^Journal of Gemmology

Home , Icositetrahedron, Las Juntas Formation, Yttrium lithium fluoride

Volume 23 No. 4. October 1992 ^Journal of Gemmology

THE GEMMOLOGICAL ASSOCIATION AND GEM TESTING LABORATORY OF GREAT BRITAIN OFFICERS AND COUNCIL

Past Presidents: Sir Henry Miers, MA, D.Sc, FRS Sir William Bragg, OM, KBE, FRS Dr. G.F. Herbert Smith, CBE, MA, D.Sc. Sir Lawrence Bragg, CH, OBE, MC, B.Sc, FRS Sir Frank Claringbull, Ph.D., F.Inst.P., FGS Vice-President: R. K. Mitchell, FGA

Council of Management D.J. Callaghan, FGA CR. Cavey, FGA E.A. Jobbins, B.Sc, C.Eng., FIMM, FGA I. Thomson, FGA V.P. Watson, FGA K. Scarratt, FGA R.R. Harding, B.Sc., D.Phil., FGA, C. Geol.

Members' Council A. J. Allnutt, M.Sc, G.H. Jones, B.Sc, Ph.D., FGA P. G. Read, C.Eng., Ph.D., FGA H. Levy, M.Sc, BA, FGA MIEE, MIERE, FGA P. J. E. Daly, B.Sc, FGA J. Kessler I. Roberts, FGA T. Davidson, FGA G. Monnickendam E.A. Thomson, R. Fuller, FGA L. Music Hon. FGA D. Inkersole, FGA J.B. Nelson, Ph.D., FGS, R. Velden B. Jackson, FGA F. Inst. P., C.Phys., FGA D. Warren CH. Winter, FGA

Branch Chairmen: Midlands Branch: D.M. Larcher, FBHI, FGA North-West Branch: I. Knight, FGA

Examiners: A. J. Allnutt, M.Sc, Ph.D., FGA G. H. Jones, B.Sc, Ph.D., FGA L. Bartlett, B.Sc, M.Phil., FGA D. G. Kent, FGA E. M. Bruton, FGA R. D. Ross, B.Sc, FGA C. R. Çavey, FGA P. Sadler, B.Sc, FGS, FGA S. Coelho, B.Sc, FGA E. Stern, FGA A.T. Collins, B.Sc, Ph.D Prof. I.Sunagawa,D.Sc B. Jackson, FGA M. Virkkunen, M.Phil., FGA E. A. Jobbins, B.Sc, C Eng., FIMM, FGA C Woodward, B.Sc, FGA

Editor: E. A. Jobbins, B.Sc, C.Eng., FIMM, FGA Editorial Assistant: Mary A. Burland Curator: C R. Cavey, FGA

The Gemmological Association and Gem Testing Laboratory of Great Britain 27 GrevUle Street, London EON 8SU Telephone: 071-404 3334 Fax: 071-404 8843 ^Journal of Gemmology

VOLUME 23 NUMBER FOUR OCTOBER 1992

Cover Picture A 146-faced 'sphere' formed by the combination of the cube, octahedron, rhombdodecahedron, trisoctahedron, hexoctahedron, icositetrahedron and tetrahexahedron. (See 'Symmetrical polyhedrafor gemstones'on p.207 ).

ISSN: 0022-1252 194 J. Gemm, 1992,23,4

FORTHCOMING MEETINGS

1992 ANNUAL CONFERENCE AND PRESENTATION OF AWARDS

The second GAGTL Annual Conference is to be held on Sunday 8 and Monday 9 November at the Great Western Royal Hotel, Paddington, London.

Dr K. Nassau will deliver the keynote lecture on treatments in a full programme dealing with coloured stones, diamonds, valuation procedures and the Duchess of Windsor's jewellery.

The Conference will be followed on the evening of Monday 9 November by the Presentation of Awards which will take place at Goldsmiths' Hall, Foster Lane, London EC2. This year the awards will be presented by Dr K. Nassau.

MEMBERS' MEETINGS

London On 24 November 1992 at the City Conference Centre, Mark Lane, London EC3R 7JN, lectures will be given on the gemstone deposits of Africa and the trade associated with them. Admission by ticket only, at a cost of £5.00 for GAGTL members, £10.00 a member and a guest, and £8.00 for non-members. For further details and tickets contact the GAGTL.

Midlands Branch Meetings will be held at Dr Johnson House, Bull Street, Birmingham. Further details from Gwyn Green on 021-440 1428 or 021-445 5359.

25 September 1992 Open Forum. Any questions to our panel. 30 October 1992 Bring and Buy. Specimens, books, equipment - 10% to Branch funds. 1 November 1992 Annual Practical Gemmology Seminar, to be held at the Cobden Hotel, Birmingham. Tickets £18.00 from David Larcher, Midlands Branch Chairman, c/o GAGTL. 27 November 1992 Nigel Dunn. 'Jewellery through the ages'. 5 December 1992 Fortieth Anniversary Dinner. 27 January 1993 Edgar Taylor. 'Fossicking in Wales'. 26 February 1993 Robert Campbell-Legg. 'The art of the engraver'. 26 March 1993 Peggy Stock. 'Crystal healing'. 30 April 1993 AGM and filmshow.

North West Branch Meeting to be held at Church House, Hanover Street, Liverpool 1. Further details from Irene Knight on 051-924 3103.

21 October 1992 Dr Jamie Nelson. 'Optical attributes of a diamond'. 18 November 1992 Annual General Meeting. J].. Gemm.Gemm.,, 19921992,, 2323,, 4 191955

OxidatioOxidationn treatmentreatmentt ooff ththee sapphiresapphiress frofromm ShandonShandongg ProvinceProvince,, ChinChinaa Wang Chuanfu, Chuanfu, Yang Yang Yaoshan Yaoshan and andLi Guoxun Li Guoxun

3030fLab,1 Lab, GeneraGenerall ResearcResearchh InstitutInstitutee foforr Non-FerrouNon-Ferrouss MetalMetalss BeijinBeijingg 100088100088,, P.RP.R.. ChinChinaa

AbstracAbstractt weighweightt anandd ththee A1Al22003 conten contentt shoulshouldd bbee helheldd aatt neanearr IItt iiss nonoww welwelll knowknownn thathatt a larglargee numbenumberr ooff dardarkk blubluee ththee saturatiosaturationn solubilitsolubilityy (10-(1O-11wt%).1 lwt%). TheThe saltssalts werewere sapphiresapphiress araree founfoundd iinn ShandonShandongg ProvinceProvince,, ChinaChina.. IInn mixemixedd anandd placeplacedd intintoo ththee carbocarbonn cruciblcruciblee insidinsidee a ordeorderr ttoo improvimprovee ththee gradgradee ooff thesthesee sapphiressapphires,, ththee temperature-controlletemperature-controlledd furnacefurnace.. AAss showshownn iinn FiFi traditionaltraditional heating treatment was used at the temperatemperature gurguree 11,, PPtt (platinum(platinum)) wirwiree was useusedd aass ththee anodanodee andand ture ooff 1700°C1700°C.. HoweveHoweverr ththee blubluee huhuee ooff sapphirsapphiree wawass ththee sapphirsapphiree samplsamplee was alsalsoo coilecoiledd bbyy ththee platinumplatinum almost lost and became a grey colour. Instead, a new almost lost and became a grey colour. Instead, a new wirewire.. ThThee carbocarbonn cruciblcruciblee wawass useusedd aass ththee cathode.cathode. methomethodd wawass applieappliedd ttoo enhancenhancee ththee claritclarityy ooff ththee sapphiresapphire ssoo aass ttoo improvimprovee ititss qualityquality.. IInn thithiss methomethodd ththee AAtt ththee cathodecathode,, aluminiualuminiumm metametall containincontainingg a littlelittle electrolysielectrolysiss techniqutechniquee usinusingg moltemoltenn saltssalts wawass useusedd ttoo titaniutitaniumm wawass produceproducedd anandd depositedepositedd oonn ththee botbot producproducee a ververyy vigorouvigorouss oxidatiooxidationn ooff ththee corundum.corundum. totomm ooff ththee cruciblecrucible.. OncOncee ththee electrolytelectrolytee was 2+ ThThee Fe2 + containecontainedd iinn ththee sapphirsapphiree wawass partlypartly oxidized;oxidized; moltenmolten,, ththee anodanodee anandd samplesample werweree immersedimmersed aass a resultresult thethe samplessamples treatedtreated byby electrolysis electrolysis show show a a very very togethetogetherr intintoo ththee batbathh anandd electrolysielectrolysiss was concon beautifubeautifull coloucolourr witwithh a lighlightt blubluee huehue.. ThThee absorptionabsorption ducteductedd aatt a celcelll voltagvoltagee ooff 3.3.00 voltvoltss foforr 30-430-455 spectrspectraa ooff ththee specimensspecimens alsalsoo confirconfirmm thathatt ththee sapphiresapphire minutesminutes,, thethenn ththee anodanodee anandd samplsamplee werweree taketakenn outout colour was improved.improved. ooff ththee batbathh anandd coolecooledd aatt ththee ratratee ooff 9°Clmin.9°C/min. IntroductioIntroductionn RecentlyRecently,, larglargee naturanaturall corunducorundumm resourceresourcess havhavee beenbeen foundfound inin ShandongShandong Province,Province, China.China. HoweverHowever / therethere areare onlyonly a fewfew gem-gradegem-grade sapphiressapphires amongamong 1 thesethese corundumscorundums andand manymany ofof themthem showshow anan especiallyespecially distinctdistinct pleochroismpleochroism.. TheseThese sapphiressapphires showshow bluish-violebluish-violett colourscolours perpendicularperpendicular toto thethe c-axisc-axis ofof thethe crystal,crystal, andand greengreen oror greenish-yellowgreenish-yellow colourscolours parallelparallel toto thethe c-axis.c-axis. TheseThese stonesstones cannotcannot bebe usedused asas gemstonesgemstones butbut thetheyy mightmight possiblpossiblyy convertconvert toto gem-gradegem-grade sapphiressapphires afterafter treatment.treatment. UsuallyUsually 6 thesethese sapphiressapphires araree heatedheated atat differentdifferent temperaturestemperatures inin thethe rangerange ofof 1400-1S50°C1400-1850°C forfor varyinvaryingg periodperiodss ofof time.time. ThisThis maymay enhanceenhance thethe clarityclarity ofof thesethese sapsap phires,phires, butbut treatedtreated samplessamples showedshowed bluish-greybluish-grey oror greygrey colours.colours. TheThe sapphiressapphires whichwhich showshow greygrey colourscolours wouldwould notnot sell.sell. InIn thisthis investigationinvestigation suchsuch stones were treated by a new method using an Fig.Fig. I.1. ElectrolysisElectrolysis testtest assemblyassembly stones were treated by a new method using an I1 thermocouple;thermocouple; 22 carboncarbon crucible;crucible; 33 PtPt anodeanode withwith oxidationoxidation techniquetechnique withwith moltenmolten saltssalts atat thethe sample;sample; 4 electrolyte;electrolyte; 55 aluminium; aluminium ;6 6 direct direc tsupply. supply . temperaturetemperature ofof 940°C940°C only.only. TheseThese treatedtreated sapphiressapphires cancan showshow goodgood blueblue hueshues andand betterbetter clarityclarity comcom ForFor thethe heatingheating treatmentstreatments thethe sapphiressapphires werewere paredpared withwith thethe sapphiressapphires treatedtreated byby thethe heatingheating placedplaced inin thethe carboncarbon cruciblescrucibles andand heatedheated inin a highhigh method.method. frequencyfrequency furnacefurnace inin air,air, andand heldheld forfor 1010 hourshours atat thethe temperaturetemperature ofof 1700°C1700°C andand thenthen cooledcooled atat thethe raterate ofof ExperimentalExperimental approximatelyapproximately 9°Clmin.9°C/min. TheThe treatedtreated samplessamples werewere TheThe moltenmolten saltssalts usedused areare AlFA1F3,, Na3Na3 AlFA1F66,, CaFz,CaF2, cutcut andand polishedpolished toto presentpresent flatflat parallelparallel surfacessurfaces Ti02 andand A122003. TheThe compositioncomposition isis approximatelyapproximately whichwhich werewere examinedexamined spectroscopicallyspectroscopically perpenperpen 75.5%75.5% Na3Na3 AlFA1F66,, 5%5% AlFA1F33,, 5%5% CaFz,CaF2, 4.5%4.5% Ti02 byby diculardicular toto thethe c-axisc-axis ofof thethe sapphires.sapphires.

Results Most samples can be changed to a light blue colour from dark blue after electrolysis. The clar (,) o ities of the samples were obviously improved. The c: ~ samples showed a pure blue colour perpendicular to .c I-

Discussion The blue sapphire is a single crystal of AIz0 3 containing minor Fe and Ti oxides. The pure Alz03 single-crystal is colourless and absolutely transpa rent. Small amounts of Fe and Ti contained in the

(,) o crystal can absorb certain wavelengths of light and § this results in the sapphire having colour. The .c I-< colour and clarity of the sapphire entirely depend on o .ctil the contents and states ofTi and Fe contained in the < sapphire crystal. There is a high content of Fe in the dark sapphire, especially Fez+, which leads to the sapphire looking dark blue. By decreasing the Fe content or oxidising FeZ + to Fe3+, the dark sapphire 420 470 520 570 620 670 720 would turn to lighter blue and the clarity would be Wavelength (nm) improved. The traditional heat treatment method is used for Fig. 3. Absorption spectrum after electrolysis treatment the purpose of the oxidation of FeZ + ions, but this oxidation process requires a high temperature, approximately 1700°C. However the Ti ions in the crystal may diffuse outwards and be lost under such a high temperature (over 1300°C).The sapphire that loses only a little Ti exhibits a grey colour. So the sapphire sample heated at 1700°C shows bluish grey, but its clarity is improved. Figures 2 and 4 show that absorption peaks occur at 4S0nm after heat treatment, and these have been assigned to H (I). (,) Fe The heat treatment has led to the oxidation ~ of Fez+ to Fe3+ inside the crystal. Comparing Oi .c Figure 2 with Figure 4, the absorption band at I-< o 3 til around SSOnm, associated with Ti + (I), is reduced ~V or disappears after heating. Meanwhile, Ti traces were found in the crucible after the heat treatment. This suggests that some Ti contained in the sap phire was surely lost because of heat treatment. 420 470 520 570 620 670 720 In order to oxidize the sapphire, but prevent it Wavelength (11m) losing Ti, the electrolysis technique was used. The fluoride melts can corrode the crystal lattice of the Fig. 4. Absorption spectrum after heat treatment. sapphire (AIz0 3) at the temperature of only 940°C. J. Gemm., 1992, 23, 4 197

Alumina (A1203) can be readily dissolved by the Based on above conclusions the following model fluoride melts. The saturation solubility is above 11 is presented to explain the transformations taking wt% at the temperature of 940°C. Thus the mass place during the electrolysis and heating treatment transfers are very easy to execute at the interface of the sapphires: between the sapphire and the molten salts. During (l)heat treatment can promote the oxidation of the electrolytic process, much oxygen and a little Fe2+ to Fe3+ in the sapphire crystal, which fluorine gas were produced on the Pt anode. improved the clarity of sapphire; Fluorine and oxygen have a very strong ability to (2) in the 1700°C heating process, some Ti ions of oxidize at high temperatures. The fluorine atom is the sapphire were lost which made sapphire very small, so fluorine and oxygen may enter the show a grey colour; crystal lattice and oxidize Fe2+ to Fe3+ and the (3) during electrolysis at 940°C, the Fe2+ of the content of Fe3+ increases significantly inside the sapphire was oxidized to Fe3+, which improved sapphire. The absorption bands at 450nm have been the sapphire colour significantly; assigned to Fe3+ (1) and the broad absorption bands (4) at 940°C with the electrolysis process, the Ti ions beyond 570nm have been associated with Fe3+ (2). of the sapphire cannot be lost, and the sapphire The spectra so obtained confirm oxidation of Fe2+ could even absorb some Ti ions from the molten to Fe3+ (see Figures 2 and 3). salts, so retaining or even increasing the Ti The samples that were treated by electrolysis content and colour of the sapphire. develop a light blue colour from dark blue and the grey hue was not observed. During electrolysis at 940°C, Ti ions diffuse with difficulty because of the Acknowledgements relatively low temperature. Meanwhile the Ti ion The authors are grateful to Beijing Syntone Gem concentration (as TiCy of the electrolyte is about Plant, which supplied the samples for investigation. 4%wt, more than the concentration of Ti in the sapphires. Thus, even though there is the diffusion of Ti ions, they diffuse into the sample from the melt, which probably leads to the Ti content of the References sapphires increasing slightly; this is consistent with 1. Schmetzer, Karl, Bank, H., 1980. Explanations of the the spectra. The absorption near 550nm has been absorption spectra of natural and synthetic Fe and Ti 3+ (1) containing corundums. Neues Jahrbuch fur Mineralogie, associated with Ti . Before treatment, samples Abhandlungen, 139, 2, 216-25. exhibited a weak absorption band at 550nm and 2. Eigenmann, K., Gunthard, Hs.H., 1972. Valence states, after electrolysis it still persisted, or has an en redox reactions and bi-particle formation of Fe and Ti-doped hanced intensity of absorption maybe owing to sapphires. Chemical Physics Letters, 13, 1, 58-61. diffusion from melt to crystal (compare Figure 2 [Manuscript received 3 February 1992; revised 13 July with Figure 3). 1992]

CONGRATULATIONS TO THE DEUTSCHE GEMMOLOGISCHE GESELLSCHAFT E.V. ON THE OCCASION OF THEIR 60TH ANNIVERSARY

It is a pleasure to salute the achievements of May the DDG prosper in the future and the German Gemmological Association in maintain the high standards of enquiry, promoting the scientific study of gems and reporting and communication established dissemination of information from one of the worldwide through its meetings and journal. most famous centres for coloured gemstones in the world.

With very best wishes from

The Gemmological Association and Gem Testing Laboratory of Great Britain

27 Greville Street, London, EC IN 8SU 198198 J.J. Gemm.,Gemm., 1992,1992, 23,23, 4

DeterminationDetermination ofof ththe e agagee andand originorigin ofof emeraldsemeralds usingusing rubidium-strontiumrubidium-strontium analysisanalysis Ph. Vidal!,Vidal1,B. B. Lasnier Lasnie?-2 andJ-P.and J-P. PoirofPoirot3

1 I Universite Université Blaise Blaise Pascal Pasca let e tURA URA lOCNRS, 10CNRS Clermont-Ferrand,, Clermont-Ferrand France, France 2Universitede2Université de Nantes,Nantes, c.R.G., C.R.G., France France 3S3Servicervicee PublicduPublic du ControledeControle de Diamants, Diamants, c.c.I.P., C.C.I.P., Paris, Paris ,France France

AbstractAbstract ofof powderpowder fromfrom thethe specimenspecimen mustmust bebe dissolveddissolved forfor TheThe rubidium-strontiumrubidium-strontium methodmethod hashas beenbeen usedused ttoo determination.determination. HoweverHowever onlyonly a fewfew milligramsmilligrams ((aa determindeterminee thethe ageage ofof naturalnatural andand syntheticsynthetic emeraldsemeralds.. fewfew percentpercent ofof a carat)carat) areare neededneeded forfor thethe analysis,analysis, Precise agesages of of emeralds emeralds from from Precambrian Precambrian Shields Shields (Bra (Brazil,andan d thethe takingtaking ofof smallsmall samplessamples fromfrom a batcbatchh ooff zil, Zambia,Zambia, Madagascar)Madagascar) havehave beenbeen calculated.calculated. AlthoughAlthough stonesstones maymay bebe consideredconsidered acceptable.acceptable. thethe ageage ofof emeraldsemeralds ofof geologicallygeologically youngeryounger formationsformations iiss TheThe rubidium-strontiumrubidium-strontium geochronologygeochronology methodmethod moremore difficultdifficult toto establish,establish, ColombianColombian emeraldsemeralds araree probably 6161 ± ± 55 million million years years old. old. (Faure,(Faure, 1986),1986), usesuses thethe transformation,transformation, throughthrough thethe emissionemission ofof ~-rays,ß-rays, ofof thethe rubidiumrubidium 8787 isotopeisotope intointo 87 IntroductionIntroduction thethe strontiumstrontium 8787 isotope.isotope. TheThe 87RbRb iiss saisaidd ttoo decadecayy 87 "Where"Where doesdoes thisthis emeraldemerald comecome from?"from?" isis aa toto 87SrSr anandd iitt doedoess ssoo aatt a constanconstantt ratratee whicwhichh iiss mosmostt commoncommon questionquestion askedasked bbyy collectors.collectors. NoNott satisfiedsatisfied easilyeasily expressedexpressed asas a 'half'half life'.life'. TheThe timetime takentaken forfor 11 bbyy ththee beautbeautyy alonalonee ooff a gem,gem, theythey alsalsoo wanwantt toto knowknow gramgram ofof RbRb toto decaydecay toto 0.50.5 gramgramss (the(the halfhalf life)life) iiss wherewhere itit hashas beebeenn formeformedd byby MotherMother Nature.Nature. TToo aboutabout SO50 thousandthousand millionmillion years,years, andand thethe product,product, penetratepenetrate thethe secretsecret ofof anan emerald,emerald, thethe gemmologistgemmologist 0.50.5 gramsgrams ofof Sr,Sr, isis knownknown asas radiogenicradiogenic strontium.strontium. studiesstudies itsits inclusions,inclusions, reflectingreflecting ititss paragenesis,paragenesis, andand maymay thusthus determinedetermine occasionallyoccasionally a likelylikely geoggeog AnalyticalAnalytical TechniqueTechnique usedused onon EmeraldsEmeralds raphicalraphical originorigin whewhenn onlyonly a fewfew depositsdeposits ofof thethe samesame DetailsDetails ofof thethe Rb-SrRb-Sr techniquestechniques asas carriedcarried outout inin typetype areare known.known. thethe Clermont-FerrandClermont-Ferrand (France)(France) LaboratoryLaboratory withwith ItIt isis alsoalso thethe inclusionsinclusions thatthat enableenable a gemmologistgemmologist regardregard toto sampling,sampling, controlcontrol ofof purity,purity, cleaning,cleaning, toto distinguishdistinguish withwith certainty,certainty, man-mademan-made emeraldsemeralds equipment,equipment, processingprocessing,, andand calculationscalculations ofof ages,ages, byby andand chrome-bearingchrome-bearing berylsberyls (named(named syntheticsynthetic emeremer meansmeans ofof 'model-age''model-age' oror 'isochron'isochron method',method', cancan bbee alds).alds). NeverthelessNevertheless therethere areare somesome syntheticsynthetic emeremer obtainedobtained fromfrom oneone ofof thethe authorsauthors (P.(P.V.) V.).. aldsalds thatthat havehave nono typicaltypical inclusions.inclusions. ThenThen itit becombecom eses difficultdifficult toto objectivelyobjectively affirmaffirm theirtheir artificialartificial Results:Results: origin,origin, eveneven ifif subjectivelysubjectively iitt isis suspected:suspected: ththee TheThe resultsresults areare summarizedsummarized inin TableTable I andand maymay investigationinvestigation ofof tracetrace elements,elements, byby destructivedestructive bbee consideredconsidered inin threethree groups:groups: proceduresprocedures throughthrough neutronneutron activationactivation analysisanalysis EMERALDSEMERALDS FROMFROM PRECAMBRIANPRECAMBRIAN ROCKSROCKS (Brazil,(Brazil, (NAA),(NAA), forfor example,example, mamayy thenthen becombecomee necessarynecessary Madagascar,Madagascar, Zambia)Zambia) havehave significantlysignificantly highhigh enen (Schrader,(Schrader, 1983).1983). richmentrichment inin radiogenicradiogenic strontium;strontium; thethe majormajor AnotherAnother approachapproach inin solvingsolving thesethese problemsproblems isis toto reasonsreasons areare theirtheir age,age, andand theirtheir ratherrather highhigh rubirubi determinedetermine exactlyexactly ththee ageage ofof anan emerald.emerald. Generally,Generally, diumdium content.content. WhereWhere highhigh radiogenicradiogenic strontiumstrontium iiss anan emerald'semerald's ageage willwill bebe closelyclosely relatedrelated toto thatthat ofof thethe presentpresent inin a mineralmineral withwith lowlow initialinitial (non(non- environmentenvironment ofof itsits growth,growth, whichwhich cancan bebe dateddated bbyy radiogenic)radiogenic) strontiumstrontium thethe conditionsconditions areare favourablefavourable isotopicisotopic geochronology.geochronology. AmongAmong thethe methodsmethods comcom forfor calculatingcalculating a 'model'model age'.age'. ThisThis cancan bebe donedone foforr monlymonly usedused inin geochronologygeochronology (Faure,(Faure, 1986),1986), ththee thethe emeraldsemeralds inin thisthis groupgroup andand thethe determineddetermined rubidium-strontiumrubidium-strontium (Rb-Sr)(Rb-Sr) methodmethod isis thethe oneone ttoo 'model''model' agesages areare obtaineobtainedd withwith nearlynearly 2%2% precision.precision. offeroffer mostmost prospectprospectss inin thethe studystudy ofof emeraldsemeralds andand TheyThey matchmatch withwith thethe knownknown evolutionevolution ofof thesethese theirtheir hosthost rocks.rocks. Indeed,Indeed, itit iiss knownknown thatthat somesome PrecambrianPrecambrian shields.shields. naturalnatural emeraldsemeralds cancan containcontain measurablemeasurable quantitiesquantities EMERALDSEMERALDS FROMFROM YOUNGYOUNG ROCKSROCKS (Colombia,(Colombia, ofof rubidium,rubidium, a geochemicalgeochemical companioncompanion ofof potaspotas Pakistan,Pakistan, Afghanistan),Afghanistan), havehave lowlow radiogenicradiogenic stronstron SIUm.sium. tiumtium enrichments,enrichments, becausebecause ofof theirtheir youngeryounger agesages NormalNormal Rb-SrRb-Sr analysisanalysis methodsmethods cannotcannot bbee andand theirtheir lowlow rubidiumrubidium contents;contents; theythey alsoalso havehave routinelyroutinely appliedapplied toto cutcut gemstonesgemstones asas smallsmall amountsamounts relativelyrelatively highhigh primarprimaryy strontiumstrontium contents.contents. TheseThese

Table I - Rb/Sr analyses of emeralds from various localities. Model Age with primary initial 87Sr/86Sr weight Rb Sr(I)- 87Rb/86Sr = 0.705. Million Origin mg Qig/g) (/xg/g) (2) 87Sr/86Sr years (Ma) Brazil em. 1* 16.4 76.9 0.085 1148. 42.59 2517 em.2* 66.0 77.4 0.098 1779. 59.07 2273 Santa Terezinha em. 1 169.7 11.8 162.8 0.210 0.72036 em.2 92.8 21.9 3.48 18.49 0.8357 496 sch 74.0 14.3 308.3 0.0134 0.72061 Socoto em. 234.4 51.3 1.24 119.4 2.717 1180 mi. 24.0 1062. 11.1 956.0 25.65 1814 Itaberai em. 1 76.4 14.3 1.02 38.64 0.98805 514 em.2 46.9 17.0 1.77 26.33 0.88830 489 mi. 81.4 209. 2.32 334.1 3.55 597 Madagascar em. 1 179.7 76.0 2.26 96.9 1.5578 618 em.2 142.9 93.7 2.85 94.9 1.3744 497 Zambia em. 1 91.4 28.1 0.029 1627. 12.309 500 em.2 94.1 94.4 0.005 10934. 65.65 598 Colombia em. 1 195.3 1.0 0.45 6.29 0.7197 (Penas em.2 161.6 2.26 0.28 22.6 0.7324 Bianca) em. 3 108.1 1.42 0.20 18.61 0.7316 em. 4 114.1 1.80 0.17 27.43 0.7380 ca. 56.0 1.47 42.8 0.0995 0.71281 Pakistan cm. 130.7 5.0 0.85 16.83 0.71599 Afghanistan cm. 151.1 16.5 7.15 6.69 0.71388 Lennix 31.9 0.45 0.038 13.9 0.7122 Gilson 1 42.7 1.59 n.d. n.d. 2 30.1 1.55 n.d. n.d.

