Volume 22 No. 2. April 1990 The Journal of Gemmology

GEMMOLOGICAL ASSOCIATION OF GREAT BRITAIN OFFICERS AND COUNCIL

President: *Sir Frank Claringbull, Ph.D., F.Inst.P, FGS Vice-President: R. K. Mitchell, FGA Chairman: *D. J. Callaghan, FGA Vice-Chairman: *N. W. Deeks, FGA Honorary Treasurer: *N. B. Israel, FGA

Members elected to Council: *A.J.AUnutt,M.Sc, J. W Harris, B.Sc, *J.B. Nelson, Ph.D., Ph.D.,FGA M.Sc,Ph.D. FRMS, EInst.P, FGA C. R. Burch,B.Sc, J. A. W Hodgkinson, FGA W Nowak, CEng., FGS D. Inkersole, FGA ER.Ae.S.,FGA *C. R. Cavey, FGA B. Jackson, FGA M. J. O'Donoghue, E J. E. Daly, B.Sc, *E. A. Jobbins, B.Sc, C.Eng., MA, FGS, FGA FGA FIMM, FGA R. J. Peace, BSc, *A. E. Farn, FGA *G. H.Jones, B.Sc, Ph.D., C.Chem., FRSC, FGA A. J. French, FGA FGA *P. G. Read, C.Eng., G. Green, FGA D. G. Kent, FGA MIEE, MIERE, FGA *R. R. Harding, B.Sc, D. M. Larcher, FGA *K. Scarratt, FGA D.Phil, FGA A. D. Morgan, FIBF, FGA E. Stern, FGA *C. H. Winter, FGA

^Members of the Executive Committee

Branch Chairmen: Midlands Branch: J. Leek, FGA North-West Branch: W Franks, FGA

Examiners: A. J. Allnutt, M.Sc, Ph.D., FGA D. G. Kent, FGA E. M. Bruton, FGA P Sadler, B.Sc, FGS, FGA A. E. Farn, FGA K. Scarratt, FGA R. R. Harding, B.Sc, D.Phil., FGA E. Stern, FGA E. A. Jobbins, B.Sc, C.Eng., FIMM, FGA M. Virkkunen, M.Phil., FGA G. H. Jones, B.Sc, Ph.D., 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 Secretary: Jonathan P. Brown, FGA, Barrister

Saint Dunstan's House, Carey Lane, London EC2V 8AB (By Goldsmith's Hall) Telephone: 01-726 4374 The Journal of Gemmology

VOLUME 22 NUMBER TWO APRIL 1990

Cover Picture An unusual Guyanese agate showing long, interlocking 'quartz' crystals with banded agate filling the interstices. (See 'An unusual agate from Guyana', p.76)

ISSN: 0022-1252 WORLDWORLD MAMAPP OOFF GE GEMM DEPOSIT DEPOSITSS bbyy th thee Swis Swisss Gemmologica Gemmologicall Societ Societyy IndividualIndividual gegemm depositdepositss identifie identifiedd From only £13.50 worldwide From only £13.50 worldwide plus postage FullFull colourcolour illustrationillustrationss o off gems gems,, plus postage deposits and mining operations and packing deposits and mining operations and packing on reverse side lb order your Map please use the on reverse side To order your Map please use the _.. coupon on p. 126 - ~ ­ coupon on p. 126 _ ..,...,. .. "".,.""..,-'" -.­ _.. .--' ------~--'-

Essential for jewellers: IdealIdeal forfor studentsstudents ooff gemmology gemmology:: Essential for jewellers: • Full colour illustrations essential for For displays or window • Fullstud ycolour illustrations essential for •backdrop For displayss or window study backdrops • Key printed in English, Spanish, Can be overprinted with • KeyGerman printed, French in English,, Italian anSpanish,d •compan Can bey logooverprinted, name an withd German,Portugues French,e Italian and addrescompanys logo, name and Portuguese address • Thematic map Editor: Dr Edward • A special gift for valued clients • A special gift for valued clients • ThematicGübelin map Editor: Dr Edward Giibelin 92cm x 128cm, supplied flat or folded 92cm x 128cm, supplied flat or folded

GEMMOLOGICAL ASSOCIATION OF GREAT BRITAIN GEMMOLOGICALSaint Dunstan's House ASSOCIATION, Carey Lane, LondoOF GREATn EC2 VBRIT\I~ 8AB. Saint Dunstan's House, Carey Lane, London EC2V 8AB. J.J. Gemm.,Gemm., 1990,22,21990,22,2 6677

A contributioncontribution toto thethe distinguishingdistinguishing characteristicscharacteristics ofof sapphiresapphire fromfrom KashmiKashmirr Dr H.H.A. A. HänniyHanni,, FGAFGA

MineralogicalMineralogical Institute,Institute, UniversityUniversity ofof BaselBasel,, SwitzerlandSwitzerland

AbstracAbstractt KashmirKashmir Province)Province) iinn India.India. TheThe deposits,deposits, whichwhich ThisThis investigationinvestigation waswas undertakenundertaken toto contributecontribute toto occuroccur atat aann altitudaltitudee ofof aboutabout 4400m4400m,, werewere intermit­intermit­ thethe knowledgeknowledge ofof sapphiresapphire fromfrom Kashmir,Kashmir, andand overover 5050 tentlytently minedmined aatt severalseveral localitieslocalities (Ol(Oldd Mine,Mine, NewNew cutcut stonesstones werewere studied.studied. ComparisonComparison ofof thethe observedobserved Mine,Mine, Valley).Valley). TheThe productioproductionn includeincludedd somsomee largelarge inclusionsinclusions withwith thosethose describeddescribed inin otherother publications,publications, crystalscrystals anandd a largelarge quantityquantity ooff medium-sizedmedium-sized andand identified in in part part using using the scanningthe scanning electron electron microscope micro­ smallersmaller crystals.crystals. TheThe coloucolourr anandd transparenctransparencyy ofof thethe scopeSEM/EDS, SEM/EDS, confirmed confirmed the results the ofresults earlier of findings earlier find­ stonesstones varievariedd considerablconsiderablyy (Middlemiss,(Middlemiss, 1931;1931; RoyRoy,, ings (tourmaline, pargasite and zircon inclusions). In (tourmaline, pargasite and zircon inclusions). In 1949),1949), andand miningmining figuresfigures forfor somsomee yearyearss clearlyclearly addition, some some internal internal characteristics characteristics are newly are described:newly de­ scribed: plagioclase,plagioclase, uraninite,uraninite, allaniteallanite andand rutilerutile (?)(?) showshow thatthat ththee operationoperation wawass ofteoftenn unprofitableunprofitable.. DueDue occurringoccurring inin variousvarious forms,forms, healedhealed fissuresfissures andand zonedzoned toto thethe lowlow yielyieldd andand ofteoftenn inferioinferiorr qualitqualityy ooff thethe growth. SpectralSpectral properties properties are arepresented. presented. The significanceThe signifi­ sapphire,sapphire, mininminingg wawass frequentlfrequentlyy interruptedinterrupted andand canceof origin of origin reports reports is discussed. is discussed. managementmanagement changechangedd onon manymany occasionsoccasions.. A recentrecent articlearticle describingdescribing allall aspectaspectss ofof ththee depositdeposit cancan bebe IntroductionIntroduction foundfound inin AtkinsoAtkinsonn anandd Kothavala,Kothavala, 1985.1985. InIn hihiss bookbook Sapphire,Sapphire, thethe blueblue varietyvariety ofof corundum,corundum, isis pro­pro­ onon corundum,corundum, HughesHughes (in(in presspress)) alsalsoo presentpresentss a ducedduced fromfrom numerousnumerous depositsdeposits distributeddistributed world­world­ comprehensivecomprehensive lislistt ofof literaturliteraturee oonn sapphirsapphiree fromfrom wide.wide. TheThe termterm KashmirKashmir SapphireSapphire ,isjs usedused toto Kashmir.Kashmir. denotedenote thethe originorigin ofof a stonestone fromfrom a specificspecific location,location, andand shouldshould notnot bebe regardedregarded asas a termterm describingdescribing OriginOrigin ofof studystudy materialmaterial eithereither qualityquality oror colour.colour. SomeSome ofof thethe earlierearlier workedworked TheThe followinfollowingg studstudyy wawass carriecarriedd outout onon cutcut depositsdeposits areare nono longerlonger inin production,production, theirtheir supplysupply sapphiressapphires submittedsubmitted ttoo ththee SwissSwiss FoundatioFoundationn forfor beingbeing eithereither exhaustedexhausted oror nono longerlonger economicallyeconomically thethe ResearchResearch ofof GemstonesGemstones (SSEF(SSEF)) LaboratoryLaboratory inin viable.viable. ThisThis wouldwould alsoalso seemseem toto bebe thethe casecase ofof thethe ZurichZürich (Figur(Figuree 1).1). RoughRough corunducor}lndumm ooff gemgem qualityquality sapphiresapphire depositsdeposits ofof Kashmir.Kashmir. fromfrom SoomjamSoomjam wawass nonott availablavailablee ttoo ththee authorauthor,, andand SapphireSapphire depositsdeposits cancan bebe classifiedclassified intointo a numbernumber suchsuch materialmaterial isis aatt presenpresentt nonott beinbeingg minedmined.. StudyStudy ofof types,types, onon thethe basisbasis ofof theirtheir genesisgenesis oror geologicalgeological ofof inferiorinferior gradegrade materialmaterial (of(of whicwhichh mucmuchh iiss availavail­­ settingsetting (Deer(Deer et ai.,al, 1980;1980; Kiefert,Kiefert, 1987).1987). BasalticBasaltic able),able), isis ooff limitedlimited significancesignificance whewhenn informatioinformationn onon occurrencesoccurrences ofof thethe mineralmineral (e.g.(e.g. inin Australia,Australia, Mala­Mala­ transparenttransparent gemgem qualityquality iiss requiredrequired.. ThThee authorauthor wi,wi, Thailand,Thailand, Cambodia,Cambodia, etc.),etc.), oftenoften producingproducing tootoo receivedreceived cloudcloudyy materialmaterial togethetogetherr witwithh hoshostt rockrock dark,dark, greenish-bluegreenish-blue stones,stones, dodo notnot hosthost thethe mostmost fromfrom SoomjamSoomjam frofromm twtwoo independenindependentt anandd reliablereliable covetedcoveted blubluee corundum.corundum. SapphiresSapphires fromfrom pegmatiticpegmatitic sources.sources. ThThee samplesampless frofromm botbothh sourcessources appearedappeared dykesdykes andand metamorphicmetamorphic depositsdeposits areare oftenoften tootoo lightlight identicalidentical andand correspondedcorresponded witwithh informatioinformationn givengiven oror exhibitexhibit mixedmixed colours,colours, andand areare nonott generallygenerally inin thethe originaloriginal literatureliterature (Mallet(Mallet,, 1882;1882; LLaa ToucheTouche,, consideredconsidered toto bebe ofof particularparticular valuevalue (Montana,(Montana, 1890;1890; Bauer,Bauer, 1896).1896). CorundumCorundum,, whichwhich occuroccurss inin Tanzania,Tanzania, SriSri Lanka).Lanka). Nevertheless,Nevertheless, thethe productionproduction lenseslenses anandd pocketspockets,, isis hostehostedd bbyy a rockrock oftenoften ofof roughrough materialmaterial withwith excellentexcellent colourcolour fromfrom thethe describeddescribed aass kaolin.kaolin. A samplsamplee ooff thithiss fine-grainedfine-grained latterlatter typetype ofof depositsdeposits isis considerable.considerable. TheseThese sap­sap­ 'plumasitic''plumasitic' rocrockk wawass examineexaminedd andand containcontainss feld­feld­ phiresphires maymay attainattain totopp classclass qualityquality afterafter cuttingcutting spar,spar, sheetsheet silicatesilicatess anandd alsalsoo blacblackk tourmalinetourmaline,, asas (such(such asas somesome fromfrom Burma,Burma, SriSri Lanka,Lanka, Kashmir).Kashmir). describeddescribed bbyy LLaa TouchTouchee (1890).(1890). ThThee samplsamplee mate­mate­ rialrial studiedstudied wawass supplementedsupplemented bbyy a transparenttransparent HistoricalHistorical reviewreview sapphiresapphire crystalcrystal provideprovidedd bbyy a museum.museum. AccordingAccording toto a numbernumber ofof authorsauthors (Mallet,(Mallet, 1882;1882; EarlierEarlier descriptiondescriptionss andand photomicrographphotomicrographss ooff LaLa Touche,Touche, 1890),1890), sapphiresapphire waswas discovereddiscovered inin 18811881 diagnosticdiagnostic inclusionsinclusions (Phukan(Phukan,, 1966;1966; Schubnel,Schubnel, atat SoomjamSoomjam inin thethe districtdistrict ofof PadarPadar (Jammu(Jammu andand 1972;1972; GubelinGübelin andand KoivulaKoivula,, 1986)1986) araree scarce,scarce, butbut

