainly a function oftemperature, this study sought to use graphite to deter-mine the highest temperatures reached during the region-al metamorphic event.

X-ray diffraction analyses of the graphite wereapplied to a preexisting temperature calibration curve.Regionally, the metamorphic temperatures for thegraphite ranged from 523°C to 880°C. Graphite samplesspecifically from tanzanite-bearing hydrothermal depositsyielded a temperature range of 690°C–715°C. This rangeis higher than that estimated from fluid inclusions in thetanzanite (390°C–444°C), and supports previous observa-tions that the tanzanite did not coexist with the graphiteduring the high-temperature regional metamorphism.Rather, the tanzanite was introduced later by hydrother-mal solutions through fault zones. JL

Gemstone bonanza at Yogo Gulch. S. Voynick, WildWest, Vol. 11, No. 1, June 1998, pp. 36–41, 81.

This article describes the historical events and fascinat-ing people involved in sapphire mining at Yogo Gulch,Montana. It travels in time from Jake Hoover’s discoveryof the translucent blue stones at Yogo Creek in 1895,through the mine’s numerous British and American own-ers, to the current owner, Roncor Inc. Dr. George F. Kunz,of Tiffany & Co., originally confirmed the identity of theblue pebbles from Jake Hoover’s sluice box as “sapphiresof unusual quality.” Jake Hoover stayed involved, even-tually taking on partners, until 1897, when he sold hisquarter share to his partners for $5,000 so he could jointhe Alaskan gold rush. Two months later, British inter-ests purchased his share for $100,000.

Production at Yogo started in 1896 and continuedalmost without interruption until July 1923, when a flashflood destroyed the mine infrastructure. From 1898through 1923, the Yogo dike yielded 16 million carats ofrough sapphire, resulting in 675,000 carats of fine blue cutsapphire worth $25 million. Charles T. Gadsden, appoint-ed mine supervisor in 1902, resided at Yogo from 1903


until his death in 1954, even though the mine (locallyknown as the English mine) had been inactive for morethan 30 years.

In 1956, Yogo returned to American ownership. Sincethen there has been only minor, intermittent production,by a variety of American owners and lessees, none ofwhich has had significant success. While mining hasnever progressed deeper than 250 feet (about 77 m), it isbelieved that the dike exceeds a mile (1.6 km) in depthand contains reserves estimated at 40 million carats ofgem-quality rough sapphire. [Editor’s note: For furtherdetails, see K. A. Mychaluk, “The Yogo sapphire deposit,”Spring 1995 Gems & Gemology, pp. 28–41.]

Kim Thorup

Geological evolution of selected granitic pegmatites inMyanmar (Burma): Constraints from regional set-ting, lithology, and fluid-inclusion studies. K. Zaw,International Geology Review, Vol. 40, No. 7,1998, pp. 647–662.

Pegmatite veins and dikes 2–5 m wide and 30–150 m longcommonly occur along a 1,500-km-long, north-to-southtrending belt of tungsten- and tin-bearing granitoids inMyanmar (Burma). Five pegmatites (Sakangyi, Gu Taung,Payangazu, Taunggwa, and Sinmakhwa) are described indetail. Gem minerals found in these pegmatites includetourmaline, beryl (aquamarine), and topaz. The peg-matites show distinct internal mineralogic zoning, withfelsic minerals (e.g., feldspar and muscovite) more abun-dant in the core, and quartz and schorl tourmaline moreabundant in the outer zones. As determined by fluid-inclusion microthermometry, the pegmatites formed at230°C–410°C. The Na/K ratio of fluid inclusions indi-cates the presence of substantial potassium in the peg-matite-forming fluids; no evidence was observed forphase separation of these fluids. Troy Blodgett

Geological setting and petrogenesis of symmetricallyzoned, miarolitic granitic pegmatites at Stak Nala,Nanga Parbat-Haramosh Massif, NorthernPakistan. B. M. Laurs, J. D. Dilles, Y. Wairrach, A.B. Kausar, and L. W. Snee. Canadian Mineralogist,Vol. 36, Part 1, 1998, pp. 1–47.

