Origin determination of gemstones (2014) by ssefgemlab

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 emo9on connec9ng to history a$label for investment © Swiss Gemmological Institute SSEF Rothko:$un9tled Jose$Boomsma:$Tribute$to$Rothko$EBlue$

Origin determination is always an expert opinion ! © Swiss Gemmological Institute SSEF 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.$ © Swiss Gemmological Institute SSEF 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$$ characteris9c$for$the$origin$(mining$area).$ The$origin$is$expressed$based$on$wellE established$criteria$(e.g.$inclusions,$ chemical$composi9on...).$ Challenges:$$ $New$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:$ $$scien9fically$and$gemmologically$highly$ educated$staff$$ $sophis9cated$analy9cal$instrumenta9on$ $reference$samples$from$different$mines$ $con9nuous$research$ $long$established$experience$ © SSEF Swiss Gemmological Institute Photo © H.A. Hänni, SSEF 2004

© Swiss Gemmological Institute SSEF 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$tectonoE metamorphic events$(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 $(45E5$ma)$due$to the collision between the$Indian$plate 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 XEray ﬂuorescence$(EDXRF)$ Raman$Microspectrometry FTIR$Infrared$Spectrometry UVEVisENIR$Spectrophotometer Photoluminescence Eventually:$ LAEICPEMS$(laser abla9on induc9vey coupled plasma mass spectrometry)$ LIBS$(laser induced$breakdown$spectroscopy)$ © Swiss Gemmological Institute SSEF © Swiss Gemmological Institute SSEF Raman microspectrometry

Chemical data versus spectroscopic data

UV-Vis Spectrometry

from H.A. Hänni, Journal of Gemmology 1994

Basaltic Kashmir Burma Ceylon

Laser Ablation Inductively Coupled Plasma Mass Spectrometry LA-ICP-MS © SSEF Swiss Gemmological Institute With$Dr.$Thomas$Pehke at the Geochemical$Lab,$$ University$of Berne,$Switzerland © Swiss Gemmological Institute SSEF Laser ablation © T. Pettke,, University Berne Local hea9ng and vaporiza9on

Raw data

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

Surface contamina9on$!$

Data processing

Surface contamina9on$!$

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

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

Fe #(ppm)# Ga#(ppm)# From:$P.$Halicki,$SSEF$(Masterthesis)$ Sapphire Results: Burma( Madagascar Kashmir Burma Ti #(ppm)# Mg#(ppm)# From:$P.$Halicki,$SSEF$(Masterthesis)$ Sapphire Results:

75 24.04.2012 Zentraler Weiterbildungskurs SGG Trace(element concentrations generally indicate origin(„trends“,(but( are often(not( resulting(in( conclusive results Possibilities & 24.04.2012 Zentraler Weiterbildungskurs SGG 30 Comparison Peucat et al (2007) Kashmir this study (et(al.(2007( 80 Thailand (Bo Phloi) + Cambodia Peucat et al (2007) From:$P.$Halicki,$SSEF$(Masterthesis)$ Kashmir sapphire

The(Maharaja of(Jammu(and Kashmir,(( circa(1900( www.kashmirphotos.org/history.html The velvety blue of Kashmir sapphires Sapphires$from$Kashmir$contain$subE microscopic$inclusions$which$scaher$the$ transmihed$light.$$ As$a$result,$these$stones$ogen$show$a$$ highly$appreciated$velvety$blue$colour.$ Photo © H.A. Hänni, SSEF © Swiss Gemmological Institute 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$(prisma9c)$ Characteristic inclusions in Kashmir sapphires Corroded plagioclase

Photo © H.A. Hänni, SSEF Photo © H.A. Hänni, SSEF

The Kashmir - Madagascar challenge !

Kashmir

Madagascar Blocky zoning with red$VISEﬂuorescence Very dense zoning „Parquet“Estructure Dark-grey colour layer-(zone)Photo © H.A. Hänni, SSEF Kashmir Madagascar subtle$„dust“$ ﬂakes and patches dense and wellEshaped (rhombic)$ „dust“$ patches Photo © H.A. Hänni, SSEF

Kashmir Madagascar Fine$and partly curved „dust“$lines and tracks Dis9nct and straight „dust“$lines Photo © H.A. Hänni, SSEF © SSEF Swiss Gemmological Institute Characteris9c blocky zoning Kashmir – Sri Lanka – Madagascar - Basaltic ogen narrow zoning ogen narrow zoning with dark zones Very regular narrow zoning Usually quite included Ogen rather$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 Metamorphic UVEVis spectrum 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).$

© Swiss Gemmological Institute SSEF Ruby Burmese ruby

Courtesy of Albion

Art

collection

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

Dahaw mine$:$East$of Mogok 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 &$healed ﬁssures Carbonates$

LW$UV$reac9on SW$UV$reac9on$

New Ruby Deposit: Montepuez in Mozambique

Mozambique (Montepuez) Rubies$from$Amphibolite$ Photos © H.A. Hänni, SSEF Inclusions:$ Rounded$crystal$inclusions,$$ ru9le$needles,$twinning$planes,$$ green$amphibole.$ E$Inclusions$±$similar$to$Mogok,$Burma$ E$Trace$elements$±$similar$to$Winza Montepuez Ruby © Swiss Gemmological Institute SSEF Photos © H.A. Hänni, SSEF

Rubies from Winza Characteris9c inclusions:$$ E$curved hollowEchannel E$whi9sh$granular$ﬂuid$inclusions E$blue to greyish colour zones

Colour zoning in corundum from 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) © Swiss Gemmological Institute SSEF 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