©©Copyrigh Copyrightt thethe GemmologicalGemmological AssociationAssociation ISSN:ISSN: 0022-12520022-1252 68 J. Gemm., 1990, 22,2 individual characteristics have been identically de­ - scattering of light on microscopically small flat scribed. In the sapphires studied here, new inclu­ inclusions of an unknown nature (films of rutile sions were identified in addition to the classical or fluid inclusions?), which are distributed both diagnostic Kashmir inclusions (pargasite, tourma­ homogeneously and oriented in rows through­ line, milky Unes with short traverse streaks, see out the stone. (Figure 4). Gübelin and Koivula, 1986). As far as possible, - zonal growth as sequences of transparent (blue these new inclusions were mineralogically identi­ or colourless) and turbid white lamellae with fied by Scanning Electron Microscope with Energy sharp borders (Figure 5). Dispersive System (SEM/EDS). - lamellar or block-like textures of different crys- Absorption spectra exhibit a characteristic tallographic planes with slightly varying refrac­ course, different from other sapphire curves. Thus, tive indices which tend to disturb the light path. a second diagnostic criterion in addition to the inclusions is available for origin determination. Spectral behaviour, inclusion paragenesis and trace element content has been discussed with colleagues Absorption spectra experienced in sapphire identification. The blue colour of Kashmir sapphire can be The new internal characteristics revealed in this explained by iron and titanium contents (Schmetzer paper have been used for the determination of and Bank, 1981). The absorption spectra exhibit the origin, as they have consistently been shown to be characteristic maxima caused by Fe2+/Ti4+ pairs, typical of sapphire from Kashmir. The presence of and Fe3+. Occasionally, light red portions occur in all mineral inclusions identified so far in Kashmir larger, bi-coloured crystals or as light pink crystals. sapphire can be satisfactorily explained by the Likewise, the occurrence of light rubies has been geological setting at Soomjam. This paper reveals noted (Middlemiss, 1931). In fact, small quantities and discusses the additional characteristics. of chromium have been occasionally observed in The determination of origin by characteristics Kashmir sapphire, identifiable by the emission line typical of the locality must be carried out in at 693nm in the absorption spectrum or by energy- comparison with the properties of all other occur­ dispersive X-ray fluorescence spectroscopy (Stern rences of sapphire. Some properties may be charac­ and Hänni, 1982). The blue colour of sapphire is the teristic but not diagnostic for a definite population, result of the relative absorption of all colours but since they are also found in stones from other blue (transmission from ca. 420-470nm). The spec­ localities. Thus, a fundamentally safe assignment of tral part from red, yellow and green is absorbed by a each stone to a specific locality does not always broad band centred at 580nm for the ordinary ray exist. Further discussion of the certainty of deter­ a (o) and at 690nm for this extraordinary (e) ray. mining origin is presented in Hänni, 1988 . Fe2+/Ti4+ pairs are responsible for this absorption behaviour. Absorption in the UV and VIS is also caused by Fe3+ eventually present, with absorption maxima at 374, 388 and 450nm. The presence of Habit and colour of Kashmir sapphire 2+ 3+ The crystals normally display a simple pyramidal Fe /Fe pairs, mainly in green and greenish form with small basal planes (Goldschmidt, 1918). sapphire, results in an absorption maximum at 700 (e vibration) and 600nm (o vibration) affecting the They are either totally or partially transparent, and 3+ the frosted to coarse surfaces are covered with a colour. Even small amounts of Cr in sapphire lead white crust (Bauer, 1896; Middlemiss, 1931), see to an absorption at 600nm and the fluorescence line Figure 2. The small, semi-translucent crystals of a at 693nm. More information can be found in grey colour and with a coarse surface are often still Bosshart (1981) and Schmetzer and Bank (1981). encountered as rough stone material today. They The intensities of the absorption Unes of Kash­ appear to have been found in large amounts and are mir sapphire at 374, 388 and 450nm are similar to suitable to a degree for heat treatment ('Kashmir- those for sapphire from Sri Lanka (weak) and Geuda', Figure 2). Grey crystals of this kind have weaker than those for sapphire from Burma (fairly been described by Middlemiss (1931). strong). The maximum transmissions for the e A particularly marked characteristic of much vibration lie characteristically at 350, 420 and Kashmir sapphire is the velvety blue colour, due to 470nm. The absorption curve edge starts to rise at slightly reduced transparency of the stones. It is the below 370nm, usually passing into the general result of a cumulation of effets: absorption at 320-330nm. A low Cr3+-content re­ - turbidity due to microscopic and sub- sults in a small band at 410nm (e vibration). Thus, microscopic features of an unknown nature the most important portion of the absorption curves (Tyndall Effect on segregations of rutile (?) dust of sapphire for determination of origin lies between particles). Figure 3. 500 and 280nm. J. Gemm., 1990,22,2 69

Fig. 1. Three cut Kashmir sapphires (6-14ct) showing different degrees of transparency and colour saturation.

Fig. 2. Corundum crystal of low quality from Soomjam, and a slice of parent rock containing black tourmaline. The milky crystals are used for heat-treatment (so-called 'Kashmir Geuda'), blue pieces at right after treatment. Width of photo ca. 10cm. 70 J. Gemm., 1990,22,2

Inclusions described in literature (as either they do not reach the surface, or they are Descriptions and illustrations of internal charac­ fluids, or because the crystals are corroded, not teristics in sapphire from Kashmir are relatively rare idiomorphic, etc.). In addition, there is also the compared to those from other deposits. On the basis pressure of time when analysing very precious of optical study, Phukan (1966) described the gems. In this paper, the following abbreviations are following characteristic features :- used to indicate the method of identification: PI - oriented rutile needles, partly decomposed LM Optical light microscopy P2 - fine dust, scattered between rutile needles or SEM Scanning electron microscopy with energy- concentrated in cloudy patches of extremely dispersive system fine particles EMP Electron microprobe analysis P3- zircon, with or without 'winged' fracture XRD X-ray diffraction analysis haloes P4 - opaque black prismatic crystals, surrounded Structural features by liquid feathers The methods recommended by Schmetzer (1986) P5- liquid feathers, partly with tiny drops for the optical measurement of crystallographic arranged in rows growth and colour zoning were used by Kiefert P6 - healing feathers with grid-like patterns (1987) for the study of zoning in sapphire. Due to P7 - flat liquid films or fluid-filled cavities the lack of suitable material, they could not be Schubnel (1972) considered the characteristic applied in the case of the Kashmir sapphire. The inclusions (the first two of which were identified evaluation of crystallographic features on a large using the electron microprobe) to consist of :- number of Kashmir sapphires supplied valuable 51 - tourmaline, greenish and possessing irregular evidence for the determination of origin (Peretti, forms Schmetzer, 1989). Narrow twin lamellae parallel to 52 - pargasite, fine light green needles up to 6mm the rhombohedron face rarely occur in Kashmir in length sapphire (Figure 7). 53 - partly corroded colourless crystals (his Figure Healed fissures 26b, p. 166) They presumably originated during various S4- flat fluid films. phases of crystallization of the corundum. The According to Gübelin and Koivula (1986), the patterns of these original fissure planes can be very following inclusions are typical of Kashmir sap- diverse and in varying stages of healing (see Roed- phire:- der in Gübelin and Koivula, 1986, p. 84). Feathers Gl - zoned texture and cloudy haziness and veils consisting of minute cavities and negative G2- randomly-scattered brush-stroke-like inclu­ crystals can exhibit various forms, although they are sions and nebulous clouds formed of a mainly simple, lobular fissure plane. G3- wispy pennant-like inclusions attached to Occasionally, this can be bent or folded, but seldom strings overlapping. Depending on the stage of healing of G4 - corroded (profiled) zircon crystals the original fissure, the veils can exhibit various G5 - pargasitic hornblende patterns (Figures 8-12):- G6- tourmaline - covered with isometric voids to short tubes, G7 - 'flags' of sealed fluid remnants. graded in size from outside to inside, occa­ sionally in a sort of fishbone pattern (Figure 8): Confirmation of known and new inclusion types of type P5. Modern gem microscopy profits over the old - covered with connecting canals, but also with monocular microscopy through the availability of extensively dissolved networks (Figure 9). improved illumination and binocular observation. - containing flat cavities or negative crystals, Only the use of powerful oblique illumination (e.g. which often possess trigonal step patterns and by fibre optics) against a dark background will sometimes black, opaque platelets (graphite ?) reveal certain types of inclusions, for example as partial fillings. (Figure 10). cloudiness, fine dust tracks and very fine rutile - flat negative crystals with minute satellites, needles. In the past, such features could not be presumably formed by bursting of the main recognized, and thus cannot be expected to be cavity and healing of the fissure plane (Figure reported in earlier literature. ID. After observation of an inclusion, the next step is - very incompletely healed fissures with a frost its identification. A definite identification requires pattern (Figure 12). knowledge of its chemical composition and its The small cavities, flat negative crystals or inter­ crystal structure. One is usually restricted in the linked canals are suspected of containing fluid possibilities of analysing inclusions in gemstones inclusions. J. Gemm., 1990,22,2 71

Fig. 3. Turbidity induced by dust particles (rutile?) occurring Fig. 4. Flaky inclusions of an unknown nature lying in one or in zonal lamellae and as fine dust tracks or traces. 30X. several parallel planes. 50X.

Fig. 5. Sequence of transparent and milky bands originating Fig. 6. Reflecting zoned growth in the form of various crystal- from zoned growth. 10X. lographic planes and blocks. 20X.

Fig. 7. Very small intercalated twin lamellae. 15X. Fig. 10. Healed fissure with flat, strongly recrystallised cavi­ ties (negative crystals), a few containing opaque crystallites. 50X. 72 J. Gemm., 1990,22,2

Fig. 8. Graded healed fissure with short tubes and residual Fig. 9. Healing fissure with a more or less disintegrated droplets. 30X. network of canal structures. 30X.

Fig. 11. Apparently burst negative crystal with healed fissure Fig. 12. Incompletely healed fissure with a frost pattern. 30X. plane containing minute cavities. 50X.

Fig. 13. Lines of dust-like tracks or trails, which cross at acute Fig. 14. Intersecting long and shorter dust lines (running in angles and exhibit fine diagonal striations. 25X. three directions). 25X. J. Gemm., 1990,22,2 73

Fig. 15. Green inclusions of tourmaline crystals in Kashmir Fig. 16. Long pargasite needle exposed on surface and analy­ sapphire, mainly corroded and broken, seldom sed by SEM/EDS. 45X. idiomorphic. 30X.

Fig. 17. Long zircon needle exposed on surface and analysed Fig. 18. Corroded zircon crystal inclusion. 60X. by SEM/EDS. 40X.

Fig. 19. Strongly corroded plagioclase inclusion exhibiting Fig. 20. Opaque cube of uraninite with stress fissures. A rounding and indentation. 50X. number of such crystallites reach the surface and could, therefore, be analysed (SEM/EDS). 40X. 74 J. Gemm., 1990, 22,2

These needles are so thin, that they are either colourless or pale green (Figure 16). Pargasite occurring as inclusion in corundum has been described in ruby from Burma (Schubnel, 1972) and in ruby from Tanzania (Schubnel, 1972; Eppler, 1973). Compare: S2, G5. Zircon (SEM) has been found with varying length:width ratios. A ratio of 3:1 is common. A particularly long zircon needle (SEM) displayed a ratio of 18:1 (Fig 17). Stress fissures are nearly always found around the shorter zircons. They contain traces of uranium which explains the occurrence of the fissures, caused by an increase in Fig. 21. Allanite (orthite) inclusions occur rarely in Kashmir volume. Some of the zircons are indented perpen­ sapphire. 30X. dicular to the long axis and occasionally contain Solid inclusions small opaque inclusions (Figure 18). Compare: P3, Rutile (LM) could not be analytically confirmed. G4. Kashmir sapphire can contain few short rutile Plagioclase (SEM, Ca-rich) was often observed, needles, and it is assumed that the very fine dust but could seldom be analysed. Plagioclase occurs in particles occurring in zones may be developing small, strongly resorbed crystals, sometimes in rutile crystallites. The formation of rutile needles groups. Twinning is sometimes present. The col­ normally has not taken place. It is assumed that the ourless plagioclase is most easily identified by its frequent lamellar turbidity is also due to the habit - rounded form and often containing indenta­ presence of extremely fine rutile dust in layers tions (Figure 19). Compare: S3. (Figures 3-5). Compare: PL The segregation of Uraninite (SEM) occurs as cubic black crystals, rutile needles from the corundum may have been from which stress fissures usually radiate (Figure prevented during fairly rapid cooling, and only 20). The crystals often possess the same width as dust-like particles were formed and are observed as growth lamellae into which they are arranged. turbid zones in most of the Kashmir sapphire. The Rarely, uraninite can form inclusion groups with nature of the very fine particles which usually form zircon. indistinct, more or less linear white trails is still Allanite (SEM, with traces of U and Th) was unclear. Such lines traverse the sapphire roughly identified in one case. Again, stress fissures radiate perpendicular to possible crystal faces, forming from the colourless to pale reddish brown crystals acute angles with each other (Gübelin and Koivula, into the hosting sapphire, presumably due to its 1986, p. 342). They are constructed of short traverse content of radioactive elements (Figure 21). lines (Figure 13) and could also represent minute rutile features. Compare: P2, G2, G3. Significance of determination of origin of Kash­ A further form of such minute white structure are mir sapphire the small, cruciform bodies, also shown by Gübelin Kashmir sapphire is considered by laymen to be and Koivula (1986). They seem to be composed of unrivalled, but such a judgement cannot be justified three intersecting planes of dust concentrations, as each deposit can produce high and low grade also crystallographically oriented (Figure 14). Com­ material. The question arises why sapphire from pare: Gl. this region is so highly regarded. The fantasy is, of Mineral inclusions in Kashmir sapphire were course, affected by the idea of gemstones originat­ already observed in the last century (Mallet, 1882). ing in the past from legendary regions of the Tourmaline and pargasite are considered to be the inaccessible East! The mines in question, however, classical mineral inclusions specific to the deposit. are considered to have been exhausted for the last Zircon has also been mentioned in earlier publica­ fifty years, and most of the valuable stones of the tions (Phukan, 1966; Schubnel, 1972; Gübelin and productive period may lie in the depths of the Koivula, 1986). treasuries of the Maharajahs. Thus, the few Kash­ Tourmaline (dravite, SEM) occurs as short green­ mir sapphires on the free market are avidly sought. ish crystals occasionally forming groups of inclu­ The determination of origin of Kashmir sapphire sions. The stout crystals seldom possess any clear is of particular importance. Often, large price crystallographic forms and could represent partly differences are noted on the market between sap­ dissolved crystals (Figure 15). Compare: SI, G6. phire from Kashmir, accompanied by a credible Pargasite (EMP, alumino-pargasite to alumino- original report, and from other sources, despite tschermakitic hornblende) forms fine long needles. being otherwise visually similar. The non- J.J. Gemm.,Gemm., 1990,22,21990, 22,2 7575