In the early 1980s, bi- and tri-colored tourmalines up to10 cm in length were discovered in “pockets” (miaroliticcavities) in granitic pegmatites in the Stak Valley ofnorthern Pakistan. Of the nine pegmatites in this area,only one has been mined economically, from which tensof thousands of crystals have been recovered; at present,production has dwindled. Because the well-crystallizedtourmalines have cracks and inclusions, they havegreater value as specimens than as cut gemstones. Theschorl-elbaite crystals are typically color zoned, fromblack at the base to green, locally pink, and colorless or(rarely) pale blue at the termination.

The pegmatites are flat lying, 1–3 m thick, and 30–120m long; they are zoned both texturally and chemically.

The crystallization sequence produced a narrow outerzone, followed by a coarser wall zone, and finally a coarsecore zone characterized by an enrichment in mineralscontaining H2O, F, B, and Li (e.g., tourmaline, lepidolite,and topaz), along with a decrease in other elements suchas Fe. The valuable tourmaline occurs in the miaroliticcavities with albite, quartz, K-feldspar, muscovite/lepido-lite, topaz, and other minerals. The origin of the cavities,which are concentrated along the crest of a broadantiform in the pegmatites, is explained by an increase invapor pressure during the final stages of magma crystal-lization. Late rupturing of the cavities permitted theremoval of residual fluids that otherwise would havecaused etching or alteration of the pocket minerals. Thepegmatites are believed to have formed about 5 millionyears ago, on the basis of age dating (40Ar/39Ar geo-chronology) of the lepidolite. These are among theyoungest gem-bearing pegmatites in the world; they wereexposed by rapid uplift due to the collision of the Indianand Asian plates. AAL

The geology, mineralogy, and history of the Himalayamine, Mesa Grande, San Diego County, California.J. Fisher, E. E. Foord, and G. A. Bricker, Rocks &Minerals, Vol. 73, No. 3, May-June 1998, pp.156–180.

The Himalaya mine, located on Gem Hill in the MesaGrande pegmatite district of Southern California, hasbeen North America’s largest producer of gem and spec-imen-grade tourmaline since its discovery 100 years ago.During the first period of mining, pink and red tourma-line was very popular with the Dowager Empress ofImperial China, and large amounts of tourmaline wereshipped to China for carving. The boom ended in 1911,when the Chinese aristocracy was overthrown duringthe Boxer Rebellion. Production of tourmaline from themine is estimated at over 100 tons, which is remarkablesince the dike averages less than one meter thick! Inaddition to tourmaline, the mine has produced manyfine crystals of other pegmatite minerals and gemstones,including morganite and goshenite beryl, apatite, quartz,and microcline; numerous specimens are found in muse-ums and private collections. Mining has been sporadic,driven by the price of tourmaline. The periods of greatestactivity have been 1898–1912, 1952–1963, and 1977 tothe present.

There have been more than 20 mineralogical and geo-logical studies of the Himalaya dike system. There aretwo main dikes in the mine, referred to as the upper andlower dikes. Both contain gem-bearing pockets, but mostof the work has been done on the upper dike because itproduces the valuable pink tourmaline, while the lowerdike produces green tourmaline. Recent work has pro-duced an extensive honeycomb of tunnels inside GemHill, and it remains to be seen if the mine will continueto produce in the years to come. Jim Means


Madagascar rubies debut. G. Roskin, Jewelers’ Circular-Keystone, Vol. 169, No. 8, August 1998, pp. 40, 42.