( 1 ) Primary strontium content has been determined by subtracting the laboratory strontium blank ( 1. 8ng) from the analyzed strontium in the sample. (2) 86Sr = primary 86Sr + blank 86Sr. * Precise locality unknown. em: emerald; mi: mica; ca: calcite; sch: schist. three factors combine to give low measured 87Sr/ minerals and host-rocks. In the context of this 86Sr ratios and 'model ages' are not precise enough investigation, the Penas Bianca (Colombia) emer to give satisfactory results. alds are in isotopic equilibrium with their associated However, the use of several samples from the calcite, and those from Santa Terezinha (Goias same deposit enables the use of another technique State, Brazil) are in equilibrium with their host- to obtain the age, called the isochron method. This rock. Rubidium and therefore radiogenic strontium is illustrated in Figure 1, where four samples of Colombian emeralds (Penas Bianca deposit) plotted Fig. 1. Four Penas Bianca (Colombia) emeralds isochron pro viding a 61 ± 5 Ma age. on a graph of 87Sr/86Sr vs 87Rb/86Sr indicate an age of 61 ± 5 million years (Ma). SYNTHETIC EMERALDS: Lennix emeralds con 87Sr/86Sr tain low Rb and low Sr with no detectable additional Sr due to the radioactive decay of Rb. The Sr + content is lower than in most natural emeralds. Similar results were obtained from Gilson synthetic 0.730 - + + emeralds. We conclude that for these samples the synthetic emeralds have Rb-Sr chemical and isotopic characteristics very different from those of natural emeralds. 0.720 - +

Prospects •calcite The rubidium-strontium method has the poten 0.710 - tial to authenticate and even date emeralds. In comparison with natural emeralds, synthetic emer alds may have noticeably different characteristics. 87Rb/86Sr 1 1 Other studies should be undertaken, and it would 10 20 be interesting, from the genetic point of view, to determine isotopic compositions of associated 200 J. Gemm., 1992,23,4

Table II - Acid leaching experiments on Zambian emerald sample. Model Age with primary initial 87Sr/86Sr weight Rb Sr(I)- 87Rb/86Sr = 0.705. Million 87 86 mg (Mg/g) Og/g) (2) Sr/ Sr years (Ma) Unground sample 77.2 130.0 0.38 2188. 13.270 403 ground sample residue 102.5 10.8 0.44 71.56 1.226 510 solution 1.6 0.20 0.53 1.135 0.7115 could be contained within emeralds, possibly in the structure. This phenomenon is widely-known in structural canals (as in morganites), or possibly also minerals rich in rubidium and poor in primary in fluid and solid inclusions. With this in mind, strontium, such as micas, which undergo a thermal Giuliani and Weisbrod (1988) have studied phlogo- event after crystallization. Besides, it seems that pite inclusions in Brazilian emeralds. Even primary emeralds should be more sensitive to the radiogenic strontium should be interesting to localize. Table II strontium loss than associated micas, according to shows the results of a pilot test in which a few Table I results (Socoto, Bahia State; Itaberai, Goias opaque sulphide granules and thin tubes parallel to State - Brazil). the c-axis were studied. Their fluid content could not be determined by Raman probe for their section Acknowledgements (less than 0.1mm) is too small to measure by this The authors are particularly grateful to MM P. method. A second approach was by conventional Cario, P. Fumey, G. Giuliani, and M. Piat, for isotopic analysis of a sample. Thirdly, part of the providing them with emeralds of known origins. sample was finely ground, the powder was leached They are also greatly indebted to Mme M. May for with acid, and residues as well as leachates were her translation work. separately analyzed. It is clear from these analyses that all the rubidium and radiogenic strontium is References contained in the emerald structure, and not inside Faure, G., 1986. Principles of isotope geology. Wiley. fluid inclusions which would have been released Giuliani, G., Weisbrod, A., 1988. Scanning electron microscopy during leaching. (SEM) and its applications: determination of solid and daughter minerals in fluid inclusions from some Brazilian emerald Finally, it is advisable to comment on the reason deposits. Anais do VII Congresso latino-americano de Geologia, for the spread of model ages of Precambrian Belem, Para, v.I: 445-58. emeralds (see Tables I and II) beyond analytical Schrader, H.W., 1983. Contribution to the study of the distinction error. This spread is probably attributable to of natural and synthetic emeralds. J. Gemm. 18, (6), 531-43. variable loss, along dislocations, of radiogenic strontium which is loosely held in the crystal [Manuscript received 29 October 1991; revised 15 July 1992] J. Gemm,, 1992, 23, 4 201

Identification of fissure-treated gemstones Dr H.A. Hänni

Swiss Gemmological Institute (SSEF), Basel, Switzerland

Introduction light path is shorter than it might be if the crack The subject of enhancing the appearance of were not present and the colour thus weaker. Also various gemstones in which fractures have a de the reflecting fractures are conspicuously lighter to trimental effect on their beauty or saleability has the observer (or darker if the fracture plane is been addressed previously by a number of authors observed from behind the 'mirror' of the reflecting (e.g. Ringsrud, R., 1983; Kane, R., 1984; Scarratt, plane). K., and Harding, RR., 1984; Martin, D.D., 1987; If a filler replaces the air previously in the Hänni, H.A., 1988; Koivula, J.I., et ai, 1989; fracture, and the filler substance has a refractive Themelis, T., 1990; Shida, J., 1991; Kammerling, et index higher than air and near to that of the treated al, 1991; Hänni, H.A., 1992). stone, it inhibits a reflection of light rays from most Fissures in gemstones, originate from mechanic incoming directions. The light may then travel al tension, pressure or temperature stress. They across the fracture plane and is not deviated or originally contain vacuum, gas or a fluid. If such reflected. The fracture no longer acts as an obstacle fractures reach the surface of the stone, the narrow in the light path. voids of the fractures are filled with air. All of the On many occasions fractures, pores or grain above media possess refractive indices considerably boundaries of polycrystalline stones are used to lower than that of the gemstone itself. The fractures introduce colour into the material. Recently jadeite are therefore capable of reflecting light. This is an has been treated with acid, then heated to widen the undesirable capability that would be considerably grain boundaries and increase the porosity. The reduced if they were to be filled with a substance of a stones are now easier to treat with an artificial resin. similar refractive index to that of the gemstone. The result is called B-Jade and in the Far East leads The objective of this short review is to bring the to a superabundance of supposed Imperial jade. topic of artificially introduced filling substances, Another example is represented by an originally which may be used in gemstone enhancement colourless, heavily fractured corundum which is cut procedures to the attention of the reader. It seems to into beads for necklaces (Figure 1). The beads are the author that developments in this field have treated with a ruby-red stain, which may be seen on either not been given sufficient exposure, or have fractures and twin planes. The material makes a gone unnoticed by certain elements of the trade very convincing imitation of ruby (Schmetzer et al., during the last few years. It is also important to be 1992). able to differentiate clearly between natural de posits on fracture planes (e.g. iron hydroxide) and How treatments are performed organic artificial matter, commonly but very often For decades, if not centuries, fillings of oils and incorrectly called 'oil'. resins with a viscosity low enough to penetrate into fractures have been used to seemingly improve the Why a treatment can be effective quality of the stones. The lower the viscosity of the Light entering a faceted gemstone only re- filling medium, the more complete is the penetra emerges after multiple internal reflections between tion into the fissure. Sometimes vacuum techniques several facets. Along its path the light is absorbed are used to improve the result. The range of fillers selectively and in a manner that the transmitted encompasses numerous substances: apart from spectral colours result as the perceived colour of the those such as vegetable and mineral oils with gemstone. The shorter the distance the light travels, volatile components (Figure 2), there are the more the weaker the absorption and the lighter the colour. durable fillers like fats and resins. Compounds such Should the light path be interrupted by a fracture, as synthetic epoxy resins are frequently used today because it is reflected at this point, the length of (Themelis, 1990); these possess the advantage of a

Fig. 1. Fractures stained red do not make a ruby! this picture Fig. 2. Emerald with oil-treated fracture. Extensive 'lakes of shows part of one button shaped bead in a necklace. air' form their lobular patterns near the fracture The material was originally near-colourless corun opening when the oil dries out. Magnification 20x. dum. Magnification 25x.

more stable adhesion to the stone. This leads to a This may be done by prolonged immersion in longer lasting improvement in appearance which is solvents and/or acids, possibly with the assistance of not possible with volatile compounds like oil and ultrasonics or steam. The use of a vacuum may paraffin used traditionally. The latter are released extract previously inserted 'oil'. The procedure of quite easily due to their solubility in soaps, deter cleaning may, depending on the intended filler to be gent and solvents. used, take many hours or even days (Themelis, The most stable fracture filler material is glass, 1991). which is introduced into fractures in its molten For a good penetration into the fractures, a low state. For the moment, diamond and corundum are viscosity filler is essential. This objective is reached the only gemstone species treated by this method. with oil, paraffin (Figure 3) or resin by slightly Only these species resist the required high tempera heating these and using a vacuum to assist in the ture without being seriously damaged (Kane, 1984; treatment. Special additives are sometimes used to Hänni, 1986). All other stones like quartz, tourma lower the viscosity as far as to 260 centistokes. line, beryls, jade, lapis lazuli etc are normally A well known product name is sometimes used treated with natural or artificial organic com for a group of epoxy resins with similar characteris pounds. tics: Opticon. Most emeralds in the trade today are treated in the rough or cut state with 'Opticon' or a Emeralds similar product. Other epoxy resins such as Araldite Before a filler is applied to an emerald, a cleaning NU 471, Dobeckot 505, Novogen P40 etc have process should be used to remove all dirt and similar effects as fillers. Their refractive indices are residual filler material from any former treatments. in the range 1.5 to 1.6.

Fig. 3. Resin treated fracture in an emerald, with spectral Fig. 4. Ruby with a fracture, probably treated with wax or colour flashes and dendrite-shaped gas bodies. Opti paraffin. A typical dendrite-like pattern is visible. con treated fractures may look like this. Magnification 20x. J. Gemm., 1992, 23, 4 203

Fig. 5. Sapphire with a filling of artificial resin, showing Fig. 6. A facet of a heat and glass treated ruby. A cavity (and all dendrite-like patterns of gas bodies. In UV light the open fractures) have been filled with glass, identifiable filling has a whitish fluorescence. Magnification 40x. by its lower lustre compared with corundum. Within the glass part an air bubble is cut by the surface. Magnification 20x. Epoxy resins can be used with or without a adhere on rough stones. Sulphuric or hydrochloric hardener. If the resin is used without a hardener, it acid may also be used to remove foreign material on remains soft and usually entirely fills the fracture. and in the open fractures of corundum. Gas bubbles and other structures like viscous The treatment requires the presence of boron or fingering are rare in the fissure.planes. When the lithium to lower the melting point of the silica- artificial resin is mixed with a hardener, polymerisa compound forming the melt. The melt, besides tion takes place. A shrinking effect causes fine filling the fractures, also acts as a solvent or flux fissures and pseudo-dendritic patterns to occur in respectively and enables some recrystallization of the filler plane, making it easier to detect. the fracture planes. Treatments with glassy substances today appear Corundum to be performed faster and/or at lower temperatures Although some historical filling substances are than some time ago, since the included rutile 'silk' encountered today (most probably wax or paraffin) may not be affected during the glass infilling the majority of fractures in ruby and sapphire are treatment. treated with a boro-silicate melt. Before treatment, a process of cleaning is performed to remove all dirt How treatments are identified and residual filler material from any former treat Some of the filler materials contain air or gas ments. Also natural deposits like iron hydroxide or bodies, forming individual bubbles or dendrite-like clay minerals must be dissolved. A cleaning treat patterns. Such patterns, when present, prove the ment is normally carried out by using hydrofluoric existence of two different phases on a fissure plane. acid, which attacks all silicate minerals that may still Many of the organic fillings show a bright fluoresc-

Fig. 7. Artificially healed fracture in a ruby. Under the flux Fig. 8. Treated cleavage fractures in a brilliant-cut diamond. effect of the glass the fracture plane has recrystallized. Yellow and violet interference colours together with In newly formed crystalline cells, the glass has been gas bodies are characteristic for the Yehuda treatment. trapped, devitrified and formed bunches of white radiating crystals. Magnification 40x. 204 J. Gemm., 1992, 23, 4

E ..

,""V :D Dill . 21; 10:I.' HI., : 100 1. ) Ie_ )1 U . 34.2 lot •

.1.. • :IOlI tl ....III 2.-«1-11

Diagram I. Infrared spectra of untreated emerald, Opticon (artificial epoxy resin), and emerald treated with artificial epoxy resin. FTIR-Spectrum recorded by E. jcgge, SSEF laboratory, Zurich.

ence under ultraviolet light which is visible either filler. Also, if stones were subjected subsequently to with the unaided eye or a loupe. different treatments without proper cleaning, the The presence of oil can be indicated by bathing IR spectrum may be difficult to interpret. the stone in a solvent such as acetone or hexane for a Glassy substances, at the surface of a stone may short period . The soluble oil is diluted by the be recognized by their different lustre compared solvent. Under a microscope the drying out of the with that of corundum (Figure 6, Hanni , 1986). If solvent which has replaced some of the oil is easily glassy fillings are to be identified within the stone, visible. Lobular air dendrites develop at the fracture Raman spectroscopy may be the most useful openings. Such a reaction does not appear with method. In many cases, voids filled with artificial resin treated fractures, since resins are less soluble. glass are whitish. The glass has served as a flux, Artificial resin fillings are often apparent by their recrystallized the fracture plane and sealed itself orangy or violet colour flashes (Figures 4 & 5). A into a newly formed geometric void. In some further prooffor a foreign organic filling is possible instances devitrification starts, resulting in the by means of the hot needle. Ifthe needle is put next appearance of radiating fibrous crystals that emerge to the fracture opening, the filling turns to a liquid from trapped gas bubbles (Figure 7). state and moves slightly.The examination should be Heavy liquids possess a high refractive index. observed through the microscope and performed This property is utilized for the Yehuda fracture very carefully. The 'observation' of a foreign filling treatment of diamond (Figure 8). Also with this in a fracture by microscopic inspection may be quite fracture treatment, the filler shows vivid colour easy,but the 'identification'of a particularfiller may flashes, and the fracture planes contain gas bubble s be difficult. Organic fillers, can be detected by and 'lakes' (see Koivula et al., 1989). The heavy infrared spectroscopy (see Diagram I). The infrared elements are identifiable by X-ray spectroscopy spectrometer appears to be the most reliable tool for (Scanning Electron Microscope SEM or Energy an identification, but owing to the numerous Dispersive X-ray Fluorescence Analysis EDS varieties of organic compounds, and the difficulties XFA). Glassy fillings in corundum show the pre due to the superimposition of the stone's spectra sence of silica and Yehuda treated diamond s indi over the filler spectra, this may prove to be a cate the presence of lead and occasionally bismu tho handicap for an exact identification of a particular J. Gemm., 1992, 23, 4 205

Outlook (whatever substance is used) and omit any comment Although the above mentioned treatments are to individual stones. However, the author considers not new, it appears that many trade members have that disclosure of the glass filling of any gemstone little knowledge of some of them or do not wish to should be mandatory. complicate their business by acknowledging their In any case the final consumer should be in presence on the market. The use of colourless oiling formed of the commonly used practices by his is accepted as a common enhancement practice. gemstone specialist to prevent damaging action by This rather historic treatment method is being people with unfair goods. increasingly replaced by more stable treatments that utilize modern filler substances. Whilst the Acknowledgement newer treatment methods in no way represent single The author thanks Kenneth Scarratt and Alan cases, it is unfortunate that only a small number of Jobbins for their very helpful editing of the manu stone dealers, jewellers or goldsmiths have the time, script. the knowledge, the motivation or the equipment to check or confirm these treatments. So it will References probably take a long time for trade opinions about Hänni, H.A., 1986. Glass-like fillings in rubies and sapphires. this kind of treated stone to change and make an Swiss Watch & Jewelry Journal, 9/1986, 779. impact on the market place. Hänni, H.A., 1988. An oil well in your garden? Swiss Watch & Jewelry Journal, 3/1988. At present time the CIBJO rules require only a Hänni, H.A., 1992. Identification des fissures traitées. Revue de disclosure of fracture treatments performed with gemmologie a.f.g., 110, 10-12. substances other than colourless oil. This means Kammerling, R.C., Koivula, J.I., Kane, R.E., Maddison, P., Shigley, J.E., Fritsch, E., 1991. Fracture filling of emeralds. that almost all emeralds, an important number of Gems & Gemology, 27, 187-99. rubies and many sapphires should be labelled or Koivula, J.I., Kammerling, R.C., Fritsch, E., Fryer, C.W., sold respectively as treated gemstones. The exact Hargett, D., Kane, R.E., 1989. The characteristics and identification of the numerous more or less viscous identification of filled diamonds. Gems & Gemology, 25, 68-83. oils (vegetal, animal or synthetic), fats, paraffins, Martin, D.D., 1987. Gemstone durability- Design to Display. natural and artificial resins is rarely simple and Gems & Gemology, 23, 63-77. often impossible. The analyses might be expensive Ringsrud, R., 1983. The oil treatment of emeralds in Bogota, and finally come only to the result that the stone is Colombia. Gems & Gemology, 19, 149-56. treated and has a foreign organic substance in its Scarratt, K. & Harding, R.R., 1984. Glass infillings in natural ruby. Journal of Gemmology, 19, 293-7. fissures. Because of the multitude of organic com Schmetzer, K., Hänni, H.A., Jegge, E.P. & Schupp, E.J., 1992. pounds which could serve as fillers it may be more Dyed natural corundum as a ruby imitation. Gems & appropriate not to draw an arbitrary line between Gemology, 28, 2, 112-5. 'permitted' treatments and those which are not Shida, J., 1991. Enhanced emeralds - How it must be dealt with. ICA Gem News, Hawaii meeting, lecture and abstract. tolerated without declaration. Themelis, T, 1990. Oiling emeralds. Cornerstone, July, 21-4. This would mean a change in the CIBJO rules Themelis, T, 1991. Personal communications. that govern this problem. To the author it seems advisable to handle all fracture treatments in the same way, either to disclose all fracture filled stones [Manuscript received 22 November 1991; revised 14 June or to consider fracture filling as a common practice 1992] 206 J. Gemm., 1992, 23, 4

Members having gained their Diploma in Gemmology or the Gem Diamond Diploma (FGA or DGA) may now apply for use of the Coat of Arms on their stationery or within adveitisments.

Laboratory members are also invited to apply for use of the Laboratory Logo.

It is still a requirement of GAGTL, in accordance with the Bye Laws,thot written permission be granted by the Council of Management before use.

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Tel: (071) 404 3334 Fax:(071)404 8843 J.J. Gemm.,Gemm., 1992,1992, 23,23, 4 207207

SymmetricalSymmetrical polyhedrapolyhedra forfor gemstonesgemstones Jos Lurie, Ph.D.,Ph.D., FGAFGA

TechnikonTechnikon Witwatersrand,Witwatersrand, SchoolSchool ofof MinesMines,, POPO BoxBox 3293,3293, Johannesburg,Johannesburg, SouthSouth AfricaAfrica

AbstractAbstract FacetedFaceted 'spheres''spheres' cutcut recentlyrecently areare described.described. RegularRegular convexconvex polyhedrpolyhedraa includinincludingg platoniplatonicc solids,solids, rhombicrhombic formsforms andand otherother equidimensionalequidimensional formsforms areare discusseddiscussed withwith respectrespect toto faceface shapeshape andand number,number, andand theirtheir inter-relationships.inter-relationships. TheyThey areare placeplacedd intointo symmetrysymmetry classes.classes. TheThe well-knownwell-known crystallographiccrystallographic hexoctahedralhexoctahedral classclass withwith itsits twotwo platonicplatonic solids,solids, oneone rhombirhombicc formform anandd foufourr variablevariable formsforms isis discussed.discussed. CombinationsCombinations ofof thethe / firstfirst threethree formsforms andand alsoalso ofof thethe sevenseven formsforms witwithh facetingfaceting anglesangles areare given.given. TheThe platonicplatonic dodecahedrondodecahedron Dodecahedron Dodecahedron andand icosahedronicosahedron areare variouslyvariously combined.combined. TheThe littlelittle Dodecahedro Dodecahedro knownknown rhombicrhombic triacontahedrontriacontahedron withwith facetingfaceting anglesangles iiss given.given. CombinationsCombinations ofof thesthesee threethree closelyclosely relatedrelated formsforms areare given.given. TheThe virtuallyvirtually unknownunknown fourfour variablevariable formsforms withwith thethe samesame symmetrysymmetry werewere derivedderived theoreticallytheoretically andand a combinationcombination ofof thethe sevenseven formsforms withwith itsits 362362 facesfaces isis illustrated.illustrated. Dodecahedron IntroductionIntroduction Dodecahedro TheThe gemstonegemstone collectioncollection ofof a talentedtalented amateuramateur faceterfaceter,, DicDickk Rothkugel,Rothkugel, waswas recentlyrecently examined.examined. PossiblyPossibly thethe mostmost intriguingintriguing ofof thethe itemsitems ofof anan interestinginteresting collectioncollection isis a 'sphere''sphere' ofof smokysmoky quartzquartz withwith 3232 symmetricallysymmetrically arrangedarranged facetsfacets weighingweighing 2020 caratscarats andand 15mm15mm inin diameter.diameter. This,This, togethertogether withwith anan articlearticle byby PaulPaul C.C. SmithSmith onon makinmakingg a spheresphere ofof thisthis Dodecahedron Icos.lh dron sort,sort, provideprovidedd inspirationinspiration toto investigateinvestigate thethe fascifasci Dodecahedron Icosahedron natingnating realmrealm ofof symmetricalsymmetrical polyhedrapolyhedra inin orderorder toto producproducee alternatalternatee designsdesigns thatthat woulwouldd challengechallenge thethe enthusiasticenthusiastic faceter.faceter. FindingsFindings includedincluded severalseveral Fig.Fig. 2.2. TheThe platonicplatonic polyhedra.polyhedra. formsforms relaterelatedd ttoo ththee pentagonapentagonall dodecahedrondodecahedron andand thethe icosahedronicosahedron.. HavingHaving cutcut anotheranother spheresphere onon thethe FigFig.. I.1. FacetedFaceted spheres:spheres: A - a combinationcombination cubiccubic zirconiazirconia previousprevious designdesign bubutt ofof amberamber cubiccubic zirconiazirconia ofof 4545 sphere;sphere; B -- aa smoky smoky quartzquartz triacontahedron.triacontahedron. carats,carats, DickDick RothkugelRothkugel subsequentlysubsequently producedproduced a 47-carat47-carat triacontahedrontriacontahedron onon mmyy calculatedcalculated data.data. TheseThese twotwo gemgem polyhedrpolyhedraa areare illustratedillustrated inin FigureFigure 1.1. TheThe beautybeauty ofof thesethese cutscuts isis inin thethe symmetrysymmetry ofof thethe facetsfacets andand thethe lightlight patterpatternn reflectedreflected frofromm them.them.

RegularRegular polyhedrapolyhedra ThereThere areare onlyonly fivefive convexconvex polyhedrapolyhedra eacheach ooff identicalidentical facesfaces thatthat areare regularegularr polygonspolygons withwith equalequal internalinternal angles.angles. ThisThis factfact waswas knownknown byby thethe GreekGreek philosopherphilosopherss andand thethe polyhedrpolyhedraa areare thereforetherefore referrefer redred toto asas thethe platonicplatonic solids.solids. TheseThese are:are: thethe tet-tet- 208 J. Gemm., 1992,23,4

Table 1: Some equidimensional polyhedra Non-crystallographic Crystallographic | Class Hexicosahedral Hexoctahedral Hextetrahedral Face form

Symmetry* 6A5 10A3 15A2 3A4 4A3 6A2 4A3 3A2 15P C 9P C 6P Trigonal icosahedron Trigonal octahedron Tetrahedron 20 8 4 A Platonic forms - Square hexahedron Square hexahedron (cube) 6 (cube) 6 • Pentagonal dodecahedron - - 12 * Rhombic triacontahedron Rhombic dodecahedron Rhombic dodecahedron 30 12 12 • Non-platonic forms Trigonal pentadodecahedron Trigonal tetrahexahedron Trigonal tetrahexahedron 60 24 24 A Trigonal trisicosahedron Trigonal trisoctahedron Trigonal tristetrahedron 60 24 12 • Trapezoidal hexcontahedron Trapezoidal icosatetrahedron Deltoid dodecahedron 60 24 12 t Hexicosahedron Hexoctahedron Hextetrahedron 120 48 24 A * A denotes a rotation axis of symmetry, subscripts indicate repetitions/3600 ; P denotes a plane of symmetry ; C denotes a centre of symmetry. rahedron (four faces), the hexahedron (or cube with component faces involved the more closely the six faces), the octahedron (eight faces), the penta polyhedron approaches a spherical form. Thus the gonal dodecahedron (12 faces) and the icosahedron dodecahedron and the icosahedron are the more (20 faces). These are illustrated in Figure 2. Note interesting forms to investigate. that the only polygonal faces involved are the There are three additional symmetrical polyhedra equilateral triangle, the square and the regular with the rhombus as face form (Figure 3). They are: pentagon. These polyhedra all fulfil the Euler (18th the variable rhombohedron (6 faces), the fixed Century Swiss mathematician) characteristic name rhombic dodecahedron (12 faces) and the variable ly: Vertices + Faces - Edges = 2. triacontahedron (30 faces). Because of the regular arrangement of their The closed forms of higher symmetry are constituent faces and consequent symmetry such classified in Table 1. The crystallography classes are polyhedra are visually pleasing. Obviously the more well known; the proposed new symmetry class, the hexicosahedral, is now added. The author Fig. 3. Rhombic forms. has constructed models of each of the seven forms of this new class. Rhombic dodecahedron

Crystallographic polyhedra Of the above platonic solids only the tetrahedron, the cube and the octahedron are encountered in crystallography (where faces are parallel to planes of atoms in their structure). There are actually several dodecahedra possible crystallographically but these do not have equilateral pentagonal polygon faces. Rhombohedron For instance, the pyritohedron, a form in which the mineral pyrite sometimes crystallizes is, in fact, a pentagonal dodecahedron but the pentagon faces have a side of odd length and consequently the form has much lower symmetry. Interestingly, the so- called 'iron cross' interpenetrant twin form has higher symmetry. The tetrahedral pentagonal dode cahedron has irregular pentagonal faces and even lower symmetry. Garnets often crystallize as dode Triacontahedron cahedra in which the faces are rhombs (Figure 4). J.J. Gemm.,Gemm.,1992 1992,, 23,23, 4 209209

./T"\ Octahedron mm<&. 2 Cube 7Q9

Dodecahedron

Fig.Fig. 4. CombinationsCombinations ofof cube,cube, octahedronoctahedron andand dodecahedron.dodecahedron. ThereThere areare a largelarge numbenumberr ofof otherother polyhedrapolyhedra encounteredencountered inin crystalscrystals butbut thethe facefacess ofof thesethese areare notnot regularegularr polygonspolygons.. ThoseThose ofof ththee mosmostt symmetricalsymmetrical crystalcrystal classclass ((ooff 32) namely,namely, ththee so-calledso-called HexocHexoc- tahedratahedrall Class,Class, IsometricIsometric System,System, generallygenerally havhavee thethe mosmostt facesfaces andand areare equidimensional.equidimensional. TheyThey provideprovide FigFig.. S5. HexoctahedraHexoctahedrall combinations.combinations. ththee besbestt basibasiss foforr ththee developmentdevelopment ooff facetedfaceted spheres.spheres. TheTheyy compriscomprisee th thee followinfollowingg formsforms:: twtwoo octahedrooctahedronn wouldwould,, iinn factfact,, producproducee ththee dodedode platoniplatonicc solids,solids, namelynamely,, ththee cubcubee (hexahedron(hexahedron)) andand cahedrocahedronn iiff thesthesee bevelbevelss werweree extendeextendedd oorr symmetsymmet octahedronoctahedron;; ththee rhombirhombicc dodecahedrododecahedronn (1(122 faces,faces, ricallricallyy groungroundd downdown.. ThThee threthreee formformss havhavee ththee samesame ththee tetrahexahedrotetrahexahedronn (24)(24),, ththee trisoctahedrotrisoctahedronn (24)(24),, symmetrsymmetryy anandd cacann bbee combinecombinedd aass illustratedillustrated ththee icositetrahedroicositetrahedronn (24(24)) anandd ththee hexoctahedronhexoctahedron (Figur(Figuree 4)4). NotNotee ththee relativrelativee developmendevelopmentt ooff thethe (48)(48 ).. simplsimplee formformss iinn eaceachh modelmodel.. ThThee cubcubee anandd ththee octahedrooctahedronn havhavee aann interestinginteresting ThThee remaininremainingg foufourr formformss ooff ththee clasclasss araree nonott relationshirelationshipp iinn thathatt ththee cubcubee hahass 6 facefacess anandd 8 fixed iinn respecrespectt ooff inter-faciainter-faciall angleangless anandd interceptsintercepts quoins,, ththee octahedrooctahedronn 6 quoinquoinss anandd 8 faces.faces. witwithh ththee crystallographicrystallographicc axesaxes.. TherTheree areare,, iinn fact,fact, Furthermore,, eaceachh ooff ththee cubcubee anandd octahedrooctahedronn havhavee severaseverall variantvariantss ooff eaceachh forformm possiblepossible.. 1122 edgeedgess whilwhilee ththee rhombirhombicc dodecahedrododecahedronn hahass 1122 WhaWhatt mamayy bbee regarderegardedd aass ththee ultimatultimatee facetedfaceted facesfaces.. BevelleBevelledd edgeedgess ooff botbothh ththee cub cubee anandd ththee spherspheree witwithh pleasinpleasingg symmetrsymmetryy iinn thithiss clasclasss iiss produceproducedd bbyy combinincombiningg ththee sevesevenn formformss ooff ththee FigFig.. 6.. ModeModell off a 146-facel46-facedd 'sphere''sphere.'. hexoctahedrahexoctahedrall clasclasss ttoo producproducee a 146-face146-facedd spheresphere.. A resulresultt iiss showshownn iinn FigurFiguree 55.. ThosThosee representativesrepresentatives ooff eaceachh ooff ththee variablvariablee formformss havhavee beebeenn chosechosenn thathatt havhavee ththee simplessimplestt relationshirelationshipp witwithh ththee crystallogcrystallog raphiraphicc axeaxess ooff ththee IsometriIsometricc SystemSystem,, i.ei.e.. thetheyy havhavee

i 1 d^/

Slcr.,; t.lgnlITI Fig 7, Stereogram \\ / ' quadrant of quadrant of model in model in Fig. 6. Fig. 6. 210 J. Gemm., 1992, 23, 4

the lowest Miller face symbols. These have the angles, the bevel angles for fitting adjacent faces simplest relationship with one another and the fixed together and also the plane face angles. Involved forms and the greatest degree of co-zonality. The was considerable spherical trigonometry but the parallel-perspective view of the combination was most formidable task was assembling the model. produced by means of a drawing technique using This was accomplished after several unsuccessful the stereographic projection of the poles of the attempts and by evolving a procedure for controll faces. ing angular distortion. The model obeys the Euler The cube faces have been made dominant to equation having 146 faces, 240 vertices and 384 serve as 'table' facets. A model in seven colours to edges. Parallelism of interfacial edges in the pers represent the seven forms has been constructed out pective view indicates the various zones in which of sheet perspex. This is shown in Figure 6. One faces lie and presents the faceter with a modus in quadrant of the stereogram is shown in Figure 12. respect of cutting order of facets. The angles for Construction of the model required the interfacial faceting are given in Table 2 below.

PLANA Hexicosahedral polyhedra The first three polyhedra of this class have an 1 13 analogous inter-relationship to that between the 3. combinations are all the same, namely, six five-fold, 8 8 ^yjX*£&/ | 15"- /9\ ten three-fold, 15 two-fold rotation axes and 15 13 planes of symmetry and a centre of symmetry.