desirabilitydesirability ofof 'documents'documents ofof origin'origin' forfor gemsgems isis Eppler,Eppler, w.P.,W.F., 1973.1973. PraklischePraktische Gemmologie. Ruhle-DiebenerRühle-Diebener discussediscussedd bbyy HughesHughes (1990).(1990). Obviously,Obviously, a definitedefinite Verlag,Verlag, Stuttgart.Stuttgart. geographicalgeographical originorigin isis nonott a guaranteguaranteee ofof highhigh Goldschmidt,Goldschmidt, V.,V., 1918.1918. AtlasALias der Krystallformen,Kryslallformen, CarlCarl WintersWinters Universitatsbuchhandlung.Universitätsbuchhandlung. BandBand V.-Heidelberg.V.-Heidelberg. quality,quality, andand valuevalue shouldshould bbee determineddetermined byby thethe Gubelin,Gübelin, E.].,E.J., Koivula,Koivula, ].1.,J.I., 1986.1986. PhOloallasPhotoatlas of inclusions in beautbeautyy ofof a stone,stone, governedgoverned byby itsits colour,colour, size,size, gemstones. ABCABC Edition,Edition, Zurich,Zürich, 342-3.342-3. transparencytransparency andand cut.cut. Hanni,Hänni, H.A.,H.A., 1987.1987. OnOn corundumcorundum fromfrom UmbaUmba Valley,Valley, Tanzania.Tanzania. J. Gemm., XXXX,, 5,5, 278-84.278-84. ThThee originorigin ofof manmanyy stonesstones cannotcannot bbee statedstated withwith Hanni,Hänni, H.A.,H.A., 1988'.1988a. CertitudeCertitude dede lala determinationdétermination dede l'originel'origine certainty,certainty, andand eveneven localitieslocalities well-knowwell-knownn forfor theirtheir desdes gemmes.gemmes. Revue de Gemmologie a.f.g., decembre,décembre, 4-54-5.. bb productionproduction ofof qualityquality materialmaterial alsoalso producproducee inferiorinferior Hanni,Hänni, H.A.,H.A., 1988 •. AnAn oiloil wellwell inin youryour garden?garden? Swiss WalchWatch andand bb JewelryJewelryJournal, Journal, 3,3, 461-4.461-4. stonesstones (Hanni,(Hänni, 1988 ).). InIn nono respecrespectt shouldshould a Hughes,Hughes, R.R.W. w.,, 1990.1990. A questionquestion ofof origin.origin. Gemological Digesl.Digest. 'superior''superior' originorigin bebe usedused asas anan excuseexcuse toto increaseincrease thethe Hughes,Hughes, R.W.,R.W., (in(in press)press).. Corundum. Butterworths,Butterworths, London.London. valuevalue ofof a poopoorr stone.stone. Kiefert, L., L., 1988. 1988. Mineralogische Mineralogische Untersuchungen Untersuchungen zur zur Charakterisierung Charakler- isierung und UnlerscheidungUnterscheidung nalurlichernaturlicher und synthetischersYnlhelischer AcknowledgementsAcknowledgements Sapphire. Diplomarbeit,Diplomarbeit, Universität Universitat Heidelberg. Heidelberg. LaLa Touche,Touche, T.D.,T.D., 1890.1890. TheThe sapphiresapphire minesmines ofof Kashmir.Kashmir. SeveralSeveral peoplepeople mustmust bbee acknowledgedacknowledged forfor helpinghelping Rec.Geol.Surv.India,Rec.Geol.Surv.lndia, 22,22, 59-6959-69.. inin thethe realizationrealization ofof thisthis work,work, andand inin particular:particular: Mallet,Mallet, P.R.,F.R., 1882.1882. OnOn sapphiressapphires recentlrecentlyy discovereddiscovered iinn thethe M.M. Hatik,Hatik, Feldmeilen,Feldmeilen, Ziirich,Zürich, forfor permissiopermissionn toto north-wesnorth-westt Himalayas.Himalayas. Rec.Geol.Surv.India,Rec.Geol.Surv.lndia, XVXV,, 140.140. studystudy severalseveral KashmirKashmir sapphiressapphires overover a lengthylengthy Middlemiss,Middlemiss, C.S.,C.S., 1931.1931. Precious and semi-precious gemslonesgemstones of of Jammu and Kashmir. MineralMineral SurveySurvey ReportReport IX,IX, JammuJammu periodperiod.. P.E EntremontEntremont (Paris)(Paris) andand F.E NotariNotari (Geneva)(Geneva) andand KashmirKashmir Government.Government. forfor roughrough materialmaterial andand information.information. R.R. HughesHughes Peretti,Peretti, A.,A., 1989.1989. PersonalPersonal communication.communication. AIGSAIGS (Bangkok),(Bangkok), forfor a comprehensivecomprehensive literatureliterature Phukan,Phukan, S.,S., 1960.1960. StudiesStudies onon inclusionsinclusions inin somesome IndianIndian list.list. ProfessorProfessor R.R. GuggenheimGuggenheim andand M.M. DiiggelinDüggelin gemstones.J.Gemm.,gemstones. J.Gemm., X,X, 1-7.1-7. Roedder,Roedder, E.,E., 1982.1982. FluidFluid inclusionsinclusions inin gemstonesgemstones valuablevaluable (SEM(SEM Laboratory,Laboratory, UniversityUniversity ofof Basel)Basel) forfor theirtheir defectsdefects inin Gemmological Symp. Proceedings 1982, G.I.A.G.I.A. continualcontinual readinesreadinesss ttoo analyseanalyse mineralmineral inclusions.inclusions. SantaSanta Monica,Monica, 479-502.479-502. G.G. BosshartBosshart (SSEF(SSEF Laboratory,Laboratory, Ziirich)Zürich) forfor hishis Roy,Roy, B.c.,B.C., 1949.1949. Corundum.Corundum. Indian Minerals, 3,3, 3,109-74.3, 109-74. competentcompetent supportsupport andand circumspectcircumspect discussiondiscussion ooff Schmetzer,Schmetzer, K.,K., Bank,Bank, H.,H., 1980.1980. ExplanationsExplanations ofof thethe absorptionabsorption spectraspectra ofof naturanaturall andand syntheticsynthetic Fe-Fe- andand Ti-containingTi-containing thisthis manuscriptmanuscript.. R.A.R.A. SchedlerSchedler (London)(London) forfor pro­pro­ corundums.corundums. N.Jb.Miner.Abh., 139,216-25.139, 216-25. vidingviding thethe EnglishEnglish translation.translation. Schmetzer,Schmetzer, K.,K., Bank,Bank, H:,H., 1981.1981. DieDie FarbursachenFarbursachen unundd FarbenFarben derder MineralartMineralart Korund.Korund. Z.DI.Gemmolo.Ges.,Z.Dt.Gemmolo.Ges., 31,31, 265-80.265-80. Schmetzer,Schmetzer, K.,K., 1985.1985. EinEin verbesserteverbesserterr ProbenhalterProbenhalter undund seineseine AnwendungAnwendung aufauf ProblemeProbleme derder UnterscheidunUnterscheidungg naturlichernatürlicher und synthetischersynthetischer Rubine Rubine sowie sowie natürlicher naturlicher und synthetischerund synthetis­ ReferencesReferences Amethyste.cher Amethyste. Z.Dt.Gemmol.Ges., Z.DI.Gemmol.Ges., 34, 29-46. 34, 29-46. Atkinson,Atkinson, D.,D., Kothavala,Kothavala, R.Z.,R.Z., 1983.1983. KashmirKashmir SapphiresSapphires Gems Schmetzer,Schmetzer, K.,K., 1986.1986. NatürlicheNalurliche und synthetischesYnlhelische Rubine.Rubine. & Gemology, XIX,XIX, Summer,Summer, 64·76.64-76. Eigenschaften und und Bestimmung. Bestimmung. E.Schweizerbart'sche E. Schweizerbart'sche Verlagsbuchhandlung Ver­ Bosshart,Bosshart, G.,G., 1981.1981. DistinctionDistinction ofof syntheticsynthetic andand naturanaturall rubiesrubies (Nägelelagsbuchhandlung u. Obermiller), Stuttgart. (Nagele u. Obermiller), Stuttgart. bbyy ultra-violetultra-violet spectrophotometry.spectrophotometry. J. Gemm., XVIIIXVIII,, 145-60.145- Schmetzer,Schmetzer, K.,K., 1989.1989. PersonalPersonal communication.communication. Bauer60., M., 1896. Edelsteinkunde. C.H. Tauchnitz, Leipzig, Schubnel,Schubnel, H.J.,H.J., 1972.1972. Pierres précieusespreciepses dansdans Iele monde. monde. HorizonsHorizons Bauer, M., 1896. Edelsleinkunde. C.H. Tauchnitz, Leipzig, dede France.France. 326-8.326-8. Stern, W.B.w.B. Hänni,Hanni, H.A., H.A., 1982. 1982. Energy-dispersive Energy-dispersive X-ray X-ray spectrometry: spec­ Deer,Deer, W.A.W.A.,, Howie,Howie, R.A.R.A. Zussman,Zussman, J.,J., 1980.1980. An IntroductionIntroduclion to trometry: a non-destructivenon-destructive tooltool inin gemmology. J.Gemm.,J.Gemm., lhethe rock-forming minerals. Longman,Longman, London.London. XVIII,285-96.XVIII, 285-96. 76 J. Gemm., 1990,22, 2

An unusual agate from Guyana J.G. Gosling, FGA

Pattingham, Staffordshire

Fig. 1. Amerindians collecting agates in a gully leading to the Ireng river.

In a far off part of the world there is a country that lapidary workshop in the capital, Georgetown, and has the Kanuku or Blue Mountains, the Kaieteur also arranging for the collection of raw materials in Falls with a sheer drop of nearly 800 ft, large areas of the interior. Then after a period of training for a unexplored jungle, arid savannahs and breathtaking group of young Guyanese the artistic products were scenery. The Republic of Guyana is located on the arranged for the sale and export. northern Atlantic coast of South America and is To the 'Black pearl of Guyana' (Gosling, 1976), an bordered by Surinam, Brazil and Venezuela. About international interest in gold and diamond deposits, the size of Great Britain, Guyana has a population of and the many varieties of jasper (Gosling, 1986) that some 850,000, most of whom live on the narrow occur, may now be added a very unusual form of coastal plain. The mineral-rich interior comprises agate that may prove to be unique to Guyana. 70 per cent of the land area and is relatively In the early 1970s an investigation of the agate uninhabited. As a result of geological expeditions in deposits in the north Rupununi savannahs was Guyana a new industry was set up in 1973. This was carried out by a survey team from the Geological achieved by the setting up of a small industrial Survey and Mines Department in Georgetown.

© Copyright the Gemmological Association ISSN: 0022-1252 J. Gemm., 1990, 22, 2 77

The quantity and quality found encouraged the doubtedly used by ancient mankind and containing Ministry of Energy and National Resources to set fine examples of cave paintings deep underground. up a new industry based on the utilization of these The savannahs are gently rolling plains covered materials. This project was assisted by British with sandpaper trees and Itè palms by the water Technical Aid arranged by the Ministry of Overseas courses. The roads are rough tracks of red ferrugi­ Development and the author was privileged to carry nous lateritic soils which are very dusty and full of out the scheme for the people and Government of potholes in the dry season and almost impassable in Guyana. the wet season. Initial prospecting was carried out along the During the initial surface collection considerable banks of the Ireng, Takutu and Manari rivers. In quantities of agates were found in the dry gullies order to obtain information about conditions under which carry the surplus water off the savannahs in the ground, trial pits and trenches were dug wher­ the rainy season into the river. A small number of ever there were good indications of agates. These agate boulders were collected in the low cliffs at the trial pits and trenches, in addition to providing edge of the river. These were mostly cut into

Fig. 2. Amerindian digging out agates. samples of the deposits excavated allowed inspec­ magnificent matching book-ends and a set was tion of the rocks in the walls of the pit or trench. presented to the Prime Minister at the official While working on the commercial collection of the opening of the lapidary workshop in Georgetown. agates some were found to have percussion cracks These agates were carefully checked and packed and it is interesting to speculate on the original into the Landrover and the boxes were transported geological movements in the area. The best deposits to Lethem and then to Georgetown on a DC3 plane were found near Sunnyside on the Ireng river some that was part of a regular transport flight to 34 miles north of Lethem. The Ireng river is the Georgetown. natural boundary with Brazil. The area is bounded At our various camp sites we found that as by the Good Hope Mountains in the north and the southern Guyana is almost on the Equator and there Kanuku or Blue Mountains in the south. These was very little twilight and that the night settles in mountains are largely unexplored and are the site of very quickly - which is instantly the signal for every ancient burial grounds, while further south near frog to give voice and for the fireflies or 'candleflies' Aishalton are some wonderful deep caves un- to light up the darkness with their brilliant displays 7788 JJ.. Gemm.Gemm.,, 19901990,22,2, 22, 2

Fig. 4. Guyanese agate showing complex interlocking quartz crystal structure and infilling with banded agate.

Fig. 3. Pit in river terrace deposits showing agates in situ.

FigFig.. 55.. ExamplExamplee ooff bandebandedd agatagatee founfoundd neanearr SunnSunnysidey side oonn ththee FigFig.. 66.. SliceSlicedd GuyanesGuyanesee agatagatee useusedd aass a clocclockk face,. bankbankss ooff ththee IrenIrengg riverriver.. J. Gemm., 1990,22,2 79

Fig. 7. Teaching seminar at the lapidary workshop in Georgetown showing the cutting of banded agate with a diamond saw. of luminescence. the use of 80, 220 and 400 grit sizes of silicon The agates are found on the Rupununi savannah carbide great care had to be taken to wash off all and occur in gravel beds that overlie the Takatu traces of the grit being used before proceeding to Formation. Most of the agates found in these the next finer grade as we found it was very easy to gravels are very beautiful examples of the banded miss a few particles trapped in the cavities of the varieties and are of many different colours and coarse quartz matrix which resulted in disastrous patterns. At the same location are found some scratches. In the final polishing of the agate using agates of a very different type. These were known to cerium oxide on a felt mop, considerable problems the local geologists as 'fire agates' and were formed were experienced in removing the polishing com­ of a criss-crossing open lattice of quartz crystals pound that had dried in the small holes in the open (like frost on a window pane) with banded agate quartz crystal lattice. filling the interstitial cavities. The outer surfaces of This special Guyanese agate is very unusual and these agates showed a rough fibrous structure quite specimen blocks and clock faces aroused intense unlike that found on the more usual type of agate interest; its formation will surely intrigue geolo­ boulder. These were quite unlike any type of agate gists. The project continues to flourish and it is that the author had experienced and may well be hoped in time to expand to other areas of the unique to Guyana. country. After transporting the materials to the workshop in Georgetown it was found that the cutting and References polishing of this 'fire agate' was similar to normal Gosling, J., 1976. The 'Black Pearl' of Guyana. Journal of lapidary practice, but that care had to be taken in Gemmology, XV, 209-11. sawing and grinding to avoid damaging the long Gosling, J., 1986. A description of jasper found at the Orinduik crystals of quartz. The lapidary workshop was Falls, in Guyana, South America. Journal of Gemmology, 20, equipped with two 24" diamond saws and there was 91-2. always intense interest in cutting agate as each one displayed new shapes, patterns or colours. During [Manuscript received 24 April 1989.] 8080 JJ.. Gemm.Gemm.,, 1990,22,21990,22,2

SpectroscopicSpectroscopic evidenceevidence forfor heatheat treatmentreatmentt ooff blubluee sapphiressapphires fromfrom SriSri LankaLanka -- additionaladditional datadata Dr Karl SchmelzerSchmetzer1l and Dipl.-Min. Lore Kie/ert!Kiefert2

1 I MarbacherMarbacher Str.Str. 22b,22b, D-8067D-8067 Petershausen,Petershausen, WestWest GermanyGermany 2Griffith2Griffith University,University, Queensland,Queensland, AustraliaAustralia

