NEWSLETTER No. 8, February 2009 - SSEF Alumni · Damage analysis on cut gemstones Prof. Henry A....

SSEF Alumni Newsletter No. 8 [email protected] page 1

NEWSLETTER No. 8, February 2009

Dear SSEF ALUMNI Members

We hope that you had a good start into the year 2009 and that it is going to be a successful and prosperous year for all of us despite the presently difficult circumstances.

Again, we have some exciting and interesting events in store for you this year. Professor Henry Hänni will kick off with his lecture on the 16th February 2009, you will find all details below.

Apart from this, I hope you will have the same pleasure as me in reading the two featured ar-ticles about pearls from Dr. Michael S. Krzemnicki and about diamonds from Laurent Cartier.

Looking forward to seeing you all again,

Leon Ascot

Contents:

SSEF Alumni Events: 1 Next SSEF Alumni Lecture Damage analysis on cut gemstones Prof. Henry A. Haenni

Gemmological Articles and Notes:

2 Unknown beauties: non-nacreous natural pearls Michael Krzemnicki

7 Kalimantan Diamonds Laurent E. Cartier & Daniel Nimmervoll

SSEF ALumni Events:

Monday 16th February 2009, 7 pm

Damage analysis on cut gemstones

Gemstones may be damaged during mining, cutting, setting, and wear.Working in a laboratory where thousends of stones are analysed throughout the year, we some-times encounter stones with damages, which tell us a story about “how this could happen”...

Based on his long experience and with the support of mean-ingful photos, Prof. Henry A. Hänni from the SSEF Swiss Gemmological Institute will show you pitfalls and no-go’s when working with or wearing gemstones.

The lecture (10.- Entry fee) will be held as again at the Restaurant FalconeBirmensdorferstrasse 150, ZurichAfter the lecture, we will enjoy a relaxing dinner together with Henry Hänni at the restaurant.

Please register at [email protected]


Gemmological Articles and Notes:

Image 1: Cross-section of a natural pearl. The central zone with radial calcite prisms is evident. The lightly coloured layer of nacre lies above it (aragonite). The black point in the centre is the drill hole of the pearl. © H.A. Hänni, SSEF Swiss Gemmo-logical Institute.

Unknown beauties: non-nacreous natural pearlstext & photos: Dr. Michael S. Krzemnicki, SSEF

When one thinks of pearls, the common image and properties that come to mind are of a white colour and pearly lustre. The second part in this series of articles on natural pearls intends to shed light on the fact that this is not always the case.

Natural pearls are always an effigy of the corresponding mollusk species’ shell, in which they form, for example, by a small injury to the outer skin of the mollusk organism. This has the ef-fect of transporting some mantle cells into deeper tissue, which in the most fortunate of cases results in the formation of a more or less round pearl sac in which a pearl can grow. Its internal structure then resembles the structure of the shell. This means that shells which show nacre will commonly also produce nacreous pearls. But because many mullosk species (but also marine gastropods, which will be discussed in the next article of this series)- including those without na-cre- can produce pearls, it is not surprising that many non-nacreous pearls exist, which instead show a porcelain-like lustre.

Fundamentally there are two different reasons why a pearl may not have mother-of-pearl: 1) these are immature pearls from nacreous oysters, or 2) pearls from non-nacreous mollusks.

Examining the cross section of a natural pearl with nacre (image 1), this often shows a zone of radially oriented calcite pillars (calcium carbonate, rhombohedric), which exhibits a brown colouration caused by organic substance. This zone is overgrown in a second growth phase by a more or less thick layer of tiny aragonite platelets (calcium carbonate, orthorhombic) that are responsible for the attractive pearly lustre. This zoning is a direct effigy of the mollusk shell’s structure. The responsible exterior skin (mantle epithelium) of the organism, which rests di-rectly on the shell and forms the shell (or the pearl), changes its routine during its evolution and production of calcite carbonate (biomineralisation). It makes no difference whether the mantle epithel lying on the shell deposits calcium carbonate there, or if it lies in a pearl sac in the mol-


lusk flesh as a result of injury. It goes through the same stages of carbon-ate production.