Table 2: Faceting angles for the construction of the 146-faced 'sphere' Upper hemisphere Angle Facet Indices 0 1. Cube Any 26.6 2. Tetrahexahedron 80 20 40 60 32.2 3. Trapezohedron 10 30 50 70 36.7 4. Hexoctahedron 6 14 26 34 46 54 66 74 45.0 5. Dodecahedron 80 20 40 60 48.2 6. Trisoctahedron 6 14 26 34 46 54 66 74 54.4 7. Octohedron 10 30 50 70 57.7 8. Hexoctahedron 4 16 24 36 44 56 64 76 63.4 9. Tetrahexahedron 80 20 40 60 68.2 10. Trapezohedron 6 14 26 34 46 54 66 74 70.2 11. Trisoctahedron 10 30 50 70 74.5 12. Hexoctahedron 7 13 27 33 47 53 67 73 90 13. Cube 80 20 40 60 90 14. Dodecahedron 10 30 50 70 90 15. Tetrahexahedron 6 14 26 34 46 54 66 74 Lower hemi sphere Repeat of upper hemisphere in reverse order. Orientation controlled by facets 13,14 & 15. J. Gemm., 1992, 23, 4 211

Three of the two-fold axes which are normal to each other may be chosen as reference axes thus enabling the models to be viewed in analogous orientation (cf Pentagonal dodecahedron crystallographic axes). A number of dodecahedral/icosahedron com binations are shown in Figure 8. The simple polyhedra, the dodecahedron and the icosahedron, are placed at the ends and the series of combined polyhedra illustrate a continuously increasing de velopment of the one simple form and a simul taneous diminishing development of the other, depending on the order in which they are looked at. The combination in which the two forms are in equilibrium or more or less equally developed, i.e. where they are reduced to regular pentagons and hexagons of equal side length (a design of the soccer football) is particularly pleasing. This is, in fact the sphere described by Paul Smith and made by Dick Rothkugel (see Figure 1). The 60 coigns of this combination also represent the relative positions of the atoms of the 3rd trimorph of carbon (the others: graphite and diamond) recently discovered and referred to as 'buckyballs' (see Figure 9). Thus, while none of the forms of this symmetry class are encountered in external morphology in crystal lography some are nevertheless, represented in molecular structure. For faceters who may be interested the interfacial angles which are applic able to each of the combinations illustrated and any others of different development are: Dodecahedron/dodecahedron: 63.44° Icosahedro Dodecahedron/icosahedron: 37.38° n Icosahedron/icosahedron : 41.81°

Combinations with the triacontahedron Fig. 8. Dodecahedron/icosahedron combinations. Further designs involve bevelling the interfacial edges of the two forms (30 in each case). A Fig. 9. Arrangement of carbon atoms in a 'buckyball'. dodecahedron modified in this manner has 42 faces (Figure 10, models 12, 11, 10) while the modified icosahedron has 50 faces (Figure 10, models 6,7 and 8). The equilibrium combination of the former constitutes an alternative design for the soccer football (Model 11). These bevels, in fact, constitute the positions of a triacontahedron, i.e. symmetrical grinding down of the bevels eliminating the other faces will produce a 30-faced triancontahedron in both cases. In fact this author was unaware of its existence and 'discovered' it by modifying the dodecahedron. The faces are all identical rhombs with plane face angles of 63.44° and 116.56° and interfacial angle of 36°. This form is illustrated in Figures 1 and 3. It is in fact one of a number of possible triacontahedra and is thus, in contrast to the pentagonal dodecahedron, the ico sahedron and the other platonic solids, a variable form. The various triacontahedra have sets of plane face 212 J. Gemm, 1992, 23, 4

Table 3: Faceting angles for the construction of Examples of combinations of the three forms the triacontahedral 'sphere' together of this symmetry class are also given in Figure 10 (models 13, 14, 15 and 16). 13 placed .e 7 -C7 nearest the dodec has the dodec as the dominant 4 form and the other two forms subordinate. Similar -, / 5 6 \ 7/ y\ 3 / \ V ly, 14 represents the icosahedron dominant and 15 6w^ / c /2 y 2 x" \\ the triacontahedron dominant. Notice that throughout the two fixed forms have regular poly 7 VP( 1 N4V2 >7 gonal faces: equilateral triangles (icosahedron), \ 2 \ 5 \ \ 1 l\/ 5 J regular pentagons (dodecahedron). The ultimate 3 design in terms of symmetry, number of faces and \ /\ 2 J^\A aesthetics is, I believe, the equilibrium form where XX/ 5 \s#9 the triacontahedral faces become perfect squares 7^^^ 7 and the polygons all have identical side lengths (model 16). No. Degree Indices (80) Faceting settings for this combination are given 1 0.0 Any 2 31.7 8 24 40 56 72 in Table 3. 3 37.4 80 16 32 48 64 4 58.2 80 16 32 48 64 5 63.4 8 24 40 56 72 6 79.2 80 16 32 48 64 7 90.0 4 12 20 28 36 44 52 60 68 76 Lower hemisphere repetition in reverse order with 7 facets | common. Ratio of diameter/side length = 4. angles ranging between 108° and 120° (a) and ^5c between 72° and 60° (b). In each triacontahedron a + b = 180°. Although not a platonic solid since internal face angles are not the same the triacon juJ^^C^^ tahedron represents the ultimate of the forms possible consisting of identical rhombs. Another two are the crystallographic forms: the rhom- \ /H^ bohedron (a variable form typified by calcite) and the rhombic dodecahedron (a fixed form) both shown in Figure 3.

Table 4: Faceting angles for one of the variable forms of the triacontahedron

3^ ^—-J? Fig. 11. Stereogram of triacontahedral forms. 2 3 / 2 / \ V Figure 11 is the stereogram of the combination ^\ 1 projected with a dodec face horizontal. The com / l bination fulfils the Euler equation (62 + 60 - 120 = 1 \ 3 3 2). 2 2 The triacontahedron itself makes an attractive 1 faceted sphere (Figure 1). Angular values of one of 3\ /3 the variable forms are given in Table 4. 2 ^> From purely theoretical considerations it was realised that a further four variable forms must exist to complete the seven entities of the symmetry No. Degrees Indices (80) group. These were first conceptualised from a 1 31.75 0 16 32 48 64 stereographic projection, angles calculated and 2 58.25 8 24 40 56 72 3 90.00 4 12 20 28 36 drawings produced by modifying those of the first 44 52 60 68 76 three forms. Nomenclature was slightly problema Lower hemisphere: repetition in reverse order; tical (see Table 1). No. 3 facets common. These four additional forms together with the Ratio: Sphere diameter/rhomb side = 3.2 three already discussed are shown in Figure 12. A J. Gemm, 1992, 23, 4 213

Fig. 10. Combinations of triacontahedral class. combination of the seven forms with 362 faces is dered. Analysis reveals that: also shown. As before, examples of the variable 1. All those symmetrical forms consisting of forms with the simplest relationship to the fixed equilateral triangular faces have been considered: forms are shown. The entire group have been drawn the tetrahedron, the octahedron, the icosahedron in the same orientation - three orthogonal two-fold (all platonic solids). They involve respectively 3, 4 symmetry axes have been chosen as convenient and 5 60° vertices meeting at a coign. One more (6) reference axes (cf crystallographic axes) for this would total 360° and constitute a plane. Other forms purpose. For the combination: vertices (360) + consisting of equilateral triangles (there are five) faces (362) - edges (720) = 2. Some mathemati have variable face numbers meeting at vertices and cians regard this as proof of the existence of the therefore lack or have low symmetry. polyhedron! 2. The only form possible consisting of square faces is the platonic cube. 3 90° vertices are a Conclusion maximum. Although there are an infinite number of 3. The only form possible consisting of regular polyhedra possible in consequence of the possibility pentagonal faces is the platonic pentagonal dode of varying the relative development of the compo cahedron. Only 3 vertices of 108° can form a coign. nents of combined forms I believe that in respect of 4. The three non-platonic forms consisting of simple convex closed forms (those made of identical rhomb faces include the crystallographic rhom- plane faces capable of independent existence) with bohedron (variable) and rhombic dodecahedron maximum symmetry all the possibilities from a and also the triacontahedron (variable) now de purely geometric point of view have been consi scribed in detail. Although the faces of these do not 214 J. Gemm., 1992,23,4

Dodecahedron Dodecahedro

Dodecahedron Dodecahedron Dodecahedro Dodecahedro

Dodecahedron Dodecahedro Dodecahedron Dodecahedro

Trapezoidal hexacontahedron Hexicosahedron

Fig. 12. Combination of the hexicosahedral polyhedra. conform to platonic definition they do have two coigns and 3 obtuse vertices forming the other fold symmetry and the triacontahedron additional coigns. ly has the full symmetry of the platonic pentagonal 5. The additional forms with the same symmetry dodecahedron and the icosahedron. These rhombic as the foregoing have all been considered. Other forms involve 3, 4 and 5 acute vertices forming multiple identical faced (60, etc.) forms exist but they have lower symmetry. An example is the Fig. 13. The pentagonal hexcontahedron. pentagonal hexcontahedron which lacks planes of symmetry (Figure 13). 6. The four additional forms of the isometric hexoctahedral class (all variable) have been consi dered since they do represent the highest crystallographic symmetry. 7. Numerous other simple forms, some crystallographically possible, have not been considered because of relatively low symmetry.

References Smith, Paul C., 1976. Faceting small spheres. Lapidary Journal, August 1976. Cundy, H. Martyn, Rollet, A.P, 1952. Mathematical Models. Oxford. J. Gemm., 1992, 23, 4 215

Notes trom the Laboratory -16 Kenneth Scarratt

Gemmological Association and Gem Testing Laboratory of Great Britain London EC1N8SU

An interesting large spinel A client recently submitted 'for interest only' a cushion-shaped red spinel (Figure 1). The stone weighed 149.92ct, measured approximately 32.5 x 31.5 x 15.7mm, and was in a specially made case. The gemmological properties were consistent with natural spinel. The refractive index was 1.716, and when the stone was bathed in light filtered through a solution of copper sulphate the typical organ pipe spectrum (Anderson, 1990) was observed with the hand spectroscope. The fluoresc ence under long-wave ultraviolet was an intense red and under short-wave the appearance was some what 'chalky'. The stone contained numerous, and well formed, crystal inclusions (Figure 2). Some needle-like inclusions were also present. When viewed between crossed polars the stone displayed strain birefringence. At two points on the stone's girdle the remains of drill holes (Figure 3) were observed, indicating that the stone was ancient and had been reçut from the old traditional style of fashioning for spinel - essentially a polished crystal in which the basic crystal form is retained; such stones are usually drilled in various directions to facilitate different settings, including the possibility for it to be worn in Fig. 1. The !49.92ct red spinel displaying the typical red a turban. colour. (Photo K. Scarratt)

Fig. 2. A closer view of the red spinel in Figure 1 and its well Fig. 3. A side view of the spinel shown in Figures 1 and 2 formed crystal inclusions. (Photo K. Scarratt) showing the semi-circular remains of a drill hole at the girdle. (Photo K. Scarratt)

Fig. 4. The 'Black Prince's Ruby', a large spinel which is displayed in the front of the Imperial State Crown of the British Crown Jewels. The octahedron model has been positioned in a similar orientation with the faces of the 'Black Prince's Ruby'. (Photo E.A.Jobbins)

Originally the stone might well have been in a A Treated Diamond with an unusual blue colour similar form to that of the 'Black Prince's Ruby' (an historical name for the large spinel displayed in the Whilst searching through the private coloured front of the Imperial State Crown of the British diamond collection of a New York dealer friend, I Crown Jewels). The 'Black Prince's Ruby' (with an came across the treated diamond seen in Figure 5. octahedron model in similar orientation) is shown The colour was unusual enough for me to want to in Figure 4; it measures 43.3 x 33.8 x 20.1mm and examine the stone in more detail and the dealer was weighs 220.50ct inclusive of its setting and inset only too pleased for me to do so. He stated that he cabochon-cut Burma ruby. There are four drill had had the stone treated in New York some years holes in the 'Black Prince's Ruby'. Given the present previously. weight and dimensions of the two stones, it is Infrared spectroscopy determined the diamond possible that prior to recutting the 149.22ct to be of the type la category and an examination of cushion-shaped stone was originally larger than the the stone's visible spectrum determined the pre 'Black Prince's Ruby'. sence of a strong 'General Radiation Band' and GR1. The normal face-up colour of the stone was an Fig. 5. 0.40ct treated blue diamond seen in reflected lighting conditions. (Photojobbins/Scarratt) unusual shade of bright blue that tended towards turquoise (Figure 6). When viewed from a slight, and increasing angles, from the normal to the table, and also from the pavilion, much of the colour is lost (Figure 7). Peculiar yellow patches are also visible from certain angles (Figure 8). The most interesting feature was the concentra tion of blue colour in the culet area (Figure 9) which is indicative of electron irradiation (Fritsch and Shigley, 1989). Whilst we have observed such colour concentrations in treated diamonds on many occa sions, this must be one of the strongest examples recorded. J.J. Gemm.,Gemm., 1992,23,41992, 23, 4 217217

Fig.Fig. 6. TheThe 0.40ct0.40ct treatedtreated blubluee diamonddiamond iinn FigurFiguree 5 displayingdisplaying Fig. 7. Side view of the treated blue diamond showing the lack thethe 'normal'normal colour'colour' seenseen bbyy thisthis stonestone.. (PhotoJobbins(Photojobbins/l of colour in the body of the stone. (Photo J obbinsl ScarraClScarratt)) ScarraCl )

Fig.Fig. 8. TheThe treatedtreated blubluee diamonddiamond viewedviewed fromfrom thethe pavilion,pavilion, Fig.Fig. 9.9. EnlargeEnlargedd viewview ofof thethe pavilionpavilion areaarea ofof thethe treatedtreated blue andand showingshowing thethe laclackk ofof colourcolour inin thethe bodbodyy ofof thethe stone.stone. diamonddiamond seenseen inin FiguresFigures 7 andand 8.8. TheThe colourcolour cconcenoncen· PeculiaPeculiarr yellowyellow patchepatchess areare alsoalso present.present. (Photo JobJob- trationtration inin thethe culetculet areaarea indicatesindicates electronelectron treatreatmenttment.. binslScarraCl)bins/Scarratt) ((PhotoPhoto .J7obbinsIScarralt) ob bins/'Scarratt)

'Impregnated''Impregnated',, 'Bleached'Bleached'' oorr 'B-Jade'B-Jade'' Fig.. 1010.. ResiResinn impregnateimpregnatedd jadeitjadeitee oorr 'B-Jade''B· Jade. ThThee disdiscc oonn the WWee havhavee nonoww hahadd ththee opportunitopportunityy ttoo examineexamine righrightt weighinweighingg 1.56c1.56ctt anandd ththee cabochocabochonn oonn ththee leftleft weighinweighingg 5.65ct5.65ct.. (Photo(Photo K. ScarrallScarratt)) whawhatt iiss beinbeingg termetermedd 'bleached'bleached'' oorr 'B-Jade'B-Jade'' fromfrom twtwoo sourcesourcess iinn HonHongg KongKong.. ThThee first treatetreatedd samplesampless (a piecpiecee ooff rougroughh anandd a fashionefashionedd disdiscc oorr 'pi')) werweree donatedonatedd ttoo ththee LaboratorLaboratoryy bbyy DominicDominic MoMokk ooff HonHongg KonKongg anandd ththee seconsecondd sesett (treated(treated rougroughh anandd a treatetreatedd cabochoncabochon)) werweree provideprovidedd bbyy MrMrss AnnAnnee PauPaull ooff HonHongg KongKong,, viviaa AlaAlann HodgkinHodgkin- sosonn iinn ththee UUKK (Figur(Figuree 10)10).. ThThee treatmentreatmentt procesprocesss involveinvolvess ththee removaremovall ooff ththee browbrownn 'iro'ironn stainedstained'' areaareass iinn lowelowerr qualityquality jadeitjadeitee samplessamples,, bbyy soakinsoakingg iinn hydrochlorihydrochloricc aciacidd anandd thethenn impregnatinimpregnatingg ththee resultanresultantt materiamateriall witwithh a resinresin.. ThThee resiresinn mamayy bbee ooff ththee AralditAralditee typtypee oorr OpticoOpticonn -- ththee resiresinn ofteoftenn useusedd foforr ththee fracturfracturee filling ooff emeraldsemeralds.. ThThee treatetreatedd materiamateriall appearappearss ttoo havhavee aa mugmughh highehigherr lustrlustree thathann ononee woulwouldd expecexpectt foforr jadeitjadeitee (Figur(Figuree 1111)) anandd thithiss mamayy bbee ththee firstfirst indicatioindicationn thathatt a piecpiecee ooff jadeitjadeitee mamayy havhavee beebeenn treatetreatedd iinn thithiss mannermanner.. BotBothh ththee treatetreatedd ovaovall cabochocabochonn weighinweighingg 5.65ct5.65ct 218218 J.J .Gemm., Gemm ,1992, 1992 ,23, 23 ,4 4

NATURAL ..J

ESIN IMPREGNATED R "S ..JADE"

I I I I I I I I I I 3se9 . 0 3698.3 3e37.8 3377.0 3218.3 30ee.B 2894 . 9 2734 . 2 2e73.e 2412 . 8 wavanumDa.. (em-i)

Fig.Fig .12. 12 . ComparativeComparative infrared infrared curves,curves ,in in absorbence, absorbence ,of of natural natura luntreated untreated jadeitejadeite and and resin resin impregnated impregnated oro r'B-Jade'. 'B-Jade' . andand the the disc disc weighing weighing 1.1.56c 56ct tfluoresced fluoresced aa dull dul lblue blue forfo r jadeite.jadeite . TheThe SG,SG , obtainedobtained byby hydrostatichydrostatic underunder short-waveshort-wave ultravioletultraviole t light.light . TheThe cabochoncabochon weighing,weighing ,was was 3.31, 3.31 ,which which is i salso also within within the the normal norma l fluorescedfluoresced anan overalloveral l eveneven blueblue underunder long-wavelong-wave rangerange for fo rjadeite. jadeite .Using Using the the hand-held hand-held spectroscope, spectroscope , ultravioletultraviole tlight ligh twhereas whereas the the disc disc was wa sa a more more patchy patchy thethe normalnorma l jadeitejadeite absorption absorption lineline at a t437nm 437nm couldcould blue.blue .Of Of the the two two treated treated rough rough specimens, specimens ,the the larger large r bebe seen seen stronglystrongly inin allal l thethe treatedtreated specimens.specimens . TheThe weighingweighing 40. 40.7le 7lctt fluoresced fluoresced aa bright bright greenish-blue, greenish-blue , normalnorma l jadeitejadeite 'chromium'chromium lines'lines 'were were alsoalso readilyreadily whilstwhils t thethe smallersmaller weighingweighing 21.21.73c 73ct t fluorescedfluoresced aa apparent.apparent . brightbright blueblue underunder long-wavelong-wave ultravioletultraviole t light.light . AA hot ho tpoint poin twas wa sapplied applied to to the the surfaces surfaces of of the the two two UnderUnder short-waveshort-wave ultravioletultraviole t thethe twotwo rough rough specispeci fashionedfashioned specimensspecimens andand thethe testtes t areasareas examinedexamined mensmens fluorescedfluoresced aa moremore chalkychalky versionversion ofof theirthei r throughthrough the the microscope microscope for fo rsigns sign sof of 'sweating' 'sweating 'from from long-wavelong-wave colour. colour . thethe resin, resin ,but but nono signs signs of of 'sweating''sweating 'or or any any surface surface TheThe refractiverefractive indexindex taken taken fromfrom thethe flat flat back back of of movementmovemen t werewere observed.observed . TheThe twotwo roughrough specispeci thethe treatedtreated cabochoncabochon waswas 1.655,1.655 , whichwhich is i s'normal' 'normal ' mensmens bothboth hadhad aa thickthick coatingcoating ofof thethe resin,resin , andand Fig.Fig .II. 11 . AA close clos e viewview ofo f thethe 1.56ct1.56c tresin resin impregnatedimpregnated jadeitejadeit e whenwhen thethe samesame testtes t waswa sapplied applied toto themthem thethe resinresin discdis cin in Figure Figure 14,14 ,showing showing thethe unusually unusually highhigh lustre. lustre . 'powdered:'powdered' . (P(Photo holO J obbins/SJobbinslScarratt) carratl) AnAn infraredinfrared spectrumspectrum waswa s takentaken ofof thethe treatedtreated cabochoncabochon (Figure (Figure 12)12 )and and compared compared with with a a piece piece of of jadeitejadeite from from thethe LaboratoryLaboratory collection.collection . AdditionalAdditiona l featuresfeatures ata t 2969,2969 , 2942,2942 , 29282928 andand 2827cm-2827cm"11 werewere notednoted in in the the cabochon's cabochon's spectrum spectrum and and these these corres corres pondpond with with those those reported reported for fo rOpticon. Opticon .

CastCast polyester polyester resin resin as as an an imitation imitation of of tortoise tortoise- shell,shell ,horn, horn ,ivory, ivory ,bone bone and and jet jet CastCas t polyesterpolyester resinsresins inin variousvarious colourscolours andand ofof differingdiffering internalinterna l structuralstructura l patternspatterns areare beingbeing distributeddistributed byby aa companycompany inin WestWes t Sussex,Sussex , (UK).(UK) . TheThe materialmateria l isi ssaid said toto bebe of of a a quality quality suitablesuitable forfo r J. Gemm., 1992, 23, 4

machining, drilling, threading, boring, and special ized turning, and takes an exceptionally high polish. Rods are being supplied from 20mm to 128mm in diameter and 1.5 metres in length. Rectangular sections, also in 1.5 metre lengths, are available in sizes from 25 x 35mm to 45 x 75mm. The material is also available in sheet form. Amongst others, the colours and textures manu factured are those of ivory, bone, tortoise-shell, horn and jet (Figure 13). Given that the sale, or produc tion, of items of adornment from ivory, tortoise- shell and horn is unacceptable to many people and governments, it is likely that polyester resin as a substitute may make an increasing appearance on the market in the future. All colour types have a similar refractive index, hardness, SG, and IR spectrum. Separation from the natural materials may be achieved by either Fig. 14. The structures seen in the cast polyester resin imita tions of: top row, left to right - horn and tortoise-shell refractive index or SG determination (see Table 1), (2), bottom row - 'onyx marble' and ivory. (Photo E.A. or more simply by microscopic observations. Jobbins) The structures seen in the ivory imitation bore a little resemblance to ivory itself. Slightly wavy an interesting colour distribution which gives an structural lines may be observed along the length, overall impression of the imitated material (Figure and in cross-section a slightly swirled structure may 14) but the structure is sufficiently different from be seen (Figures 14 and 15). However, these should tortoise-shell (Figure 20) for it to cause no problems not be mistaken for the more distinctive elephant with identification. ivory structures (Figures 16 and 17). The horn imitation has a structure quite different Very little is visible in the bone imitation in the from the rhinoceros horn (Figure 21) it is supposed way of structure (Figure 13, right) whereas the to imitate, with swathes of colour in cross-section structure of bone itself is very distinctive, (see (Figure 14) and a 'woodgrain' appearance along its Figures 18 and 19). The tortoise-shell imitation has length.

Fig. 13. The 'varieties' produced in cast polyester resin to imitate (rods, from left to right) tortoise-shell, 'onyx marble', jet, r tortoise-shell, horn and bone. (Photo E.A. Jobbins) 220 J. Gemm., 1992, 23, 4

Fig. 15. The slightly swirly structure seen in the cross-section Fig. 16. An ivory bead showing the distinctive'engine turning' of the cast polyester resin imitation of ivory. (Photo K. structure common to elephant ivory. (Photo K. Scar Scarratt) ratt)

pSvt'

Fig. 17. A thin section of elephant ivory showing the typical Fig. 18. The structure seen along the length of bone - xlO. fine undulating structure seen on magnification - xlO. (Photo E.A.Jobbins) (PhotoE.A.Jobbins)

Fig. 19. The cross-section structure of bone- xlO. (Photo E.A. Fig. 20. Magnified view of the structure seen in natural tor J ob bins) toise-shell-xlO. (PhotoE.A.Jobbins) J. Gemm., 1992, 23, 4 221

TORTOXSE SHELL XMXTATXON

HORN XMXTATXON ~

632e.7 6014.2 e702.7 e391.2 e079.7 4768.1 3622.1 Wevenumbe.. (em-i)

Fig.24 Comparative infrared spectra, in transmission, of the cast polyester resin imitations of tortoise-shell and horn.

TORTOXSE SHELL XMXTATXON XMXTATXON TORTOXSE SHELL XMXTATXON

TORTOXSE SHELL

632e.7 6014.2 5702.7 e391.2 e079.7 4766.1 44e6.6 414e.1 S833.6 Se22.1 Wevenumbe.. (em-i)

Fig.25 Comparative infrared spectra, in transmission, of the cast polyester resin imitation of tortoise-shell and natural tortoise-shell. 222 J. Gemm., 1992, 23, 4

Fig. 22. Polished section of natural jet, showing 'wood grain' structure (moistened with light oil) - x25. (Photo E.A. Jobbins)

Fig. 21. Section of rhinoceros horn showing the 'congealed Fig. 23. Dry fracture surface of natural jet (above) with sawn hair-like' structure. (Photo E.A. Jobbins) section below-x25. (Photo E.A. Jobbins)

Table 1 structure with brownish reflections (Figures 22,23) Material RI SG H whereas the polyester resin imitation shows no Ivory (elephant) 1.54 1.7- 2lA- structure at all. A hot point placed on the surface of 1.9 23/4 jet will give off the characteristic smell of burning Bone 1.54 2.00 2Vi coal, whereas the polyester resin gives off a 'sweet' Horn (rhinoceros) - 1.29 - and somewhat 'sickly' odour. Tortoise-shell 1.55 1.29 2Vz Positive identification of cast polyester resin may be achieved by infrared spectroscopy. Figure 24 Jet 1.66 1.33 m compares the tortoise-shell and horn imtations Cast Polyester Resin 1.548 1.20- V/z whilst Figure 25 compares natural tortoise-shell 1.22 with the resin imitation. The principal infrared A high magnification examination of the surface features for cast polyester resin are situated at 5957, structure of jet will sometimes reveal a wood-like 5799, 5245, 5153,4668,4621, and 4574cm"1. J. Gemm., 1992,23,4 223

A Note from the Bahrain Laboratory*

Although the Laboratory receives a much greater proportion of pearls for testing than gems, it does see more amber and its simulants than the London Laboratory. One of the reasons for the popularity of amber in Bahrain is that, owing to its light weight and 'pleasant feel', it is a material ideally suited for fashioning into 'worry beads'. Seeing this quantity and variety of amber, inevit ably means that the Bahrain Laboratory encounters various forms of enhancement in the course of testing. Some of these enhancements reveal clear identification features that allow for a straightfor ward description, whilst others are not so co operative. Recently an example of the type of problem encountered when testing amber arrived in the Laboratory. A necklace consisting of 47 yellow/ orange faceted beads (see Figure 26) was submitted Fig. 26 A necklace of 47 surface colour enhanced amber beads. (Photo for examination. N. Sturman) The usual tests associated with the identification of amber were carried out. The necklace floated in saturated brine, hot needle tests applied to a number of beads produced the characteristic aromatic odour of amber, and sectility tests revealed that the material splintered in the manner normal for amber (these last two tests may only be applied with extreme care and only to an 'inconspicuous area' of the sample, e.g. inside the drill hole of a bead). The problems began to arise when the necklace was examined with the aid of a microscope. The colour appeared to be confined to the surface and formed a symmetrical pattern on the facets of each Fig. 27 The effect seen when the amber necklace seen in Figure 26 is bead. Detailed examination revealed that the sur bathed in ultraviolet light. (Photo N. Sturman) face colour was concentrated in the centre of each facet with the edges only showing the much paler underlying colour. However, the lustre of the sur dum (Nassau, 1981), but in reverse. In this instance face was even and no form of 'coating' could be seen. the beads were pale or colourless at the facet edges When the necklace was immersed, the colour with the concentration of colour being in the central pattern bore a similarity to that normally seen on area of each facet. the facets of an immersed diffusion-treated corun- In addition to the unusual colour distribution, the beads revealed a peculiar and striking fluoresc ence (Figure 27) when exposed to both long-wave *The Gem and Pearl Testing Laboratory of Bahrain is and short-wave ultraviolet light. Where the colour a government laboratory set up and operated with the was concentrated the fluorescence was one of a dull assistance of GAGTL. Ahmed Bubshait is the head of the Laboratory and currently Nick Sturman is the chalky greenish-brown, whilst in the areas of no GAGTL officer on secondment. This is the first note colour it was a very bright chalky bluish-white. from Ahmed and Nick to be included in 'Notes from the Inclusions such as plant-life, bubbles, swirls and Laboratory', and we look forward to more in the future. thread-like tubules indicated that the material was 224224 J.J. Gemm.,Gemm., 1992,1992, 23,23, 44

inging aa much much darker darker exterior exterior (Figure (Figure 28). 28) .The The Labora Labora tory'story's conclusionconclusion waswas 'surface'surface colourcolour enhancedenhanced amber~amber'. AcknowledgementsAcknowledgements ItIt isis withwith thanksthanks thatthat thethe authorauthor acknowledgesacknowledges thethe assistanceassistance ofof hishis colleaguescolleagues inin thethe Laboratory,Laboratory, inin particularparticular SteveSteve KennedyKennedy whowho producedproduced thethe visiblevisible spectrumspectrum ofof thethe treatedtreated blueblue diamond,diamond, andand concon firmedfirmed thethe SG's SG' sof of the the impregnated impregnated jadeite jadeite and and cast cas t polyesterpolyester resin.resin. HeHe alsoalso wisheswishes toto recordrecord hishis appreappre ciationciation ofof thethe tremendoustremendous assistanceassistance givengiven byby AlanAlan JobbinsJobbins inin thethe productionproduction ofofthe the photomicrographsphotomicrographs.. AlsoAlso acknowledgedacknowledged isis thethe generositygenerosity ofof MrMr PeterPeter KaplanKaplan forfor allowingallowing thethe authorauthor toto examineexamine hishis colouredcoloured diamonddiamond collection.collection. TheThe authorauthor alsoalso wisheswishes toto thankthank MrsMrs M.E.M.E. HutchinsonHutchinson ofof thethe Fig.Fig. 2828 Example.Examples ofof .urfacesurface enhancedenhanced amberamber showingshowing thethe deepdeep yeUowyellow AncientAncient MonumentsMonuments LaboratoryLaboratory (English(English HeritHerit exteriorexterior contrastingcontrasting withwith thethe colourlesscolourless toto near-colourlessnear-colourless interior.interior. EachEach specimenspecimen haahas beenbeen speciallyspecially sectionedsectioned andand age)age) forfor bringingbringing thethe castcast polyesterpolyester resinresin imitationsimitations polishedpolished toto displaydisplay thethe etrecteffect ofof thethe treatment.treatment. (Photo K.K. toto hishis notice.notice. BothBoth AhmedAhmed BubshaitBubshait andand NickNick Scarratt) SturmanSturman acknowledge,acknowledge, withwith gratefulgrateful thanksthanks,, thethe assistanceassistance ofof theirtheir colleaguescolleagues inin BahrainBahrain andand notnot pressepressedd amber.amber. ThisThis waswas confirmedconfirmed byby thethe London.London. absenceabsence ofof thethe characteristiccharacteristic strainstrain patternspatterns normalnormal ly associated with some forms of pressed amber. ly associated with some forms of pressed amber. ReferencesReferences TheThe nanatur turee ofof thisthis enhancementenhancement isis notnot certaincertain butbut Anderson,Anderson, B.w.,B.W., 1990. Gem Testing. 10th10th ed.ed. revisedrevised bbyy E.A.E.A. itit maymay bebe similarsimilar toto ththee heat-treatedheat-treated amberamber discusdiscus JJobbinsobbins.. p.219p.219.. ButtButterworthserworths,, London.London. sedsed byby ScarrattScarratt (1986)(1986) andand inin BurlandBurland (1992).(1992). InIn Burland,Burland, M.M.,, 1992. 19911991 ConferenceConference andand PresentatioPresentationn ofof suchsuch casecasess ththee surfacesurface colourcolour concentrationconcentration isis a AwardsAwards.. Journal o/Gemmology,of Gemmology, 23,23, 1,42., 42. by-producby-productt ofof ththee 'clarification'clarification process'process~. CloudyCloudy Fritsch,Fritsch ,E., E., Shigley, Shigley, J.E., J.E., 1989. 1989 Contribution. Contribution to the t oIdentification the Identifi ca tion ooff treatetreatedd ColoreColoredd DiamondsDiamonds:: DiamondDiamondss witwithh PeculiarPeculiar ambeamberr whicwhichh hahass alreadalreadyy beebeenn fashionefashionedd intintoo ththee Color-Zoned Pavilions. Pavilion s.Gems Gems and and Gemology, Gemology, 25 25,, 2, 95-101.2, 95-10 I. desiredesiredd formform,, iiss graduallgraduallyy heateheatedd bbyy 50° stepssteps upup toto NassauNassau,, K.K.,, 1981.1981. Heatt TreatinTreatingg RubRubyy anandd SapphireSapphire:: TechnicalTechnical approximatelapproximatelyy 200°200°CC iinn aann ordinarordinaryy domestidomesticc typtypee AspectsAspects.. Gems and Gemology, 17,3,17, 3, 121-3\..121-31. ovenoven.. ThiThiss procesprocesss clarifieclarifiess ththee ambeamberr bubutt somesome Scarratt,Scarratt, K.K.,, 1986.1986. Notess FroFromm ThThee LaboratorLaboratoryy - 6. JournalJournal 0/of Gemmology, 20, 22,, 95-795-7.. timetimess lessenlessenss thethe interiorinterior colourcolour toto aa pointpoint wherewhere it it is is almosalmostt colourlesscolourless,, whilswhilstt aatt ththee samsamee timtimee producproduc- [[ManuscriptManuscript rreceivedeceived 33 AugustAugust 1992]1992] J.J. Gemm.,Gernrn., 1992,1992,23, 23, 44 225225