AbstractAbstract identificationidentification ofof heaheatt treatmenttreatment ofof naturalnatural sapphiressapphires DifferencesDifferences inin thethe absorptionabsorption spectraspectra ofof particularparticular byby spectroscopicspectroscopic investigationsinvestigations areare founfoundd inin thethe types of naturalnatural blueblue untreateduntreated and and heat heat treated treated sapphires sap­ 3+ paperspapers ooff NassaNassauu (1981)(1981) andand CrowningshieldCrowningshield andand phires areare duedue toto thethe presencpresencee oror absenceabsence ofof Fe3+Fe NassauNassau (1981)(1981),, whowho mentionedmentioned ththee absencabsencee ooff thethe absorptionabsorption bandsbands ofof distinctdistinct intensities.intensities. TheseThese featuresfeatures 22,200cm-22,200cm-11 (450nm(4S0nm)) absorptionabsorption banbandd iinn treatedtreated areare usefuluseful forfor thethe recognitionrecognition ofof artificialartificial heatheat treatmenttreatment 3 + 3+ in samples ofof the the trade. trade. sapphires,sapphires, whicwhichh iiss assigneassignedd toto Fe + replacinreplacingg Ae+Al inin thethe corundumcorundum structurestructure.. TheThe aimaim ofof thethe presentpresent paperpaper isis toto elucidateelucidate thisthis differencdifferencee inin spectroscopicspectroscopic Heat treatmenttreatment of of milky milky white, white, bluish bluish or oryellowish yellow­ propertiesproperties ofof treatetreatedd andand untreateuntreatedd samples,samples, whichwhich ish sapphiressapphires fromfrom SriSri LankaLanka hashas beenbeen performedperformed isis usefuluseful foforr diagnostidiagnosticc purposes.purposes. forfor thethe lastlast tenten yearsyears (or(or eveneven longer)longer) inin orderorder toto NaturalNatural blubluee sapphiresapphiress cacann bbee subdividesubdividedd intointo developdevelop anan intenseintense blueblue colorationcoloration ofof thethe samples.samples. twotwo basicbasic typestypes,, dependindependingg onon ththee presencpresencee oror ThoughThough technicaltechnical detailsdetails ofof thethe processesprocesses usedused byby absenceabsence ofof thethe Fe2+Fe2+ /FeIFe3+3+ charge-transfercharge-transfer absorp­absorp­ commercialcommercial treaters,treaters, e.g.e.g. inin Bangkok,Bangkok, areare keptkept tiontion bandband inin ththee neanearr infrareinfraredd aatt 1l,SOOcm-11,5 00cm-1 secret, somesome information information about about colour colour improvement improve­ (870nm)(870nm) witwithh polarizatiopolarization..Ln _L c > II\\ c. c. Blue Blu esapphires sapphire s ment ofof thesethese so-calledso-called 'geuda-sapphires''geuda-sapphires' hashas beenbeen withouwithoutt a prominenprominentt Fe22++/FeIFe 3+ banbandd (natural(natural sap­sap­ publishedpublished inin recentrecent yearsyears (e.g.(e.g. Harder,Harder, 1980,1980, 1982;1982; phiresphires ofof typetype II)) araree knowknownn frofromm e.g.e.g. Mogok,Mogok, CrowningshieldCrowningshield andand Nassau,Nassau, 1981;1981; Gunaratne,Gunaratne, Burma;Burma; differentdifferent localitieslocalities iinn SriSri LankaLanka;; UmbaUmba 1981; Nassau, 1981;1981; Keller,Keller, 1982;1982; Abraham,Abraham, 1982). 1982). Valley,Valley, Tanzania;Tanzania; MontanaMontana,, USAUSA;; Kashmir,Kashmir, India;India; InIn general,general, thethe developmentdevelopment ofof colourcolour isis basedbased onon blueblue sapphiressapphires witwithh a dominandominantt Fe2+Fe2+ /FeIFe 3+ bandband heatheat treatmenttreatment ofof naturalnatural samplessamples underunder reducingreducing (natural(natural sapphiressapphires ooff typetype IIII)) areare knowknownn fromfrom alkalialkali conditionsconditions atat temperaturestemperatures above lSS0°C1550°C forfor severalseveral basaltsbasalts asas mothermother rocks,rocks, e.g.e.g. fromfrom differentdifferent localitieslocalities hours.hours. ThisThis processprocess causescauses a dissolutiondissolution ofof rutilerutile inin AustraliaAustralia andand ThailandThailand;; Jos,Jos, NigeriaNigeria;; Pailin,Pailin, needleneedless oror particlesparticles inin thethe corundumcorundum host,host, i.e.i.e. thethe Cambodia.Cambodia. AbsorptioAbsorptionn spectraspectra ofof typtypee I naturalnatural formationformation ofof a solidsolid solutionsolution betweenbetween thethe hosthost blueblue sapphiressapphires araree picturepicturedd inin FigureFigure 1,1, typicaltypical crystalcrystal andand guestguest mineralsminerals (see(see Nassau,Nassau, 1982;1982; absorptionabsorption spectraspectra ooff typtypee IIII naturanaturall blubluee sapphiressapphires HarderHarder andand Schneider,Schneider, 1986).1986). TheThe reversereverse ofof thisthis werewere recentlyrecently publishepublishedd inin thithiss journajournall bbyy KiefertKiefert processprocess isis commerciallycommercially usedused forfor thethe formationformation ofof andand SchmetzerSchmetzer (1987)(1987).. rutile precipitatesprecipitates in syntheticin synthetic and naturaland natural sapphires. sap­ TheThe coloucolourr ofof bothboth,, heaheatt treatetreatedd andand non-heatnon-heat phires. InIn orderorder toto developdevelop oror improveimprove asterism,asterism, treatedtreated naturanaturall blubluee sapphiresapphiress ooff typtypee I iiss causedcaused thesethese samplessamples areare annealedannealed atat temperaturestemperatures betweenbetween exclusivelyexclusively bbyy ththee FeFe2+2+ /TiITi4+ intervalenceinter valence transfertransfer 1100 and 1500°ClS00°C for several hours. absorption,absorption, thethe absorptioabsorptionn maximamaxima ofof whicwhichh areare InIn practicalpractical gemmology,gemmology, thethe detectiondetection ofof heatheat foundfound atat 17,880cm-17,880cm"11 (559nm(SS9nm)) [polarization..Lc[polarization _L c> > \\II 1 treatmenttreatment inin naturanaturall sapphiressapphires asas wellwell asas thethe recogni­recogni­ c)c] andand atat 14,300cm14,300cm" -I (699nm)(699nm) [polarization[polarization II| |c c = ~ ..L_L tiontion ofof naturanaturall blueblue samplessamples asas untreateduntreated sapphiressapphires c)c] (Schmetzer(Schmetzer anandd Bank,Bank, 1980;1980; BurnBurnss anandd Burns,Burns, isis performedperformed inin generalgeneral byby microscopicmicroscopic investiga­investiga­ 1984;1984; Schmetzer,Schmetzer, 1987).1987). AllAll samplessamples ofof thisthis particu­particu­ tions,tions, whichwhich areare basedbased onon thethe presencepresence oror absenceabsence ofof larlar typetype reveareveall aann identicalidentical pleochroispleochroismm ooflightf light blueblue distinctdistinct features,features, e.g.e.g. onon thethe presencepresence ofof rutilerutile II|| cc andand intenseintense blueblue toto bluishbluish violet..Lviolet J_ c.c. In In thisthis typetype needlesneedles oror two-phasetwo-phase inclusionsinclusions inin untreateduntreated sam­sam­ ofof blueblue sapphiresapphire,, thethe presencpresencee oorr absenceabsence ooff a weakweak plesples asas wellwell asas onon thethe presencepresence ofof internalinternal stressstress Fe3+Fe3+ absorptionabsorption atat 22,200cm"22,200cm-11 (4S0nm)(450nm) doedoess notnot fracturesfractures aroundaround singlesingle crystalcrystal inclusionsinclusions inin heatheat influenceinfluence colourcolour oror pleochroispleochroismm ooff ththee samples.samples. treatedtreated samplessamples (Nassau,(Nassau, 1981;1981 ; Crowningshield Crowningshield andand HeatHeat treatmentreatmentt ooff milkymilky whitwhitee so-calledso-called 'geuda''geuda' Nassau,Nassau, 1981;1981; Koivula,Koivula, 1986;1986; GiibelinGübelin andand Koivula,Koivula, sapphiressapphires fromfrom SriSri LankaLanka (an(andd onlonlyy thithiss typtypee ofof heatheat 1986).1986). H9wever,However, somesome hintshints towardstowards a possiblepossible treatedtreated sapphiressapphires wilwilll bbee discussediscussedd iinn thithiss paper)paper) J.J. Gemm.,Gemm., 1990,22,21990,22,2 8181

WAVELENGTH (nm) 350 400 500 600 700

e

d

c

b

a

30 25 20 15 WAVENUMBER (1000 em -1)

Fig.Fig. 1.1. AbsorptionAbsorption spectraspectra ofof naturanaturall untreateduntreated andand heatheat treatedtreated blueblue sapphires.sapphires. !Untreated|Untreated samplessamples:: (a)(a) Mogok,Mogok, Burma,Burma, (b)(b) SriSri Lanka,Lanka, i| (c)(c) Montana,Montana, USAUSA,, (d)(d) Umba,Umba, Tanzania.Tanzania. HeatHeat treatedtreated samples:samples: (e)(e) anandd (f)(f) SrSrii Lanka,Lanka, samplessamples ofof thethe trade,trade, (g)(g) andand (h)(h) SriSri Lanka,Lanka, samplessamples treatedtreated byby thethe authors.authors. 8282 J.J. Gemm.,Gemm., 1990,22,21990, 22, 2 producesproduces absorptionabsorption spectraspectra withwith dominantdominant Fe2+Fe2+ I/ thoughtthought toto bebe usefuluseful asas anan unequivocalunequivocal criterioncriterion forfor Ti44++ absorptionabsorption bandsbands butbut withoutwithout anyany FeFe22++ IFe/Fe33++ untreateduntreated blueblue sapphire,sapphire, butbut thethe absenceabsence ofof Fe33++ intervalencein ter valence transfertransfer absorptionabsorption (Figure(Figure 1).1). InIn absorptionabsorption bandsbands ofof distinctdistinct intensitiesintensities isis usefuluseful toto addition,addition, samplessamples ofof thethe tradetrade andand alsoalso thosethose classifyclassify a samplesample ofof undoubtedlyundoubtedly naturalnatural originorigin samplessamples treatedtreated byby thethe authorsauthors inin generalgeneral diddid notnot (proved(proved byby microscopicmicroscopic examination)examination) asas artificiallyartificially revealreveal anyany absorptionabsorption bandsbands ofFeof Fe33+ inin thethe blueblue andand heatheat treatedtreated naturalnatural blueblue sapphire.sapphire. ultravioletultraviolet rangerange atat 22,200,22,200, 25,80025,800 andand 26,600cm-'26,600cm"1 (at(at 450,450, 388388 andand 376nm).376nm). AnAn absorptionabsorption spectrumspectrum ReferencesReferences ofof thisthis typetype waswas nevernever observedobserved byby thethe authorsauthors inin Abraham,Abraham, I.S.D.,J.S.D., 1982.1982. HeatHeat treatingtreating corundum:corundum: thethe BangkokBangkok untreateduntreated naturalnatural blueblue sapphiressapphires fromfrom differentdifferent operation.operation. Gems & Gemology, 18,18, 79-82.79-82. localities.localities. Burns,Burns, R.G.,R.G., Burns,Burns, V.M.,V.M., 1984.1984. OpticalOptical andand MossbauerMössbauer spectraspectra 3+ of transition-metal-dopedtransition-metal-doped corundum corundum and periclase. and periclase. Advanced Ad­ TheThe absenceabsence ofof Fe3+Fe absorptionabsorption bandsbands inin heatheat Ceramics,vanced 10 Ceramics,, 46-61. 10,46-61. treatedtreated samples,samples, whichwhich werewere spectroscopicallyspectroscopically Crowningshield,Crowningshield, R.,R., Nassau,Nassau, K.,K., 1981.1981. TheThe heatheat andand diffusiondiffusion foundfound toto bebe presentpresent inin untreateduntreated samplessamples beforebefore treatmenttreatment ofof naturalnatural andand syntheticsynthetic sapphires.sapphires. Journal of treatmenttreatment waswas appliedapplied byby thethe authors,authors, isis explainableexplainable Gemmology, 17,528-41.17, 528-41. Gubelin,Gübelin, E.I.,E.J., Koivula,Koivula, J,I.,J.I., 1986.1986. Photoatlas of inclusionsinclusions in byby thethe conversionconversion ofof trivalenttrivalent ironiron toto bivalentbivalent ironiron inin gemstones. ABCABC Edition,Edition, Zurich.Zürich. connectionconnection withwith thethe dissolutiondissolution ofof ruti)erutile particlesparticles Gunaratne,Gunaratne, H.S.,H.S., 1981.1981. 'Geuda'Geuda sapphires'sapphires' - theirtheir colouringcolouring afterafter thethe scheme:scheme: elementselements andand theirtheir reactionreaction toto heat.heat. Journal of Gemmology, Ti0 + (Al3+,Fe3+)203(Al3+,Fe3+) 0 ~-> (Al(Al33++,Ti4+,Fe2+)2,Ti4+,Fe2+) 003 17,292-300.17, 292-300. 2 2 3 2 3 Harder,Harder, H.,H., 1980.1980. EdelsteineEdelsteine durchdurch BrennenBrennen vovonn Korunden.Korunden. rutilerutile corundumcorundum (colourless)(colourless) corundumcorundum (blue)(blue) Fortschrifte der Mineralogie, 58,58, BeiheftBeiheft 1,45-6.1, 45-6. AccordingAccording toto thisthis scheme,scheme, inin samplessamples inin whichwhich Harder,Harder, H.,H., 1982.1982. QualitatsverbesserungQualitätsverbesserung vonvon Edelsteinen,Edelsteinen, titaniumtitanium contentscontents exceedexceed ironiron contents,contents, nnoo residualresidual insbesondereinsbesondere vonvon Korunden,Korunden, durchdurch WarmebehandlungWärmebehandlung Fe3+ absorptionabsorption bandsbands areare expectedexpected toto bbee presentpresent (Brennen).(Brennen). Aufschluss, 33,33, 213-26213-26.. - Harder,Harder, H.,H., Schneider,Schneider, A.,A., 1986.1986. IsomorpherIsomorpher EinbauEinbau vovonn EisenEisen afterafter extendedextended heaheatt treatment.treatment. SimilarSimilar factsfacts areare ununtt TitanTitan zurzur ErklarungErklärung derder blaueblauenn FarbeFarbe vovonn Rutil-Rutil- undund 3+ responsibleresponsible forfor thethe absenceabsence ofof Fe + absorptionabsorption Spinell-haltigen seidig seidig weissen weissen Korunden Korunden nach nach einer einer Wärmebehandlung. War­ bandbandss inin thethe spectraspectra ofof syntheticsynthetic Verneuil-grownVerneuil-grown Neuesmebehandlung. Jahrbuch für Mineralogie. Neues Jahrbuch Monatshefte, fur Mineralogie. Monats­ blueblue sapphiressapphires withwith a chemicalchemical compositioncomposition reveal­reveal­ 1986hefte,, 209-18. 1986,209-18. Keller,Keller, P.C.pc.,, 1982.1982. TheThe Chanthaburi-Chanthaburi-TraTratt gemgem field,field, Thailand.Thailand. inging higherhigher amountsamounts ofof titaniumtitanium thathann iron.iron. Gems&Gems & Gemology, 18,18, 186-96.186-96. However,However, inin somesome heatheat treatedtreated naturalnatural samples,samples, Kiefert,Kiefert, L.,L., Schmetzer,Schmetzer, K,K., 1987.1987. BlueBlue andand yellowyellow sapphiresapphire fromfrom residuesresidues ofof smallsmall amountsamounts ofFeof Fe3+ werewere observedobserved byby KadunaKaduna Province,Province, Nigeria.Nigeria. Journal of Gemmology, 2020,, spectroscopicspectroscopic investigationsinvestigations.. TwoTwo possiblpossiblee explana­explana­ 427-42.427-42. Koivula,Koivula, I.!.,J.I., 1986.1986. CarbonCarbon dioxidedioxide fluidfluid inclusionsinclusions asas prooprooff ofof tiontionss cacann bbee quotequotedd foforr thithiss observationobservation;; oonn ththee oneone natural-colorenatural-coloredd corundumcorundum.. Gems&Gems & Gemology, 22,22, 152-5.152-5. handhand,, ththee timtimee ooff heaheatt treatmentreatmentt cacann bbee totooo shorshortt ttoo NassauNassau,, K.K,, 1981.1981. HeaHeatt treatetreatedd rubrubyy anandd sapphiresapphire:: technicaltechnical finalizfinalizee ththee reactioreactionn accordinaccordingg ttoo ththee schemschemee givegivenn aspectsaspects.. GemsGems& & Gemology, 1717,, 121-31121-31.. above or, on the other hand, the amounts of iron in NassauNassau,, K.K,, 1982.1982. CommenCommentt oonn 'Hea'Heatt treatintreatingg corundum~corundum'. above or, on the other hand, the amounts of iron in LetteLetterr bbyy G.AG.A.. TombsTombs.. GemsGems& & Gemology, 18,18, 109109.. ththee samplesampless mamayy exceeexceedd ththee amountamountss ooff titaniumtitanium.. InIn SchmetzerSchmetzer,, K.K,, 19871987.. ZuZurr DeutunDeutungg dederr FarbursachFarbursachee blauerblauer additionaddition,, ththee influenceinfluencess ooff differendifferentt reducinreducingg oror SaphirSaphiree - eineinee DiskussionDiskussion.. NeuesNeuesJahrbuchfur Jahrbuch für Mineralogie. oxidizinoxidizingg atmosphereatmospheress oonn ththee reactioreactionn describeddescribed Monatshefte, 1987,1987, 337-43337-43.. hahass nonott yeyett beebeenn studiestudiedd iinn detaidetaill bbyy ththee authors.authors. SchmetzerSchmetzer,, K.K.,, BankBank,, H.H.,, 19801980.. ExplanationExplanationss ooff ththee absorptionabsorption 3+ spectrspectraa ooff naturanaturall anandd synthetisyntheticc FeFe-- anandd Ti-containingTi-containing AccordinAccordingg ttoo thesthesee factsfacts,, ththee presencpresencee ooff Fe3+Fe corundumscorundums.. NeuesN eues JahrbuchJ ahrbuch fürfur Mineralogie.M ineralogie. AAbhandlungen, bhandlungen, absorptioabsorptionn bandbandss ooff distincdistinctt intensitieintensitiess iiss notnot 139139,216-25., 216-25. J.J. Gemm.,Gemm., 1990,22,21990, 22, 2 8383

