The quest for Kashmir sapphires and Burma rubies Origin ...€¦ · The$Star%of%Kashmir%...

© Swiss Gemmological Institute SSEF

The beauty of colour

Dr.$Michael$S.$Krzemnicki,$Swiss$Gemmological$Ins9tute$SSEF$$

Photos$©$M.S.$Krzemnicki,$SSEF,$except$where$indicated$otherwise$

ScoCsh$Gemmological$Associa9on$E$Conference,$Saturday$3$May$2014$

The quest for "Kashmir" sapphires and "Burma" rubies

Origin determination of gemstones: Possibilities, Challenges and limitations !

The$Star%of%Kashmir%Sapphire$from$Kashmir$of$approx.$20$ct,$$Geneva$May$2013,$3.5$mio$US$$SSEF$Test$Report$No.$66221$

Burmese ruby

A$superb$ruby$of$6.04$ct$set$in$a$ring$with$diamonds$by$Etcetera.$$$Sold$for$a$world$auc9on$record$price$of$US$$551‘000$per$carat$(Chris9e‘s$Hong$Kong,$May$2012).$$SSEF$report$59356$&$Appendix.$$

Photo$©$Chris9e‘s$

A$number$of$sources$of$coloured$stones$are$known$since$historic$9mes$and$their$gems$have$been$treasured$over$centuries$for$their$beauty$and$rarity.$

Bagan,$Burma$©$P.$Boegli,$Flickr.com$ © Swiss Gemmological Institute SSEF

The$relevance$of$the$origin$of$a$gemstone$E  emo9on$E  connec9ng$to$history$E  a$label$E  for$investment$


Relevance$of$origin$$Prices$$Auc9on$$$Etcetera$ruby$!$$Emo9onen$$Label$$Sicherheit,$Wertanlage,$investment,$$$Exper9se$as$with$art$work$(Rothko)$$$$

Rothko:$un9tled$

Jose$Boomsma:$Tribute$to$Rothko$EBlue$

Origin determination is always an expert opinion !


The$origin$determina9on$of$gemmological$laboratories$is$always$based$on$scien9fic$analyses$(e.g.$trace$element$composi9on,$absorp9on$spectra,$Raman$microspectrometry$etc.)$and$me9culous$

microscopic$observa9ons.$$

Thus$it$is$possible$that$two$different$labs$may$issue$a$different$origin$for$a$given$gemstone.$


Origin determination:

Combining(classical(approaches(with(advanced(scienti5ic(analytical(methods(

The$origin$of$a$gemstone$on$a$report$is$always$an$opinion$of$experts,$indica9ng$its$most$probable$geographic$origin.$$It$describes$stones$which$originate$from$a$mining$opera9on$in$that$geographic$area.$$It$is$related$to$the$geological$seCng$$characteris9c$for$the$origin$(mining$area).$$The$origin$is$expressed$based$on$wellEestablished$criteria$(e.g.$inclusions,$chemical$composi9on...).$$$Challenges:$$E $New$mining$areas$are$discovered.$

E$The$analy9cal$methods$get$more$and$more$sophis9cated.$

© SSEF Swiss Gemmological Institute

Near$Bawpadan$in$Mogok$

Origin$determina9on$at$SSEF$is$relying$on:$$E $$scien9fically$and$gemmologically$highly$educated$staff$$

E $sophis9cated$analy9cal$instrumenta9on$

E $reference$samples$from$different$mines$

E $con9nuous$research$

E $long$established$experience$

© SSEF Swiss Gemmological Institute Photo © H.A. Hänni, SSEF 2004


$1)$Observa9ons$and$collec9on$of$analy9cal$data$$2)$Interpreta9on$of$observa9ons$and$data$$3)$Weigh9ng$of$evidences$and$consistency$check$$4)$Conclusion(s)$$$$Important:$Independent$assessment$of$a$gemstone$by$second$(third$etc...)$expert$(gemmologist)$and$mutual$discussion$!!$

Four steps of origin determination:

Deposits connected to Pan-African tectonometamorphic events

Distribu9on$of$corundum$deposits$connected$to$PanEAfrican$tectonoEmetamorphic$events$(750E450$ma)$by$the$collision$of$eastern$and$western$Gondwana.$$In$midEJurassic$(about$160$ma),$India$started$to$drig$towards$north.$

Distribu9on$of$marbleEhosted$ruby$deposits$along$the$Himalayan$orogeny$(45E5$ma)$due$to$the$collision$between$the$Indian$plate$and$Eurasia.$$

Dahaw$mine$:$Mogok$East$

marble-hosted deposits

after Jobbins & Berrangé, 1981

Corundum from alkali basalts

Ter9ary$and$quaternary$basalts$and$related$

corundum$deposits$in$SouthEEast$Asia.$

Jobbins & Berrangé, 1981!

Pailin!