TheThe ChemicalChemical PropertiesProperties ofof ColombianColombian emeraldsemeralds DrDr DietmarDietmar SchwarzSchwarz

InstituteInstitute forfor Geosciences,Geosciences, JohannesJohannes GutenbergGutenberg University,University, Mainz,Mainz, GermanyGermany

AbstractAbstract

NinetyNinety emeraldsemeralds fromfrom differentdifferent mInIngmining regionsregions N ((MuzoMuzo,, Coscuez,Coscuez, Yacopi,Yacopí, ChivorChivor/SomondocolSomondoco,, andand GachahiGachalá)) in in thethe CordilleraCordillera Oriental/Colombia Oriental/Colombia were were ex examined t amined byby micro-X-ray-spectroscopymicro-X-ray-spectroscopy (microprobe).(microprobe). TheThe resultsresults ofof thethe chemicalchemical analysesanalyses areare discusseddiscussed usingusing thethe correlationcorrelation diagramsdiagrams AIAl220O3/MgO,/MgO, A1203/Na20,Al2O3/Na2O, Al20Al2O33/FeOtoD/FeOtot, Na20/MgO,Na2O/MgO, Na20lFeONa2O/FeOtototD, andand FeOtotlFeOtot/ MgOMgO..

1.1. IntroductionIntroduction TheThe ColombianColombian emeraldemerald occurrencesoccurrences areare situatedsituated inin thethe so-calledso-called 'emerald-belt''emerald-belt' ofof thethe CordilleraCordillera Oriental.Oriental. WithinWithin thisthis beltbelt twotwo mineralizedmineralized zoneszones cancan bebe distinguished:distinguished: thethe WesternWestern zonezone containingcontaining thethe Pa j ar'\ ito miningmining regionsregions ofof Muzo,Muzo, Coscuez,Coscuez, andand YacopiYacopi ((FigurFiguree 1)1) andand thethe EasternEastern zonezone withwith thethe miningmining regionsregions Chivor/SomondocoChivor/Somondoco andand GachalaGachalâ (Figures(Figures 1 andand 2).2).

2.2. ChemicalChemical datadata InIn thethe coursecourse ofof ourour examinationsexaminations aa totaltotal ofof 9090 BOGOTA emeraldsemeralds originatingoriginating fromfrom differentdifferent miningmining regionsregions ofof thethe CordilleraCordillera OrientalOriental/Colombi/Colombiaa werewere chemicalchemical lyly analyzedanalyzed byby micro~-ray-spectroscopymicro>X-ray-spectroscopy (microp(microp ~ 50 km • Vi llav i cenc i o robe).robe). InIn detail,detail, emeraldsemeralds fromfrom thethe followingfollowing localilocali Fig.Fig. I.1. TheThe ''emeralemeraldd belt'' ofof thethe CordilleraCordillera OrientallColombiaOriental/Colombia tiesties werewere examinedexamined (number(number ofof samplessamples inin parenthparenth withwith thethe WesternWestern ((Muzo-Coscuez-YacopfMuzo-Coscuez-Yacopi)) andand thethe eseseses)): EasternEastern ((Chivor/Somondoco-GachalâChivorISomondoco-Gachala)) mineralimineralizatiozationn MuzoMuzo (20)(20) zonezoness. 11 == PenasPenas BlancasBiancas II11 == SagradaSagrada FamiliaFamilial/ CoscuezCoscuez (07)(07) 2 == LaLa ChapaChapa PavaranadoPavaranado YacopiYacopi (11)(11) 3 == CoscuezCoscuez 1212 == ChivorChi vor ChivorChi vor (14)(14) 4 = SantaSanta RosaRosa 1313 == BuenavistaBuenavista ('Polpito'('Polpito' andand 'El'El Oriente'Oriente' areas)areas) S5 = MuzoMuzo 1414 == MundoMundo NuevoNuevo 6 == MaripflCoperMaripi/Coper IS15 == LasLas CrucesCruces/E/EIl ToroTorol/ GachalaGachalâ (08)(08) 7 == Yacop!Yacopi . EIEl DiamanteDiamante ('Vega('Vega dede SanSan Juan',Juan', 'El'El Diamante'Diamante' andand 'Las'Las Cr.uces'Cruces' 8 == LaLa MinaMina (Glorieta(Glorieta) 1616 == VegaVega dede SanSan JuanJuan areas)areas) I/AposentoAposeDloss ForFor anotheranother 3030 samplessamples thethe minesmines ofof originorigin couldcould 9 == ElPenonEl Penon 1010 = AchioteAchiote/Somondoc/Somondocoo notnot bebe exactlyexactly determined,determined, thesethese areare designateddesignated inin a generalgeneral mannermanner asas 'Colombian'Colombian emeralds:emeralds'. zonezone withwith thethe regionsregions ofof ChivorChivor/Somondoc/Somondocoo andand TableTable 1 givesgives thethe chemicalchemical datadata (width(width ofof variavaria GachalaGachalâ areare compiledcompiled inin TableTable 2 (induding(including thethe datadata tionstions andand meanmean concentrations)concentrations) forfor emeraldsemeralds fromfrom fromfrom KozlowskiKozlowski et al., 1988,1988, forfor emeraldsemeralds fromfrom thethe WesternWestern mineralizationmineralization zonezone (covering(covering thethe Achiote-Somondoco).Achiote-Somondoco). TheThe chemicalchemical datadata ofof 4 samsam regionsregions ofof Muzo,Muzo, CoscuezCoscuez andand Yacopi).Yacopi). TheThe chemicchemic plesples showingshowing colourcolour zoningzoning areare givengiven inin TableTable 3.3. alal datadata forfor emeraldsemeralds fromfrom thethe EasternEastern mineralizationmineralization TableTable 4 containscontains a compilationcompilation ofof literatureliterature datadata 226226 J.J. Gemm.,Gemm., 1992,1992, 23,23, 4

EmeraldEmerald asas a membermember ofof thethe beryberyll groupgroup hashas ththee chemicalchemical formulaformula Be3AIzSi6018.Be3Al2Si60i8. TheThe oxideoxide concenconcen trationstrations thatthat correspondcorrespond toto thisthis idealideal compositioncomposition areare Si02 = 67.07%,67.07%, A1Alz0203 = 18.97%18.97% andand BeOBeO = l3.96%.13.96%. ButBut itit hashas beenbeen knownknown forfor a longlong timtimee thatthat naturalnatural berylsberyls onlyonly inin rarerare casescases comecome .to4:o thisthis standardstandard composition,composition, mostlymostly theythey showshow distinctdistinct deviationsdeviations fromfrom itit (thi(thiss isis a well-knownwell-known behaviourbehaviour thatthat cancan bbee observedobserved alsoalso inin manymany otherother minerals).minerals). TheseThese discrepanciesdiscrepancies gogo backback toto thethe factfact thatthat certaincertain latticelattice componentscomponents cancan substitutesubstitute forfor eacheach otherother andand somesome additionaladditional ('extraneous')('extraneous') elementselements (that(that dodo notnot appearappear inin thethe chemicalchemical formula)formula) maymay enterenter ththee crystalcrystal structure.structure. AAss wewe cancan seesee fromfrom thethe chemicalchemical datadata ofof TablesTables 1-4,1-4, inin thethe casecase ofof emeraldemerald thesethese 'extraneous''extraneous' elementelementss areare mainlymainly magnesium,magnesium, sodium,sodium, iron,iron, and,and, naturally,naturally, thethe colouringcolouring agentsagents chromiumchromium andand vanavana dium.dium. Therefore,Therefore, thethe discussiondiscussion ofof thethe chemicalchemical characteristicscharacteristics ofof thethe berylberyl varietvarietyy emeraldemerald maymay bbee restrictedrestricted initiallyinitially toto thesthesee 5 elementselements.. ButBut inin viewview ofof geochemical-geneticgeochemical-genetic considerationsconsiderations itit isis certainlycertainly ...... ofof interestinterest toto includeinclude inin futurefuture certaincertain tracetrace eleele ments.ments. t(~ OurOur investigations,investigations, realizedrealized onon emeraldsemeralds fromfrom differentdifferent localitieslocalities (Brazil,(Brazil, Schwarz,Schwarz, 1990;1990; NorwayNorway . ::: ::::::: andand Australia,Australia, Schwarz,Schwarz, 1991a;1991a; HabachtalHabachtal andand UralUral .... " MountainslUSSR, Schwarz, 1991b) have clearly " .... , Mountains/USSR, Schwarz, 1991b) have clearly .,...... o ...... , . shownshown thathatt thethe contentscontents ofof thethe 'extraneous''extraneous'element elementss ...... present,present, inin part,part, considerableconsiderable widthswidths ofof variations . ThisThis isis valivalidd notnot onlyonly forfor samplessamples comingcoming fromfrom ththee aK-.'.v.i b cl 3 d samesame miningmining region,region, bubutt alsoalso forfor thethe (mean)(mean) concenconcen trationstrations inin emeraldsemeralds fromfrom differentdifferent localitieslocalities (se(seee Fig.Fig. 2.2. ThThee ColombianColombian emeraldemerald occurrencesoccurrences (geographic(geographic alsoalso SectionSection 3).3). ItIt isis a factorfactor thathatt inin manmanyy formerformer situation)situation) inin thethe regionregion ChivorlSomondoco-GachahLChivor/Somondoco-Gachalâ. studiesstudies waswas notnot takentaken intointo accountaccount sufficiently.sufficiently. (Modified(Modified afterafter KozlowskiKozlowski elet ai,al, 1988).1988). Sometimes,Sometimes, inadmissibleinadmissible oror generalizedgeneralized concluconclu I1 == Achiote/SomondocoAchiote/Somondoco 2 = ChivorChivor sionssions basedbased onlyonly oonn a fefeww chemicalchemical datadata havehave beenbeen 3 = BuenavistaBuenavista drawndrawn toto characterizecharacterize thethe chemicalchemical propertiepropertiess ooff 4 = MundoMundo NuevoNuevo emeraldsemeralds originatingoriginating fromfrom a certaincertain miningmining fieldfield oror a 5 = LasLas Cruces/EICruces/El Toro/E!Toro/El DiamanteDiamante certaincertain geographicgeographic region.region. 6 = VegaVega dede SanSan JuanJuan 7 = SagradaSagrada Familia/PavaranadoFamilia/Pavaranado WithWith regardregard toto magnesiummagnesium andand sodiumsodium ouourr a = TertiaryTertiary studiesstudies showshow thathatt thethe contentscontents ofof thesethese elementselements iinn b = CretaceuusCretaceous ColombianColombian emeraldsemeralds areare low. * c = pre-Cretaceouspre-Cretaceous TheThe lowestlowest meanmean concentrationsconcentrations (0.25%(0.25% Na20Na20 d = faultsfaults SFSF = SanSan FernandoFernando faultfault andand 0.34%0.34% MgO)MgO) werewere observedobserved inin thethe emeraldsemeralds fromfrom thethe miningmining regionregion ofof Gachahi.Gachalâ. TheThe highesthighest fromfrom earlierearlier studiesstudies (Zambonini,(Zambonini, 1928;1928; TsherepivsTsherepivs- contentscontents ofof thesethese oxidesoxides (about(about 1%1% MgOMgO anandd kaya,kaya, 1971;1971; Hanni,Hänni, 1980;1980; Hanni,Hänni, 1982;1982 ; Schrader,Schrader, 0.7-0.8%0.7-0.8% Na20)Na20) areare shownshown byby crystalscrystals fromfrom YacopYacopif 1987,1987, andand Aurisicchio,Aurisicchio, 1988)1988) andand alsoalso thethe valuevaluess foforr *Th* Thee concentrationconcentration bandbandss forfor thethe elementselements chromium,chromium, vanavana widthwidth ofof variationsvariations andand meanmean concentrationsconcentrations ofof 2266 dium,dium, iron,iron, sodiumsodium andand magnesiummagnesium werewere delimiteddelimited empiricallyempirically emeraldsemeralds fromfrom differentdifferent (but(but notnot exactlyexactly known)known) byby thethe followingfollowing valuesvalues (in(in wt%wt% Cr,O"Cr203, V,O"V203, FeO,FeO, Na,ONa20 anandd miningmining areasareas inin ththee CordillerCordilleraa OrientalOriental thathatt werweree MgO;MgO; Schwarz,Schwarz, 19881988 andand 1990):1990): examinedexamined byby thethe author.author. lowlow mediummedium highhigh PartialPartial analysesanalyses ofof ColombianColombian emeraldsemeralds cancan bbee chromiumchromium ,0.2<0.2 0.2-0.40.2-0.4 >0.4>0.4 foundfound inin StaatzStaatz et al. (1965),(1965), BarrigaBarriga & VillalbaVillalba vanadiumvanadium ,0.2<0.2 0.2-0.40.2-0.4 >0.4>0.4 ironiron ,0.5<0.5 0.5-1.00.5-1.0 >1.0>1.0 (1973),(1973), SchraderSchrader (1981)(1981) andand LandaisLandais (in(in Giibelin,Gübelin, sodiumsodium d.O<1.0 1.0-2.01.0-2.0 >2.0>2.0 1982).1982). magnesiummagnesium d.5<1.5 1.5-2.51.5-2.5 >2.5>2.5 J. Gemm., 1992, 23, 4 227

Table 1: Chemical data (width of variations and mean concentrations for the number of samples given in parentheses) of Colombian emeralds from the mining regions of Muzo, Coscuez and Yacopi. Muzo (20) Coscuez (07) Yacopi (11)

Si02 65.47-67.63 67.07 66.81-67.81 67.31 66.10-67.08 66.65 AIM 16.24-18.11 17.23 15.40-17.02 16.19 16.54-17.67 16.98

Cr203 0.06- 0.69 0.27 0.02- 0.08 0.05 0.02- 0.09 0.06

V203 0.05- 0.81 0.29 0.03- 0.08 0.05 0.02- 0.10 0.08 FeO 0.03- 0.16 0.07 0.05- 0.40 0.19 0.04- 0.25 0.17 MnO < - 0.05 0.02 < - 0.03 0.02 < - 0.06 0.02 MgO 0.44- 1.10 0.65 0.59- 1.48 1.00 0.67- 1.27 0.98

Na20 0.24- 1.02 0.53 0.53- 1.03 0.72 0.56- 1.04 0.80 CaO < - 0.02 - < - 0.01 - < - 0.01 -

K20 < - 0.02 0.01 < - 0.02 0.01 < - 0.02 -

Ti02 < - 0.02 0.01 < - 0.02 0.01 < - 0.03 - Obs.:< = element concentration below detection limit of the analytical method

Table 2: Chemical data (width of variations and mean concentrations for the number of samples given in parentheses) of Colombian emeralds from Chivor and Gachalâ (including the data of Kozlowski et al., 1988, for emeralds from Achiote/Somondoco). Chivor (14) Gachalâ (08) Somondoco (07)

SiQ2 66.22-68.20 67.59 66.77-67.55 67.22 64.18-65.55 64.96

A12Q, 16.64-17.71 17AI 16.69-17.48 Y7A5 17.04-18.84 18.25

Cr2Q3 0.01- 0.50 018 0.02- 0.43 O]0 0.01- 0.34 0.17

V203 0.03- 0.23 O08 0.02- 0.15 O09 0.01- 0.13 0.08 FeO < - 0.50 (U0 0.03- 0.12 O07 0.14- 0.60 0.30 MnO < - 0.03 O02 < - 0.03 O02 0.0 - 0.05 0.02 MgO 0.32- 0.85 063 0.15- 0.48 034 0.74- 1.65 1.11

Na2Q 0.20- 0.54 039 0.14- 0.29 025 0.70- 1.50 1.01 CaO < - 0.02 - < - 0.02 O01 0.0 - 0.02 0.01

K2Q 0.01- 0.08 O02 < - 0.01 O01 0.03- 0.09 0.05

TiQ2 < - 0.04 O02 < - 0.02 O01 0.0 - 0.03 0.01 Obs.: < = element concentration below detection limit of the analytical method

Table 3: Chemical data of Colombian emeralds showing colour zoning. (X) (B) (C) (D) R K R K R K R —K

SiQ2 66.50 66.19 66.31 66.67 65.84 65.40 64.63 64.19

A12Q, 17:27 17J52 1^44 1^99 17.04 16.93 16.44 17.51

Cr2Q3 028 O05 016 003 0J7 O01 064 0.01

V2Q3 OH O04 021 O06 O20 O05 056 003^ FeO O06 O06 O05 OK) O05 OB O06 0.03 MnO < < ^ - - - - - MgO 071 069 041 087 046 089 067 084

Na2Q 058 055 032 091 045 088 054 070^ CaO < < < O01 O02 < O01 <__

K2Q O01 O01 < < O03 O02 O03 (M)3_

TiQ2 < < O01 O02 < < < 0.02 Obs. : R = green border zone K = colourless central zone < = element concentration below detection limit of the analytical method - = no data for this element 228 J. Gemm., 1992,23,4

Table 4: Chemical data of Colombian emeralds: compilation of literature data from Zambonini (1928), Tsherepivskaya (1971), Hänni (1980), Hänni (1982), Schrader (1987), and Aurisicchio (1988). The width of variation and mean concentrations of 26 emeralds analyzed by the author coming from different (but not exactly known) localities in the Cordillera Oriental are also given. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15)

SiQ2 65.26 65.07 65.8 66.0 66.4 66.6 65.2 64.6 67.15 64.98 64.39 65.95 65.34 65.23-68.48 66.58

A12Q3 17.60 18.51 16.7 16.9 16.9 17.7 16.3 16.3 17.94 17.43 17.55 17.19 16.51 15.54-18.33 17.17

Cr2Q3 - 0.13 0.8 0.6 0.2 0.3 0.2 0.2 0.58 0.32 0.22 0.03 0.37 0.01- 0.93 0.15

V2Q3 0.3 0.4 0.8 0.6 0.10 0.11 0.06 0.05 0.64 < - 1.27 0.24 FeO 0.08 0.65 0.1 0.0 0.0 0.0 0.0 0.0 0.05 0.07 0.04 0.10 0.31 < - 0.23 0.08 MnO 0.06 0.02 0.0 0.1 0.0 0.0 0.0 0.0 - - - - < < - 0.07 MgO 0.77 0.24 0.5 0.4 1.4 1.0 1.0 1.2 0.31 0.34 0.17 0.97 0.67 0.13- 1.52 0.66

Na20 0.50 0.43 0.4 0.4 1.0 0.6 0.8 0.8 0.27 0.18 0.07 0.74 0.49 0.11- 1.16 0.46 CaO 0.09 0.65 0.0 0.0 - - - - 0.01 0.01 0.01 0.01 - < - 0.02 -

K20 0.22 0.16 0.0 0.0 ------< < - 0.05 -

Ti02 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.Ï - - - - < < - 0.04 - Obs.: (1)= Zambonini (1928) (Muzo) (13) = Aurisicchio (1988) (Muzo) (2) = Tsherepivskaya (1971) (Muzo) (14) = width of variations of 26 Colombian emeralds (this paper) (3), (4)= Hänni (1980) (15) = mean concentrations of 26 Colombian emeralds (this paper) (5)-(8)= Hänni (1982) < = element concentration below detection limit of the analytical method (7), (8)= Trapiche' emeralds - = no data for this element (9)-(12)= Schrader (1987) (9, 10,' 11 Chivor) and Coscuez. Comparing the Na and Mg concentraa- the literature it has been pointed out that emerald tions of emeralds coming from the two mineralizeed crystals found immediately side by side in the same emerald zones of the Cordillera Oriental, it is vein may show quite different shades of green, obvious that there are no distinct differences. Thilis Besides this, many emeralds (from the most diffe- fact indicates that the geological-geochemical proo- rent occurrences) distinguish themselves by a dis- cesses that are responsible for the introduction of tinct colour zoning (compare also Table 3). This the elements sodium and magnesium in the twvo clearly shows that the supply of chromium in the mineralization zones are basically of the samne emerald 'mother liquor' suffered strong variations nature. Besides this it shows that regional minertr- through time and space. alization processes (e.g. with the participation of thhe As can be seen from the analytical data, all these evaporites present in the whole region) are mor»ree considerations are valid in an analogous manner also than probable locally restricted events (as is, foor for the element vanadium. It must be emphasized example, the case when contact metamorphism is that the samples from Colombia are amongst those related to the emplacement of pegmatites).* with the highest vanadium concentrations of all The iron contents in Colombian emeralds are lo>ww emeralds analyzed by the author up to the present, to very low throughout. The highest iron concentraa- They are surpassed only by the Norwegian emer- tion of the samples examined by the author waas aids from the Eidsvoll/Lake Mjosa deposit (mean observed in a Chivor emerald (0.50% FeO). Thtie concentration of four samples = 1.29% V203; Somondoco emeralds examined by Kozlowski et al.iL Schwarz, 1991) and the so-called 'V-beryls' from (1988) exhibited FeO concentrations from 0.144- Salininha/Bahia, Brazil. At this point we should like 0.60% with a mean concentration of 0.30% FeO3.. to emphasize again the fact that the mean concen- Barriga and Villalba (1973) and Landais (in Gübe>e-- trations of vanadium and chromium in Colombian lin, 1982) report FeO contents of 0.9% and up to emeralds are of the same order of magnitude (the 0.72% respectively for emeralds from Muzo. mean concentrations of the 90 emeralds examined The elements responsible for the brilliant greemn by the author during the present investigation are colour of the Colombian emeralds are chromium 0.16% Cr203 and 0.18% V203 respectively). In and vanadium. Contents of these vary widely. Thilis many samples the vanadium content is even dis- behaviour is also known of emeralds coming from tinctly higher than the chromium concentration, other (genetically different) localities. Frequently in On the other hand there are many emeralds that — show a more or less pronounced dominance of *A detailed compilation and a discussion of the different hypotheses used to explain the genesis of the Colombiaîan chromium. A third 'type' of Colombian emeralds emerald occurrences is given by Schwarz, 1991c). contains comparable amounts of these colouring J. Gemm., 1992, 23, 4 229

Table 5: Chemical data of some Colombian Sinkankas (1981) and Kozlowski et al (1988; a emeralds showing different ratios of the colour- crystal from the Juntas mine in Achiote/ influencing elements chromium, vanadium, and Somondoco) mention stones with a distinct colour iron. zoning consisting of a green emerald core sur rounded by a colourless border zone. Cr203 v o FeOtot 2 3 Among the data of former investigations (com Yacopi 0.02 0.10 0.25 piled in Table 4) the high CaO content of a Muzo Chivor 0.11 0.04 0.50 emerald (analyzed by Tsherepivskaya, 1971) is just 0.34 0.08 < as striking as the high concentrations (compared to Gachalâ 0.43 0.15 0.09 0.02 0.10 0.03 the data published by other authors) of K20 in Muzo 0.69 0:59 0.05 emeralds from Muzo reported by Zambonini, 1928 0.34 0.81 0.08 (0.22%) and Tsherepivskaya, 1971 (0.16%). 0.51 0.52 0.09 Coscuez 0.02 0.03 0.40 Mining 0.31 1.27 0.13 3. Discussion of element correlation diagrams region 0.06 0.69 0.43 3.1 Correlation diagram Al203/MgO not known 0.93 0.54 0.10 In the diagram of Figure 3, the representative elements (see also Table 5). Surely, the significance points of the chemical analyses (mean concentra of the element vanadium as agent for the green tions) of emeralds from Colombia, Brazil, Australia, colour of emerald has not been taken into considera Norway, Austria, and the USSR are marked. For tion adequately in the past. It would be desirable comparison purposes the data for pegmatite beryls with regard to a future discussion on the definition from the mining regions of Governador Valadares of the term 'emerald' to give more importance to the and Araçuai-Salinas, Minas Gerais, Brazil, are also element vanadium. From the mineralogical point of shown. view it is surely not justified to consider the It is interesting to note in this diagram, the large chromium content as only criterion for the delimita variation of the contents of A1203 and MgO in tion emerald-green beryl. emeralds from different occurrences. The lowest Table 3 shows the chemical data of four Col mean concentrations of MgO (0.05%) of all samples ombian emeralds presenting a distinct colour zon examined by the author up to the present are shown ing with an almost colourless central part and a by the emeralds from the Emmaville mining region green border zone ('rim'). As can be expected, the in New South Wales, Australia. The highest mean colour zoning is clearly related to the concentrations concentrations of this oxide (about 3%) were of the colouring elements chromium and vanadium. observed in Brazilian emeralds from the occurr The contents of these elements are distinctly higher ences Salininha/BA, Santa Terezinha/GO, and in the border zone. On the other hand the iron Itaberai/GO. The representative points for emeralds concentrations are in the same order of magnitude from the different Colombian deposits are placed, in the different parts of the crystals. It seems that throughout, in the upper left part of the population there is no correlation between the content of this area. This means that their magnesium contents are element and the intensity of the green colour. The low and their aluminium concentrations are high. concentrations of the elements sodium and magne The distinctly developed diagonal distribution sium are much higher in the central zones of three trend (with negative slope) of the population field samples, however, in the fourth one these concen verifies that the introduction of magnesium into the trations show almost no variation. By this, we can emerald-/beryl structure follows the substitution conclude that for the crystals examined the incor reaction (1). poration tendency of the elements sodium and (l)Al3+'VI = Mg2+-VI magnesium is contrary to that observed for the colouring agents chromium and vanadium! 3.2 Correlation diagram Al203/Na20 Emeralds from Colombia showing a colour zon The representative points in the correlation dia ing are relatively common. Crystals with a colour gram Al203/Na20 (Figure 4) show a behaviour that less or a weakly coloured greenish central core and a is analogous to the one observed in the diagram deep green border zone ('rim') have been described, Al203/MgO: the clearly developed diagonal trend among others, by Scheibe (1926) and Ringsrud with negative ascent shows that the rising Na (1986) from Muzo. MacFadden (1934) describes an content of the emeralds is accompanied by a emerald from Somondoco with several concentric decrease of the A1203 concentration. This be 'colour-rings' around a colourless central core that haviour is based on the following substitution becomes increasingly darker from the inner to the reaction (2). outer regions. (2) A13+'VI - Me2+'VI + Na1+ (channel) 232300 JJ.. Gemm.,Gemm., 1992,1992, 2323,, 4

CorrelatioCorrelationn diagramdiagramss foforr AlAI,03/MgO203/MgO (Fig(Fig.. 3)3),, AlAI,OjNa20203/Na20 (Fig(Fig.. 4),4), Alz20 33/FeIFe""tot (Fig.(Fig. 5)5),, NaNa20/Fe""20/Fetot (Fig.(Fig. 7)7),, Fe,o,/MgOFetot/MgO (Fig.(Fig. 8),8), withwith ththee representativerepresentative pointpointss (mean(mean concentrationconcentrationss forfor emeraldsemeralds fromfrom ColombiaColombia,, BrazilBrazil,, AustraliaAustralia,, NorwayNorway,, AustriAustriaa anandd thethe USSUSSRR (data(data frofromm thithiss paperpaper andand fromfrom Schwarz,Schwarz, 1990;1990; Schwarz,Schwarz, 1991a1991a anandd Schwarz,Schwarz, 1991b).1991b).