RedRed andand orangeorange corundumcorundum (ruby(ruby andand padparadscha)padparadscha) fromfrom MalawiMalawi 1 1,2l 22 Dr U. Hennl,Henn , ProfProf. Dr H. Bank ,2 and Dipl.-Min. F. H. BankBank

1 1 DeutscheDeutsch eStiftun Stiftungg EdelsteinforschunEdelsteinforschungg (DSEF)(DSEF),, D-658D-65800 Idar-ObersteinIdar-Oberstein,, WesWestt GermanGermanyy 2Mineralogisch-Petrographisches2Mineralogisch-Petrographisches InstitutInstitut derder UniversitiitUniversität Heidelberg,Heidelberg, D-6900D-6900 Heidelberg,Heidelberg, WesWestt GermanyGermany

AbstractAbstract broughtbrought witwithh somsomee moremore materialmaterial andand largerlarger cryscrys­­ Physical, chemical, spectroscopicalspectroscopical and and microscopi­microscopical talstals forfor examination,examination, alsoalso orangeorange colouredcoloured corun­corun­ cal featuresfeatures ofof redred andand orangeorange corundumcorundum fromfrom MalawiMalawi dums.dums. areare described.described. TheThe stonesstones investigatedinvestigated showshow goodgood gemgem quality.quality. TheThe rubiesrubies varyvary inin colourcolour fromfrom palepale redred toto darkdark red.red. TheThe variationvariation ofof colourcolour intensityintensity isis accompaniedaccompanied bbyy PhysicalPhysical featuresfeatures a remarkableremarkable variationvariation ofof thethe physicalphysical datadata (refractive(refractive TheThe determinatiodeterminationn ofof thethe physicaphysicall characteris­characteris­ indices,indices, birefringencebirefringence,, specificspecific gravity)gravity) asas wellwell aass tics,tics, refractiverefractive indicesindices,, birefringencbirefringencee anandd specificspecific chemical characteristicscharacteristics (chromium (chromium and and iron iron contents). contents). gravitygravity demonstrateddemonstrated a remarkablremarkablee risrisee iinn constantsconstants ofof thethe rubiesrubies investigateinvestigatedd (Tabl(Tablee 1).1). TheThe refractiverefractive IntroductionIntroduction indicesindices increaseincrease fromfrom 1.1.76 7600 ttoo 1.1.77 7700 fornfor ne andand 1.1.76 7688 AnAn occurrenceoccurrence ofof gemgem qualityquality corundumcorundum iinn toto 1.7801.780 forfor nno0 witwithh 6nAn = 0.000.0088 ttoo O.OlD.0.010. AlsAlsoo thethe 3 SouthernSouthern MalawiMalawi waswas reportedreported byby BloomfieldBloomfield specificspecific gravitygravity increasesincreases fromfrom 3.963.96 toto 4.04g/cm . (1958).(1958). TheThe localitylocality describeddescribed isis situatedsituated onon thethe RutlandRutland (1969(1969)) describedescribedd refractivrefractivee indicesindices ooff nnee = ChimwadzuluChimwadzulu Hill,Hill, approximatelyapproximately 5050 milesmiles southsouth ofof 1.762-1.7631.762-1.763 andand nno0 = 1.771-1.7721.771-1.772 foforr reredd corun­corun­ LakeLake Nyasa,Nyasa, closeclose toto thethe frontierfrontier ofof Mozambique.Mozambique. dumsdums fromfrom MalawiMalawi.. ThThee intensintensee reredd andand dardarkk redred (Figure(Figure 1).1) . TheThe corundumscorundums occuroccur inin situsitu inin aann specimensspecimens investigatedinvestigated bbyy ththee authorauthorss havhavee refrac­refrac­ epidotizedepidotized amphibolite.amphibolite. TheThe crystalscrystals areare embeddedembedded tivetive indices,indices, whicwhichh werweree nevernever describeddescribed and/orand/or inin a coarsecoarse aggregateaggregate ofof hornblendehornblende crystals,crystals, enen­­ closedclosed inin a matrixmatrix ofof epidoteepidote andand plagioclase.plagioclase. | K ç FirstFirst gemmologicalgemmological investigationsinvestigations werewere carriedcarried \ outout bbyy RutlandRutland (1969).(1969). HeHe examinedexamined roughrough crystalscrystals \ ,/ TANZANIA ofof blue,blue, pink,pink, yellow,yellow, palepale greengreen andand darkdark greyish­greyish- •-' TANZANIA greengreen colours,colours, showingshowing wellwell developeddeveloped basalbasal pina­pina- ZAMBIAZAMBIA } / X ,'-''" 1 coidscoids andand lessless rhombohedralrhombohedral faces.faces. TheThe crystalscrystals j ._0 •.~'-'-\.-.. _.~'-'.'\... _ .....y ,,_ ...... _.•' , •.1 werewere 5 toto 40mm40mm inin lengthlength andand hadhad a distinctdistinct basalbasal

partingparting.. LaterLater hehe investigated,investigated, togethertogether withwith E.A.E.A. Nyas a l"? Jobbins,Jobbins, somesome lotslots ofof severalseveral hundredhundred cutcut stones,stones, *••'* 1 X** 3 weighingweighing upup toto 12ct12c t each.each. TheThe colourscolours ofof thesethese \ 1 ) corundumscorundums variedvaried fromfrom yellowyellow toto blue,blue, palepale blue,blue, / MOZAMBIQUMOZAMBIQUEE / greyish-bluegreyish-blue andand greenish-blue.greenish-blue. TheThe reredd stonesstones J<• werewere smallersmaller inin sizesize andand palepale inin colour.colour. OnlyOnly somesome \ \\ stonesstones showedshowed fine colours,colours, comparablecomparable withwith goodgood H>- v Vs. 1 *•"*"""" \ \\\i "\\ rubiesrubies fromfrom Thailand.Thailand. TheThe quantityquantity ofof thethe minedmined U**""" \ . N J A * mineralmineral isis unknownunknown andand forfor a longlong timetime nothingnothing waswas 1 ' > V \ J Chimwadzulu Hill -4A heardheard aboutabout thatthat occurrence.occurrence.

InIn AprilApril 19881988 thethe authorsauthors obtainedobtained somesome speci­speci­ i mensmens ofof corundum,corundum, showingshowing partlypartly fine rubyruby Cf • qualityquality withwith varyingvarying colourcolour intensityintensity fromfrom palepale redred \ Blantyre J | toto intenseintense andand darkdark redred (Bank(Bank andand Henn,Henn, 1988;1988; t. /"* ' \s .•*/ BankBank et at.,al., 1988).1988). TheThe crystalscrystals showedshowed wellwell dede­­ \ V velopedveloped basalbasal pinacoidspinacoids andand werewere upup toto 15mm15mm iinn *(./ 101000 milesmiles length.length. DistinctDistinct basalbasal partingparting waswas alsoalso visible.visible. Later,Later, inin MarchMarch 1989,1989, oneone ofof thethe authorsauthors hashas visitedvisited Fig.Fig. I.1. TheThe ChimwadzuluChimwadzulu HillHill corundumcorundum occurrenceoccurrence inin thethe minemine atat thethe ChimwadzuluChimwadzulu HillHill (Figure(Figure 2)2) andand Malawi.Malawi.

© CopyrightCopyright thethe GemmologicalGemmological AssociationAssociation ISSNISSN:: 0022-1250022-12522 84 J. Gemm., 1990,22, 2

Fig. 2. One of the authors near the Chimwadzulu Hill (visible in the background) corundum occurrence in Malawi. published before for rubies. Hitherto, such high ranges hitherto measured for stones from Sri Lanka values of refractive indices were measured and and Tanzania, published only for orange corundums from the Umba Valley in Tanzania (Bank, 1970) and green Chemical features stones (Webster, 1983). The refractive indices, Chemical analyses of the trace elements chro- birefringence and specific gravity of the orange mium and iron were carried out with the micro- coloured corundums from Malawi are in the known probe. The results are shown in Table 1 together

Table 1. Physical and chemical features (in wt.%) of rubies and orange coloured corundums from Malawi.

colour An SG(g/cm3) Cr Fe ne reddish 1.760 1.768 0.008 3.96 0.08 0.38

pale red 1.761 1.769 0.008 3.97 0.20 0.32

red 1.765 1.773 0.008 3.99 0.29 0.53

red 1.766 1.775 0.009 4.02 0.48 0.51

intense red 1.768 1.778 0.010 4.04 0.79 0.50

dark red 1.770 1.780 0.010 4.05 1.55 0.64 orange 1.763 1.771 0.008 3.97 0.04 0.38

orange 1.765 1.773 0.008 3.98 0.11 0.74 J.J. Gemm.,Gemm., 1990,22,21990,22,2 8585

b

200 350 500 650 800 (nml

Fig.Fig. 3.3. AbsorptioAbsorptionn spectrspectraa ofof a reredd (a)(a) anandd a darkdark reredd (b(b)) corunducorundumm fromfrom Malawi.Malawi.