Analytical instruments used for origin determination at SSEF

$E  XEray$fluorescence$(EDXRF)$E  Raman$Microspectrometry$E  FTIR$Infrared$Spectrometry$E  UVEVisENIR$Spectrophotometer$E  Photoluminescence$

Eventually:$E  LAEICPEMS$(laser$abla9on$induc9vey$coupled$plasma$mass$spectrometry)$E  LIBS$(laser$induced$breakdown$spectroscopy)$



Raman microspectrometry

UV-Vis Spectrometry

© SSEF Swiss Gemmological Institute"from H.A. Hänni, Journal of Gemmology 1994!

Chemical data versus spectroscopic data

© SSEF Swiss Gemmological Institute!

Basaltic!

Kashmir!

Burma!

Ceylon!

Laser Ablation Inductively Coupled Plasma Mass Spectrometry LA-ICP-MS


With$Dr.$Thomas$Pehke$$at$the$Geochemical$Lab,$$University$of$Berne,$Switzerland$


Laser ablation

© T. Pettke,, University Berne

Local$hea9ng$and$vaporiza9on$


Data processing

LA-ICP-MS Pearls

10

100

1000

10000

100000

1000000

10000000

100000000

30 40 50 60 70 80 90 100 110 120

time (sec.)

co

un

ts

Mn

Ca

I

Ba

Mg

homogeneous(signal(

Setting(of(integrals(for(data(processing(is(easy(

Integration time

Raw data

From:$P.$Halicki,$SSEF$(Masterthesis)$

Surface$contamina9on$!$

Spikes$!$ Spikes$!$Spikes$!$

Surface$contamina9on$!$

Data processing


© Swiss Gemmological Institute SSEF From:$P.$Halicki,$SSEF$(Masterthesis)$

Madagascar!

Kashmir!Sri Lanka!

Burma!

Fe#(ppm

)#

Ti#(ppm)#

Sapphire Results:


Madagascar!

Kashmir!

Sri Lanka!

Fe#(ppm

)#

Ga#(ppm)#From:$P.$Halicki,$SSEF$(Masterthesis)$

Sapphire Results:

Madagascar(

Kashmir(

Burma(

Madagascar!

Kashmir!

Burma!

Ti#(ppm

)#

Mg#(ppm)#From:$P.$Halicki,$SSEF$(Masterthesis)$

Sapphire Results:

20.12.2011 75


24.04.2012

Zentraler Weiterbildungskurs SGG

30

Comparison

Peucat et al (2007) Kashmir this study

Trace(element(concentrations(generally(indicate(origin(„trends“,(but(are(often(not(resulting(in(conclusive(results.(

Possibilities & Limitations:

24.04.2012

Zentraler Weiterbildungskurs SGG

30

Comparison

Peucat et al (2007) Kashmir this study

Peucat(et(al.(2007(20.12.2011 80

Thailand (Bo Phloi) + Cambodia

Peucat et al (2007)


Kashmir sapphire

The(Maharaja(of(Jammu(and(Kashmir,((circa(1900(www.kashmirphotos.org/history.html(

The velvety blue of Kashmir sapphires

Sapphires$from$Kashmir$contain$subEmicroscopic$inclusions$which$scaher$the$transmihed$light.$$$As$a$result,$these$stones$ogen$show$a$$highly$appreciated$velvety$blue$colour.$

Photo © H.A. Hänni, SSEF


Characteristic inclusions in Kashmir sapphires

healed$fissure$with$interrupted$fluid$tubes$

Subtle$„dust“$tracks$

Photos: © H.A. Hänni, SSEF

Zoning$pahern$no$ru9le$needles$in$Kashmir$sapphires$!$

Pargasite$needles$(prisma9c)$

ShortEprisma9c$greenish$dravite$(tourmaline)$ Prisma9c$but$corroded$zircons$

Characteristic inclusions in Kashmir sapphires

Corroded$plagioclase$ Photo © H.A. Hänni, SSEF


The Kashmir - Madagascar challenge !


Origin$determina9on$=$combina9on$of$data$$$

Kashmir- Madagascar-

Blocky$zoning$with$red$VISEfluorescence$ Very$dense$zoning$

„Parquet“Estructure$ Dark-grey-colour-layer-(zone)-





subtle$„dust“$flakes$and$patches$

dense$and$wellEshaped$(rhombic)$„dust“$patches$





Fine$and$partly$curved$„dust“$lines$and$tracks$

Dis9nct$and$straight$„dust“$lines$



Characteris9c$$blocky$zoning$

Kashmir – Sri Lanka – Madagascar - Basaltic

ogen$narrow$zoning$

ogen$narrow$zoning$with$dark$zones$

Very$regular$$narrow$zoning$

Usually$$quite$included$

Ogen$$rather$pure$

Ogen$$rather$pure$

Usually$$included$

Characteris9c$$Inclusions:$E$pargasite$...$

Characteris9c$Inclusions:$

E$apa9te,$diaspore...$

Ogen$only$$few$inclusions$

Characteris9c$$Inclusions:$

E$UEpyrochlore$

Metamorphic$$UVEVis$spectrum$



Basal9c$UVEVis$spectrum$

Low$Fe$Low$Fe3+$

Low$Fe$Slightly$higher$Fe3+$

Higher$Fe$Slightly$higher$Fe3+$

High$Fe$High$Fe3+$

New source: Fancy sapphires from Batakundi, Kashmir area (Pakistan)

Sleeping$beauty$?$

New source: Fancy sapphires from Batakundi, Kashmir area (Pakistan)

Usually$included$(graphite),$milky$and$with$dis9nct$colour$zoning$(Cr).$


Ruby

Burmese ruby


The$ruby$ring$of$Marie$José,$Queen$of$Italy$

Courtesy of Albion Art collection!