If a pearl is removed from the oys-ter at a premature stage then the mantle epithel of the pearl sac which is responsible for calcium carbonate production will often not find itself in a stage of nacre production. The result is mostly a beige to brownish immature pearl composed of radial calcite pillars. Such immature pearls are normally relatively small (image 2). A part of the pearl is sometimes already covered in nacre, whereas another section of the mantle epi-thel of the pearl sac remains in the calcitic prism growth stage. Although such immature pearls are relatively common if one looks at the total production of natural pearls, they are rarely used for jewellery.

Pearls from mollusks without mother-of-pearl:

Curious beach visitors will have re-marked that many mollusks show no mother-of-pearl. Their surface lustre can at best be described as porce-lain-like. Because of the enormous diversity of mollusk species, these porcelain-like pearls can be found in a huge range of colours and shapes. The following section will introduce some saltwater oysters and their cor-responding non-nacreous pearls.Pearls of the pen shell family (Pinnidae)- Pinna and Atrina:

Image 2: The pearl dealer Abdul Hammed Hassan Al-Mannai showing natural pearls from Bahrein. Closer inspection of the crop shows some immature brown pearls .

© M.S. Krzemnicki. SSEF Swiss Gemmological Institute.

Pen clams (Pinnidae) are found worldwide and are characterised by their elongated triangu-lar shape (image 3) and their vertically oriented position on the seafloor (hence the name pen shells), where they attach themselves through a network of fibres. They remain more or less stationary for the duration of their life cycle. The species Atrina vexillum is mostly found in the Southeast Pacific. Its shell can reach 30cm in length. Its pearls are mostly considerably violet to dark grey in colour. A distinct colour zonation is often found, sometimes combined with a lightly iridiscent thin nacreous coating. The shape is button to slightly baroque. The pearls formed are usually relatively small. Atrina vexillum pearls can be exceptionally attractive due to their partially intensive violet to dark purple colours.

The elongated and triangular Pinna shell is found from the Mediterranean to the Pacific. The


Image 3: Atrina vexillum (violet-grey) and Pinna Bicolor (beige to dark brown) shells and pearls. The internal section of the shell shows a thin iridiscent mother-of-pearl layer in both pen shells. © M.S. Krzemnicki. SSEF Swiss Gemmological Institute.

Image 4: Necklace with Pinna pearls. © M.S. Krzemnicki. SSEF Swiss Gemmological Institute.

shells are mostly made up of brown calcite layers and sometimes exhibit a fine lightly iridiscent layer of aragonite platelets. The examined Pinna bicolor pearls from Southeast Asia are normally round to drop-shaped and with a beige to dark brown colour.

If one closely examines the surface with a loupe, then the interesting honeycomb-like polygonal structure composed of interlocking calcite pillars becomes evident (Image 5). If a light source is

Image 5: Honeycomb-like polygonal structure on the surface of a Pinna pearl brought about by the front

end of calcite pillars. © H.A. Hänni. SSEF Swiss Gemmological Institute.

positioned behind the pearl, individual calcite pillars act like a fibre-optic light guide.

Pearls from the Mytilidae fam-ily– Modiolus:


Image 6: Modiolus philippinaria shell and pearls . © M.S. Krzemnicki, SSEF Swiss Gemmological Institute

The species Modiolus modiolus is also known as the horse mussel and is found globally. It is a part of the Mytilidae family. The pearls of this species are often distinctly purple to violet, some pearls are nearly white. These pearls are often button-shaped, whereby the backside of these is often dark violet and the upper side purple. The pearls of the Modiolus species are mostly relatively small.

Giant clam Tridacna gigas:

The Tridacana gigas is also known as the giant clam or man-eating clam. It is found in the tropi-cal waters of the Indo-Pacific. It commonly lives in symbiosis with sea algae which reside in its mantle lips and supply the oyster with organic substance and nutrients. As a result of photosyn-thesis of these algae, the mantle lips of these oysters exhibits a an attractive bright blue pattern. It can reach over a metre in size and can weigh up to 500kg. Its pearls can become accordingly large. The world’s largest pearl, which weighs 6.4kg, originated from a Tridacna gigas clam. Due to its size and its frightening exterior appearance, one can hardly call this whitish grey calcium carbonate concretion a piece of jewellery.