witwithh ththee valuevaluess ooff refractivrefractivee indices,indices, birefringencebirefringence lowestlowest physicaphysicall anandd chemicachemicall valuevaluess (n(nee = 1.760,1.760, non0 andand specificspecific gravity.gravity. FromFrom ththee reddisreddishh toto thethe darkdark = 1.768,1.768, CCrr = 0.08wt%0.08wt%,, FFee = 0.38wt%0.38wt%)) showsshows a reredd rubyruby a distincdistinctt increaseincrease ofof ththee chromiumchromium typicatypicall chromiumchromium spectruspectrumm witwithh twtwoo broabroadd absorp­absorp­ contentscontents fromfrom 0.00.088 toto 1.1.55wt.%C 55wt. %Crr isis visible.visible. SuchSuch tiotionn bandbandss iinn ththee greegreenn anandd violeviolett rangrangee anandd a highighh valuevaluess ofof 1.1.55wt%C 55wt%Crr werweree hitherthithertoo onlyonly mea­mea­ minimuminimumm iinn ththee blubluee regioregionn ooff ththee spectrumspectrum.. A suresuredd inin rubierubiess fromfrom Mogok/Burma,Mogok/Burma, LongidolLongido/ seconsecondd absorptioabsorptionn minimuminimumm iiss situatesituatedd iinn ththee UUVV TanzaniaTanzania andand Manyari/KenyaManyari/Kenya (Kuhlmann,(Kuhlmann, 1982)1982).. rangrangee atat 363nm363nm.. ThThee rubierubiess witwithh mediumediumm physicalphysical ThThee iroironn contentscontents ofof ththee rubierubiess frofromm MalawiMalawi varyvary andand chemicachemicall datdataa (n(nee = 1.761-1.7681.761-1.768,, nno0 = 1.7691.769-- betweebetweenn 0.30.322 andand 0.64wt%F0.64wt%Fee andand araree relativelrelativelyy highhigh 1.778,1.778, CrCr = 0.20-0.79wt%0.20-0.79wt%,, FFee = 0.32-0.50wt%)0.32-0.50wt%) comparecomparedd witwithh iroironn concentrationconcentrationss ooff rubierubiess fromfrom shoshoww aann increasincreasee ooff ththee Cr3+H -line-liness iinn ththee reredd rangrangee aatt otheotherr occurrencesoccurrences.. OnlOnlyy foforr somsomee stonestoness frofromm SrSrii 695,66695, 6699 anandd 659n659nmm anandd onlonlyy ononee CrH3+ -absorption-absorption­- LankaLanka,, Umba/TanzaniUmba/Tanzaniaa anandd GreenlanGreenlandd werweree com­com­ banbandd iinn ththee greegreenn regioregionn aatt 555n555nmm (Figur(Figuree 3a)3a).. parablparablee valuevaluess determinedeterminedd hitherthithertoo (Zwaan(Zwaan,, 19741974;; AdditionallAdditionallyy a decreasdecreasee ooff ththee absorptioabsorptionn minimumminimum KuhlmannKuhlmann,, 1982).1982). ThThee orangorangee colourecolouredd corundumscorundums iinn ththee blubluee rangrangee iiss visiblevisible.. ThiThiss decreasdecreasee anandd ththee frofromm MalawMalawii shoshoww chromiuchromiumm anandd iroironn contentscontents,, increasincreasee ooff ththee Cr-lineCr-liness iinn ththee reredd regioregionn araree duduee ttoo whicwhichh araree comparablcomparablee witwithh yellow-orangyellow-orangee ttoo ththee risrisee iinn ththee chromiuchromiumm contentcontent.. ThThee rubrubyy fromfrom orange-broworange-brownn specimenspecimenss frofromm ththee UmbUmbaa ValleValleyy iinn MalawMalawii witwithh ththee higheshighestt physicaphysicall anandd chemicachemicall TanzaniTanzaniaa (Schmetze(Schmetzerr et ai.,ai, 1982).1982). valuevaluess (n(nee = 1.7701.770,, nDo0 = 1.7801.780,, CrCr = 1.55wt%,1.55wt%, FeFe = 0.64wt%0.64wt%)) showshowss onlonlyy ththee sharsharpp Cr3+H -line-liness iinn ththee reredd SpectroscopicaSpectroscopicall featuresfeatures rangrangee ooff th thee spectruspectrumm witwithh maximmaximaa aatt 700,694,675700, 694, 675,, SpectroscopicaSpectroscopicall investigationinvestigationss werweree carriecarriedd outout 666699 anandd 659n659nmm (Figur(Figuree 3b)3b).. FroFromm orangorangee ttoo violeviolett a witwithh a PerkiPerkinn ElmeElmerr LambdLambdaa 9 SpectrophotometerSpectrophotometer completcompletee absorptioabsorptionn cacann bbee recognizerecognizedd iinn thithiss iinn ththee 800-200n800-200nmm rangerange.. OnlOnlyy ththee rubrubyy witwithh ththee samplesample.. 8686 J.J. Gemm.Gemm.,, 1990,22,21990, 22, 2

c: o :;:; u c: :;:; x w

200 350 500 650 800 (nm)

Fig.Fig. 4.4. AbsorptionAbsorption spectrumspectrum ofof anan orangeorange corundumcorundum fromfrom Malawi.Malawi.

TheThe orangeorange colouredcoloured corundumscorundums fromfrom MalawiMalawi prismatic,prismatic, doubledouble refractivrefractivee crystalcrystalss (Figure(Figure 5)S),, showshow absorptionabsorption spectraspectra withwith bandsbands ofof CrH3+ andand whichwhich sometimessometimes formform clusterclusterss (Figur(Figuree 6).6). TheseThese FeH3+ (Figure(Figure 4).4). SuchSuch a typetype ofof absorptionabsorption spectraspectra inclusionsinclusions werewere identifiedidentified bbyy microprobemicroprobe analysesanalyses waswas describeddescribed byby SchmetzerSchmetzer et al. (1982)(1982) withwith asas zircons.zircons. OtheOtherr doublydoubly refractivrefractivee mineraminerall inclu­inclu­ yellow-orangeyellow-orange toto orange-brownorange-brown corundumscorundums fromfrom sionssions werweree determinedeterminedd bbyy chemicalchemical analyseanalysess withwith thethe UmbaUmba ValleyValley inin Tanzania.Tanzania. CrH3+ causescauses a broadbroad thethe microprobemicroprobe asas anorthiteanorthite andand hornblendehornblende.. Orien­Orien­ absorptionabsorption bandband inin ththee greengreen rangerange withwith a maximummaximum tatedtated interbeddedinterbedded rutile-needlerutile-needless werweree observeobservedd inin atat SSSnm.555nm. BandsBands causedcaused byby FeH3+ areare situatedsituated atat 4S0,450, somesome stonesstones (Figur(Figuree 7)7).. MorMoree frequentfrequent isis fine 388388 andand 377nm377nm inin thethe blueblue andand violetviolet partpart ofof thethe distributeddistributed rutilrutilee dust,dust, interbeddedinterbedded alonalongg growthgrowth absorptionabsorption spectrum.spectrum. planesplanes ooff thethe corundumcorundum hoshostt (Figur(Figuree 8).8). Black,Black, opaqueopaque inclusionsinclusions werweree alsalsoo observeobservedd (Figure(Figure 9)9),, hiicroscopicalfeaturesMicroscopical features bubutt notnot identifieidentifiedd inin detaildetail,, alsalsoo somsomee flat, rounded,rounded, FineFine channels,channels, smallsmall blackblack crystals,crystals, shortshort rodsrods doubledouble refractivrefractivee crystalcrystalss (Figure(Figure 10)10).. (presumably(presumably ofof hornblende),hornblende), twinningtwinning planes,planes, heal­heal­ 2.2. Liquid inclusions inging fissures (containing(containing bothboth liquidliquid andand gas)gas) andand HealingHealing fissures anandd liquiliquidd feathersfeathers araree thethe mostmost colourcolour zoningzoning werewere describeddescribed asas inclusionsinclusions inin frequentfrequent inclusioninclusionss inin thethe corundumcorundumss investigated.investigated. corundumscorundums fromfrom MalawiMalawi byby RutlandRutland (1969).(1969). A TwoTwo differentdifferent typestypes ooff feathersfeathers werewere observedobserved.. OneOne remarkableremarkable three-phase-inclusionthree-phase-inclusion inin a yellowyellow consistsconsists ofof elongatedelongated,, mormoree oror lessless paralleparallell orien­orien­ corundumcorundum fromfrom thisthis localitylocality waswas mentionedmentioned byby tatedtated cavitiescavities (Figur(Figuree 11),11), containingcontaining twotwo inmiscibleinmiscible GrubessiGrubessi andand MarconMarcon (1986),(1986), a cavity,cavity, surroundedsurrounded liquidsliquids oror botbothh liquidliquid andand gasgas.. ThThee seconsecondd typetype isis byby fingerprint-likefingerprint-like healinghealing fissures,fissures, isis filled withwith a builtbuilt upup bbyy irregularlyirregularly shapedshaped cavitiescavities (Figure(Figure 12)12),, liquid,liquid, gasgas andand rutile-needles.rutile-needles. generallygenerally filled witwithh liquidliquid anandd gasgas.. MicroscopicalMicroscopical studiesstudies ofof thethe rubiesrubies andand orangeorange 3.3. Twinning lamellae lamellae and and growth growth structures structures colouredcoloured corundumscorundums fromfrom MalawiMalawi yieldedyielded threethree LamellarLamellar twinnintwinningg (Figure(Figure 13)13) wawass observedobserved inin generalgeneral groupsgroups ofof inclusions.inclusions. nearlynearly alalll rubierubiess anandd orangorangee corundumscorundums fromfrom 1.1. Mineral inclusionsinclusions Malawi.Malawi. ThThee twinningtwinning lamellaelamellae areare ofteoftenn orientatedorientated NearlyNearly allall corundumscorundums fromfrom MalawiMalawi investigatedinvestigated parallelparallel toto thethe threthreee rhombohedronrhombohedron planeplaness (Figure(Figure showshow enclosedenclosed crystalcrystal inclusions.inclusions. TheThe mostmost fre­fre­ 14)14) andand araree investeinvestedd witwithh thithinn holloholloww tubes,tubes, filled quentquent typetype ofof enclosedenclosed mineralsminerals areare rounded,rounded, withwith doublydoubly refractivrefractivee mineralmineral substance,substance, presum-presum- J. Gemm., 1990,22,2 87

Fig. 5. Ruby from Malawi enclosing rounded zircons. 40X. Fig. 6. Ruby from Malawi with clusters of rounded zircon inclusions. 50X.

Fig. 7. Orange corundum from Malawi showing a net of Fig. 8. Ruby from Malawi showing rutile dust, interbedded orientated rutile-needles. 15X. along growth planes of the corundum host. Darkfield. 10X.

Fig. 9. Orange corundum from Malawi with black, opaque Fig. 10. Pale red corundum from Malawi with flat, rounded, mineral inclusions. 40X. transparent, doubly refractive crystal inclusion. 35X. 88 J. Gemm., 1990, 22, 2

Fig. 11. Ruby from Malawi showing liquid feather, consisting Fig. 12. Ruby from Malawi with liquid feather, consisting of of elongated, more or less parallel orientated cavities, irregularly shaped cavities, generally filled with containing two inmiscible liquids or both liquid and liquid and gas. 35X. gas. 30X.

Fig. 13. Ruby from Malawi showing lamellar twinning. Cros­ Fig. 14. Ruby from Malawi with twinning lamellae orientated sed polars. 10X. parallel to the rhombohedral planes of the corundum host. Crossed polars. 15X.

Fig. 15. Ruby from Malawi with thin hollow tubes, filled with Fig. 16. Ruby from Malawi showing distinct colour zoning. doubly refractive mineral substance (boehmite?). 10X. 15X. J. Gemm., 1990, 22, 2 89 ably boehmite (Figure 15). Typical growth struc­ References tures showing hexagonal symmetry perpendicular Bank, H., 1979. Hochlichtbrechender orangefarbiger Korund to the c-axis of the corundum host crystal have been aus Tansania. Z. Dt. Gemmol. Ges., 19, 1-3. observed (Figure 16). In some stones the colour is Bank, H., Henn, U., 1988. Rubies worth cutting from Malawi. Gold + Silber, 3, 121-2. distributed along these growth planes. Such colour Bank, H. Henn, U., Lind, Th., 1988. Rubine aus Malawi. Z. Dt. zoning is sometimes visible by the naked eye. Gemmol. Ges., 37, 113-9. Bloomfield, K., 1958. The Chimwadzulu Hill ultrabasic body. Conclusions Transactions Geol. Soc. South Africa, Vol. LXI. Grubessi, O., Marcon, R., 1986. A peculiar inclusion in a yellow Production of corundum in the East African state corundum from Malawi. J.Gemm., 20, 163-5. Malawi started at the end of the fifties of this Kuhlmann, H., 1983. Emissionsspektralanalyse von natürlichen century, but for a long time nothing was reported und synthetischen Korunden, Beryllen und Chrysoberyllen. Heidelberg, Dissertation. about the occurrence and the mining. In 1988 red Rutland, E.H., 1969. Corundum from Malawy. J. Gemm., 11, and orange corundums were obtained from that 320-3. locality, sometimes showing fine gem quality. The Schmetzer, K., Bosshart, G., Hänni, H.A., 1982. Naturfarbene rubies enclose a remarkable variation of colour und behandelte gelbe und orange-braune Sapphire. Z. Dt. intensity from pale red to dark red. In relation to Gemmol. Ges., 31, 265-79. Webster, R., (Anderson, B.W.), 1983. Gems, Their Sources, that variation of colour intensity an alteration of the Descriptions and Identification, 4th Ed., Butterworths, physical characteristics such as refractive indices, London. birefringence and specific gravity was demons­ Zwaan, P.C., 1974. Garnet, corundum, and other gem minerals trated. The variation of the physical values is due to from Umba, Tanzania. Scripta Geol., 20, 1-41. the concentrations of the trace elements chromium and iron.

Acknowledgements Financial support was given by grants of the Wirtschaftsministerium des Landes Rheinland- Pfalz, FRG, within a project for applied research. [Manuscript received 20 May 1989.] 9090 J.J. GemmGemm..,, 19901990,22,,22,22

HET KASTEEL F.G.AHETHET KASTEELKASTEEL Threechang initialse your careethat rcould

ThThee GemmologicalGemmological recogniserecognisedd andand respectedrespected AssociatioAssociationn ofof GreatGreat bbyy companiescompanies andand BritaiBritainn hashas beenbeen activelyactively organisationsorganisations throughoutthroughout involveinvolvedd inin thethe ververyy thethe gemmologicalgemmological world. beginninbeginningg ofof GemmologyGemmology Indeed,Indeed, eacheach yearyear manymany of of aass anan independenindependentt thethemm investinvest inin thethe futurefuture byby sCiencsciencee.. sponsorinsponsoringg theirtheir O\vnown Today,Today, thethe AssociationAssociation candidatescandidates.. takestakes pridepride inin itsits TheThe GemmologicalGemmological internationainternationall reputationreputation asas Association'Association'ss coursecourse hashas a learnelearnedd societysociety beebeenn speciallyspecially compiledcompiled into into dedicatededicatedd toto ththee a seriesseries ofof teachingteaching modules modules promotiopromotionn ofof thathatt areare bothboth readablereadable andand gemmologicagemmologicall educationeducation lavishllavishlyy illustratedillustrated.. anandd ththee spreadspread ofof TogetherTogether theythey provideprovide aa gemmologicagemmologicall knowledge.knowledge. comprehensivcomprehensivee step-bystep-by-ste- ste~p guide to the fascinating TheThe AssociationAssociation''ss HET KASTEEL guide to the fascinating world of gemmology. And an covetecovetedd FellowshipFellowship isis a world of gemmology. And an HET KASTEEL opportunity to earn the marmarkk ofof excellenceexcellence only Gemnx)k)gk^ opportunity to earn the coveted initials FGA - bestowebestowedd uponupon individualsindividuals coveted initials FGA — ofGreat Britain Fellow of the Gemmological whwhoo successfullsuccessfullyy undertakundertakee of Great Britain Fellow of the Gemmological Association of Great Britain. ththee association'association'ss writtewrittenn Association of Great Britain. To find out more complete the coupon below and anandd practicapracticall examinationsexaminations coveringcovering all all aspectsaspects of of To find out more complete the coupon below and we will immediately forward the Association's gemmologygemmology asas a science.science. we will immediately forward the Association's Not surprisingly, this prestigious diploma is prospectus giving full details of this unique course. Not surprisingly, this prestigious diploma is prospectus giving full details of this unique course. ,,------Please complete and re[U rn lo: (;emmo l o~ i c;" Association Training Scheme, I~ l In PleasSa int eUu completnsta n'se lIouse and retur. C anr~v to :La Gemmologicane. Lundon EC~V8Alll Associatio. n'l etTrainin: UI ·72fi4:l74g Scheme , I I Saint Dunstans House, Carey' Lane, London EC2V 8AB. Tel: 01-726 4374 I Name I Name I Positio~~n : I Company I Company I Address I I Address I I &_ I ~------. Telephone------. --~ J.J. Gemm.,Gemm., 1990,22,21990,22,2 9911