(1)(1) Carnaiba/BACarnaiba/BA (38)*(38)* (13)(13) EidsvollEidsvoIl,, NorwayNorway (04)(04)** (2)(2) Capoeirana/MGCapoeirana/MG (16)*(16)* (14)(14) UraUrall Mountains,Mountains, USSRUSSR (ID(11)** (3)(3) BelmonBelmontt Mine/MGMine/MG (48)*(48)* (IS)(15) HabachtalHabachtal,, AustriaAustria (10)(10)** (4(4)) Socot6/BASocoto/BA (63)*(63)* (16(16)) UntersulzbachtalU ntersulzbachtal,, AustriaAustria (06)*(06)* (5(5)) Taua/CETaua/CE (11)*(11)* (17)(17) 'Colombia'Colombia'' (exac(exactt minesmines ofof originorigin notnot known)known) (30)*(30)* (6(6)) Piren6polis/GOPirenopolis/GO (07)(07)** (18(18)) YacopiYacopi,, ColombiaColombia (11)( 11)** (7)(7) Salininha/BASalininha/BA (05)*(05)* (19)(19) CoscuezCoscuez,, ColombiColombiaa (10)(10)** (8)(8) ItaberailGOItaberai/GO (13)*(13)* (20)(20) Muzo,Muzo, ColombiaColombia (20)(20)** (9)(9) SantaSanta Terezinha/GOTerezinha/GO (29)*(29)* (21)(21) Somondoco,Somondoco, ColombiaColombia (Kozlowsk(Kozlowskii elet al., 19881988)) (07)(07)** ((10) 10) Poona/WesternPoona/Western AustraliaAustralia (12)*(12)* (22) Gachala,Gachalâ, ColombiaColombia (08)*(08)* (11)(11) Menzies/WesterMenzies/Westernn AustraliaAustralia (04)(04)** (23(23)) ChivorChivor,, ColombiaColombia (14)*(14)* (12)(12) EmmaviIle/NSW,Emmaville/NSW, AustraliaAustralia (05)(05)** (CI(Cl)) PegmatitePegmatite berylsberyls frofromm ththee Ara<;uai-SalinasAraçuai-Salinas region/MGregion/MG (Correia(Correia NevesNeves elet al., 19841984)) (09)*(09)* (C2(C2)) PegmatitePegmatite berylberylss frofromm thethe GovernadoGovernadorr ValadareValadaress region/Mregion/MGG (Correi(Correiaa NeveNevess elet al., 19841984)) (05)(05)** **= = numbernumber ofof analyzedanalyzed samplessamples

1 2 3 4 5 6 7 8 9 1010 1111 1212 1313 1414 1515 1616 1717 1818 1919 2020 2121 2222 2323 Ô*ADAOOI.~~~D600 ••H *.~V~.®@®®O@®• • v <$>#®®®©@@©

3~--,---,----,---,-ic---'--"---'--~LJI_ AIAl220 3 T , , I 7 , , 4 - © • — ie.0 '::~:- • 2® ©1 ®;@ '0. I7.0 — 0.1::— I 7.0 * * V ® • @ • * 16,0I6.0 -—• • @* *". ~".O— I 6.0 .0 D - •A 0 1< 15.0_I 5.0 — *•fr — II~~ 5.0

A I414.0_0 t.0 . _14.014.0 .'~ ·0# 0 J 0 f"" ^ 0 o - • "o~ ~".o 13.0-13.0 — f------I—13. ~.O0 I L-~~~~'I~~O~~-'~~2l~o~~-'-'~3~O~~ ,!o ' ' 2!o -•Na 0 I +MgO 2

Fig. 3. Fig. 4.

Fig. S. Fig. 7.

hjs i Al20 1.0 I.5 3 , . , . Y . . . . I , 1 No O '.0 2 I9.0- — 19.0 t • © 0 18.0- —18.0 0 ©1 10'© = • ~ —17.0 '" • * V • 0 16.0 — • * * -I6.0 • • 0 • (5 c, l'O 15.0- & t-'—I5.15•0 'i , ", «- ~14.0— I 4.0 @ • O o I-® • • • @ 13.0- 1-— 1313.•00 ... '.0I

' ' ' ' oU ' ' • ,!o ' ,'.5 ' -•FeC>to t J.J. Gemm.,Gemm., 1992,1992, 23,23, 4 231231

Fig.Fig. 88.. FeOtot,-~~ __~'lo~~~~~~~~~~~-. t

2.0 2.0

• '0:>

0 * °6 0 * •

2.0

Fig.Fig. 6.6. CorrelationCorrelation diagramdiagram forfor NaNa,O/MgO20/MgO withwith thethe representativerepresentative pointpointss (single(single analyses)analyses) forfor emeraldsemeralds fromfrom Colombia,Colombia, Brazil,Brazil, Australia,Australia, NorwayNorway,, Austria,Austria, andand thethe USSRUSSR (data(data fromfrom thisthis papepaperr andand fromfrom SCHWARZ,SCHWARZ, 1990;1990; SCHWARZ,SCHWARZ, 1991a1991a andand SCHWARZ,199Ib).SCHWARZ, 1991b).

1 = ColombiaColombia 2 = BrazilBrazil 3 = NorwayNorway 4 = AustraliaAustralia 5 = UralUral MountainsMountains 6 = HabachtalHabachtal

Nt^O 11.00 22.00 33.00 4.04.0

A 1 1 1 1 I1 1 1 1 1 I1 1 1 1 1 I1 1 , , . I1 I '1• 1 t .2 3.0-J • 2 r-— 33..O0 63A 3 '1474 • OsOS H *6*6 - • :.-: . * • •j :••••~.• • * • ~.. - ...... ,. . .,., ..* " A ..tf V* Jß • 2.02.0 -— ". ". " ' r-— 2.02.0 • t'.i... ••':. *. • • • •• 1} • O••• .,qr • •• ~ .. • ?"t • v ••• 'V(I ••: 0 " I· • • ~ •• ~.. • •• - .. ...' ¥ •••• '1· ...: ..: " •• • • • ~ •• -.t'~'" •• ,. : •• ...... ,t.. ... • ... 1.01-0 _— .. . ,:.. ;,.;.,.,.,.. .. . • —_1.0 l0 o • .&.e' ..... • •..,1"...,. • • .. ~:~ ..•. : .. - ,.-.. . ~ .?f>.~ <> :.'.. •• • %*i.?£-~ ~~. -J.- - ' L Y·~A.··t·· •. '1""'~;"~· v'~:. • ,~.... h i i [ i Ii i i i i Ii i i i i I| • • , , I| , 1.01.0 2.02.0 3.03.0 4.04.0 +MgO^•MgO 232 J. Gemm., 1992, 23, 4

The substitution of the trivalent aluminium by The Na20/FeOtot correlation diagram (Figure 7) bivalent metal (Me) ions (in emerald predominantly shows a general diagonal distribution trend (with Mg2+) requires a charge compensation. This is positive ascent) of the representative points, but this achieved practically exclusively by the additional is developed less distinctly than we have seen in the incorporation of monovalent sodium in channel correlation diagrams discussed before. This means positions. that the processes controlling the incorporation of The representative points for all Colombian the elements iron and sodium into the emerald emeralds in the Al203/Na20 correlation diagram are structure cannot always be directly correlated. situated in the upper left region of the population Partly, this behaviour goes back to the fact that iron, area: their mean Na concentrations are low, the at least in part, is present in the form of the trivalent mean concentrations of aluminium, however, are ion which needs no charge compensation by sodium high. when introduced into the emerald structure. On the other hand, it must also be taken into consideration 3.3 Correlation diagram Al203lFeOtot that the incorporation of sodium into emerald is The general trend of the representative points in largely controlled by the substitution of aluminium the correlation diagram Al203/FeOtotai (Figure 5) through magnesium. shows indeed a diagonal distribution pattern (with Because of their low iron and sodium concentra negative ascent). This is however far less well tions the representative points for the Colombian developed than in the correlation diagrams of A1203 emeralds in the Na20/FeOtot diagram are restricted with MgO and Na20. The absence of a clearly to the lower left area of the population field. defined diagonal distribution trend indicates that the incorporation of iron into the emerald/beryl 3.6 Correlation diagram FeOtot/MgO structure does not always follow the 'ideal' substitu At first sight the correlation diagram FeOtot/MgO tion reactions (3a) and (3b). (Figure 8) doesn't show a definite distribution (3a)Al3+'VI = Fe3+'VI pattern. The variation of the mean magnesium 3+ VI 2+ VI 1+ (channel) concentrations in emeralds from different occurr (3b) A1 ' = Fe ' + Me ences is very strong. On the other hand the mean The Colombian emeralds with their low iron FeOtot contents are normally less than 1%. The only content (mean concentrations of emeralds from exception from this behaviour is shown by the different occurrences <0.3% FeOtot) are placed in samples from the Santa Terezinha de Goiâs mining the upper left part of the population field. region. A special chemical feature of these emeralds It is of particular interest that the pegmatite is the poor variation of the (always high) magne beryls examined by Correia Neves et al. (1984) are sium content in combination with strongly varying placed distinctly outside the 'emerald' population iron concentrations (compare Schwarz, 1990). field. Of special interest with regard to the chemical differentiation of emeralds on the one hand and 3.4 Correlation diagram Na2OIMgO pegmatite beryls on the other hand may be the fact As can be seen from the data of the chemical that the representative points of the pegmatite analyses of Tables 1-4, magnesium and sodium are beryls from the mining regions of Araçuai-Salinas the only uni- and bivalent 'extraneous' elements and Governador Valadares (both in Minas Gérais present in higher concentrations in the Colombian state, Brazil) are situated completely outside the emeralds (surely, emeralds from some other locali 'emerald' population field. ties also contain, in part, higher contents of Fe2+). The Colombian emeralds are amongst the sam Structural chemical considerations and the dis ples with the lowest iron and magnesium contents tribution patterns of the representative points in the so far analysed by the author. Their representative different correlation diagrams confirm for these two points are placed within the lower left area of the elements the crystallochemical reaction (4). population field in the FeOtot/MgO diagram. 3+ VI 2+ VI 1+ (channel) (4) A1 ' = Mg ' + Na Acknowledgements The magnesium/sodium incorporation into the The author wishes to thank the following people emerald/beryl structure follows practically com and institutions for their kind co-operation during pletely this 'ideal' substitution reaction. This is the visits to the emerald mines in the Cordillera shown by the very clearly developed diagonal Oriental, for the donation of material for examina distribution pattern (with positive ascent) of the tion and for making available bibliographic data, representative points in the correlation diagram maps etc.: Vicente Giordanelli Duran, Adolfo Na20/MgO (Figure 6). Pacheco Hernandez and Diego Estrada Piedrahita from Ecominas, Jorge Alfonso Cabra Paez and

3.5 Correlation diagram Na20/FeOtot Alvaro Tenjo Gutierrez (Coexminas Ltda.), Wilson J.J. Gemm.,Gemm., 1992,1992, 23,23, 4 233233

A.A. QuinteroQuintero (Minas(Minas dede ChivorChivor Ltda.),Ltda.), ManuelManuel Ringsrud,Ringsrud, R.,R., 1986.1986. TheThe CoscuezCoscuez mine:mine: A majormajor sourcesource ooff RubianoRubiano LamourouxLamouroux andand RubensRubens D.D. LlinasLlinas RiveraRivera ColombianColombian emeralds.emeralds. GemsG ems && Gemology, 22,22, 2,2, 67-79.67-79. Scheibe, R., R., 1926. 1926. Die Die Smaragdlagerstätte Smaragdlagerstatte von Muzovon Muzo (Kolumbien) (Kolum (Universidad(Universidad NationaNationall dede Colombia),Colombia), JaimeJaime BarajasBarajas bien) unundd ihreihre naherenähere Umgebung.Umgebung. N.Jb.Miner., Geol.,Geol., B.B. andand AndulfoAndulfo CepedaCepeda Q.,Q.? ElizabethElizabeth CortesCortes CastilCastil Palaone.,Paläont., Beilageband Beilageband LIV LIV,, Abt., Abt., B, B,419-47. 419-47. lolo (Ingeominas)(Ingeominas) andand MariaMaria A.A. DelgadoDelgado Chaparro.Chaparro. Schrader,Schrader, H.H.W. W,, 1981.1981. ZurZur UnterscheidungUnterscheidung vonvon natiirlichennatürlichen undund MrMr J.J. ZangZang andand DrDr Schulz-DobrickSchulz-Dobrick fromfrom thethe synthetischensynthetischen Smaragden.Smaragden. Diplomarbeit.Diplomarbeit. FachbereichFachbereich Geowissenschaften,Geowissenschaften, JohannesJohannes GutenbergGutenberg UUniversitä niversitatt Mainz.Mainz. InstituteInstitute ofof Geosciences,Geosciences, UniversityUniversity ofof Mainz,Mainz, Schrader,Schrader, H.W,H.W., 1987.1987. NatiirlicheNatürliché undund synthetischesynthetische Smaragde.Smaragde. kindlykindly gavegave assistanceassistance duringduring thethe microprobemicroprobe invesinves EinEin BeitragBeitrag zurzur KristallchemieKristallchemie derder Berylle.Berylle. Dissertation.Dissertation. tigations.tigations. Fachbereich Geowissenschaften, Geowissenschaften, Johannes Johannes Gutenberg Gutenberg Universität Uni TheThe authorauthor isis alsoalso gratefulgrateful toto thethe followingfollowing Mainz.versitat Mainz. Schwarz,Schwarz, D.,D., 1988.1988. AAss propriedadespropriedades quimicasquímicas dasdas esmeraldasesmeraldas institutionsinstitutions forfor financial supportsupport andand thethe provisionprovision BrasileirasBrasileiras.. XXXV Congr.Bras.Geol., Belém.Betem. In: ANAISANAIS...... ofof facilities:facilities: GermanGerman AcademicAcademic ExchangeExchange ServiceService 1,348-62.1, 348-62. (DAAD),(DAAD), GermanGerman AgencyAgency forfor TechnicalTechnical CoCo Schwarz,Schwarz, D.,D., 1989.1989. SmaragdabbauSmaragdabbau inin Kolumbien:Kolumbien: NeueNeue operationoperation (GTZ),(GTZ), GermanGerman ResearchResearch AssociationAssociation Aspekte.Aspekte. Z.Dt.Gemmol.Ges., 38,4,155-60.38, 4, 155-60. Schwarz, D.,D., 1990. 1990. Die Die chemischen chemischen Eigenschaften Eigenschaften der Smaragde. der Smar (DFG),(DFG), andand thethe FritzFritz ThyssenThyssen Foundation.Foundation. I.Brasilien.agde. I.Brasilien. Z.Dt.Gemmol.Ges., Z.DI.GemmoI.Ges., 39, 4, 233-72. 39, 4, 233-72. Schwarz, D.,D., 1991a. 1991a. Die Die chemischen chemischen Eigenschaften Eigenschaften der Smaragde. der Smar ReferencesReferences agde. II.II. AustralienAustralien undund Norwegen.Norwegen. Z.Dt.Gemmol.Ges., 40,40, 1,1,39-66. 39-66. Aurisicchio,Aurisicchio, C.,C., 1988.1988. ReappraisalReappraisal ofof thethe crystalcrystal chemistrychemistry ooff Schwarz, D., D., 1991b. 1991b. Die Die chemischen chemischen Eigenschaften Eigenschaften der Smaragde. der Smar beryl.beryl. Amer.Mineral., 73,73, 826-37.826-37. agde. III.III. Habachtal/OsterreichHabachtal/Österreich undund UralgebirgelUdSSR.Uralgebirge/UdSSR. BarrigBarrigaa Villalba,Villalba, A.M.,A.M., BarrigaBarriga deldel Diestra,Diestra, A.M.,A.M., 1973.1973. La Z.DI.Gemmol.Ges.,Z.Dt.Gemmol.Ges., 40 40,, 2/3, 2/3,103-43. 103-43. esmeralda de Colombia. ColegioColegio MayorMayor dede NuestraNuestra SenoraSenora deldel Schwarz,Schwarz, D.,D., 1991c.1991c. GeologieGeologie undund GeneseGenese derder SmaragdvorkomSmaragdvorkommen Rosario.Rosario. PoncePonce dede LeonLeon HermanosHermanos LTDA.LTDA. Bogota.Bogotá. mender Cordillera der Cordillera Oriental, Kolumbien.Oriental, Z.Dt.Gemmol.Kolumbien. Z.DI.Gem CorreiaCorreia Neves,Neves, J.M.,J.M., Monteiro,Monteiro, R.L.B.B.,R.L.B.B., Dutra,Dutra, C.V.,C.V., 1984.1984. Ges.,mol.Ges., 40, 4, 201-31. 40, 4, 201-31. ComposicaoComposicao quimicaquímica dede berilosberilos pegmatiticospegmatíticos dodo BrasilBrasil e seuseu Sinkankas, J., J., 1981. 1981. Emerald Emerald and and other other beryls. beryls. Radnor Radnor Pennsylvania. Pennsyl significado petrológico petrologico e metalogenético.e metalogenetico. Rev.Bras.Geociencias, Rev.Bras. Geoeien Chiltonvania. Book Chilton Company. Book Company. 14, cias,3, 137-46. 14,3,137-46. Staatz,Staatz, M.H.,M.H., Griffins,Griffitts, WR.,W.R., Barnett,Barnett, P.R.,P.R., 1965.1965. DifferencesDifferences Giibelin,Gübelin, E.,E., 1982.1982. GemstonesGemstones ofof Pakistan:Pakistan: emerald,emerald, rubyruby andand inin thethe minorminor elementelement compositioncomposition ofof beryberyll inin variousvarious spinel.spinel. Gems&Gems & Gemology, 18,3,18, 3, 123-9.123-9. environments.environments. Amer.Min., 50,1783-95.50, 1783-95. Hanni,Hänni, H.A.,H.A., 1980.1980. MineralogischeMineralogische undund mineralchemischemineralchemische Tsherepivskaya,Tsherepivskaya, 1971,1971, inin Sinkankas,Sinkankas, J.,J., 1981.1981. EmeraldEmerald andand otherother Untersuchungen an an Beryll Beryll aus aus alpinen alpinen Zerrklüften. Zerrkliiften. Inaugural-Dissertation Inaugu beryls. RadnorRadnor Pennsylvania.Pennsylvania. ChiltonChilton BookBook Company.Company. Universitätral-Dissertation Basel. Universitat Basel. Zambonini,Zambonini, 1928,1928, inin Sinkankas,Sinkankas, J.,J., 1981.1981. Emerald and other Hanni,Hänni, H.A.,H.A., 1982.1982. A contributioncontribution toto thethe separabilityseparability ofof naturalnatural beryls. RadnorRadnor Pennsylvania.Pennsylvania. ChiltonChilton BookBook Company.Company. andand syntheticsynthetic emeralds.J.Gemm.,emeralds. J.Gemm., 18,2,138-44.18, 2, 138-44. Kozlowski,Kozlowski, A.,A., Metz,Metz, P.,P., Jaramillo,Jaramillo, J.H.A.,J.H.A., 1988.1988. EmeraldsEmeralds fromfrom Somondoco,Somondoco, Colombia:Colombia: chemicalchemical composition,composition, fluidfluid inclusionsinclusions andand origin.origin. N.]b.Miner.Abh.,N.Jb.Miner.Abh., 159,159, 1,23-49.1, 23-49. MacFadden,MacFadden, C.K.,C.K., 1934.1934. EmeraldEmerald mininminingg inin Colombia.Colombia. Gems && Gemology, 1,6,1, 6, 149-54.149-54. [Manuscript[Manuscript receivedreceived 1414 August August 1991]1991 ] 234 J. Gemm., 1992,23,4

Gemmological Abstracts

ANDERGASSEN, W., 1990. Inclusione a pio fasi bamboo corals are also excluded from the order. in un corindone giallo. La Gemmologia, 15, Leaves many non-gem species protected and 3/4, 33-5, 4 photos in colour. problems are anticipated when it comes to A yellow sapphire weighing 2.27ct contained a separating banned species from those which may negative crystal in which liquid C02 was identified. still be traded. Do not rely on assurances from The stone was Sri Lankan in origin. M.O'D. vendors. R.K.M.

ANDERSON, A.L., 1991. Curves and optics in BROWN, G., LINTON, T., 1992. Halogen lamps - non-traditional gemstone cutting. Gems & a warning. Australian Gemmologist, 18, 1, 2-4, Gemology, 27, 4, 234-9, 8 figs. 2 figs. This author is getting some attractive effects by Tungsten-halogen lamps emit UV light combining curved facets with crownless open- strongly from about 300nm which is passed table cuts. The pavilion has a combination of freely by the quartz glass envelope and can cause large plane facets and curved ones which give a serious damage to skin, eyes and other tissues. mobile pattern of reflections as the stone is All such lamps should include lead glass or other moved. Generally more effective in closed settings filters to eliminate these harmful rays. and better for large stones of pale to medium Photographic filters are less useful since they are colour than for those of deep colour. R.K.M. damaged by heat. R.K.M.

BALFOUR, I., 1991. Famous diamonds of the CASSEDANNE, J.-P., 1991. L'aigue-marine au world XLVII - The Centenary Diamond. Brésil. Revue de Gemmologie, 108, 3-7, Indiaqua Annual 199'i, 255, 4 figs (2 in colour). [second part], 8 photos (3 in colour), 1 fig. The 599 carat rough diamond from the Geological and mineralogical details are given Premier Mine was cut and polished under the for the more important Brazilian aquamarine supervision of Gabi Tolkowsky to produce a part gem deposits. Techniques of recovery are heart-shaped, part shield-shaped gem of 273 described. M.O'D. carats which was unveiled at the Tower of London to commemorate the 100th anniversary CAVENEY, R.J., 1991. De Beers Diamond of De Beers. P.G.R. Research Laboratory Report, Part V: Now for the backroom ... Indiaqua Annual BALFOUR, I., 1991. Famous diamonds of the 1991, 246, 3 figs. world XLVI - Some notable diamonds in A 14.2 carat good-quality industrial 1990. Indiaqua Annual 1991, 251-4, 9 figs (7 monocrystal diamond was synthesized at the De in colour). Beers Diamond Research Laboratory in Contains details of recent diamonds plus new Johannesburg. The synthesis took over five information on older diamonds which has come hundred hours of high temperature/high to light since the author's book Famous Diamonds pressure running, and required prolonged was published three years ago. Recent diamonds maintenance of the delicately balanced include the shield-shaped 89.01 carat 'Guinea conditions necessary for successful synthesis. Star', a 101 carat pear-shaped stone and an The production of a synthetic diamond of this emerald-cut light pink 28.67 carat gem. P.G.R. size is extremely expensive, and would not normally be commercially viable. However, this BROWN, G., 1992. Trade embargo on coral. stone was produced for experimental purposes Australian Gemmologist, 18, 1, 5-6. to test the technology and equipment. The 14.2 Export and import of native corals is now carat stone is yellow in colour, a characteristic of prohibited in Australia, including black coral synthetics containing nitrogen. Synthetic mono harvested since 1981 and some other types since crystals are generally sliced into industrial 1990. Precious white, pink and red corallium products and are not suitable for use in corals are exempt at the moment and gold and jewellery. P.G.R. J.J. GemmGemm.,, 1992,1992, 2323,, 44 232355

COLLYER,COLLYER, T.,T.3 RODRIGUESRODRIGUES,, E.G.,E.G., MACHADO,MACHADO, carvecarvedd hardstonehardstone vasvasee withwith spotspot RIRI ofof 1.741.74 waswas J.I.L.,J.I.L., 1991.1991. DaDass MalachitvorkommenMalachitvorkommen dederr grossular,grossular, confirmeconfirmedd byby X-rayX-ray diffractiondiffraction SerraSerra Verde,Verde, Curionopolis,Curionopolis, ParaPani,, Brasilien.Brasilien. analysis;analysis; a finefine greegreenn jadeitjadeitee hadhad heatheat damagedamage ZeitschriftZeitschriJt der Deutschen GemmologischenGemmologischen arounaroundd thethe girdlgirdlee afterafter a repairepairr ttoo ththee ringring mount,mount, GesellschaJt,Gesellschaft, 4040,, 2/3,2/3, 99-10299-102,, 2 illustrationsillustrations suggestingsuggesting thathatt itit wawass waxedwaxed - stonestone shouldshould havehave (one(one inin colour),colour), bibl.bibl. beebeenn removedremoved beforbeforee usinusingg heat;heat; a lapislapis lazulilazuli TheThe malachitmalachitee iiss mineminedd iinn ththee municipalitymunicipality ooff witwithh narronarroww curvecurvedd bandinbandingg iiss describeddescribed;; anan XX- CurionopoliCurionopoliss inin ththee south-eastsouth-east ofof Para.Para. ItIt isis thethe rayray ooff a 9696 caratcarat baroqubaroquee pearpearll revealedrevealed a largelarge first mineablemineable deposidepositt ooff gemgem qualityquality malachitemalachite interiointeriorr cavitcavityy partlpartlyy filled bbyy a smallsmall shellshell beadbead iinn BrazilBrazil.. MiningMining iiss connectedconnected withwith ththee anandd cement;cement; fashionablefashionable blackblack jewellerjewelleryy iiss neighbourinneighbouringg golgoldd depositsdeposits andand foundfound iinn exceedingexceeding availablavailablee blackblack onyonyxx suppliesuppliess anandd hydrothermallhydrothermallyy formeformedd veins.veins. TheThe materiamateriall iiss variousvarious substitutessubstitutes araree beinbeingg offeredoffered includingincluding aa suitablesuitable foforr cabochonscabochons,, beadbeadss anandd objetsobjets d'art.d'art. blacblackk dolomite/quartdolomite/quartzz whicwhichh iiss illustrated.illustrated. AtAt timetimess itit iiss founfoundd togethertogether withwith chrysocollachrysocolla AnAn orange-yelloorange-yelloww sapphiresapphire hadhad nono relevantrelevant anandd otherother CCuu materials,materials, similarsimilar toto thethe 'Eilat''Eilat' absorption,absorption, nono reactionreaction toto LUV,LUV, nono pleochroismpleochroism stones.stones. E.SE.S.. anandd a purplispurplishh iridescenciridescencee unknownunknown inin sapphiresapphire anandd wawass identifiedidentified aass a coatedcoated stone,stone, soakingsoaking iinn DUDA,DUDA, R,R., MOLNARMOLNAR,, J.J.,, 1992.1992. DieMineralieDieMineralienn ausaus warwarmm HClHCl removedremoved thethe coloucolourr - otherother coatings,coatings, dedenn slowakischenslowakischen Edelopal-Lagerstatten.Edelopal-Lagerstätten. similarsimilar ttoo 'Aqua-Aura','Aqua-Aura', areare anticipated;anticipated; twtwoo Lapis, 17,4,17, 4, 23-823-8,, 9 photophotoss iinn colourcolour,, 2 maps.maps. sapphiressapphires withwith repeaterepeatedd twintwin layerlayerss werewere thoughtthought DetailDetailss ooff somesome ofof thethe typetypess ofof precioupreciouss anandd naturanaturall untiluntil curvecurvedd bandinbandingg andand gasgas bubblesbubbles commoncommon opalopal,, withwith briefbrief descriptionsdescriptions ooff werewere detecteddetected,, suchsuch twinning,twinning, probablprobablyy duedue toto accompanyinaccompanyingg mineralsminerals andand generagenerall geologygeology araree heatingheating ttoo reducereduce thethe bandebandedd structure,structure, cancan bebe givegivenn foforr ththee classiclassicc CzechoslovakiaCzechoslovakiann locatiolocationn ooff confusingconfusing anandd carefulcareful immerseimmersedd examinatioexaminationn ooff Cervenica-Dubnik.Cervenica-Dubnik. M.O'D.M.O'D. stonesstones iiss calledcalled forfor.. RK.M.R.K.M.