Strongly saturated, slightly purplish red rubies that haveyielded cut stones up to 3 ct have been found recently inMadagascar. Characteristic inclusions are rounded trans-parent crystals, “treacle” type graining, and nests ofshort, flat, acicular 60° needles. The rubies containuneven, strong, parallel growth lines and fingerprint-likeveils, similar to those seen in both Burmese and Thaimaterial. The color is somewhat dark in tone, and theruby fluoresces moderate red to long-wave UV radiation.A dealer in Pittsburgh, Pennsylvania, is distributing thefaceted material in the U.S. MM

A recent find of kunzite at the historic Katerina mine,Pala District, San Diego County, California. J.Fisher, Mineral News, Vol. 15, No. 1, January 1999,pp. 1, 6–7.

This article reports on the reopening of the Katerina minein Southern California, historically one of the larger pro-ducers of kunzite in the region. Lilac-colored materialfrom this mine was first identified as spodumene byGeorge F. Kunz early in the 20th century; subsequently,this gem material was named kunzite in his honor.Following a short history of the mine, details are given onthe development work being done by the current owners,O. Komarek and B. Weege. A condensed geologicaloverview is also presented. Although the specimensfound in late 1998 are of modest quality, the mine hasproduced significant amounts of attractive gem materialin the past. MG

Update on ruby output in Kenya. Jewellery News Asia,No. 170, October 1998, p. 63.

About 50%–60% of the rough ruby produced at the minenear Kasigau in southern Kenya is of marketable quality.The mine, which has been producing commercially since1995, is located in Tsavo National Park, 500 km fromNairobi, Kenya. The top two grades of ruby roughaccount for 4%–5% of the overall output. Ruby reservesare expected to last 20 years. The rough material, whichmust be heat treated to improve clarity and color, is soldthrough auctions and then fashioned into beads, cabo-chons, and faceted stones. Prices of polished stones rangefrom $15/ct for low-quality to $5,000/ct for top-qualitymaterial. Other colored gems found in the area includekornerupine, red spinel, rhodolite and tsavorite garnet,sapphire, tanzanite, and tourmaline. MM

INSTRUMENTS AND TECHNIQUESThe application of ground-penetrating radar to mineral

specimen mining. B. K. Lees, Mineralogical Record,Vol. 29, No. 4, 1998, pp. 145–153.

Ground-penetrating radar (GPR) is a shallow-depth geo-physical exploration method based on detecting the elec-trical properties of rocks as they are produced by radar

waves. Through interpretation of the GPR data, struc-tures in the rock are inferred. This method is commonlyapplied to environmental waste and archaeological prob-lems. After explaining the technique, Mr. Lees describeshis use of GPR to locate rhodochrosite-bearing cavities atthe Sweet Home mine in Colorado.

Both the depth of penetration of radar waves into therock and the resolution of the resulting data are a func-tion of the wave frequency. A 100 MHz antenna, with asignal that penetrated about 25 feet (7–8 m) into therock, yielded a reliable resolution down to about 1 to 2feet. The technique allowed the miners to visualizestructural characteristics that influence the location ofcavities, as well as the cavities themselves, but the datacould not be used to tell if the cavities actually containedrhodochrosite crystals. Twelve cavities were discovered,one of with a signal that produced $40,000 worth ofspecimen and gem material. The total cost of the GPRsurvey was $13,000. The author suggests that GPR willbecome more viable in the future for near-surface miner-al specimen exploration as better software is developedand the cost of the system decreases. JL

JEWELRY MANUFACTURINGAND GEM CUTTINGAutomatic bruting. J. Lawrence, Diamond International,