TheThe diamonddiamond drilldrill usedused inin thethe CambayCambay beadbead industryindustry R. V. Karanth R.V. Karanth Department of Geology, MS University of Baroda, Vadodara-390002, India Department of Geology, MS University of Baroda, Vadodara-390002, India

AbstractAbstract ConstructionConstruction ofof boboww drilldrill A simplesimple butbut veryvery effectiveeffective diamond-tippeddiamond-tipped bowbow drilldrill ToTo constructconstruct a boboww drilldrill,, iitt requirerequiress neitheneitherr greatgreat constructedconstructed byby indigenousindigenous technologytechnology isis beingbeing usedused bbyy expertiseexpertise nonorr expensiveexpensive gadgets.gadgets. ButBut forfor thethe thethe CamCamba bayy lapidarylapidary toto perforateperforate toughtough andand hardhard silicasilica diamonddiamond bitsbits,, ththee drilldrill uniunitt cancan bbee constructedconstructed fromfrom beads.beads. ToTo startstart withwith a singlesingle diamonddiamond drilldrill isis usedused forfor thethe materialsmaterials throwthrownn outout aatt a junjunkk yardyard.. EveEvenn thethe markingmarking andand thenthen furtherfurther fullfull lengthlength drillingdrilling isis carriedcarried outout byby a doubledouble diamonddiamond bitbit driller.driller. EachEach beadbead isis diamonddiamond bitbitss useusedd araree nonott speciallyspecially splinteredsplintered oror perforateperforatedd fromfrom bothboth thethe endsends soso asas toto meet meet at at the the centre. centre . cut,cut, butbut thetheyy araree thethe discardeddiscarded rougroughh piecepiecess thathatt areare ConstructionConstruction ofof thethe primitive,primitive, yetyet efficient,efficient, bowbow drilldrill unfitunfit forfor jewellerjewelleryy purposespurposes.. A loolookk aatt ththee materialsmaterials unit;unit; intricaciesintricacies ofof thethe mechanismmechanism ofof singlesingle asas wellwell aass usedused forfor itsits constructioconstructionn cancan explaiexplainn ttoo a greatergreater doubledouble diamonddiamond bitbit drilldrill andand thethe resultantresultant featuresfeatures willwill extentextent howhow a beabeadd cacann bbee soldsold atat a fractiofractionn ooff a bebe discusseddiscussed inin thethe paper.paper. penny.penny. TheThe bowbow drilldrill consistsconsists ooff twtwoo maimainn unitunitss (Figure(Figure 1),1), viz.viz. (1)(1) ththee bow madmadee fromfrom a lonlongg bambobambooo stickstick measuringmeasuring aboutabout three-fourthsthree-fourths ofof a metrmetree anandd a IntroductionIntroduction loosely-tiedloosely-tied thicthickk stronstrongg strinstringg anandd (2)(2) thethe arrowarrow PerforationPerforation ofof hardhard andand toughtough stonesstones likelike chalce­chalce­ consistingconsisting ofof a woodewoodenn rorodd abouaboutt 12-14cm12-14cm long,long, donydony isis a highlyhighly difficultdifficult job.job. However,However, itit isis beingbeing 1cmlcm thickthick fixed withwith metalmetal stickssticks aatt eitheeitherr end.end. executedexecuted atat easeease byby thethe lapidarylapidary ofof CambayCambay withwith thethe GenerallyGenerally thethe metalmetal stickstick useusedd isis ththee steelsteel ribrib meantmeant helphelp ofof primitiveprimitive diamond-tippeddiamond-tipped bowbow drilldrill atat anan forfor holdingholding umbrellumbrellaa cloth.cloth. TheThe uppeupperr metametall sticstickk isis astonishingastonishing speed.speed. ItIt takestakes lessless thanthan a minuteminute forfor aboutabout Icmlcm longlong andand ththee lengtlengthh ooff ththee lowerlower oneone drillingdrilling a beadbead ofof oneone centimetrecentimetre diameter.diameter. dependsdepends oonn thethe lengthlength ooff ththee beabeadd ttoo bbee drilleddrilled CambayCambay (Khambhat:22°19'N(Khambhat:22°19'N andand 72°38'E)72°38'E) isis a (usually(usually 2-3cm long)long).. TheThe totopp ooff ththee drillindrillingg endend isis largelarge towntown inin westerwesternn India,India, situatedsituated atat thethe estuaryestuary providedprovided witwithh a diamondiamondd bit.bit. ofof MahiMahi RiverRiver whichwhich flows intointo thethe GulfGulf ofof Cambay.Cambay. ForFor perforating,perforating, ththee stringstring ofof ththee boboww isis tiedtied TheThe towntown isis knownknown forfor gemgem cuttingcutting forfor moremore thanthan aroundaround ththee drill-shafdrill-shaftt witwithh ononee looloopp anandd drivedrivenn toto twotwo thousandthousand years.years. ArchaeologicalArchaeological excavationsexcavations andand frofro bbyy oneone hanhandd whilwhilee ththee otherother hanhandd iiss busbusyy inin havhavee unearthedunearthed a largelarge numbernumber ofof ornamentalornamental beadsbeads pressinpressingg thethe drill-shaftdrill-shaft againstagainst ththee beadbead.. IInn orderorder toto processedprocessed inin thethe EarlyEarly HistoricHistoric timestimes (Mehta,(Mehta, protectprotect ththee palpalmm fromfrom thethe uppeupperr steelsteel rib,rib, a piecpiecee ooff 1968).1968). EvenEven todaytoday a majoritymajority ofof itsits populationpopulation isis coconutcoconut shelshelll isis kepkeptt inin betweenbetween.. TToo havhavee a betterbetter involvedinvolved inin gemgem cutting.cutting. gripgrip overover ththee bowbow,, thethe artisaartisann preferpreferss toto tietie thethe AccordingAccording toto JanakiJanaki (1972),(1972), CambayCambay waswas anan bow-stringbow-string arounaroundd hihiss forefingerforefinger witwithh oneone loop.loop. iJnportantimportant internationalinternational tradetrade centrecentre sincesince thethe 10th10th TyingTying thethe stringstring aroundaround hishis skilfulskilful indexindex finger alsoalso CenturyCentury ADAD fromfrom wherewhere gemstonesgemstones werewere amongamong thethe helpshelps inin producinproducingg subtlesubtle changeschanges inin ththee movemove­­ importantimportant itemsitems exported.exported. ArkellArkell (1937),(1937), PossehlPossehl mentsments ofof thethe drill-shaft.drill-shaft. (1981),(1981), FrancisFrancis (1982)(1982) andand KaranthKaranth (1988)(1988) havehave TheThe beadbead ttoo bbee perforateperforatedd iiss placeplacedd oonn a woodenwooden givengiven thethe detailsdetails ofof beadbead makingmaking inin Cambay.Cambay. platformplatform (Figure(Figure I).1). A slislitt isis provideprovidedd iinn thethe RecentlyRecently GorelickGorelick andand GwinnettGwinnett (1988)(1988) havehave platformplatform foforr holdinholdingg longerlonger beadbeadss iinn propeproperr positionposition attemptedattempted toto interpretinterpret thethe mechanismmechanism ofof drillingdrilling ofof atat thethe tiJnetime ooff boringboring.. TheThe slislitt iiss helheldd tightightt witwithh thethe beadsbeads withwith thethe helphelp ofof thethe scanningscanning electronelectron helphelp ofof a metalmetal ringring.. AtAt thethe timtimee ooff drillindrillingg watewaterr isis microscopemicroscope (SEM)(SEM) picturespictures ofof drilldrill holehole impress­impress­ mademade toto falfalll drodropp bbyy dropdrop oonn ththee beabeadd whicwhichh actactss asas a ions.ions. TheirTheir explanationsexplanations are,are, however,however, inadequate.inadequate. coolantcoolant asas welwelll asas lubricantlubricant.. ItIt isis quitequite appropriateappropriate toto TheThe presentpresent author,author, havinhavingg studiedstudied thethe CamCamba bayy mentionmention thethe wawayy watewaterr isis transported.transported. beadbead indu~tryindustry forfor nearlynearly a decade,decade, isis attemptingattempting toto TheThe earthenwareearthenware popott useusedd forfor holdinholdingg waterwater iiss givegive a detaileddetailed accountaccount ofof diamond-tippeddiamond-tipped drillingdrilling boredbored withwith a holholee andand a tubulatubularr earthenwareearthenware piecpiecee iiss carriedcarried outout byby thethe artisansartisans ofof CamCambay bay.. cementedcemented toto itit.. A metametall stickstick isis insertedinserted deepdeep intointo

© CopyrightCopyright thethe GemmologicalGemmological AssociationAssociation ISSN:ISSN: 0022-1250022-12522 92 J. Gemm., 1990, 22, 2

Fig. 1. Complete drilling unit: A - bow with string; B - drill shaft; C - bead; D - wooden platform; E - metal ring for tightening; F - earthen bowl for collecting mixture of silica powder and water; G - water transporting stick; H - cotton cloth; I - water pot; J - coconut shell. the tube with a piece of cotton cloth around it. Water opposite ends for marking. The single bit drill is creeps through the damp cloth and is eventually placed on the bead and rotated with the help of the transported along the stick and finally falls on the bow string. Initial play of the rotating drill shaft on bead. The cloth piece is also used in regulating the the bead results in a rather broader rim (Figure 3: flow of water by loosening or tightening it. Once compare A-B with C-D and E-F). The depth of the again the metal stick used here is the umbrella rib. depression seldom exceeds a millimetre or two. The It is interesting to note that almost invariably the main boring is performed by using the double bit pots used here are broken at the rim. Either the drill. Whilst drilling the scooped out powder from driller has picked up a broken pot discarded at the the bead falls out along with the thin flow of water junk yard or he has not bothered to replace it when that drops on the bead and this powder is then the rim is broken. The explanation given by a collected carefully in a bowl placed below the lapidary is 'whether broken or whole, it serves the platform. Not that the artisan is interested to purpose'. maintain cleanliness of his surroundings from the Drilling is executed in two steps, viz., (1) mark­ messy fluid that stains, but it has a special signifi­ ing and (2) full length drilling. Different drill points cance which will be described briefly in a later are used for these two purposes, namely single section. diamond bit driller and double diamond bit driller The most important part of the drilling operation respectively (Figure 2). The bead whether small or is, however, the position of the diamond bit placed long, is bored from both ends so as to meet at the at the drilling end. centre thus producing a continuous hole. To start with, the place for drilling is marked with a shallow depression (Gwinnett and Gorelick, Diamond bits (1988) prefer to call it a guide hole or starter hole) by Diamond bits used for drilling are of very small using a single diamond bit drill. Generally the bead dimensions, weighing about 5 cents/point/grains (1 is taken for drilling before the final step of carat =100 cents), i.e. 10mg. Bits with rugged polishing, so that marking the place for boring surface are prepared for boring. If the bit has a becomes easier on a rough ground surface. If the smooth surface, such as crystal face, it is made bead is already polished, it is again ground at uneven with the help of another diamond fragment. J.J. Gemm.,Gemm., 1990,22,21990, 22, 2 9393

(a) (c)

(d ) (b)

E

I I

I I I I I I I I I

F (e )

Fig.Fig. 2a.2a. SingleSingle diamonddiamond bitbit drilldrill witwithh diamonddiamond bibitt fixed inin thethe tiptip ofof thethe metalmetal stick.stick.

Fig.Fig. 2b.2b. DoubleDouble diamonddiamond bitbit drill:drill: A-A-BB - originaloriginal widthwidth ofof metametall stick;stick; CoDC-D - widtwidthh ofleadingof leading end;end; E-F -- effectiveeffective lengthlength thatthat cancan getget intointo drilleddrilled hole.hole.

Fig.2c.Fig. 2c. SketchSketch drawndrawn fromfrom siliconesilicone impessionimpession ofof drilldrill hole:hole: FigureFigure 1ala ofof GorelickGorelick andand Gwinnett,Gwinnett, 1988.1988.

Figs.2d.Figs. 2d. andand 2e2e Cross-sectionCross-section ofof holehole undeunderr drillingdrilling andand sketchsketch ofof drilldrill holholee impressionimpression respectively:respectively: V-groovedV- grooved sideside wallwall;; W - slopslopee ofof thethe leaolingleading edge;edge; X - deepestdeepest parpartt drilled;drilled; Y - centralcentral elevationelevation atat thethe leadingleading edgeedge showingshowing conchoidalconchoidal fracturefracture patternpattern;; Z­Z - scrapedscraped outout andand chippedchipped offoff fragmentsfragments fromfrom sideside walwalll andand thethe gapgap betweenbetween drilldrill bits.bits. 9494 J.J. Gemm.Gemm.,, 1990,22,21990,22,2

A 1..( >1 8 C'", 7\0

t:. ' A ,C [) B @'- .-

(a ) (b)

EI", ~Fr A IE ),8

(c)

( (l )

Fig.Fig. 3.3. PatternsPatterns producedproduced byby singlesingle bitbit (a,b)(a,b) andand doubledouble bitbit (c,d)(c,d) drillsdrills respectively:respectively: A-A·BB - widtwidthh ofof broadebroaderr depressiodepressionn createdcreated bbyy initialinitial playplay ofof markermarker drill;drill; CoDC-D - diameterdiameter ofof markermarker diamonddiamond bit;bit; E-FE-F - diameterdiameter ofof holholee createcreatedd bbyy doubledouble bibitt driller.driller. SketchSketch (e)(e) illustratingillustrating thethe widthwidth ofof thethe broaderbroader axisaxis ofof thethe doubledouble bitbit drilldrill (E-F(E-F)) anandd widtwidthh ofof ththee trimmetrimmedd metametall holderholder (G-H).(G-H). NoteNote thethe spacespace inin whichwhich cutcut beadbead fragmentsfragments collect.collect. J. Gemm., 1990, 22, 2 95