EDIRIWEERAEDIRIWEERA,, R.N.RN.,, 1991.1991. ScientificScientific AspectsAspects ofof GARZONGARZON JIMENEZ,JIMENEZ, J.,J., 1991.1991. EsmeraldasEsmeraldas GeudGeudaa Beneficiations.Beneficiations. ZeitschriftZeitschrijt der Deutschen sinteticassintéticas e imitaciones.imitaciones. Boletin deldel Gemmologischen Gesellschajt,Gesellschaft, 40,40, 2/32/3,, 149-54,149-54, Instituto Gemologico Espanol,Espaiiol, 33,33, 9-29,9-29, 7766 1 graph,graph, 11 table,table, 11 diagram,diagram, bibl.bibl. photophotoss iinn colour,colour, 8 figs. Milky-whiteMilky-white corundumscorundums witwithh a slightslight yellowyellow ThThee wholwholee fieldfield ofof emeraldemerald synthesissynthesis anandd oror blubluee huhuee areare namenamedd 'geuda''geuda' inin Singhalese.Singhalese. ByBy imitationimitation iiss coveredcovered,, witwithh manmanyy photographphotographss ooff heaheatt treatmenttreatment somesome ofof thesthesee corundumcorundumss cacann bebe characteristicharacteristicc inclusionsinclusions.. ThoseThose ooff compositecomposite alteredaltered toto blubluee oror yellowyellow sapphires.sapphires. ThThee heatheat stonesstones areare particularlparticularlyy effective.effective. NoteNotess oonn treatmenttreatment dissolvedissolvess thethe rutilerutile inclusioninclusionss anandd chemicachemicall compositioncomposition andand oonn infrinfraa redred spectraspectra altersalters ththee colour-influencingcolour-influencing ions.ions. TheThe blueblue areare alsalsoo given.given. M.O'D.M.O'D. colourcolour iiss causedcaused bbyy iron-titaniuiron-titaniumm particlesparticles witwithh aa positivpositivee chargecharge ooff 6,6, ththee yelloyelloww coloucolourr bbyy ironiron GODOVIKOV,GODOVIKOV, A.A.A.A.,, RlPINENRIPINEN,, O.I.0.1.,, 19911991.. ionsions witwithh a positivpositivee chargchargee ofof 3,3, aatt temperaturestemperatures WunderschînWunderschinee AchateAchate vovonn dedenn FundstellenFundstellen betweebetweenn 1600-1850°C.1600-1850°C. FoForr blueblue sapphiressapphires ononee dederr MongoleiMongolei.. Lapis, 16,16 , 12,12, 35-935-9,, 1111 photosphotos requirerequiress a reducing,reducing, foforr yelloyelloww sapphiressapphires aann (9(9 inin colour).colour). oxidizingoxidizing atmosphereatmosphere.. ThThee treatmentreatmentt iiss AmonAmongg mineralmineralss reportedreported frofromm ththee northnorth conditionalconditional oonn ththee presencpresencee ofof sufficientsufficient ironiron westerwesternn GobiGobi,, MongoliaMongolia,, areare ornamentalornamental qualityquality andand titaniumtitanium particlesparticles.. E.SE.S.. agatesagates.. FroFromm ththee photographphotographss thethe specimensspecimens includincludee a widewide rangrangee ooff colours.colours. M.O'D.M.O'D. FRYERFRYER,, C.W.C.W.,, CROWNINGSHIELDCROWNINGSHIELD,, R.R,, HARGETTHARGETT,, D.D.,, MOSES,MOSES, To',T., HURWITHURWIT,, K.,K., KANE,KANE, R.E.,R.E., GÜBELINGUBELIN,, E.E.,, 1991.1991. DansDans lala valleevallée dedess rubis.rubis. 1991.1991. GemGem tradtradee lablab notesnotes.. Gems & Revue de Gemmologie, 109,109 , 7-9,7-9 ,1 1 map, map ,3 3 Gemology, 2277 44,, 248-53,248-53, 1414 figs.figs. photophotoss ((11 iinn colour).colour). A largelarge (l3cm)(13cm) yellow-browyellow-brownn clinochloreclinochlore lilIbb TheThe first parpartt ofof a reviewreview ofof thethe rubyruby depositsdeposits carvincarvingg wawass thoughtthought ttoo bbee a TangTang Dynasty,Dynasty, ofof MyanmaMyanmarr (Burma)(Burma) coverincoveringg thethe journejourneyy ttoo ChineseChinese sceptre,sceptre, abouaboutt 12001200 yearsyears old;old; a greengreen ththee sitesite andand ththee areaarea geologygeology.. M.O'D.M.O'D. diamondiamondd confirmedconfirmed bbyy uniformuniform coloucolourr anandd spectrumspectrum asas neutron-treateneutron-treatedd alsoalso hahadd naturalnatural GURNEY,GURNEY, J.J.J.J.,, LEVINSONLEVINSON,, A.A.A.A.,, SMITH,SMITH, H.S.,H.S., radiatioradiationn bumsburns oonn thethe girdlgirdlee suggestingsuggesting thatthat iitt 1991.1991. MarinMarinee miningmining ooff diamondsdiamonds offoff ththee waswas a palepale naturanaturall greegreenn enhanceenhancedd bbyy artificialartificial WestWest CoasCoastt ofof southernsouthern Africa.Africa. Gems & irradiationirradiation;; a largelarge OrientalOriental brownish-yellowbrownish-yellow Gemology, 2727,, 4,4, 206-19206-19,16, 16 figs.figs. 236 J. Gemm, 1992, 23, 4

The raised beaches of marine deposits inland jade. The imitations are conveniently listed in this area have already yielded about 100 together in a table which gives composition, million carats of mostly gem quality diamond. specific gravity and refractive index. M.O'D. Similar deposits are known to exist off-shore and new techniques have been developed to exploit HENN, U., BANK, H., 1991. Geschliffener, klar these at depths of up to 100 metres and are durchsichtiger Hackmanit von Mount St. expected to increase in yield. The deposits have Hilaire in Kanada. Zeitschrift der Deutschen been swept northward by prevailing coastal Gemmologischen Gesellschaft, 40, 2-3, 93-7, 4 currents for millions of years and extend far photomicrographs, 1 table, 1 graph, bibl. along the shores of Namibia where they are also The hackmanites were found at Mount St exploited under lease mainly by South African Hilaire in Quebec; the same locality has yielded based companies. The off-shore leases on the blue willemite in the past as well as beloeilite, a South African coast extend north from a point sodalite with albite and nepheline. The above Lamberts Bay to the present mouth of the examined ten faceted hackmanites vary in weight Orange River. These southerly beaches were from 0.27ct to 3let. They are Cl-sodalites and deposited at a time when that river reached the show distinctive photochroism. RI 1.485-1.487, sea at what is now the mouth of the Olifants SG 2.30-2.32. E.S. River. The source of these stones is the vast Orange River basin which eroded most of the HENN, U., BANK, H., 1991. Sternbronzit aus Sri region's known diamond bearing kimberlite Lanka. Zeitschrift der Deutschen pipes some thousand miles to the east over the Gemmologischen Gesellschaft, 40, 2/3, 145-8, 2 past millions of years. photomicrographs, (one in colour) 1 graph, Submarine deposits of diamonds in potholes bibl. at shallow depths enable them to be worked with Bronzite is an orthopyroxene, between vacuum hoses operated by divers, while deposits enstatite and orthoferrosilite. The star bronzite up to 100 metres deep are vacuumed up by a cabochon from Sri Lanka weighed 0.79ct and large machine known [amusingly] as a 'robotic showed a six-rayed star caused by needle-like bottom crawler', which can raise up to 100 cubic inclusions filled with a liquid. RI 1.680-1.693, metres of suspended solids an hour. There is no DR 0.013, SG 3.41. E.S. significant production from deep water yet, but that is expected to change if the Namaqualand HENN, U., BANK, H., 1992. Examination of an (SA) De Beers sampling is successful. These unusual alexandrite. Australian Gemmologist, off-shore diamond reserves are probably the 18, 1, 13-15, 5 figs. largest known - 1.5 billion carats are estimated - Underlines problems of distinguishing natural but large scale recovery from the sea- bed Brazilian alexandrite from the synthetic product presents major engineering problems, although since inclusions and growth patterns are similar prognosis would appear to be good. R.K.M. in each. Present stone was first thought to be synthetic on the evidence of a triangular tabular HANNI, H.A., 1992. Blue-green emerald from inclusion. Further investigation by infrared Nigeria. (A consideration of terminology.) spectrum proved it was genuine, and the Australian Gemmologist, 18, 1, 16-18, 4 figs. inclusion was identified as hematite, typically Discusses the distinction between green beryl natural. [Difficult] R.K.M. and blue-green emerald from Nigeria, which contains iron as well as chromium and HURWIT, K.N., REINITZ, I., MOSES, T., vanadium, altering the colour from the normally KAMMERLING, R.C., 1991. Untersuchung expected green of emerald. Dr Hanni justifies von Salzwasserzuchtperlen mit künstlichen, calling these stones by the more prestigious farbigen Kernen. Zeitschrift der Deutschen name on several counts. He suggests 'blue- Gemmologischen Gesellschaft, 40, 2/3, 81-8, 1 green emerald' is sufficient distinction. R.K.M. photograph, 4 photomicrographs, 4 graphs, bibl. HARDER, H., 1992. Vom Steinbeil bis zur The nucleus seems to have been produced Smaragde - Jade ('Imperial - Jade'). from powdered oyster shells and an inorganic Aufschlüsse 43, 65-82, 16 photos (14 in pigment. The 'beads' are dark grey-green and colour). have a diameter of 8mm. Other pearls were found Despite the title, the paper deals with both to have a nucleus of some synthetic substances jadeite and nephrite, reviewing the colour which started to melt when drilled. Comparative varieties, mineralogy and substances imitating X-rays illustrate the difference. E.S. J.J. Gemm.,Gemm, 1992,1992, 23,23, 4 237237

JOHNSTON,JOHNSTON, C.L.,C.L., GUNTER,GUNTER, M.E.,M.E., KNOWLES,KNOWLES, andand completingcompleting thethe filling.filling. BubbleBubbless werewere C.R,CR., 1991.1991. SunstoneSunstone labradoritelabradorite fromfrom thethe apparentapparent inin plastic,plastic, andand viewedviewed fromfrom sideside thesethese PonderosaPonderosa mine,mine, Oregon.Oregon. Gems & Gemology, lookedlooked likelike triplets.triplets. RK.M.R.K.M. 27,27,4,220-33 4, 220-33,, 1717 figs. ThisThis minemine produceproducess labradoritelabradorite sunstonesunstone inin KAMPF,KAMPF, A.R.,A.R., 1991.1991. TaaffeiteTaaffeite crystals.crystals. colourscolours rangingranging from yellowyellow throughthrough orange,orange, pinkpink Mineralogical Record, 22,22 , 5,5 , 343-7,343-7, 66 photosphotos inin toto deepdeep red,red, withwith greengreen asas thethe rarestrarest colour.colour. YieldYield colour,colour, 2 figs. ofof cuttablecuttable qualityquality seemsseems highhigh bubutt muchmuch isis palepale inin TaaffeiteTaaffeite hashas beenbeen reportedreported from five placesplaces colourcolour andand thethe bestbest stonesstones areare generallygenerally smallsmall inin onon earth.earth. MostMost crystalscrystals areare pyramidalpyramidal oror size.size. Mining,Mining, inin summersummer andand autumnautumn only,only, isis bipyramidalbipyramidal andand areare oftenoften truncatedtruncated bbyy basalbasal open-castopen-cast bbyy a smallsmall staffstaff usingusing a back-hoeback-hoe andand pedions.pedions. TaaffeiteTaaffeite crystalscrystals fromfrom SriSri LankaLanka (the(the bulldozerbulldozer;; estimatedestimated oreore reservesreserves soso farfar mineminedd isis onlyonly onesones ofof gemgem potentiapotentiall soso farfar found)found) areare 1.51.5 tonnes;tonnes; highhigh gradgradee materialmaterial aboutabout 500500 gramsgrams mostmost commonlycommonly mono-pyramidalmono-pyramidal (the(the mineralmineral isis a dayday inin smallsmall sizes.sizes. SpanglingSpangling isis duedue toto coppercopper hemimorphic).hemimorphic). CrystalsCrystals fromfrom thethe PitkarantaPitkäranta plateletplateletss distributeddistributed randomlyrandomly parallelparallel toto twotwo district,district, KarelianKarelian USSR,USSR, areare reportedreported toto occuroccur asas possiblpossiblee crystalcrystal directionsdirections (001)(001) andand (010).(010). RIsRIs epitacticepitactic overgrowthsovergrowths onon spinel;spinel; bipyramidalbipyramidal 1.563-1.572;1.563-1.572; SGSG avoav. 2.71,2.71, asas expectedexpected forfor crystalscrystals fromfrom Sianghwaling,Sianghwaling, China,China, appearappear toto bebe labradorite.labradorite. PonderosaPonderosa claimsclaims toto bebe thethe premierpremier twinnedtwinned byby reflectionreflection onon {OOO{0001} I}.. BipyramidalBipyramidal locatiolocationn forfor thisthis typetype ofof sunstone.sunstone. ThereThere appearappear crystalscrystals fromfrom easterneastern SiberiaSiberia andand fromfrom MountMount toto bebe considerableconsiderable reserves.reserves. RK.M.R.K.M. Painter,Painter, SouthSouth AustraliaAustralia havehave notnot yetyet beenbeen describeddescribed inin detaildetail bubutt maymay alsoalso representrepresent twinstwins KAMMERLING,KAMMERLING, RC.,R.C., KOIVULA,KOIVULA, J.I.,J.I., KANE,KANE, R.E.,R.E., onon {0001}.{0001}. M.O'D.M.O'D. FRITSCH,FRITSCH, E.,E., MUHLMEISTER,MUHLMEISTER, S.,S., MCCLURE,MCCLURE, S.F.,S.F., 1991.1991. AnAn examinationexamination ofof KOHOUT,KOHOUT, K.,K., 1991.1991. DieDie MineralienMineralien desdes nontransparentnontransparent 'CZ''CZ' fromfrom Russia.Russia. Gems && HartsteinbruchsHartsteinbruchs RockenhausenRockenhausen inin derder Gemology, 27,27, 4,4, 240-6,240-6, 6 figs. NordpfalzNordpfalz.. Lapis, 16,16, 10,10, 41-4,41-4, 8 photosphotos inin CZCZ isis availableavailable inin a widewide varietyvariety ofof colour.colour. transparenttransparent colourscolours andand isis nownow comingcoming fromfrom FineFine agatesagates -andand otherother mineralsminerals areare foundfound inin RussiaRussia inin opaqueopaque white,white, pinpinkk andand blackblack forms,forms, thethe HartsteinbruchHartsteinbruch areaarea ofof thethe GermanGerman thethe first twotwo beingbeing cabochoncabochon cutcut andand marketedmarketed Nordpfalz.Nordpfalz. M.O'D.M.O'D. asas 'PearlTearl CZ'.CZ'. UnderUnder intenseintense lightinglighting allall areare toto somesome extentextent translucenttranslucent withwith evidenceevidence ofof a KorVULA,KOIVULA, J.I.,J.I., FRYER,FRYER, C.W.,C.W., KAMMERLING,KAMMERLING, bandebandedd oror striatedstriated growth.growth. LustreLustre ofof polishedpolished RC.,R.C., 1991.1991. AlmandineAlmandine garnetgarnet inin MontanaMontana specimensspecimens waswas highhigh andand a facetedfaceted blacblackk stonestone sapphire.sapphire. Zeitschri/tZeitschrift der DeutschenDeutschen resembledresembled blackblack diamond.diamond. PinkPink exhibitedexhibited a finefine Gemmologischen Gesellschajt, Gesellschaft, 40, 40 2/3,, 2/3 , 89-89- lineline spectrumspectrum suggestingsuggesting a rare-earthrare-earth dopant.dopant. RIRI 9292,, 4 photosphotos,, bib!.bibl. beyonbeyondd thethe rangerange ofof thethe refractometer,refractometer, SGSG fromfrom SapphireSapphire crystalscrystals withwith a slightlyslightly brownishbrownish- 5.935.93 black,black, toto 6.156.15 pinkpink,, probablprobablyy varyingvarying withwith orangeorange inclusioninclusion ofof almandinealmandine garnetgarnet areare foundfound differentdifferent stabilizerstabilizer percentages.percentages. RK.M.R.K.M. inin DryDry CottonwoodCottonwood CreekCreek inin DeerlodgeDeerlodge CountyCounty northwestnorthwest ofof ButteButte inin Montana,Montana, alongalong thethe KAMMERLING,KAMMERLING, R.C.RC.,, KOIVULA,KOIVULA, J.I.,J.I., WELDON,WELDON, R,R., ContinentalContinental divide.divide. TheThe alluvialalluvial corundumcorundum 1991.1991. Identificaci6nIdentificaciön dede ghemasghemas sinteticassintéticas foundfound herehere variesvaries fromfrom colourlesscolourless toto yellow,yellow, fabricadasfabricadas poporr fusi6nfusion a lala llamallama (metodo(método blueblue,, purplepurple andand red.red. TheyThey areare ofof gemgem quality.quality. Verneuil).Verneuil). Boletin del Instituto GemologicoGemolôgico TheThe hoshostt sapphiresapphire crystalcrystal isis yellowish,yellowish, 3.55ct3.55ct Espanol, 33,33, 32-7,32-7, 8 photosphotos andand 2 figs inin colour.colour. andand measuresmeasures 9.819.81 x 9.119.11 x 3.74mm.3.74mm. TheThe FeaturesFeatures ofof thethe VerneuilVerneuil flame-fusionflame-fusion growthgrowth inclusioninclusion measuresmeasures 0.8mm0.8mm inin diameterdiameter andand isis ofof procesprocesss areare illustratedillustrated andand discusseddiscussed withwith brownish-orangbrownish-orangee colour.colour. IdentificationIdentification waswas particularparticular attentionattention paipaidd toto inclusionsinclusions andand mademade bbyy X-rayX-ray diffractiondiffraction analyses.analyses. E.S.E.S. absorptionabsorption spectra.spectra. TheThe coveragecoverage isis limitedlimited toto corundumcorundum andand spinel.spinel. M.O'D.M.O'D. KOIVULA,KOIVULA, J.I.,J.I., KAMMERLING,KAMMERLING, RC.,R.C., 1991.1991. GemGem news.news. Gems & Gemology, 27,27 ,4, 4 ,254-65, 254-65 ,20 20 figs.figs. KAMMERLING,KAMMERLING, R.C.,R.C., KorvULA,KOIVULA, J.I.,J.I., 1992.1992. DIAMONDSDIAMONDS NovelNovel assembledassembled opalsopals fromfrom Mexico.Mexico. NewsNews ofof diamonddiamond cuttingcutting inin Botswana;Botswana; a Australian Gemmologist, 18,1,19-21,518, 1, 19-21, 5 figs. figs. largelarge diamonddiamond foundfound inin China;China; proposedproposed AssembledAssembled opalopal mademade bbyy parpartt fillingfilling diamonddiamond cuttingcutting inin Shanghai.Shanghai. DiamondDiamond cabochoncabochon shapedshaped mouldmould withwith acrylicacrylic resinresin beforebefore demanddemand inin U.S.U.S. remainsremains strongstrong inin 19911991 placingplacing a sliversliver ofof black-backedblack-backed opalopal faceface downdown exportedexported stonesstones roserose 1616 perper cent,cent, importsimports alsoalso 238 J. Gemm., 1992,23,4

increased; a diamond factory is to open in Dubai sundry colour-change stones and kornerupine for melee up to half carat sizes. General Electric and sillimanite also found, cat's-eye kornerupine announce synthesis of large carbon-13 crystals, is becoming scarce. expected to be harder than normal diamond and Intergrowths of sunstone and iolite are of exceptional structural perfection suggesting reported from India, the iolite usually of the uses for new electronic devices; Indonesian 'bloodshot' type [which I named in 1955]; an Diamond Corp reports a yield of 1 carat per update on tanzanite mining reports competition 10m3 of treated gravel with substantial reserves; for workable zones over the gem rich area; a low-calcium/high- chrome garnet has been used pink-yellow bi-colour tourmaline is reported as as an indicator of diamond potential in unusual. exploration, but the nickel content of high calcium pyrope now seems to be more reliable. SYNTHETICS AND SIMULANTS Raphaeli- Stschik, Israeli diamond cutters have Laser '91 exhibition in Los Angeles included unveiled their Royal Line diamond cuts - the chrome-doped alexandrite, padparadscha colour Duchess, the Baroness and the Empress - synthetic corundum, erbium-doped YAG and reported to take advantage of flatter rough, erbium-doped yttrium lithium fluoride; giving straight-edged well-spread shapes saturated emerald green YAG doped with [remarkably similar to the Maico 'Dream-cuts' chromium, thulium or holmium; chrome-doped illustrated in this column in the last issue of LiCaF and chrome-neodymium gallium Gems & Gemology]. scandium gadolinium garnet; a star sapphire with a centre void in its star is illustrated. COLOURED STONES A 'hairy bug' in amber is described and ENHANCEMENTS illustrated; Czechoslovakian Conference Editors have experimented with Opticon revealed recently discovered ruby deposit north filled cracks in quartz and report all were low of Magnitogorsk, Russia, high quality expected; relief needing careful microscopy to detect them; synthetic malachite displayed and synthetic opal dark-field showed characteristic violet/blue from Russia discussed. Dr Edward Gübelin has flashes, probably the most reliable diagnostic a 'cross' chrysoberyl cat's-eye, the normal eye feature. An emerald crystal was found to being crossed by a growth band of different contain cavernous oil-filled areas; cracks in colour; an attractive Tanzanian green diopside is synthetic emeralds from Swat, Pakistan were illustrated and described; Mike Ridding draws filled with a substance which fluoresced strong attention to finds of large emerald and green yellow under LUV; demand for yellow sapphire beryl crystals at Jos, Nigeria, in 1990; demantoid in Sri Lanka has led to heat treatment of pale garnets are being mined again in the Urals; stones and the import of synthetic yellows, yellow manganese garnets are reported from surface coating with organic compounds, boiling Tanzania and a 23.56ct tsavorite is illustrated. with vegetable dyes which are then covered by The ban on ivory and tortoiseshell has led to wax to defeat the acid immersion test. Pink search for suitable substitutes, including 'fossil' sapphire is similarly faked; some are chewed mastodon and mammoth tusks and vegetable with a local berry [betel nut?] and then a ivory; 'recycled' ivory was said to be from old cigarette is smoked to improve the colour. tusks but proved to be thin veneers from old Paraiba tourmalines continue to be simulated; piano-keys. Peruvian opal in blue and pink self- Drs Henn and Bank list apatite, irradiated topaz, colours is coming from a mine near Arequipa - a beryl triplets, tourmaline and glass doublets and copper mining area. blue apatite cat's-eyes all offered as Paraiba A 19th Century chalcedony ring had a sepia tourmalines. R.K.M. portrait of George Washington printed or stained on it by a photographic process. KOSHIL, I.M., VASILISHIN, I.S., PAVLISHIN, V.l., Five out of six fragmentary rubies bought as PANCHENKO, V.l., 1991. Wolodarsk- natural in Vietnam proved to be synthetic when Wolynskii: geologischer Aufbau und cut; several instances of synthetics from that Mineralogie der Pegmatite in Wolynien, country have been reported but these were the Ukraine. Lapis, 16, 10, 24-40, 2 maps, 5 figs, first synthetic 'rough' examined; terrorism is 30 photos (27 in colour). hampering exploration in Sri Lanka but good The pegmatites of the Wolodarsk area of the deep red corundum has been found at Ukraine, USSR, are remarkable both for their Hambatota and at Matara; good red star spinels green (non-emerald), yellow and blue beryl from Ratnapura; yellow-green andradite and crystals and for equally fine crystals of topaz. J. Gemm., 1992, 23, 4 239

The beryl crystals display characteristic etching. ROBERT, D., 1991. La zircone, pourquoi A list of the other minerals found in the area is cubique? Revue de Gemmologie, 108, 14-17, 2 given with notes on the pegmatites and their photos in colour, 2 figs. formation. M.O'D. The relationship between natural monoclinic zirconia and the cubic artificial product is NOACK, R., 1991. Die Achate aus den described. M.O'D. sekundären Fundstellen der Lausitz. Lapis, 16, 12, 22-4, 1 map, 5 photos in colour. RÖTTERMANN, C, 1991. Argyle Diamonds - Fine ornamental agates are found at Lausitz Ein australisches Abenteuer. Zeitschrift der in the eastern part of Germany. The agates are Deutschen Gemmologischen Gesellschaft, 40, 2/3, locally known as 'Elbe-agates'. M.O'D. 155-6. A short survey of the development and O'DONOGHUE, M., 1991. Industrial review - production of the world's largest diamond mine. Gemstones. Britannica Book of the Year 1991, The Argyle mine, situated in the Kimberley p. 217. region in the north of Western Australia, is Retail, production and saleroom details of the named after an artificial lake nearby. It started gemstone market are reviewed with notes on full production in 1986 (29.2 million carats) new species and varieties and on further yielding in 1990 35 million carats. 5% are of developments in colour alteration and gemstone gem quality, amounting to 3% of world gem enhancement. Sales in the retail sector held up production. The best of the gem diamonds are reasonably well in the period under review. pink and very expensive. 75% of the production M.O'D. is marketed by the CSO. E.S.

OSTROOUMOV, M.N., 1991. L'amazonite. SAADI, J.A., 1991. Monumento geolôgico: Revue de Gemmologie, 108, 8-12, 1 map, 2 diatremas, ünicas en el mundo, portadoras de figs, 1 photo in colour. formaciones estalactiticas de rodocrosita. Occurrences of amazonite throughout the Boletin del Instituto Gemolôgico Espanol, 33, 38- world are reviewed with observations on the 43, 19 photos in colour, 1 map. cause of colour, ascribed to a colour centre The rhodochrosite mine at Minas Capillita, including Pb and Fe ions. M.O'D. Andalgala, Catamarca, Argentina, is described with notes on the geology and mineralogy. PONAHLO, J., 1991. Diferenciaciôn entre piedras Photographs graphically illustrate the preciosas naturales ysinteticas por rhodochrosite occurrence as stalactites. M.O'D. catodoluminiscencia. Boletin del Instituto Gemolôgico Espanol, 33, 47-52, 7 figs in SCHWARZ, D., 1991. Die chemischen colour. Eigenschaften der Smaragde. III. Cathodoluminescence is advocated as a Habachtal/ôsterreich und means of distinguishing between natural and Uralgebirge/UdSSR. Zeitschrift der Deutschen synthetic gemstones. Corundum and chrysoberyl Gemmologischen Gesellschaft, 40, 2/3, 103-43, varieties are discussed together with Afghan and 12 graphs, 1 table, 2 geological maps, bibl. Chilean lapis lazuli. M.O'D. The regional, geological and genetic aspects of the Habachtal, Austria, and the Urals, USSR, READ, P.G., 1990. The threat of the look-alikes. are discussed, as are the chemical properties of Canadian Jeweller. October 1990, 34, 1 fig. emeralds from both localities. Variations and Although the main thrust of gemmological average concentrations of chromium, iron, research is to do with methods of identifying the magnesium and sodium are analysed. E.S. latest synthetic gem products, and we are alert to the possibility of a synthetic when checking out Scovnx, J.A., 1992. The Gillette quarry, Haddam the potentially more valuable stones, when it Neck, Connecticut. Mineralogical Record, 23, 1, comes to the 'semi-precious' materials we may 19-28, 3 maps, 14 photos (11 in colour). not exercise the same degree of suspicion. The Gem quality crystals of elbaite and beryl have article instances amethyst, and various been recovered over the years from the Gillette composite look-alike stones, including garnet- quarry, Haddam Neck Connecticut, USA. topped doublets (which were still being listed in Prospects for future collecting are not good. Swarovski's catalogue in the 1970s). Details of M.O'D. simple identification methods are included. (Author's abstract) P.G.R. SUN, X.R., 1992. A note on corundum veinlets 240240 J.J. Gemm.,Gemrn., 1992,1992, 23,23, 4