The structure of Tridacna oyster shells consists of dense interwoven white aragonite fibres, which can partially produce flame-like surface structures. The upcoming article in this series

Image 7: Non-nacreous pearls, blister pearls and blisters of shells such as the Tridacna gigas. © H.A. Hänni, SSEF Swiss Gemmological Institute


Image 8: From left to right: file clams (Lima vulgaris) and thorny oyster (Spondylus barbatus) with white pearls and blister pearls. The Lucina pearls (Codakia tigerina) and of the scallops (e.g. Mimachlamy sanguinea, not in the image) are often light pink to distinctly pink, or yellowish to orange. © M.S. Krzemnicki, SSEF Swiss Gemmological Institute.

of articles on natural pearls, will amongst other features specifically examine flame structures characteristic of Conch and Melo pearls. As the Tridacna Gigas is considered an endangered species, it is at present internationally protected and can only be traded with valid CITES docu-mentation (Convention on International Trade in Endangered Species). This aspect will also be further highlighted in the upcoming article.

Various non-nacreous mollusks:

The SSEF Swiss Gemmological Institute has had the pleasing opportunity to examine numer-ous further shells of a wide variety of different mollusks all lacking mother-of-pearl, in the past few months. Amongst these the following are noteworthy: partially lightly transparent baroque-shaped pearls and blister pearls from thorny oysters (Spondylidae family), white to pink coloured pearls from file clams (limidae) and Lucina clams (Lucinidae), as well as yellowish orange pearls from beautiful scallops (Pectinidae).

Exceptional, interesting and beautiful!

The pearls described within this article intend to give an impression of the diversity nature has to offer. Every mollusk can form pearls, implying that accordingly exceptional pearls can also be found. This diversity represents considerable testing challenges for the SSEF Swiss Gemmo-logical Institute but is also highly instructive. Only by combining classical research methods with newest scientific methods such as micro x-ray tomography, x-radiography, X-ray luminescence, Raman micro-spectrometry and reflexion spectrometry can the question of natural/cultured and colour authenticity be resolved. Much of our current scientific knowledge stems from our long-standing research, especially through Prof. Henry A. Hänni. Those who wish to know more about the formation of natural and cultured pearls can best do so by attending a three-day SSEF pearl course (see 2009 course programme on www.ssef.ch or contact us at [email protected]).

For this second article I would again like to thank Mr. Thomas Hochstrasser (www.naturalpearls.ch/21801.html) who passed over a large number of pearls for analysis and certification to the SSEF Swiss Gemmological Institute. Besides the pearl course, the SSEF also offers an informa-tive CD-Rom about pearls (contact us at +41 61 262 06 40 or [email protected] for more informa-tion).


Kalimantan Diamonds -

Laurent E. Cartier & Daniel Nimmervoll


The discovery of diamond fields in Brazil in the 1720s, and more significantly, of major diamond deposits in South Africa in 1867, marked the advent of modern diamond production. Previous to this, India and Borneo had been the two historical producers of diamonds. The mythical Golconda diamond mines of southern India were made famous by the vivid and adventurous accounts of Jean-Baptiste Tavernier in the 17th century and overshadowed Borneo’s precious diamonds in quantity, glamour and allurement. Borneo gained prominence through Portuguese traders in the 17th century and later, more significantly in the 18th century, by the colonisation of Borneo by the Dutch. It is well documented that many Brazilian diamonds were imported to India and later re-exported as Gol-conda diamonds in the 18th century. This was done because Indian diamonds fetched higher prices than Brazilian ones. It is very likely that this was also the case for Borneo (i.e. Kalimanatan); especially con-sidering that established trade links between India and Borneo existed. The step of polishing a diamond is thought to have been ‘invented’ in Italy in the late 14th century; a skill that was later re-exported and adapted in India1. It is believed that diamond cutting knowledge traveled from India to Borneo in the 17th century2. The largest diamond certain to be of Borneo origin is the 38.23ct Banjarmasin stone, originally owned by the Sultan of Banjarmasin and can now be found in the Rijksmuseum in Amsterdam. Borneo diamonds are known for their history, as one of the ancient sources of diamonds. Its diamond production deserves to be better known, even if production figures are marginal in comparison to other countries.