No. 52, March-April 1998, pp. 67–69.Semi-automatic bruting is a technical and economic suc-cess in the diamond industry. It is superior to traditionalhand bruting for several reasons: (1) yield is typically 3%greater, resulting in 5% added value; (2) there are essen-tially no broken stones, whereas 1%–2% broken stones isconsidered normal for traditional methods; and (3) it pro-duces better roundness and proportions. In addition,salaries are lower with semi-automatic bruting, becausethe operators are typically younger and less experienced.(This is offset, though, by the fact that experiencedbruters are more productive on a volume basis.) The lim-itations of automated bruting are two-fold: (1) cementsused to bond the stone to the stone holder have limitedstrength; and (2) perfect roundness cannot be achieved, asthe software programs currently available do not centerthe stone perfectly in the machines. Nevertheless, theauthor implies that within a decade economic considera-tions will justify the expense of developing a fully auto-mated bruting machine. AAL

The case for CAD/CAM. J. Thornton, American JewelryManufacturer, Vol. 43, No. 1, January 1998, pp.62–65.

Computer-aided design (CAD) and computer-aided manu-facturing (CAM) have evolved from engineering applica-tions to the creation of elegant jewelry designs, sculpturedforms, and engravings. Cameos, medallions, rings, ear-rings, and pendants are being created by scanning, digitiz-ing, and adding colors and relief. The computer programs


enable manufacturers to merge images quickly to createjewelry to customers’ precise specifications. Pendants arecopied in minutes, and the copy can be reduced and mir-rored to make matching earrings. From creation to com-pletion, manufacturers maintain control over their prod-ucts, since outside engravers are no longer needed.

The positive experiences of two manufacturing jewel-ry companies using CAD/CAM are described, and exam-ples of some unexpected benefits of the new methods aregiven. For example, gold and silver are used in smallerquantities, because thinner pieces with flatter relief canbe produced. The engraving software has also greatlyreduced the risk of the die cracking, and individual piecescan be produced with one press stroke instead of several.According to die maker Jed Fournier of Bliss Tooling,Rhode Island, “this may only save us 15 to 30 seconds oneach piece but, on a thousand pieces, it adds up.”

MD

Cutters on quartz. S. E. Thompson, Lapidary Journal, Vol. 52, No. 4, July 1998, pp. 21–27.

Quartz is one of the most common minerals in the world,and it is also the gem material that is most available tolapidaries. The author interviewed five lapidaries, whoshare the intricacies of cutting crystalline and cryp-tocrystalline quartz, the tools they use, and the dangers(to the stone) that can be experienced during cutting andpolishing. One of the lapidaries is photographer HaroldVan Pelt, who provided photographs of his many splendidobjets d’art and of some of the tools and machinery heused to create them. MG

Electroformed objects for jewelry: Secondary ion massspectrometry characterization of Au films fromCN-free electrolytes. M. Fabrizio, C. Piccirillo, andS. Daolio, Rapid Communication in MassSpectrometry, Vol. 12, No. 13, 1998, pp. 857–863.

Electroforming of gold jewelry yields pieces that have ahigh volume/weight ratio, and can attain fine detailingequal to the more commonly used method of investmentcasting. However, electroforming is more expensivebecause of equipment costs and expenses associated withhandling the chemical solutions involved in the process.In this study, relatively inexpensive cyanide-free chemi-cal baths normally used in the electronics industry weretested for jewelry use. Different cathodes—on which thegold film is deposited—were also tested. The researchersexamined the gold films using secondary ion mass spec-trometry (SIMS) in order to identify the different chemi-cal species and complexes involved with electrodeposi-tion in each chemical bath. Hardening agents such asnanoscopic diamond and rutile were detected, as was thebrightening agent arsenic oxide. Of the chemical solu-tions tested, the ethylenediamine tetra acetic acid(EDTA) bath proved the best for jewelry forming becauseof the rate of gold deposition, the concentration range,and the service life of the solution. JL

Faceting angles. G. L. Wykoff, Rock & Gem, Vol. 28, No.3, March 1998, pp. 52–56, 58.