Mogok

Gemmarket$in$Mogok$(January$2014)$

Dahaw$mine$:$East$of$Mogok$

Introduction

Jade,(since(thousand(of(years(a(mythical(stone(appreciated(in(Far(East(and(in(the(high(cultures(of(native(Americans,(is(currently(again(rising(high(and(is(sought(after(at(auctions(in(Hong(Kong(and(elsewhere.((

Ruby-tes<ng-at-SSEF-

The$quest$for$the$perfect$ruby$from$Mogok...$

approx.$14$ct$

Inclusions in Ruby from Mogok

!!!

Ru9le$silk$ Calcite$crystals$

Twin$lamella$ Corroded$calcite$crystals$

Photos © H.A. Hänni, SSEF

Colour$swirls$

© SSEF Swiss Gemmological Institute"

Generally$included$

105$ct$

© SSEF Swiss Gemmological Institute"

Titanite$and$plagioclase$inclusion$in$ruby$from$Mogok$ www.op9cs.rochester.edu$

www.vcbio.science.ru.nl$

www4.nau.edu/microanalysis$

Scanning$Electron$microprobe$

Burmese$Ruby:$approx.$48$cts$

Approx. 48 cts!

„Cut$tongues“$and$geometric$(trigonal)$platelets$

Mong Hsu, Burma important source of rubies since the 90ies!

Many rubies from Mong Hsu have a dark blue core

Mong Hsu, unheated

Dark$blue$to$black$core$zone$(TiEenriched)$

Mong Hsu, unheated

Cross$clouds$ Dust$tracks$„comets“$

Mong Hsu, unheated

Zoning$$$

&$healed$fissures$

Carbonates$

Mong Hsu heated LW$UV$reac9on$

SW$UV$reac9on$


New Ruby Deposit: Montepuez in Mozambique


Mozambique (Montepuez) Rubies$from$Amphibolite$


Inclusions:$$Rounded$crystal$inclusions,$$ru9le$needles,$twinning$planes,$$green$amphibole.$$E$Inclusions$±$similar$to$Mogok,$Burma$E$Trace$elements$±$similar$to$Winza$

Montepuez Ruby




Ruby from Winza (Central Tanzania)


Rubies from Winza

Characteris9c$inclusions:$$

E$curved$hollowEchannel$

E$whi9sh$granular$fluid$inclusions$

E$blue$to$greyish$colour$zones$

© H.A. Hänni, SSEF

Colour zoning in corundum from Winza


Vive la France!

New rubies and sapphires from Madagascar (Didy):

A(ruby(of(25(ct(from(Didy((Madagascar)(showing(an(exceptional(clarity(

The Cinderella job....!

Unheated Burmese rubies mixed with very few heated ones, or even synthetic rubies or ruby imitations (dyed quarzite)!


The colour of ruby

ruby(

pink((sapphire(

purple(

Pigeon$blood$red$$SSEF$defini9on:$Poe9cal$and$historical$colour$term,$describing$a$saturated$and$vivid$crimson$red$colour$of$gemquality$untreated$rubies$from$Burma$(Myanmar).$$The$SSEF$does$not$apply$this$term$to$rubies$from$other$sources,$nor$to$heated$stones.$$At$SSEF$$stones$are$compared$to$colour$charts$and$reference$stones.$

Conclusions:

Origin$of$a$gemstone$should$not$be$misinterpreted$as$a$quality$grade.$$Origin$determina9on$is$always$a$expert$opinion$$It$is$based$on$a$combina9on$of$me9culous$observa9ons$and$analy9cal$data$$New$analy9cal$methods$have$made$and$will$make$important$contribu9ons,$but$due$to$overlapping$proper9es,$these$data$need$careful$interpreta9on$(no$black$box$!)$$S9ll$nowadays,$microscopy$is$a$very$important$and$useful$tool,$as$the$presence,$shape,$and$distribu9on$of$inclusions$and$zoning$features$are$very$sensi9ve$markers$of$specific$local$forma9on$processes.$$New$deposits$may$be$a$challenge$for$gemmologist,$but$are$welcomed$by$the$trade$to$answer$the$high$demand$in$gems.$$$

Thank you for your attention

For$more$informa9on,$check$www.ssef.ch$

The quest for Kashmir sapphires and Burma rubies Origin ...€¦ · The$Star%of%Kashmir%...

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