1 Diamants: Au coeur de la terre, au coeur des etoiles, au coeur du pouvoir. 2001, MNHN & Adam Biro, Paris, 352pp.

2 Spencer K.L. et al., 1988. The diamond deposits of Kalimantan, Borneo. Gems & Gemology, 24, 2, 67-80.

Landscape around Cempaka diamond mining area with pulangs visible from a distance ©LC & DN, 2008


September, the peak of the dry season. ©LC & DN, 2008


The island of Borneo is comprised of the four huge Indonesian Kalimantan provinces, the minor Sabah and Sarawak provinces of Malaysia and finally tiny Brunei. Kalimantan refers to the Indonesian part of Borneo. Interestingly, “Kalimantan literally translates as ‘river of gold and diamonds’”1. Diamond min-ing on Borneo is exclusively found in Kalimantan and is believed to date back to 600AD2. Kalimantan’s reputed historical diamond production came from the Landak drainage basin in western Kalimantan (‘Landak’ diamonds), whereas the vast majority now comes from areas around Martapura and Cempaka, some 50 kilometres away from South Kalimantan’s regional capital, Banjarmasin. The most active period of mining was the 19th century when the Dutch attempted to introduce large-scale mining, but they failed to sustain and expand the magnitude of extraction, until it receded. Production figures remain low, but Kalimantan diamonds still have a commendable reputation by virtue of their history and quality. Although gemmological research has been conducted on Kalimantan diamonds by a number of authors, there are few distinguishing features. Tay Thye Sun et al. (2005) reported percussion scars and radioactive spots to be frequent as a surface feature of Kalimantan diamonds3.

1 Tay Thye Sun et al., 2005. Kalimantan diamond: Morphology, surface features and some spectroscopic approaches. Aus tralian Gemmologist, 22, 186-195.2 ditto 3.3 ditto 3.

A true beauty. 38.23ct Banjarmasin diamond. Courtesy of Jean-Pierre Chalain, SSEF


Indonesia is an important player in world mining. It is among the world’s top producers of tin, copper and nickel. Indonesia’s mining, oil and gas sector is a key pillar of its economy, representing more than 10% of its GDP output1. Diamonds represent an insignificant share of this. USGS estimates that 23,000 carats of industrial quality and 7,000 carats of gem-quality diamonds were extracted in 20062. Indonesia is a full member of the Kimberley process certification scheme (KPCS) and Kimberley certificate export data for 2007 show 17,812.15 carats of $4,691,284.50 value, at a price of $263.38 per carat3.

1 Source: USGS 20082 Source: USGS 20083 Source: KPCS 2008

The geological origin of Kalimantan diamonds is still widely debated. It is most probable that they originate from a number of different primary sources, including both eclogitic and peridotitic mantle rocks. Smith et al. (2008) add: “It is controversial whether such diamonds formed in conventional ancient lithospheric mantle origin or in a Phanerozoic subducted slab perhaps subsequently obducted to surface”4. It is certain that the primary source is far away, but remains to be located. Diamonds lie in secondary deposits; these diamandiferous gravels are found in buried paleochannels in swamps around the Cempaka-Martapura area.

Most mining work is still done by artisanal and small-scale miners and production figures remain small. This said, production and export figures are set to rise considerably in coming years with the purchase by Gem Diamonds of the region’s sole large-scale diamond mining entreprise’s (BDI Diamond Mining Corp) Cempaka properties in 2007. Gem Diamonds now owns 80% of the field, while the Indonesian govern-ment has a minority 20% stake in the project. Mining capacity changed from contractor mining to owner mining during the second half of 2007. Cempaka is the only large-scale diamond mine in Indonesia and in Southeast Asia. 4 Smith et al. 2008. Nature and genesis of Kalimantan diamonds. 9th International Kimberlite Conference Extended Ab stract No. 9IKC-A-00297, 2008.

Large pebbles constituent of diamondiferous gravels from Cempaka-Martapura area ©LC & DN, 2008

SSEF Alumni Newsletter No. 8 [email protected]

Inside look at a Palong (wooden sluice) ©LC & DN, 2008

Ore-washing. An aya (wooden sieve) is also visible in the basin ©LC & DN, 2008

page 12


Mining has become increasingly difficult in recent years, due to the depletion of easily extractable dia-mondiferous gravels. Improved surveying and exploration is required to locate the increasingly complex paths that these paleochannels followed. The diamondiferous gravels are typically found several metres below the surface, often very near to the water table zone. The thickness of overburden differs (approx.1-10m) whereas the diamond gravels are also varying but usually over a metre thick.The sensitivity of the high water table zone brings about certain environmental issues, and Gem Diamonds suspended mining for some time in April 2008 following concerns raised by the local government about waste-water management of the mine. An environmental review process was instigated and the construc-tion of a water treatment facility ensued in June 20081.