The most important thing to know when faceting a gem-stone is not necessarily how to grind and polish, butwhich angles produce the brightest, most brilliant gem.The author explains some of the recent developments infactoring these angles and the unique cutting styles thathave resulted. The most pertinent point is that angles arebut a guide to making a brilliant stone and faceters shouldexperiment on their own; such experiments have result-ed in very innovative, and now even somewhat main-stream, styles. Although this article is a little technical inplaces, for the most part it is highly enjoyable andthought provoking. MG

JEWELRY RETAILINGHow to sell to today’s bride and groom. D. O’ Donoghue,

National Jeweler, Vol. 42, No. 13, July 1, 1998, pp.34, 38.

Approximately 2.4 million couples marry each year inthe U.S., and these couples spend nearly $3.3 billion onjewelry. Today’s couples are older and more sophisticated,and they are willing to pay more to get exactly what theywant in engagement and wedding rings. Statistics showthat nine out of 10 brides wear earrings on their weddingday, 65% give jewelry as thank-you gifts to members ofthe wedding party, and 44% of brides and grooms choosejewelry as a wedding present to each other. The author,who is beauty director of Bride’s magazine, lists tips onselling engagement rings and wedding-related jewelrygifts.

Some of the new trends dictated by this generation ofbuyers include a rising demand for platinum in weddingand engagement rings, the growing popularity of fresh-water and South Sea pearls, and a resurgence of antique-inspired filigree rings. Diamonds remain the most desir-able gems for wedding rings. Retailers are encouraged tobuild a lasting relationship with their bridal customers,from determining the best purchase within their budgetto rendering services after the purchase is made.Retailers should also keep apprised of the latest trends inthe marketplace, and offer flexible payments and uncon-ditional guarantees to make the buying process lessintimidating MD

Selling treated gemstones. R. Weldon, ProfessionalJeweler, Vol. 1, No. 5, June 1998 et seq.

This ongoing series of informative articles helps retailjewelers and their sales associates explain gemstone treat-ments or enhancements to customers “in an honest andpositive manner.” The first article, “Emerald Education,”appeared in the June 1998 issue (pp. 171–172). Othertreated gem materials discussed to date include: heatedruby (July 1998, pp. 123–124), heated sapphire (August1998, pp. 133–134), dyed or irradiated cultured pearls


(September 1998, pp. 125–126), heated aquamarine(October 1998, pp. 145–146), heated amethyst and citrine(November 1998, pp. 101–102), laser-drilled diamonds(January 1999, pp. 107–108), and fissure-filled rubies(February 1999, pp. 161–162). These articles not only pro-vide valuable information on the various types of treat-ments used to enhance a gem’s appearance, but they alsogive methods for detecting such treatments. In addition,Mr. Weldon includes tips on caring for treated or en-hanced gems and legal considerations. MM

When a cert can hurt. G. Roskin, Jewelers’ Circular-Keystone, Vol. 169, No. 10, October 1998, pp.98–101.

“Comments” on a diamond grading report, which areoften innocuous, may sound ominous to a customer ifthey are not properly communicated, which could lead tothe loss of a sale. Examples are given of comments foundon a GIA certificate that may be perceived to have nega-tive connotations but are actually of minor significance(e.g., “crown angles greater than 35°” and “surface grain-ing not shown”). Comments that are cited as being mostdamaging to a diamond sale include references to propor-tion details and minor blemishes. The problem is com-pounded when several comments are listed on the samereport. The comments on proportion details can some-times be eliminated if the diamond is recut. However, thisis time consuming and expensive, and it involves ele-ments of risk such as excessive weight loss and chipping.Fluorescence reported as moderate or strong also can hurta sale.