inin rubiesrubies fromfrom ChinaChina andand Australia.Australia. biotitebiotite [110][110] oror toto anan equivalentequivalent direction.direction. Australian Gemmologist, 18,18 ,1, 1 ,22-3, 22-3 ,3 3 figs. figs. M.O'D.M.O'D. InIn rubiesrubies fromfrom HuoHuo Shan,Shan, ChinaChina andand HartsHarts Range,Range, AustraliaAustralia,, geologicalgeological conditionsconditions havehave WATERMEYER,WATERMEYER, R,B., 1990.1990. ColourColour retentionretention anandd causedcaused shatter-likeshatter-like crackscracks whichwhich havehave distribution.distribution. Diamond International, 44,, subsequentlysubsequently beenbeen healedhealed byby darkerdarker corundumcorundum March-April,March-April, 97-101,97-101, 4 figs. infillings,infillings, oror atat a laterlater datedate byby sericitesericite [a[a fibrousfibrous SummarizesSummarizes thethe principleprincipless ofof thethe passagepassage andand formform ofof mica].mica]. SuchSuch inclusionsinclusions maymay affectaffect absorptionabsorption ofof lightlight inin a polishedpolished diamond,diamond, anandd qualityquality andand value.value. RK.M.R.K.M. outlinesoutlines thethe stepssteps whichwhich cancan bebe takentaken toto solvesolve pr9blemsprpblems ofof colourcolour concentrationconcentration andand colourcolour TOWNSEND,TOWNSEND, I.J.,I.J., 1992.1992. TheThe MintabieMintabie opalfield.opalfield. dilution.dilution. TakingTaking intointo accountaccount thethe relationshiprelationship Australian Gemmologist, 18,18 ,1,7-12,9 1, 7-12, 9 figs figs andan d betweenbetween colourcolour concentrationconcentration andand thethe geometrygeometry map.map. ofof thethe stone,stone, itit isis shownshown howhow thethe qualityquality ooff A remoteremote areaarea ofof SouthSouth AustraliaAustralia 290km290km fromfrom colourcolour inin a numbernumber ofof diamonddiamond cuttingcutting stylesstyles CooberCoober PedyPedy andand 450km450km fromfrom AliceAlice Springs,Springs, cancan bebe improved.improved. ThisThis cancan resultresult inin anan upgradeupgrade first discovereddiscovered aboutabout 19201920 butbut tootoo aridarid (rainfall(rainfall fromfrom a normalnormal toto a fancyfancy colour.colour. ColourColour averageaverage 10"10" perper annum)annum) andand tootoo difficultdifficult ooff distributiondistribution cancan alsoalso bebe improved; improved; palepale stonesstones accessaccess toto bbee workedworked seriouslyseriously untiluntil 19761976 whenwhen cancan bebe deepeneddeepened inin colour,colour, andand darkerdarker colourscolours bull-dozersbull-dozers andand pneumaticpneumatic drillsdrills werewere broughtbrought cancan bebe enrichedenriched byby introducingintroducing moremore light.light. in.in. MatrixMatrix isis a harhardd quartzquartz sandstonesandstone anandd P.G.R. mechanicalmechanical openopen castcast miningmining andand explosivesexplosives araree usedused untiluntil opalopal tracestraces foundfound whenwhen handhand workingworking WEERTH,WEERTH, A.,A., 1991.1991 . NeufundNeufundee ausaus dedemm isis employed.employed. SomeSome MintabieMintabie opalopal tendstends toto crackcrack HimalayaHimalaya undund Karakorum.Karakorum. Lapis, 16,16, 10,10 , ifif minedmined fromfrom belobeloww thethe waterwater table,table, shallowshallow 45-6,445-6, 4 photosphotos (3(3 inin colour).colour). drierdrier veinsveins areare saidsaid toto bbee freefree from thisthis defect.defect. SomeSome recentlyrecently reportedreported mineralsminerals fromfrom ththee SinceSince 19851985 output,output, includingincluding finefine black,black, hahass PakistanPakistan KarakoramlHimalayaKarakoram/Himalaya includeinclude emeraldemerald increasedincreased dramatically.dramatically. RK.M.R.K.M. from GujarGujar KilliKilli wherewhere crystalscrystals upup toto Scm5 cm lengthlength havehave beenbeen found;found; spessartinespessartine fromfrom Haramosh,Haramosh, TOGNONI,TOGNONI, C.,C, 1990.1990. AnAn automaticautomatic procedureprocedure hematitehematite fromfrom Skardu,Skardu, epidoteepidote fromfrom TurmikTurmik forfor computingcomputing thethe optimumoptimum cutcut propertiesproperties ooff nearnear Skardu,Skardu, aquamarine,aquamarine, apatiteapatite andand herderiteherderite gems.gems. La Gemmologia, 15,15, 3/4,3/4, 23-32,23-32, 2 figs. from thethe DussoDusso area.area. M.O'D.M.O'D. TheThe optimumoptimum rayray pathpath insideinside a simplesimple shapedshaped transparenttransparent bodybody isis evaluatedevaluated byby anan automaticautomatic YACOOT,YACOOT, A.,A., MOORE,MOORE, M.,M., 1992.1992. AnAn unusualunusual computingcomputing method.method. M.O'D.M.O'D. octahedraloctahedral diamond.diamond. MineralogicalMineralogical Magazine, 56,56, 111-13,6111-13, 6 photos.photos. TROSSARELLI,TROSSARELLI, C.,C, 1990.1990. UseUse ofof thethe invertedinverted A clearclear colourlesscolourless diamonddiamond weighingweighing 0.35ct0.35ct microscopemicroscope inin gemmology.gemmology. La gemmologia,gemmologia, showedshowed smallsmall dodecahedrdodecahedraa onon thethe sixsix verticesvertices ooff 15,15, 3/4,3/4, 7-21, 22 figs, 2424 photophotoss inin colour.colour. thethe octahedronoctahedron andand lauelaue picturespictures showedshowed thatthat MicroscopesMicroscopes whichwhich displaydisplay thethe undersideunderside ooff thethe specimenspecimen waswas a singlesingle crystal.crystal. X-rayX-ray metallurgical,metallurgical, biologicabiologicall oror opaqueopaque mineralmineral topographstopographs showshow thatthat crystalcrystal growthgrowth startedstarted specimensspecimens cancan bebe adaptedadapted forfor thethe examinationexamination ooff from anan imperfectimperfect andand highlyhighly strainedstrained nucleus,nucleus, inclusionsinclusions inin gemstones.gemstones. ExamplesExamples ofof somesome usesuses growthgrowth bandingbanding confirmsconfirms thatthat growthgrowth waswas onon areare given.given. M.O'D.M.O'D. {Ill}{111} planes.planes. A historyhistory ofof thethe crystal'scrystal's modemode ooff growthgrowth isis suggested.suggested. M.O'D.M.O'D. WALMSLEY,WALMSLEY, J.C.,J.C., LANG,LANG, A.R.,A.R., 1992.1992. OrientedOriented biotitebiotite inclusionsinclusions inin diamonddiamond coat.coat. Mineralogical I.C.A.I.C.A. LaboratoryLaboratory Alerts.Alerts. 1992.1992. AustralianAustralian Magazine, 56,56, 108-11,3108-11, 3 photos,photos, 1 fig.fig. Gemmologist, 18,18, 1,1, 18.18 . CoatedCoated diamondsdiamonds havehave a clear,clear, oftenoften gemgem- ValuableValuable warningswarnings ofof 'Swat'Swat emeraldemerald rough'rough' qualityquality octahedraloctahedral corecore withwith a coatcoat shellshell inin whichwhich whichwhich yieldedyielded twotwo syntheticsynthetic cabochoncabochon emeralds;emeralds; thethe diamonddiamond matrixmatrix isis denselydensely populatedpopulated byby subsub- syntheticsynthetic flux-grownflux-grown redred andand blueblue spinelsspinels fromfrom micrometre-sizemicrometre-size non-diamondnon-diamond bodies.bodies. FlakesFlakes ooff SriSri Lanka;Lanka; 'Malaya'Malaya Jade'Jade' whichwhich isis greengreen dyeddyed brownbrown biotitebiotite micamica havehave beenbeen discovereddiscovered inin thethe quartzite;quartzite; andand cracklecrackle quenchedquenched red-dyedred-dyed coatcoat ofof somesome diamondsdiamonds fromfrom Zaire,Zaire, andand maymay naturalnatural corundumcorundum whichwhich resemblesresembles somesome EastEast havehave a preferredpreferred orientationorientation withwith biotitebiotite (001(001)) AfricanAfrican rubies,rubies, nono tracetrace ofof chromiumchromium spectrumspectrum parallelparallel toto a diamonddiamond octahedraloctahedral plane,plane, foforr andand a yellowyellow fluorescencefluorescence underunder LUVLUV betray.betray. exampleexample (111)(111) withwith diamonddiamond [110][110] parallelparallel ttoo RK.M.R.K.M. J. Gemm., 1992, 23, 4 241

Proceedings of The Gemmological Association and Gem Testing Laboratory of Great Britain and Notices

OBITUARIES Denis Inkersole, FGA, for a generation the leading gemmology evening class teacher, died after a short illness on 11 August 1992. Living all his life in the East London borough of Hackney it was fitting that his teaching work took place at what is now the City Polytechnic whose premises are in an adjacent borough. Born in 1931, Denis took a Higher National Certificate in a variety of subjects but worked mainly as an industrial chemist until the early 1970's when the move of his then employers out of London gave him the chance to set up on his own as a mineral dealer, lapidary and, later on, lapidary teacher. His firm, Mineral Associates, dealt in a wide range of the less expensive but more commercial gem and ornamental minerals and his lapidary work complemented his dealing, using similar species. As the years went on, however, Denis was increasingly asked to provide faceted and sawn materials for some important commissions; his skills and patience as a lapidary teacher were rec The opening of the Tech. in March 1963. The 'usher' on the right is the late Robert (Bobby) Blott of Waters & Blott; probably at one time the ognized by other countries and he instituted lap biggest jobbing jewellers around. R.W. worked there for a time. idary classes in more than one. While all this was going on his Polytechnic classes continued in his Fellow of the Gemmological Association in 1929, characteristically chatty and friendly way. passing with Distinction. Later he assisted I.G. Denis was always ready to take on the bread- Jardine with his gemmological lectures at Chelsea and-butter work associated with class teaching Polytechnic. and this perhaps unspectacular consistency In the early thirties Ron worked for Barnetts in marked his whole life; outside «gemstones he the Burlington Arcade and later he established his worked with the Scout movement and must have own business in the same arcade. given an inspiring start in life to many boys from a During the war the business suffered badly poor area of London. when Burlington Arcade was bombed. On 10 We extend love and sympathy towards his wife September 1940 a 5001b bomb scored a direct hit and children who will sadly miss so kind and unas on the shop. Ron always said that he was the first suming a man, as we do. M.O'D. jeweller in the country to suffer bomb damage. He was always very proud of the fact that he and R.W. (Ron) Yeo, FGA, on Wednesday 26 the staff sorted through the remains of the busi February 1992 aged 81. ness and managed to salvage about 40% of the Ron Yeo's career as a jeweller and gemmologist total stock themselves during a 12 week 'sweep spanned six decades, Ron himself qualifying as a up'. Later Ron was in great demand from jew- 242 J. Gemm., 1992, 23, 4

ellers elsewhere in the country whose businesses MEMBERS' MEETINGS had suffered similar fates during the bombing of London provincial towns and cities. His practical advice On 22 September 1992 at the Ironmongers' enabled many to resurrect their companies. Hall, London EC2, the annual Trade Luncheon After the war Ron ran two shops in the West was held. End of London and then opened another shop in On 30 September 1992 at 27 Greville Street, Burlington Arcade. The Company which bore his London EC IN 8SU, the Annual General Meeting name expanded to own a number of businesses of GAGTL was held. A full report will be pub from Penzance to London, and is still in existence lished in the next issue of The Journal. today with its head office in Exeter. His passion for gemmology remained with him Midlands Branch throughout his life and his lasting legacy is the On 25 September 1992 at Dr Johnson House, South Western Trust in Exeter. He started the Bull Street, Birmingham, an Open Forum was Trust in 1962 and developed a museum, a gem held, at which questions were answered by a testing laboratory and a teaching centre. In its panel. own premises near the centre of Exeter, the Trust runs the courses of both the Gemmological North West Branch Association and the National Association of On 16 September 1992 at Church House, Goldsmiths. Hanover Street, Liverpool 1, Adrian Klein gave a He is survived by his wife and children and talk on emeralds. those who knew the larger than life personality of Ron will surely miss him. D.G. GEM DIAMOND EXAMINATION 1992 In the 1992 Gem Diamond Examination 39 Elma H. Evans, FGA (D.1988), Spring candidates sat for the Gem Diamond Diploma Valley, California, USA, died recently. examination. Of these 31 (79%) passed, 1 with Kenneth Holmes, FGA (D.1969), Edgware, Distinction. The names of the successful candi died on 31 August 1992. dates are as follows:

James Walter Hudspith, FGA (D.1976), Qualified with Distinction Leatherhead, died recently. Tees, Audrey, Glasgow.

Janet A. Marriott, FGA (D.1988), died Qualified recently. Argyrakou, Joulia, London. Baker, Paul Ronald, Ringmer, Lewes. Father John W. O'Rourke, FGA (D.1973), Barratt, Claire A., Gillingham. Australia, died recently. Fromming, David Erwin, Gerrards Cross. Georgiadou, Elizabeth, London. GIFTS TO THE GAGTL Ghisi, Maria K., Athens, Greece. The Association is most grateful for gifts of Hall, David James, London. gems and gem materials for research and teaching Houseago, James A., Lowestoft. purposes donated by the following: Jordan, Lynn Pamela, Manchester. Mr LJ. Fifield, FGA, of A. Sechaud & Co Ltd., Kejriwal, Bindu, London. London for two specimens of synthetic quartz; King, Margaret A., Scotland. John Kessler for emeralds from various locali Levine, Richard John, Leeds. ties; Lilley, Elaine, London. Marcus McCallum, FGA, for spessartine garnet Lupton, Elaine, Paddock Wood. from Namibia; MacLennan, David Jack, Glasgow. Elizabeth MacGregor, FGA, of Teresopolis, Martin, Julie, Glasgow. Brazil, for crystal specimens and gem gravels; McConnachie, David Charles, Glasgow. Mrs CM. Ou Yang, FGA, for peridot from Ng, Soon Hoh, London. China; Patel, Jagdish Ishverbhai, Wimbledon Village. Professor Chen Zhonghui and Vice Professor Patel, Pankaj, London. Yan Weixuan, FGA, for turquoise from China; Pattison, Rebecca Ann, Meopham. Professor Guoping Zhou and Mr Huang Sheng Scott, Michael A., London. for feldspar (moonstone) and saussurite from Thatcher, Alison, Woking. China. Thomas, Richard, Bridgend. Vannet, Mary A., Dundee. J. Gemm., 1992, 23, 4 243

MEMBERSHIP f93

The new magazine Gem and Jewellery News has been well received by members during 1992. Also many have now taken the opportunity to apply for use of the Coat of Arms or Laboratory logo on their business stationery.

Overseas members benefit from the new arrangements to pay by credit card or sterling draft and will pay less in 1993 than in 1992; also in 1993 their Journals will be sent by airmail. All other membership rates are held at 1992 levels, as set out below:

Subscription Rates 1993

UK Overseas Ordinary Member ^ Fellow y. £45.00 £65.00 Diamond Member J

Laboratory Member £210.00 +VAT - Gold Laboratory Member £525.00 +VAT £525.00

Members, Fellows and Diamond Members receive The Journal of Gemmology and the Gem and Jewellery News quarterly. Fellows may use FGA after their name and Diamond Members the title DGA, and both may also apply for use of the Coat of Arms on their stationery.

Laboratory Members receive The Journal of Gemmology and Gem and Jewellery News quarterly, and may apply for use of the Laboratory logo on their business sta tionery. Gold Laboratory Members may enjoy the benefits of Laboratory Members together with lower fees for diamond reports, assistance with temporary import of stones for testing, and special facilities on pearl and coloured stone reports. 244 J. Gemm., 1992, 23, 4

Walter, Keith David, Peebles. Baiter, Jonathon, London. Young, Gabrielle E.M. Wareham. Barrie, Lindsay, London. Bedwell, Victoria Lynsee, London. EXAMINATIONS IN GEMMOLOGY Bendel, Helle, London. 1992 Bindon, Julie Ann, Taunton, Birrell, Andrew Tierney, Edinburgh. In the 1992 Examination in Gemmology 515 Bradford, Nikki, Hassocks. candidates sat the Preliminary examination, 338 Burrow, Denis, Gravesend. (66%) of whom qualified, 420 candidates sat the Christian, Helen Elizabeth, Bolton. Diploma examination and 191 (45%) qualified, Clayton, Josephine A., London. 16 with Distinction. Cooper, Carolyn, London, England The Tully Medal for the candidate who sub Day, Brynley John, Oldham. mits the best set of answers in the Diploma exam Downing, Lucy N., London. ination which, in the opinion of the Examiners are Emslie, Gail, Harrogate. of sufficiently high standard, was awarded to Mr Fox, Rosemary, London. Michael Tse Kwok Wing from Hong Kong. Gemmell, James, Durham. The Anderson/Bank Prize for the best non- Geoghegan, Noel R., Wellesbourne. trade candidate of the year in the Diploma exam Hardeman, Sonia L., Alton. ination was awarded to Mr Michael Tse Kwok Harper, Jonathan, London. Wing from Hong Kong. Henn, C. John W., Wolverhampton. The Rayner Diploma Prize for the best can Hering, Peter, Cambridge. didate of the year who derives her main income Hopper, Geoffrey C, Harrow. from activities essentially connected with the Hughes, Helen, London. Jewellery trade, was awarded to Miss Anne Bailey Kneebone, Garfield David, Penzance. from Rugby, UK. Koetsier, Anya Kristina, London. The Anderson Medal for the best candidate of Ku, Sarah Joy, London. the year in the Preliminary examination was Larkins, Barry, London. awarded to Miss Sarah Hue-Williams from Leathley, A.B.D.A., York. London, UK. Lodge, Sara Anne-Marie, Birmingham. The Preliminary Trade Prize for the best Lowe, David J., London. candidate under the age of 21 years on 1st June Ludlow, Andrew Philip, London. 1991 who derives his main income from activities McDonald, Suzanne M., Edinburgh. essentially connected with the Jewellery trade was McFarlane, Neil R., Alloa. awarded to Mr Alexander Hammond from Sandy, McQueen, Janet E., Lurgan. UK. Mildenhall, Caroline, Brighton. Nandha, Manoj, Nottingham. DIPLOMA Ng, Soon Hoh, London. Qualified with Distinction O'Brien, Gillian M., North Berwick. Bailey, Anne Margaret, Rugby. Oldfield, Gemma, London. Beckett, Shona-Maria Ferguson, London. Panlilio, Regina S., London. Boote, Caroline Marguerite Elizabeth, London. Patel, Jagdish Ishverbhai, Wimbledon Village. Cheung Chi Ho, Hong Kong. Prior, Louise Charlotte, London. Dharmaratne, Pannipitiye Gamaathi Ralalage, Quinton, Sarah, Oxford. Colombo, Sri Lanka. Read, Julian, Goole. Drowley, Brigitte, London. Reffell, Keith C, Rainham. Goddard, Valerie J., Alfold. Sancroft-Baker, Raymond, London. Grossman, Julie Frances, London. Spanbok, Gary, London. Kesheng, Chen, Guilin, P.R. China. Stewart, Robert Miller, Bishops Waltham. Lang, Bernard, Basel, Switzerland. Strachan, Elizabeth, London. Magara, Yoshiaki, Fukui Pref., Japan. Taylor, David John, Isle of Wight. Marsh, Leona Claire, Harare, Zimbabwe. Travis, Peter John Booth Charles, London. Patel, Rekha Mahesh, Nairobi, Kenya. Van Papen, Lorraine F.M., Guildford. Tse Kwok Wing, Michael, Hong Kong. Vannet, Mary A., Dundee. Tucker, William J., Douglas, Isle of Man. Vaughan, Michael, Chester. Tun, Maung Win Myint, Bangkok, Thailand. Wakefield, Melanie, Horsham. Wootton, Angela B., Sheffield. Qualified - UK Wu, Mei Wan, Harlow. J. Gemm., 1992, 23, 4 245

Gem Diamond Diploma

The Gemmological Association and Gem Testing Laboratory of Great Britain takes pride in its international reputation as a learned society dedicated to the promotion of gemmological education and the spread of gemmological knowledge. The Association's Diploma in Gem Diamonds is an internationally recognised qualification which will enable you to identify and assess diamonds of all kinds. It is a passport to a soundly based career in the gem diamond industry (whether it be designing, manufacturing, mar keting, wholesaling or retailing). How can you obtain the Gem Diamond Diploma? By studying the Association's Gem Diamond correspondence course. Comprehensive and well illustrated, you learn at your own pace, in your own home, fully supported by your own expert tutor. On successful completion of the examinations, candidates may apply for Diamond Membership of the Association and, upon election, the right to the title DGA. For more information and a prospectus contact

Gemmological Association and Gem Testing Laboratory of Great Britain 27 GREVILLE STREET (SAFFRON HILL ENTRANCE) LONDON, EC 1N 8SU A • TELPHONE: 071 404 3334 FAX: 071 404 8843 •

Deraniyagala, Isanth R., Colombo, Sri Lanka. Qualified - Overseas Dharmaratne, Rosemary Olivia, Colombo, Sri Alwicher, Terrence, Nijmegen, The Lanka. Netherlands. Eguchi, Yukio, Osaka, Japan. Anantwatanapong, Angkana, Bangkok, Engel, Nora, Geneva, Switzerland. Thailand. Falco Rovira, Joaquim, Llanca, Spain. Araki, Kazuo, Hyogo Pref., Japan. Friedland, Melissa R., Omaha, Nebr., USA Arnau Graus, Concepcion, Barcelona, Spain. Galopim De Carvalho, Rui, Portugal. Asanis Nikolaos, Athens, Greece. Groeneveld, Pauline, Giessenburg, The Bakker, F.C.S., Zwaagdijk, The Netherlands. Netherlands. Ball, Pamela, Hong Kong. Haberli, Sabine Maya, Bottmingen, Switzerland. Bierlein, Chari L., Paris, Tex., USA Harjula, Katri, Helsinki, Finland. Blanch Papaceit, Gloria, Barcelona, Spain. Harman, Bronwen, Brisbane, Australia. Chan Siu Chan, Lily, Canada. Hawrelko, Donna P., West Vancouver, Canada. Cheang Chong Nun, Macau, China. Ho Po Mi, Avis, Hong Kong. Cheng Chi Chung, Hong Kong. Hoso, Sadayuki, Osaka, Japan. Cheng Sau Chun, Hemans, Hong Kong. Hui Chak Lun, Hong Kong. Cheung, Liann, Mei Ping, Hong Kong. Hwang, Mi Hee, Daejon, Korea. Cho, Hang Sun, Daejon, Korea. Jayasekera, M.C. de S., Negombo, Sri Lanka. Chow, Kenickie Tze Joak, Hong Kong. Jewitt, Laura Kathleen, Vancouver, Canada. Chow Chun Hung, William, Hong Kong. Kang, Hyun Sook, Daejon, Korea. Chow Shui Wah, Hong Kong, Kariya, Tomoko, Tokyo, Japan. de Gruyter, Barbara, Houwaert, Belgium, Karkkainen, Niilo, Espoo, Finland. de Jongh, Laurentia Melissa, Den Haag, The Karlsson, Andreas, Lannavaara, Sweden. Netherlands. Khudhairy-Gaylani, Bann, Toronto, Canada. De La Torre Lopez, Luisa, Tarragona, Spain, Kim, Gum Jo, Pusan, Korea. de Ruiter, J.E., Waddinxveen, The Netherlands, Kim, Hei Jong, Seoul, Korea. de Wit, Lambertus, Den Haag, The Netherlands. Kim, Jong Pil, Seoul, Korea. 246 J. Gemm, 1992, 23, 4

Kim, Sang-Ki, Seoul, Korea. Weissenborn, Maria, Den-Bosch, The Klumpes, Eric, Veere, The Netherlands. Netherlands. Ku Kai Leung, Hong Kong. Wijne, Lieke, Schoonhoven, The Netherlands. Kuwahara, Rie, Hong Kong. Winkelmolen, Karin, Beesel, The Netherlands. Kwong Yi Hang, Agnes, Hong Kong. Wong, Queenie, Hong Kong. Lai Sai Mui, Hong Kong. Wong Miu Wan, Mueller, Hong Kong. Lau, Grace Tin-Kwan, Richmond, Canada. Yabin, Zhang, Harbin, P.R. China. Lau, Ying Chi, Hong Kong. Yamagami, Mayumi, Tokyo, Japan. Lau Sau-Kuen Heddy, Hong Kong. Yamamoto, Atsuko, Hyogo Pref., Japan. Lau Yuen Mee, Hong Kong. Yu, Frankie, Sum-Pui, Hong Kong. Lee, Du Hee, Seoul, Korea. Yu Yim Tong, Hong Kong. Lee, Hyeon Jin, Inchon, Korea. Yuen Chai Hung, Teresa, Hong Kong. Lee Siu Yin, Ann, Hong Kong. Yumoto, Atsuko, Osaka, Japan. Leung Chee Wing, Hong Kong. Yung Tak Yi, Hong Kong. Leung Lai Ping, Florence, Hong Kong. Zaveri, Pragnesh H., Bombay, India. Li Chi Man, Hong Kong. Zhao, Liu, Harbin, P.R. China. Lum Yin Kew, Samantha, Singapore. Zinzuvadia, Jaydeep Amritlal, Bombay, India. Matsumoto, Naoko, Chicago, 111., USA McCrary Weinberg, Dianna, Madrid, Spain. PRELIMINARY Mollari, Seppo, Lannavaara, Sweden. Nakamura, Haruji, Kyoto, Japan. Qualified - UK Ng Hung Lai, Floria, Hong Kong. Bastians, Anthony, London. Ng Kwok Yin, Hong Kong. Bawden, Karen Alison, Weston-Super-Mare. Nishimura, Tadahiro, Osaka, Japan. Beckett, Shona-Maria Ferguson, London. Ohira, Shino, Japan. Bertorelli, Andrea Elsbeth Louisa, London. Park, Kyung Ok, Seoul, Korea. Bladbjerg, Tine, Rochester. Pawlyna, Andrea G., Hong Kong. Boote, Caroline Marguerite Elizabeth, London. Peh, Angeline, Hong Kong. Boulding, Philip, London. Quek Cho Siang, Jessie, Hong Kong. Boyd, Derek Stephen, Didsbury. Ramboarison, Anita, Hong Kong. Brown, Elizabeth, Lindford. Ravona, Haim, Hadera, Israel. Campbell Pedersen, Maggie, Chiswick. Rubio Barris, Ignasi, Olot, Spain. Carson, Michael Joseph, Boston. Safar, Ali Mohd, Bahrain. Chambers, Jenny Lisa, Warwickshire. See Yat Sun, Hong Kong. Clay, Gretchen Fleur, Boston. Serra Molla, Clara Ma, Valencia, Spain. Close, Helen Jane, Selby. Sharma, Kul Bhushan, Lusaka, Zambia. Cook, Bridget Rosemary Tomlin, Brighton. Siew Lai Ngoh, Georgette Williams nee, Kuala Cook, Stewart, Maidstone. Lumpur, Malaysia. Cooper, Simon Paul, Hadfield via Hyde. Siu Wai-Chung, Norman, Hong Kong. D'Arcy-Evans, Julie Anne, Little Chalfont. Slui, C, Krimpen A/D Ijsse, The Netherlands. Dale, Sharon Jean, Sutton. So Ying Yin, Hong Kong. Daniels, Razia, Chester. Sohn, Jeong Sun, Seoul, Korea. Davidson, Clare Jane, Newcastle-upon-Tyne. Takarada, Michiko, Tokyo, Japan. Day, James, Royal Tunbridge Wells. Tanaka, Mariko, Hyogo Pref., Japan. de Villiers, Patricia Aileen, London. Te Velde, Maja C, Langerak, The Netherlands. Dinnis, Simon John, Burton on Trent. Thorbjornsen, Bjorn Tore, Bergen, Norway. Donkin, Jeffrey John, Surbiton. Torregrosa Guirao, Inocencia, Guardamar Del Drowley, Brigitte, London. Segura, Spain. Earby-McFarlane, Iain Scott, Chesham. Trathen, John E., Stoney Creek, Canada. Fielding, Catherine, Avon. Tse On Na, Anna, Hong Kong. Forrest, Jacqueline Alison, Bishopsbriggs. Tsui, Vincent Kam Luen, Hong Kong. Fox, Nigel Timothy, Leeds. Van Hillo, G.J., Almere, The Netherlands. Fox, Rosemary, London. Van Keulen, Simone, Amsterdam, The Godfrey, Irmfried Adelheid, Glasgow. Netherlands. Goliama, Teddy Francis, London. Van Lamoen, H.T., Rosmalen, The Graham, Jennifer J., Glasgow. Netherlands, Green, Kimberly Helen, Melton Mowbray. van Soest, Ingrid, Hoofddorp, The Netherlands. Grossman, Julie Frances, London. J. Gemm., 1992, 23, 4 247

Gunnigan, Jane Carmel, Dartford. Sokhal, Jaswender, Staffordshire. Haddock, Brendan, Edinburgh. Sondack, Julia Ruth. Hammond, Alexander Malcolm, Sandy. Spicer, Alison Joy, Chester. Hanna, Margaret Ann, London. Stapenell, Julia Carol, Birmingham. Hardeman, Sonia L., Alton. Starkey, Julia Ruth, Burnham. Hardman, Joyce, Preston. Taylor, Christopher, Staines. Harper, Jonathan, London. Terras, Fay, Newton Abbot. Hawes, Rona Margaret, Redhill. Thompson, Graham, Grimsby. Hue Williams, Sarah Georgina, London. Thompson, Jane Margaret Devereux, Melton. Humphrey, Mary Sylvia, London. Thomson, Joanne Lesley, Peebles. Jarek, Raymond Vincent, London. Turner, Stephen Jeffrey, Glasgow. Johnson, Philip, Pensby. Wadia, Aneeta, London. Joly, Sandra Elizabeth, Rochester. Wakefield, Melanie, Horsham. Jones, Amanda Melanie, Stourbridge. Walker, Averil Lorraine, London. Jones, Jason, Hull. Wiley, Christopher, Banstead. Joseph, Denise Taouk, London. Wilkinson, Cleotilde Socorro, London. Jozwiak, Samantha Jane, London. Windwick, William, Moray. Kassam, Sultan Mohammed, London. Withers, Justine Marguerite, Redhill. Kennedy, Lisa, Cambridge. Yasin, Abdel Nasser, St. Albans. Kimber, Sarah, Aldershot. Knowles, Louise Carole, Chatburn. Qualified - Overseas Kumar, Visuvalingam Krishna, Morden. Adamali, Kunj, Nairobi, Kenya. Lakhtaria, Yashwin, London. Alaniva, Orvokki, Kannonkoski, Finland. Linde, Pamela A., Crewe. Alteen, Michael Louis, Sydney, Nova Scotia, Livingstone, Sheena, Dundee. Canada. Lu, Jei-Chih, London. Anandarajah, Dr Kandiah, Toronto, Canada. Lysons, Jon David Eric, Sunderland. Anantwatanapong, Angkana, Bangkok, MacKenzie, Hilary Morag, Greenock. Thailand. Martin, Jennifer Frances, Hanham. Antzoulakos, George, Athens, Greece. Massow, Kenneth John, Rochford. Astrom, Mikko Tapani, Helsinki, Finland. McCarthy, Emily, London. Bandara, Rupasingha Mudali Navaratna, Sri McCormack, Susan, Aintree. Lanka. McLean, Grace Lesley, Dundee. Bartfai, Tunde, Schoonhoven, The Netherlands. McNally, Angela, Edinburgh. Batis, David, Athens, Greece. Misk, Mirna, London. Beili, Zhang, Hubei, China. Molyneux, Peter Jeremy, York. Berruex, Cedric, La Chaux-de-Fonds, Morris, Patricia Elizabeth Jane, Crewe. Switzerland. Nicholson, Charles James Rupert, London. Bevers-Reinders, L.M., Rotterdam, The Nicoll, Douglas John, East Lothian. Netherlands. O'Connell, Helen Maree, Kingston. Blorstad Pedersen, Berit, Oslo, Norway. Orner, Miri, London. Bombeke, Sonja, Bergambacht, The Ozlati, Kathryn, Northampton. Netherlands. Panlilio, Regina S., London. Boyens, Christine Patricia, Hong Kong. Phillips, Lisa Wendy, South Harrow. Brom, Reinier, Wassenaan, The Netherlands. Pout, Margaret Elizabeth, Guildford. Buxani, Naina Mahesh, Hong Kong. Raphael, Menachem, Leeds. Cham Wai Hing, Hong Kong. Reilly, Clare, Sutton Coldfield. Chan, Shuk Yu, Hong Kong. Ritchie, Susan Jennifer, Edinburgh. Chan Ka Fung, Louisa, Hong Kong. Roberts, Keri Jane, Radstock. Chan Mei Wah, Carol, Hong Kong. Rodrigues, Lourdes, London. Chan W.K., Sunny, Hong Kong. Saccoh, Boulaye Doughan, London. Chansrichawla, Luxmi, Bangkok, Thailand. Sagir, Yoram, Hendon. Chedta-Thaiyawong, Kanitha, Bangkok, Sandum, Mark Antony, Ramsgate. Thailand. Saunders, Frank, Spennymoor. Cheng, Chi Chung, Hong Kong. Saxton, Carol Anne Lesley, Alton. Cheng, Sau Chun, Hemans, Hong Kong. Slater, Richard Mark, Bath. Cheung, Chi Keung, Hong Kong. Smith, Penelope Ann, Cirencester. Cheung, Shuk Mei, Hong Kong. 248 J. Gemm., 1992, 23, 4