The swampy character of the lands in this region and the associated acidity of the water means that many feel that diamond mining has a greater potential to generate income than agriculture. The village of Cem-paka, around which the mines are found, is relatively small. Most miners live in this village and very few are migrant miners. Speaking to different miners it seemed they have not been coerced into this activity. There is an established tradition of artisanal diamond mining in the area, which is well organised.

In the artisanal small-scale mining sector, financiers usually support miners. These actors reside in Mar-tapura or Cempaka itself. Miners are generally grouped in teams of seven, adopting different roles in the extraction of the diamondiferous gravels and subsequent gravity separation. High-pressure water is used to wash the ore (pasir) and later pump it into a palong (wooden sluice). The result of this gravity separation process, to which water is continuously added, is that lighter material will flow out into a separate pond. Depending on the sophistication of the palong, the material is accordingly further separated into different fractions along. Pebbles and coarser material (Quartzite quite dominant) are separated from smaller but heavier fractions, by being flushed down with the aid of a water jet. The produce of this first gravity con-centration is a first heavy fraction (umas). Black sands are common with ilmenite, magnetite and chromite as main components, and other accessory minerals and metals including corundum, gold and platinum. An aya (wooden sieve) is used to separate out any large pieces of gravel material remaining in the heavy

1 Source: Gem Diamonds. http://www.gemdiamonds.com/

Hardworking team of small-scale diamond miners just outside the village of Cempaka, south Kalimantan©LC & DN, 2008


fraction. The final well-known panning step is done using a large conical pan hewn out of wood called a dulang. Reports suggest that an adept diamond panner can take 5 minutes to wash around 5kgs of diamon-diferous gravels1; an impressive feat, even without the 37°C September heat and searing sun, under which any inch of shade is gladly embraced. Most panners use umbrellas for shade.

1 Aspinall, C., 2001. Small-scale mining in Indonesia. MMSD, no.79, 30pp.

Diamond panners in the shade of an umbrella ©LC & DN, 2008

Dug deeply and pumping water. No water, no diamonds ©LC & DN, 2008


Although geological exploration for diamond is still ongoing in different areas of the island, it is likely that Borneo will remain a small player in regards to global diamond production. Kalimantan has supplied the global diamond trade with a steady amount of good-quality diamond production over several centuries and many hope that the next Banjarmasin diamond will soon be discovered.

Acknowledgements: The authors would like to thank Abdul and Tina for their jaunty manner and Liz Tilley for her helpful comments.

Cempaka diamond panner ©LC & DN, 2008

SSEF Alumni Newsletter No. 8 [email protected] 17

How to become a Member of SSEF Alumni ?The SSEF Alumni Organisation is open for former participants of courses at SSEF Swiss Gem-mological Institute, FGA students, and further interested persons in the gemmological commu-nity.The SSEF Alumni is intended as a platform for the exchange of information and for continuous gemmological formation. Membership fee is 50 Swiss Francs per year. Please see our website for more information (www.ssef-alumni.org) or contact our President, Leon Ascot at [email protected], when you would like to participate at exclusive SSEF Alumni events and to receive the highly informative electronic newsletter four times a year.

Impressum:Editors:

Laurent E. CartierMineralogical and Petrographical Institute of the University BaselBernoullistrasse 30, 4056 Basel, [email protected] [email protected]

Dr. Michael S. KrzemnickiSSEF Swiss Gemmological InstituteFalknerstrasse 9, CH-4051 Basel, [email protected] You are invited to contribute to the newsletter with short articles of interest for other SSEF Alumni members. All contributions should be sent to Dr. Michael S. Krzemnicki

[email protected]

and will be published after editing if appropriate for this newsletter.

SSEF Alumni Membership:

NEWSLETTER No. 8, February 2009 - SSEF Alumni · Damage analysis on cut gemstones Prof. Henry A....

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