The article advises jewelers to communicate theirknowledge of the report process to their clients, so thatthey clearly understand the reason for the comments. It isparticularly important to explain whether the particularcharacteristic mentioned in the report affects the dia-mond’s beauty or durability. JEC

PRECIOUS METALSConsumption of silver in 1997 exceeds supply. Jewellery

News Asia, No. 168, August 1998, p. 36.The Silver Institute’s World Silver Survey 1998 reportedthat demand for silver exceeded supply (from mine pro-duction and the recycling of scrap) by 198 million ouncesin 1997. Consumption reached a record total of 863.4 mil-lion ounces, a growth of 6.1% over 1996. The demand forsilver in jewelry and silverware fabrication rose 5.3% to280.2 million ounces, following a growth of 15.6% in1996. Italy’s silver consumption rose 10.5% to 44.8 mil-lion ounces, and India’s rose 3.2% to 95.2 million ounces(with 66.6% of the total Indian demand used in jewelry,silverware, and gift items). There was also surging indus-trial demand for silver in the United States. This is theninth consecutive year in which conventional supplyfailed to keep up with silver demand. MM

A slippery standard for gold prices. K. Clark, U.S. News &World Report, Vol. 125, No. 19, November 16,1998, pp. 84–85.

Gold prices are down 25% from 1996, to about the levelof 1979. However, this decrease is not generally reflectedin the retail prices of finished jewelry—at least not in theUnited States, where, for example, raw gold constitutesabout 25% of the price of a typical store-bought necklace.This article suggests three ways of obtaining the mostvalue when purchasing gold jewelry at retail: (1) Buy plainclassic pieces of jewelry, where price comparisons can bemade; (2) comparison shop the malls (negotiate prices),wholesale clubs, on-line sites, and television shoppingshows; and (3) buy used pieces. Rather than being pur-chased as an investment, gold jewelry should be boughtto be worn and enjoyed. AMB

SYNTHETICS AND SIMULANTS Laboratory-created gems grow acceptance at retail. C.

Fenelle, National Jeweler, Vol. 42, No. 14, July 16,1998, pp. 74, 76, 78, 80, 82.

Laboratory-created (also called synthetic, man-made, cre-ated, or laboratory-grown) gemstones have gradually andsteadily gained acceptance in the trade. The most popularcreated stones, according to some jewelers, are syntheticalexandrite, emerald, and ruby, which can be sold for afraction of the cost of natural stones. The market has seenan increase in the number of synthetic stone suppliers, ofmanufacturers designing jewelry with synthetic gems,and of synthetic gems being displayed in retailers’ “finejewelry” cases. Consumers are showing an increasedawareness and acceptance of synthetic gems, since thesematerials allow greater accessibility to normally extrava-gant jewelry items.

While the created-gemstone industry has experiencedstable pricing in the last couple of years, there is concernabout the increasing number of gem growers and the vari-able quality of synthetic gems being released on the mar-ket. Another concern among retail jewelers is that syn-thetic gemstones are becoming exceedingly difficult todistinguish from their natural counterparts. Because syn-thetics have been fraudulently sold as natural stones,retailers are exercising caution when choosing their sup-pliers. Retailers and suppliers alike are confident that lab-oratory-created stones will continue to rise in popularitywith growing consumer acceptance. MD

TREATMENTSDiscrimination of a treated jadeite (class B)—judged from

the colloidal fillings. W. Su, F. Lu, X. Gu, Y. Wu, J.Zhang, J. Cai, and P. Zhuang, Journal of ChengduUniversity of Technology, Vol. 25, No. 2, 1998, pp.349–353 [in Chinese with English abstract].

The identification of “B jade” (i.e., jade that has beenbleached and then polymer impregnated) is an important



matter in the jade trade, and this article describes effortsto do this with microscopic observation. The first step isto identify which, if any, of three types of materials arefilling the interstitial areas in the jadeite: (1) natural min-erals formed by geologic processes during or after the for-mation of the jadeite, (2) very fine grit and/or waxemplaced during the cutting and waxing processes, and(3) colloidal (polymer) filling materials that are introducedduring the “B jade” treatment process. Once such mate-rials have been located in the sample, their hardness isdetermined with a needle probe under magnification. If itis suspected that the filling material is a polymer, this canbe confirmed by infrared spectroscopy. Taijin Lu

Fracture healing/filling of Möng Hsu ruby. R. W. Hughesand O. Galibert, Australian Gemmologist, Vol. 20,No. 2, 1998, pp. 70–74.