Cho, Jin-Ho, Seoul, Korea. Colombo, Sri Lanka. Choi, Eun-Young, Busan, Korea. Kang, So Yean, Daejon, Korea. Choi, Gyeng Hye, Seoul, Korea. Karlsson, Andreas, Lannavaara, Sweden. Chokhani, Durga Vishwanath, Bombay, India. Kauppinen, Sirpa, Helsinki, Finland. Chow Wing Yuen, Hong Kong. Kelloniemi, Katri Irene, Helsinki, Finland. Choy, Wai Ping, Daisy, Hong Kong. Kervezee, Robert Louis, Berkel-Rodenrijs, The Chui, Wai Chun, William, Hong Kong. Netherlands. Chung, Young Hee, Seoul, Korea. Kiji, Michio, Osaka, Japan. Coughlin, Donald George, Colombo, Sri Lanka. Kim, Gye Hong, Daejon, Korea. de Groot-van der Ham, L., Utrecht, The Kim, Kyoung-Soo, Taegu, Korea. Netherlands, Kim, Kyung Sook, Pusan, Korea. de Gruyter, Barbara, Houwaert, Belgium, Kim, Meong Hee, Kyunggi-do, Korea. de Wit, Lambertus, Den Haag, The Netherlands. Kim, Mi Jung, Pusan, Korea. Del Barrio Lazaro, Pedro A., Valencia, Spain. Kim, Mi-Ae, Busan, Korea. Dimitropoulos, Kostas, Athens, Greece. Kim, Taek Joong, Seoul, Korea. Duigan, Ingeborg, Hong Kong. Kim, Young Ju, Daejon, Korea. Durand, Douglas D., Toronto, Canada. Kinda, Yumiko, Osaka, Japan. Eames, Lucy, Nairobi, Kenya. Ko, Kyung Hai, Seoul, Korea. Eetgerink-Hamel, Martien, Abcoude, The Kostovetsky, Evgeny, Toronto, Canada. Netherlands. Krommenhoek, Celine Coaine, Amsterdam, Ettila, Annamari, Helsinki, Finland. The Netherlands. Farnsworth, Colleen, Hong Kong. Ku Kai Leung, Hong Kong. Farrimond, Thomas, Cambridge, New Zealand. Kuosmanen, Jussi Tapio, Vantaa, Finland. Fok, David, Hong Kong. Kuwahara, Rie, Hong Kong. Fowle, Michael John, Nairobi, Kenya. Kwan Wai Shun, Hong Kong. Fung Lai Yi, Hong Kong. Kwong Yi Hang, Agnes, Hong Kong. Garcia Garcia, Amelia, Valencia, Spain. Lam Tai Sing, Denys, Hong Kong. Garcia Moreno, Pedro, Valencia, Spain. Lanko, Jantine, Amsterdam, The Netherlands. Gemin Cherkaoui, Nadine, Indonesia. Lau, Chung Long, Hong Kong. Goyal, Hariprasad, Jaipur, Rajasthan, India. Lau, Grace Tin-Kwan, Richmond, Canada. Granlund-Jarvinen, Ingalill Maria, Kasnas, Lau, Paul, Hong Kong. Finland. Lau, Teresa Sauwan, Hong Kong. Griffiths, Mary, Canada. Lau Kit Yee, Kitty, Hong Kong. Grimster, Melanie, Toronto, Canada. Lau Yuen Mee, Hong Kong. Halme, Sini Pirjetta, Lahti, Finland. Lee, Eun-Ju, Busan, Korea. Hamza, Mohamed Hassan Mohamed, Kandy, Lee, Gang-Ho, Daejon, Korea. Sri Lanka. Lee, Heui-Yeol, Chung Cheong nam-do, Korea. Hawrelko, Donna P., West Vancouver, Canada. Lee, Hye-Jeong, Seoul, Korea. Higo, Kenji, Osaka, Japan. Lee, Jin Ah, Daejon, Korea. Hong, Suk, Seoul, Korea. Lee, Jum Sook, Pusan, Korea. Hui, King Chuen, Hong Kong. Lee, Mi Kyung, Seoul, Korea. Hui Wing Chiu, Ernest, Hong Kong. Lee, Moung-Hee, Seoul, Korea. Hung, Suet Fung, Josephine, Hong Kong. Lee, Nam Joo, Seoul, Korea. Hung Ching Ting, Hong Kong. Lee, Sang Yen, Daejon, Korea. Im, Sung-Sik, Seoul, Korea. Lee, Tonny Song, Taipei, Taiwan, China. Jang, Young-Rim, Seoul, Korea. Lee Siu Yin, Ann, Hong Kong. Jayarajah, Aravandy Pillai, Colombo, Sir Lanka. Leung, Irene Yuk Ping, Hong Kong. Jegge, Erich Peter, Zurich, Switzerland. Lie, Torgunn, Oslo, Norway. Jeong, Hyun Hee, Daejon, Korea. Lo, Teresa K.Y., Toronto, Canada. Jeong, Seok-Ran, Busan, Korea. Lo Shuk Lan, Hong Kong. Jewitt, Laura Kathleen, Vancouver, Canada. Lum Yin Kew, Samantha, Singapore. Jin, Soo Eun, Seoul, Korea. Lundsrud, Berit, Sandvika, Norway. Jingzhi, Li, Hubei, China. Ma Siu Lam, Hong Kong. Joo, Woong-Hyun, Seoul, Korea. Mathiopoulou, Regina Moser, Athens, Greece. Ju, Young Ok, Pusan, Korea. Mathon, Andries Peturs Theresia, Ammerstol, Jun, Huang, Hubei, China. The Netherlands. Kandamulla, Anuruddhika Priyadarshani, Meerdink, Handrika Catharina, Aalten, The J. Gemm., 1992, 23, 4 249

Netherlands. Taeed, Amelia, Apeldoorn, The Netherlands. Metzidie, Vassiliki, Athens, Greece. Tai Yuet Wan, Hong Kong. Michaelides, Maria, Athens, Greece. Takahashi, Masumi, Hong Kong. Mitchell, Gisela Charlotte, Hong Kong. Takarada, Michiko, Tokyo, Japan. Miyamoto, Kiyomi, Osaka, Japan. Tanabe, Hiroko, Toronto, Canada. Mollari, Seppo, Lannavaara, Sweden. Tanaka, Kazuhide, Osaka, Japan. Mommers, Use, Oss, The Netherlands. Tarkkanen, Mika, Helsinki, Finland. Nadarajah, Veeragathy, Colombo, Sri Lanka. Toft, Peter Christian, Copenhagen, Denmark. Nakagawa, Yuko, Toronto, Canada. Tonn, Heleen, Rotterdam, The Netherlands. Nam, Song-Ja, Daejon, Korea. Trifaud, Guillaume Nicolas, Bangkok, Thailand. Nayer, Kuldeep Singh, Nairobi, Kenya. Tse Siu Ling, Hong Kong. Nayer, Ranjit Kaur, Nairobi, Kenya. Tsui, Vincent Kam Luen, Hong Kong. Ng Sau Lan, Annie, Hong Kong. Tun, Maung Win Myint, Bangkok, Thailand. Ng, Siu-Ling Brenda, Hong Kong. Tuovinen, Annikki, Aanekoski, Finland. Niblock, Simon Guy, Whakatane, New Zealand. Tzerbou, Helen, Athens, Greece. Nissila, Ari Jukka, Oulu, Finland. Vader, Leonoor, Den Haag, The Netherlands. Odawara, Hiroko, Osaka, Japan. Valk, Bert-jan, Schoonhoven, The Netherlands. Oele, Kees, Schoonhoven, The Netherlands. van Gils, Heleen, Overveen, The Netherlands. Oey M.D., W.S., Z.O. Beemster, The van Vliet, Wim, Haastrecht, The Netherlands. Netherlands. Vinkka, Susanna, Hameenlinna, Finland. Oh, Sook-Hoe, Busan, Korea, von Redlich, Anna Britta Andrea, Den Haag, Orrite Jimenez, Paquita, Valencia, Spain. The Netherlands. Palme, Martina, Stockholm, Sweden. Vreeling, Jacqueline, Schoonhoven, The Park, Han-Jin, Daejon, Korea. Netherlands. Pattni, Mamta C.G., Nairobi, Kenya. Wilcox, Kimberly Anne, New York, USA. Perera, C.S.A., Colombo, Sri Lanka. Wong, Queenie, Hong Kong. Pervolaraki, Anna, Athens, Greece. Wong Chi Wing, Hong Kong. Puhakainen, Petter Juhana, Helsinki, Finland. Wong Chun Kwong, Hong Kong. Punchihewa, Yohan Laksiri, Colombo, Sri Lanka. Wong Lai Fun, Alice, Hong Kong. Ramboarison, Anita, Hong Kong. Wong Nim Chi, Phyllis, Hong Kong. Ranasinghe, Ranasinghe Liyanage D.S., Sri Xianfeng, Zhang, Hubei, China. Lanka. Yamasuga, Ryoji, Hyogo Pref., Japan. Romero Paya, Oscar, Valencia, Spain. Yan, Gao, Hubei, China. Roos, Stephan, Bienne, Switzerland. Yan, Kam Tim, Hong Kong. Roubin, Ernest, Athens, Greece. Yang, Hye Keong, Pusan, Korea. Rouleau, Jocelyne, Quebec, Canada. Yip Man Loong, Hong Kong. Ruts, Willem Gerardus, Den Helder, The Yun, Sun-Whoa, Seoul, Korea. Netherlands. Zaveri, Pragnesh H., Bombay, India. Sagiv, Lihi, Hong Kong. Zhang Ziang Dong, Hong Kong. Schembri, Joseph Michael, Toronto, Canada. Zhi, Zhan, Hubei, China. Schuivens, Chantalle, Geleen, The Netherlands. Zinzuvadia, Jaydeep Amritlal, Bombay, India. Sharma, Rashmi, Lusaka, Zambia. Shouguo, Guo, Hubei, China. MEETINGS OF THE COUNCIL OF Siew Lai Ngoh, Georgette Williams nee, Kuala MANAGEMENT Lumpur, Malaysia. At a meeting of the Council of Management Sillanpaa, Heli Marianne, Kaustinen, Finland. held on 20 May 1992 at Chapel House, Hatton Silvonen, Nanna Kaarina, Helsinki, Finland. Place, London EC1N 8RX, the business trans Sivakumar, Periyasamy, Colombo, Sri Lanka. acted included the election of the following: Song, Kyong-Mi, Seoul, Korea. Sorensen, Torfinn, Lannavaara, Sweden. Fellowship Stahl, Elone, Lannavaara, Sweden. Flint, Sara E., Leeds. D.1991 Stratmann, Rudolf Walter, Den Haag, The Netherlands. Ordinary Membership Suh, Dae-Yeol, Seoul, Korea. Almudallal, Mohammad, Abu Dhabi, UAE. Suhaib, M.H.M., Colombo, Sri Lanka. Bosey, Pauline M., Eton. Summanen, Sari Irene, Helsinki, Finland. Dansereau, Eva M., Anola, Manitoba, Canada. Syren, Riitta Anneli, Tampere, Finland. Flicker, Rowena, Dulwich, S Australia. 250 J. Gemm., 1992, 23, 4

Jones, Michael, Bournemouth. Hering, Peter, Cambridge. 1992 (FGA) Mifsud, Ivan, Sliema, Malta. Houseago, James A., Lowestoft. 1992 (FGA, Nilaratanakul, Chiraphong, Bangkok, Thailand. DGA) Pash, A., London. Jordan, Lynn Pamela, Manchester. 1992 (FGA, DGA) Laboratory Membership Kejriwal, Bindu, London. 1992 (FGA, DGA) Nash Broad Wesson, 42 Upper Berkeley Street, King, Margaret, Scotland. 1992 (FGA, DGA) London W1H 8AB. Kneebone, Garfield David, Penzance. 1992 (FGA) At a meeting of the Council of Management Koundouros, Radka Lalovaska, Athens, Greece. held on 24 June 1992 at Chapel House, Hatton 1992 (FGA, DGA) Place, London EC1N 8RX, the business trans Larkins, Barry, London. 1992 (FGA) acted included the election of the following: Lilley, Elaine, London. 1992 (FGA, DGA) McConnachie, David Charles, Glasgow. 1992 Ordinary Membership (FGA, DGA) Quinton, Sarah E., Byfleld. 1992 McFarlane, Neil R., Alloa. 1992 (FGA) Read, Julian, Goole. 1992 Mildenhall, Caroline, Brighton. 1992 (FGA) Sancroft-Baker, Raymond, London. 1992 Ng, Soon Hoh, London. 1992 (FGA, DGA) O'Brien, Gillian M., North Berwick. 1992 (FGA) Ordinary Membership Oldfield, Gemma, London. 1992 (FGA) Ayles, Catherine, Edinburgh. Patel, Jagdish, Wimbledon Village. 1992 (DGA, Branch, John Robertson, London. FGA) Goh, Kok Chin Eric, Kuala Lumpur, Malaysia. Patel, Pankaj, London. 1992 (FGA, DGA) Hanna, David Mark, Inverness. Prior, Louise Charlotte, London. 1992 (FGA) Jarek, Raymond Vincent, London. Sergoulopoulos, Alexandros, Athens. 1992 Jindrich, Patricia Lynn, Trevor, USA. (FGA, DGA) McCormack, Susan, Liverpool. Stather, Memory, Hong Kong. 1992 (FGA, Ronnie, Brenda, Leith, Edinburgh. DGA) Saxton, Carol Anne Lesley, Alton. Stewart, Robert Miller, Bishops Waltham. 1992 (FGA) Transfers to Fellowship and Diamond Taylor, David John, Isle of Wight. 1992 (FGA) Membership Tees, Audrey, Glasgow, 1992 (FGA, DGA) Barratt, Claire, Gillingham. 1992 (FGA, DGA) Travis, Peter J.B.C., London. 1992 (FGA) Beckett, Shona-Maria F., London. 1992 (FGA) Tucker, William J., Isle of Man. 1992 (FGA) Bendel, Helle, London. 1992 (FGA) Van Papen, Lorraine, Guildford. 1992 (FGA) Blanch, Gloria, Barcelona, Spain. 1992 (FGA, Vaughan, Michael, Chester. 1992 (FGA) DGA) Wakefield, Melanie, Horsham. 1992 (FGA) Boote, Caroline Margaret, London. 1992 (FGA) Walter, Keith David, Peebles. 1992 (FGA, Bradford, Nikki, Hassocks. 1992 (FGA) DGA) Burrow, Denis, Gravesend. 1992 (FGA) Wu, Mei Wan, Harlow. 1992 (FGA, DGA) Day, Brynley John, Oldham. 1992 (FGA) Young, Gabrielle, Wareham. 1992 (FGA, DGA) Drowley, Brigitte, London. 1992 (FGA) Fox, Rosemary, London. 1992 (FGA) Gold Laboratory Membership Fromming, David Erwin, Gerrards Cross. 1992 William Goldberg Diamond Corp. of 589 Fifth (FGA, DGA) Avenue, NY, USA. Galopim de Carvalho, Rui, Portugal. 1992 (FGA) At a meeting of the Council of Management Gemmel, James, Durham. 1992 (FGA) held on 23 September 1992 at 27 Greville Street, Georgiadou, Elizabeth, London. 1992 (FGA, London EC1N 8SU, the business transacted DGA) included the election of the following: Ghisi, Maria, Athens, Greece. 1992 (FGA, DGA) Fellowship and Diamond Membership Goddard, Valerie J., Alfold, Cranleigh. 1992 Osborne, Sean J., Pimlico, London. 1989/1990. (FGA) Vannet, Mary A., Dundee. 1992 Grossman, Julie Frances, London. 1992 (FGA) Webster, David E., Glasgow. 1988/1989 Hardeman, Sonia L., Alton. 1992 (FGA) Harper, Jonathon, London. 1992 (FGA) Fellowship J. Gemm., 1992, 23, 4 251

Bae, Sang-Duk, Seoul, Korea. 1991 Fellowship Bindon, Julie A., Taunton. 1992 Bailey, Anne Margaret, Rugby. 1992 Christian, Helen E., Bolton. 1992 Carter, Angela Beverley, Sheffield. 1992 Coffin, Martin R., Carlisle. 1984 Fernandes, Shyamala, Jaipur. Hopper, Geoffrey C, North Harrow. 1992 Foo, Pui Man, Hong Kong. 1991 Hughes, Helen Sylvia, London. 1992 Geoghegan, Noel Richard, Wellesbourne. 1992 Ku, Kai Leung, Hong Kong. 1992 Henn, Christopher, J.W., Shropshire. 1992 Kwong Yi Hang, Agnes, Hong Kong. 1992 Leathley, Adam B.D.A., Shiptonthorpe. 1992 Lau, Grace Tin-Kwan, Richmond, Canada. Ludlow, Andrew Philip, Buckhurst Hill. 1992 1992 McQueen, Janet E., Lurgan, Co. Armagh. 1992 Lodge, Sara, Birmingham. 1992 Lowe, David J., Blackheath. 1992 Jehu, A.G., Virginia Water. McDonald, Suzanne M., Edinburgh. 1992 Jones, Lloyd E., Gold Coast, Australia. Nandha, Manoj, Nottingham. 1992 Kiernan, Janeien E., Cheddar Gorge. Ng, Hung Lai, Hong Kong. 1992 Porter, Mark A., Hartley Wintney. Pawlyna, Andrea G., Hong Kong, 1992 Sandy, Paul R., Bournemouth. Ramboarison, Anita, Hong Kong. 1992 Smith, Richard S.N., Exmouth. Reffell, Keith C, Gillingham. 1992 Van't Hooft, Jacobus A., Uught, The Thompson, Hugh D.R., Quebec, Canada. 1979 Netherlands. Webb, Malcolm H., Chatham. 1954

Gold Laboratory Membership Ordinary Membership Arthur Langerman, 62 Pelikaanstraat, 2018 Brown, Elizabeth A., Lindford. Antwerp, Belgium. David, Ian, London. Laboratory Membership Einstein, Tamar S., Haifa, Israel. Andrew Diamonds Ltd, 11 Hatton Garden, Farrimond, Thomas, Cambridge, New Zealand. London EC1N 8HA. Green, Kimberley H., Melton Mowbray. Ruppenthal (UK) Ltd, 3rd Floor, 20-24 Kirby Griffiths, Barry, Stanstead. Street, London EC1N 8TS. Harrington, Shaun T., Ross-on-Wye. Kervezee, Robert L., Berkel Rodenrgs, The At a meeting of the Council of Management Netherlands. held on 22 July 1992 at Chapel House, Hatton Masson, Kenneth J., Rochford. Place, London EC IN 8RX, the business trans Maule, Natalie A., Alresford. acted included the election of the following: Palme, Martina, Stockholm, Sweden. Plomp, Jean V., Rotterdam, The Netherlands. Fellowship Scott, Damian T., London. Tan, Ay Lin, Singapore. 1991 Slater, Richard M., Bath. Somprachayanan, Wanpen, Bangkok, Thailand. Ordinary Membership Stratmann, Rudolf W., Den Haag, The Benjamin, Ronald, London. Netherlands. Lai, Tai, Taiwan. Wanputh, Dheeraporn, Bangkok, Thailand. Passmore, Elizabeth Louise, Manchester. Zagari, Paola, Italy. Transfers from Ordinary Membership to Fellowship Laboratory Membership Araki, Kazuo, Hyogo Pref, Japan. 1992 George Diamonds, L.D.B., 100 Hatton Garden, Bedwell, Victoria L., London. 1992 London EC1. Eguchi, Yukio, Osaka, Japan. 1992 Lawrence Henry, 67 Clerkenwell Road, London Hoso, Sadayuki, Osaka, Japan. 1992 EC1R5BH. Kariya, Tomoko, Tokyo, Japan. 1992 Kim, Hei Jong, Seoul, Korea. 1992 At a meeting of the Council of Management Kim, Sang-Ki, Seoul, Korea. 1992 held on 19 August 1992 at 27 Greville Street, Ku, Sarah J., London. 1992 London EC IN 8SU, the business transacted Magara, Yoshiaki, Fukui Pref, Japan. 1992 included the election of the following: Matsumoto, Naoko, Chicago, 111., USA. 1992 Nakamura, Haruki, Kyoto, Japan. 1992 Diamond Membership Nishimura, Tadahiro, Osaka, Japan. 1992 Scott, Michael A., Harpenden. 1992 Peh, Angeline, Hong Kong. 1992 Thomas, Richard, Bridgend. 1992 Ravona, Haim, Hadera, Israel. 1992 252522 JJ.. Gemm.Gemm.,, 1992,1992,23, 23, 4

SharmaSharma,, KuKull BhushanBhushan,, LusakaLusaka,, Zambia.. 19919922 TanakaTanaka,, MankoMariko,, HyogHyogoo PrefPref,, JapanJapan.. 19921992 ThorbjornsenThorbjornsen,, BjorBjornn T.T .,, BergenBergen,, NorwayNorway.. 19921992 TrathenTrathen,, JohJohnn E.E.,, StoneStoneyy CreekCreek,, Ont.Ont.,, Canada.Canada. 19919922 YamagamiYamagami,, MayumiMayumi,, TokyoTokyo,, JapanJapan.. 19921992 YamamotoYamamoto,, AtsukoAtsuko,, HyogHyogoo PrefPref,, JapanJapan.. 19921992 YumotoYumoto,, AtsukoAtsuko,, OsakaOsaka,, JapanJapan.. 19921992

CORRIGENDCORRIGENDAA AUSTRALIA OOnn pp.133. 133 aboveabove,, seconsecondd columcolumnn ththee FigurFiguree 77 illustratioillustrationn wawass omittedomitted;; a reprinreprintt ooff ththee pagpagee comcom B e st CololAl" pletpletee witwithh FigurFiguree 7 iiss includeincludedd witwithh thithiss issuissuee ssoo Best QlAolity thathatt iitt mamayy bbee inserteinsertedd iinn ththee correccorrectt placplacee OOnn pp.151. 151 aboveabove,, FigurFiguree 11,, linlinee 11,, afteafterr 'system''system' adaddd 'sho'showw prisprismm (A)(A),, pinacoipinacoidd (c)(c),, bipyramibipyramidd (w(w,, G • zz,, nn)) anandd rhombohedrarhombohedrall (r(r)) faces'faces';; FigurFiguree 1,1, linlinee 44,, foforr ''cc anandd dd'' reareadd 'part'partss c anandd dd'' OOnn pp.152. 152 aboveabove,, first columcolumnn linlinee 55,, foforr 'Figure'Figure lbIb'' reareadd 'Figure'Figuress lIec anandd Id'Id';; linlinee 2121,, foforr 'Vichi'Vichitt et ala11979' 1979' reareadd 'Vichi'Vichitt et al,ai, 19781978'' OOnn pp.153pp.153,, 154,154, 155155,, 151577 anandd 158158,, becausbecausee ooff a printinprintingg errorerror illustrationsillustrations areare shownshown asas negatives;negatives; replacemenreplacementt pagepagess araree includeincludedd witwithh thithiss issueissue.. Champagne AmIde, Kimberley Road, Kowloon, Hong Kong Tel: 367 9747 C"ble: "HIPSA GJEWL" Fax: 739 7654 Mailing Address: K.P.O. Box 96532, T.S.T. Hong Kong

Museums,Museums, EducationaEducationall PROMPTPROMPT EstablishmentsEstablishments & CollectorsCollectors LAPIDARYLAPIDARY I havehave whatwhat isis probablyprobably thethe largestlargest rangerange ofof genuinelygenuinely rarerare gemstonesgemstones inin thethe UKUK -- SERVICE!SERVICE! fromfrom ApophylliteApophyllite toto Zincite.Zincite. AlsoAlso rarraree GemstonesGemstones andand diamondsdiamonds cutcut toto youyourr synthetics,synthetics, i.e.i.e. Apatite,Apatite, Scheelite,Scheelite, specificationsspecifications andand repairedrepaired onon ourour BismuthBismuth Germanate,Germanate, KnischkaKnischka rubierubiess premises.premises. andand a rangerange ofof IInamori namori. . LargeLarge selectionselection ofof gemstonesgemstones includinincludingg ListsLists availableavailable rarerare itemsitems andand mineralmineral specimensspecimens iinn NEWNEW LISTLIST ofof inexpensiveinexpensive stonesstones stock.stock. suitablesuitable forfor STUDENTSTUDENTSS ValuationsValuations andand gemgem testingtesting carriedcarried out.out. (Please(Please sendsend three three first firs tclass clas sstamps) stamps ) MailMail orderorder serviceservice availableavailable..

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\Pearls Coral Amber BeadNecklaces Carvings Cameos MineralSpecimens r-, ~ / , -; T he World of Gemstones ~ ·E ;; .~ ~ 1'-----'1 · ...;,. ~ f ~ l Ruppenthal (U.K.) Limited ~ :: - ::. '"~ 5'" Gemstone of every kind, cultured pearls, coral, amber, ivory, bead necklaces, ~ I hardstone carvings, objets d'art, gold gemset jewellery, antique jewellery, ~ ~ , mineral specimens, mineral and gemstone study collections. :.. ~ :l::· We offer a first-class lapidary service. ,[ :: We are also interested in purchasing any unu sual gemstones, gemstone '"~ . necklaces, objets d'art, figur ines, cameos, intaglio s, antique jewellery from any '"~ :l:: ~ · period, antiquarian books of the gemstone industr y etc. ~ ~ ~ ;;. . ~ : 6 WarsCOnt' Mews London S howroom, ~ ~ 0:: Wam oneLan e 3rd Floor, 20-24 Kirby St reet, ~ Birmingham B /8 6JB Halton Garden, London ECI N 8TS r- ~ ~ Tel:02 / -2364306 Tel: 071-405 8068/6563 §. Fax: 021-212 1905 Fax: 07 1-8315724 v 'lntiqueJewellery Modern l Sct and 9ctGem-set Jewellery \)

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The World's Favorite Gemstone Magazine J. Gemm.Gemm.,, 19921992,23,4, 23, 4 252555

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ROUGHROUGH AUSTRALIAAUSTRALIANN ~gt~~,^JfixiàiamiQA. <_A. K^aAeu, FGA.F.G.A.

SAPPHIRESAPPHIRESS DealerDealer iinn fine, rarerare andand collectors'collectors' MineMine runrun largelarge andand smallsmall oror gemstones,gemstones, carvingscarvings andand mineralmineral speCImens.specimens. selectedselected stonesstones ifif required.required. SpecialistSpecialist suppliersupplier ofof jadejade,, fromfrom WriteWrite forfor priceprice listlist specializingspecializing iinn archaicarchaic nephritenephrite toto imperialimperial jadeitejadeite.. GlenGlen InnesInnes andand InverellInverell goodsgoods ValuationsValuations ofof collectionscollections andand ooff individualindividual itemsitems undertaken.undertaken. withwith overover 3030 yearsyears experienceexperience inin I wishwish toto purchasepurchase gemgem andand mineralmineral thethe industryindustry collections,collections, engravedengraved gemstonesgemstones (especially(especially intaglios)intaglios) andand oldold booksbooks RayRay LambertLambert FGAAFGAA onon gemgem relatedrelated subjects.subjects. Pan-PacificPan-Pacific ProductsProducts PtyPty LtLtdd ChristopherChristopher R.R. Cavey,Cavey, F.G.A.F.G.A. 137137 MeadeMeade Street,Street GlenGlen InnesInnes UnitUnit 171777 GraysGrays AntiqueAntique MarketMarket 2379,2379, AustraliAustraliaa 5858 DaviesDavies StreetStreet LondoLondonn WIYWl Y 1AlARR PhonePhone No.No. (067)(067)32120 3212066 Telephone:Telephone: 071-495071-495 17431743 Notes for Contributors The Editors are glad to consider original is consistent with clear indication of the articles shedding new light on subjects of content of the paper. It should be followed by gemmological interest for publication in the the names (with initials) of the authors and by Journal. Articles are not normally accepted their addresses. A short abstract of 50-100 which have already been published elsewhere words should be provided. Papers may be of in English, and an article is accepted only on any length, but long papers of more than the understanding that (1) full information as 10 000 words (unless capable of division into to any previous publication (whether in parts or of exceptional importance) are English or another language) has been given, unlikely to be acceptable, whereas a short (2) it is not under consideration for publication paper of 400-500 words may achieve early elsewhere and (3) it will not be published publication. elsewhere without the consent of the Editors. Twenty fivecopie s of individual papers are Papers should be submitted in duplicate on provided on request free of charge; additional A4 paper. They should be typed with double copies may be supplied, but they must be line spacing with ample margins of at least ordered at firstproo f stage or earlier. 25mm all round. The title should be as brief as

ADVERTISING IN Rates per insertion, excluding THE JOURNAL OF VAT, are as follows: GEMMOLOGY Whole page £180 Half page £100 The Editors of the Journal invite Quarter page £60 advertisements from gemstone and mineral dealers, scientific Enquiries to Mrs M. Burland, instrument makers, publishers Advertising Manager, and others with interests in the Gemmological Association, gemmological, mineralogical, 27 Greville Street, lapidary and jewellery fields. London EC1N8SU. Volume 23 No. 4. October 1992

ThcJournal of Gemmology Contents

Oxidation treatment of the sapphires from Shandong Province, China Wang Chuanfu, Yang Yaoshan and Li Guoxun 195 Determination of the age and origin of emeralds using rubidium- strontium analysis Ph. Vidal, B. Lasnier and J-P. Poirot 198 Identification of fissure-treated gemstones Dr H.A. Hänni 201 Symmetrical polyhedra for gemstones Jos Lurie, Ph.D., FGA 207 Notes from the Laboratory -16 Kenneth Scarratt 215 The Chemical Properties of Colombian emeralds Dr Dietmar Schwarz 225 Gemmological Abstracts 234 Proceedings of The Gemmological Association and Gem Testing Laboratory of Great Britain and Notices 241

ISSN: 0022-1252

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