Rubies from the Mong Hsu deposit in Shan State, north-east of Taunggyi, Myanmar, present two problems as gemmaterials. The first is their dense “silk” clouds and thestrong purplish color caused by their unusual blue cores.Ordinary heat treatment can be used to eliminate bothphenomena; the market generally accepts such heat-treated stones. The second problem lies in the fact thatMong Hsu rubies are typically heavily fractured. Thesefractures are commonly “healed” by heat treatment ofthe stones with borax and other chemicals, which causesthe surface of the stone to melt and to be redeposited inthe fractures; undigested material cools as pockets of aflux glass. This treatment, which is permanent and irre-versible, improves a stone’s durability. In the past, suchfracture healing/filling was neither reported nor detected.Now that it is a known practice, however, the trade mustdecide how to deal with it [see, e.g., the followingabstract], especially because many dealers (particularly

those in the Japanese market) reject such filled goods.Without such treatment, many of the Mong Hsu rubieswould have little gem value. RAH

Thais launch ruby disclosure system. M. Elmore, ColoredStone, Vol. 11, No. 6, November-December 1998,pp. 1, 30–33.

After four years of discussions between the Thai Gemand Jewelry Traders Association (TGJTA) and the JapanJewellery Association over the glass filling of rubies, anew classification (for stones >1 ct) has been adopted togive Thai dealers a common language for disclosing rubytreatments. The TGJTA’s classification has three cate-gories for treated stones:

A. Natural Ruby: The ruby has been enhanced by heat,but at 10× magnification no residue from the heatingprocess is visible on or within the stone.

B. Heat Enhanced Natural Ruby: The ruby has beenenhanced by heat, and at 10× magnification someresidue from the heating process is visible within thestone.

C. Heat Treated Natural Ruby with Foreign SubstancesPresent: The ruby has been enhanced by heat, and at10× magnification some residue from the heatingprocess is visible on the surface of the stone and with-in the stone.

Unheated Natural Ruby is a classification used forrubies that have not been enhanced in any way.

While Thai dealers consider the classification systemadequate, some are skeptical that the disclosure programwill be successful, as it is voluntary. The TGJTA has noenforcement mechanism, and some think a change inindustry practice will come only when consumers beginto require disclosure. MD

1998 Manuscript ReviewersGems & Gemology requires that all articles undergo the peer-review process, in which each manuscript isreviewed by at least three experts in the field. This process is vital to the accuracy and readability of the pub-lished article, but it is also time-consuming for the reviewer. Because members of our Editorial ReviewBoard cannot have expertise in every area, we sometimes call on others in our community to share theirintellect and insight. In addition to the members of our Review Board, we extend a heartfelt thanks to thefollowing individuals who reviewed manuscripts for G&G in 1998:

Mr. David AtlasDr. Grahame BrownMr. Derek CroppMr. Israel EliezriMr. Al GilbertsonMr. Mike GrayDr. Edward J. GübelinMr. Hertz Hasenfeld

Dr. Donald B. HooverMr. Mark JohnsonMr. George KaplanMr. Sheldon KwiatMr. Shane F. McClureMs. Elise MisiorowskiMs. Danusia NiklewiczMr. Glen Nord

Mr. Dale PerelmanDr. Ilene ReinitzMr. Jeremy RichdaleMr. Russell ShorDr. Sergey SmirnovMr. Basil WatermeyerDr. Christopher WelbournMr. Lazar Wolfe

TABLE OF CONTENTS · The necklace is composed of 12.5 mm turquoise beads sep-arated by diamond...

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Transcript of TABLE OF CONTENTS · The necklace is composed of 12.5 mm turquoise beads sep-arated by diamond...