Interestingly no adhesive or soldering material is fractured central elevated portion is not seen in the used to fasten the diamond bit to the metal stick, beads drilled by copper rod and loose grit of emery but the artisan follows certain indigenously de­ (Figures 4a and 4b of Gwinnett and Gorelick, 1986). veloped methods. For the single bit marker, a On the contrary, such leading edge is characterized depression is carved at the tip of the holder by using by relatively smooth central elevation. Here the a pointed steel rod driven by the bow-string and the smoothness is entirely due to abrasive action of the diamond bit is then place in it. Further, rim of the loose grit of emery, but not due to the forced carved depression is pressed against diamond bit so chipping that the rotating diamond bits induce. that it gets fixed properly in the tip and will not fall Each groove in the side wall (Figures 2d and 2e) off in action (Figure 2a). In the case of the double bit represents one way movement of the bow, i.e. when point used for full length performation, initially the the bow is moved to one side, say left, the drill bits metal stick is trimmed with a steel file up to a length carve up to a particular depth, resulting in the that may enter the bead and the tip of it is flattened. development of a groove and again when it is further Two diamond fragments are placed in the depres­ pressed and moved to the right, the bead is further sions carved on either side of the flattened metal tip cut for some more depth resulting in another (Figure 2b). After placing, the drill bit is hit gently groove. The shaft rotates for at least 10-12 revolu­ but firmly by a thick metal or wooden piece so that tions in one run of the bow for drilling one groove it gets fixed in the metal holder. This action can length. If the movement is continuous in only one better be called pressing than hitting. During the direction, the grooves would be having helical act of pressing, the thick metal piece glides over pattern (either dextro or laevo) but not in a concen­ diamond bit and rim of the metal depression clasps tric pattern. diamond tightly. Diamond bits get eroded during the action of The single bit marker tip is more or less a cutting and usually last for drilling about 100 bead permanent arrangement, but in the case of the holes of 5cm length each. Enormous heat is pro­ double bit perforator, the diamond fragment gets duced during this process, both in the upper metal loosened and falls off after boring a few beads. The portion and the drilling end. When both the ends artisan can feel its detachment during rotation. are touched, immediately after drilling, the heat can However, the detached diamond bit seldom escapes be felt at the upper metal stick that touches the the alert eyes of the artisan who puts it back in the coconut shell, whereas heat felt in the drilling end is same way as explained earlier. The broader axis of considerably less because of the continuous supply the drilling tip is always maintained wider than the of coolant. A charring effect can be seen at the place metal stick that enters the bead, lest the metal stick where the metal rod pierces the shell. gets worn out or would not enter the drill hole, In this connection it is also worthwhile discussing (compare E-F with G-H in Figure 3e). Furth­ the fading of grooves in the leading edge that ermore, the gap produced at right angles to the Gwinnett and Gorelick (1988) have observed. Un­ longer axis of the leading end (Figure 3e) offers like the prominent and deeper grooves of the side space for collecting scooped out bead fragments wall, the faint grooves are formed by the uneven which pass through the space between the drilled surface of the cutting slopes of diamond bits. Since wall and trimmed metal holder. Thus, trimming of two such sloping rugged diamond bits are in action, the metal stick, flattening of the tip and arrange­ the grooves carved out by one may be eroded or ment of diamond bits are of the utmost importance. modified by the other simultaneously rotating bit Single bit drill is incapable of doing this job as no and thus the leading edge becomes more or less space is offered by it to displace the scooped smooth. Even if the grooves are present, they are material and proceed farther. very faint and shallow. Slope of the leading edge (Figures 2d and 2e) depends on the shape and position of the diamond Scooped out silica powder bits used. The conchoidal pattern in the central The drilled out silica powder is carefully collected elevation of leading edge (Figure 2e, sketch drawn in a bowl kept below the platform. The slit provided after Gorelick and Gwinnett's silicone impressions) in the platform ensures that powder suspended in can be explained by the following mechanism: water would not flow elsewhere and be lost, but it while diamond bits scrape out the sides, the central would fall directly into a bowl. The powder thus portion situated in the gap between two drill bits collected is processed further for use as an efficient remains unscratched. At the same time, the impact agent for polishing highly precious stones like ruby, of drill bits rotating around the gap forces the bead sapphire and emerald. The details of processing, portion to be chipped off (Figure 2d). Obviously, grain size analysis and polishing laps used have been when silica mineral is chipped off, conchoidal discussed elsewhere (Karanth, 1989). However, the pattern is obtained. Curiously enough, this kind of major objection against the Cambay bead is that in 9966 JJ.. Gemm.Gemm.,, 19901990,22,2, 22, 2 somsomee exampleexampless ththee holeholess drilledrilledd frofromm eitheeitherr sidsidee araree AcknowledgementAcknowledgementss offseoffsett anandd barelbarelyy touctouchh eaceachh other'other'ss sidsidee wallwallss HelHelpp ooff ththee experexpertt lapidarylapidary,, MMrr VinoVinodd PatePatell ooff resultinresultingg iinn a crookecrookedd passagepassage.. DrivinDrivingg a strinstringg CambaCam bayy iinn providinprovidingg valuablvaluablee informatioinformationn iiss gratefullygratefully througthroughh sucsuchh perforatioperforationn becomebecomess exceedinglexceedinglyy difdif­­ acknowledgedacknowledged.. ficult. ThThee rewarrewardd ooff ththee precioupreciouss silicsilicaa powdepowderr by-producby-productt iiss ththee maimainn reasoreasonn foforr ththee CambaCambayy lapidary not going for modern ultrasonic perforator, lapidary not going for modern ultrasonic perforator, ReferenceReferencess though the latter does the job of drilling more though the latter does the job of drilling more ArkellArkell,, A.J.A.J.,, 19361936.. CambaCambayy anandd ththee beabeadd tradetrade.. Antiquity, 1010,, efficientlefficientlyy producinproducingg a continuoucontinuouss anandd eleganelegantt holehole.. 292-305292-305.. A couplcouplee ooff ultrasoniultrasonicc perforatorperforatorss installeinstalledd a fewfew FrancisFrancis,, PetePeterr Jr.Jr.,, 19821982.. IndianIndian agate beads. LapiLapiss RoutRoutee BooksBooks,, yearyearss bacbackk havhavee beebeenn mormoree oorr leslesss ignoreignoredd bbyy ththee 51pp51 pp.. lapidaries of Cambay. GwinnettGwinnett,, A.J.A.J.,, GorelickGorelick,, L.L.,, 19861986.. EvidencEvidencee foforr ususee ooff a lapidaries of Cambay. diamondiamondd drildrilll foforr beabeadd makinmakingg iinn SrSrii LankLankaa (700-100(700-10000 AD)AD).. Scanning Electron Microscopy IIII,, 473-7473-7.. TimTimee taketakenn foforr markinmarkingg anandd perforatingperforating GwinnettGwinnett,, AA.J.,. J., Gorelick,Gorelick, L.,L., 1988.1988. A possiblepossible lapidarylapidary trainingtraining MarkinMarkingg witwithh a singlsinglee drildrilll bibitt taketakess onlonlyy abouaboutt a piecpiecee frofromm ArikameduArikamedu,, IndiaIndia.. Archaeomaterals, 22,187-93., 187-93. couple of seconds, whereas the time taken for full GorelickGorelick,, L.L.,, GwinnettGwinnett,, A.J.A.J.,, 19881988.. DiamondDiamondss frofromm IndiIndiaa ttoo couple of seconds, whereas the time taken for full RomRomee anandd beyondbeyond.. Amer.Amer.Jour. Jour. Archaeol., 9292,, 547-52547-52.. lengtlengthh drillindrillingg varievariess witwithh ththee lengtlengthh ooff ththee beadbead.. AAss JanakiJ anaki,, V.A.V.A.,, 19801980.. ThThee CommercCommercee ooff CambaCam bayy frofromm ththee earliesearliestt PossehPossehll (1981(1981)) hahass statedstated,, drillindrillingg a 5mSmmm beabeadd taketakess perioperiodd ttoo ththee NineteentNineteenthh CenturyCentury.. M.S. Univ. Geography, 2200 secondsecondss anandd a 4.5c4.Scmm beabeadd taketakess abouaboutt 7 minutesminutes.. Series 1010,, 131355 pppp.. OOnn aann averagaveragee abouaboutt 5500 beadbeadss ooff Scm5cm lengtlengthh cacann bebe KaranthKaranth,, R.V.R.V.,, 19881988.. SilicSilicaa beabeadd industrindustryy iinn CambayCambay,, Gujarat,Gujarat, IndiaIndia.Jour.. Jour. Geol. Soc. India, 3131,426-31., 426-31. boreboredd iinn ononee dadayy bbyy a singlsinglee artisanartisan.. LongeLongerr beadsbeads KaranthKaranth,, R.V.R.V.,, 1989.1989. Cambay'Cambay'ss indigenouindigenouss silicsilicaa powdepowderr forfor taktakee mormoree timtimee peperr millimetrmillimetree aass carcaree hahass ttoo bbee takentaken polishing ruby, ruby, sapphire sapphire and and emerald. emerald. Journal Journal of Gemmology, of Gemmo­ ttoo keekeepp ththee drildrilll rorodd iinn propeproperr alignmenalignmentt witwithh thethe logy, 2121,, 497-9497-9.. axiaxiss ooff ththee beabeadd oorr elselsee ththee metametall rorodd bendbendss andand Mehta, R.N., R.N., 1968. 1968. Excavation Excavation at Nagara. at Nagara. M.S. M.S.Univ. BarodaUniv. Baroda Archaeol.Archaeo!. Series, 1010,, 181181 pppp.. consequentlconsequentlyy mighmightt eveevenn breabreakk oorr ththee holholee getsgets PossehlPossehl,, G.L.G.L.,, 1981.1981. CambaCam bayy bead-makingbead-making.. Expedition, 2323,, misalignedmisaligned.. 39-4739-47..

ConclusioConclusionn PerforatinPerforatingg toughtough,, harhardd silicsilicaa beadbeadss iiss a specialspecial­­ iseisedd arartt anandd involveinvolvess manmanyy intricatintricatee mechanismsmechanisms whicwhichh ththee CambaCam bayy lapidarlapidaryy hahass masteredmastered.. Indeed,Indeed, oftenoften threadingthreading thethe beabeadd withwith a crookedcrooked holehole isis difficult,difficult, neverthelessnevertheless oneone woulwouldd notnot mindmind whenwhen oneone seessees thethe efforteffort involvedinvolved inin producingproducing it.it. Prob­Prob­ ablyably crookednesscrookedness ofof thethe perforationperforation addsadds valuevalue toto suchsuch beabeadd asas itit iiss somethingsomething oddodd andand hencehence special.special. AfteAfterr all,all, notnot allall beadbeadss areare blessedblessed withwith crookedcrooked holesholes!! [[ManuscriptManuscript receivedreceived 28 November 1989]1989] J.J. Gemm.,Gemm., 1990,22,21990,22,2 9797

ReflectionsReflections onon reflectivityreflectivity PeterG.Peter G. Read, C.Eng., MIEE, FGA, Dia.Dip.Dia.Dip.

BournemouthBournemouth

Acting asas tutortutor in in the the Association's Association's correspondence correspond­ cancan alsoalso bbee useusedd asas a meansmeans ofof estimatingestimating thethe RIRI ofof a ence courses,courses, andand helpinghelping toto runrun variousvarious prepara­prepara­ gemgem bbyy ththee immersionimmersion andand ththee BeckeBecke LineLine tiontion coursescourses forfor thethe Association'sAssociation's PreliminaryPreliminary andand methodsmethods.. DiplomaDiploma examinationsexaminations hashas mademade meme realizerealize thatthat thethe TheThe thirthirdd linklink isis withwith thethe reflectivitreflectivityy metemeterr whichwhich connectingconnecting linkslinks betweebetweenn somesome ofof thethe interestinginteresting dependsdepends onon thethe FresnelFresnel relationshiprelationship betweebetweenn reflec­reflec­ phenomena in in gemmology gemmology are are often often overlooked. overlooked. tivitytivity (lustre)(lustre) andand refractivrefractivee indexindex forfor itsits operation.operation. WhileWhile mostmost ofof usus areare wellwell awareaware ofof ththee useuse ofof AlthougAlthoughh notnot capablecapable ofof givinggiving readingsreadings witwithh thethe immersionimmersion techniquestechniques iinn microscopymicroscopy,, havehave occa­occa­ samesame degreedegree ofof precisionprecision asas a refractometerefractometerr andand sionallysionally beebeenn inconveniencedinconvenienced bbyy ththee disappearancedisappearance beingbeing muchmuch mormoree dependentdependent onon ththee cleanlinesscleanliness andand ofof a gemstonegemstone inin a heavyheavy liquid,liquid, andand areare quitequite conditioncondition ofof a gem'sgem's surface,surface, ththee reflectivityreflectivity metermeter familiarfamiliar witwithh thethe reflectivitreflectivityy meter,meter, thethe connection,connection, hashas thethe bibigg advantageadvantage ofof beingbeing ableable toto identifyidentify particularlparticularlyy atat thethe studentstudent level,level, maymay nonott havhavee beenbeen diamonddiamond andand itsits highighh RIRI simulants.simulants. mademade betweenbetween thesethese practicalitiespracticalities andand thethe vitalvital AsAs a gemgem instrumentinstrument itit hahass a longlong historyhistory.. TheThe relationshiprelationship whicwhichh linkslinks themthem together.together. firstfirst devicedevice ofof thithiss kinkindd forfor gemstonegemstone identificationidentification ThisThis relationshirelationshipp isis thethe oneone whichwhich existsexists betweenbetween waswas developeddeveloped inin 19591959 bbyy L.c.L.C. Trumper2,Trumper2, whowho waswas reflectivityreflectivity andand refractiverefractive indexindex whichwhich (for(for anan awardedawarded a ResearchResearch DiplomaDiploma bbyy thethe GemmologicalGemmological isotropicisotropic mineraminerall withwith thethe incidentincident lightlight atat normalnormal AssociatioAssociationn forfor hihiss thesisthesis oonn ththee measurementmeasurement ooff RIRI toto ititss reflectingreflecting surface*)surface*) isis quantifiedquantified inin thethe byby reflectionreflection.. HisHis instrumentinstrument tooktook ththee formform ofof anan 1 simplifiedsimplified versionversion ofof Fresnel'sFresnel's equationequations :_- opticaloptical comparatorcomparator inin whichwhich thethe intensityintensity ofof reflec­reflec­ ReflectivityReflectivity (ratio(ratio ofof reflectedreflected toto incidentincident lightlight tiotionn fromfrom a gem'sgem's surfacesurface wawass visuallyvisually matchedmatched intensity)intensity) = (n-Ail(n+A)2(n-A)2/(n+A)2 againstagainst a calibratedcalibrated andand manuallymanually adjustableadjustable sourcesource WhereWhere n = refractivrefractivee indexindex ofof gemstone.gemstone. ofof illumination.illumination. However,However, becausbecausee itit was tootoo com­com­ A = refractiverefractive indexindex ofof surroundingsurrounding mediummedium pleplexx foforr economiceconomic manufacturemanufacture itit wawass notnot exploitedexploited (for(for airair = 11)) commercially.commercially. FoForr exampleexample,, expressedexpressed asas a percentage:­percentage :- TheThe adventadvent ofof thethe low-costlow-cost reflectivity metemeterr hadhad reflectivitreflectivityy ofof diamonddiamond = 1717%% ttoo awaitawait ththee introductionintroduction ofof ththee miniaturminiaturee light­light- reflectivitreflectivityy ofof quartzquartz = 4.54.5%% emittingemitting diodediode andand itsits associatedassociated photo-detectorphoto-detector.. AsAs WhenWhen a gemgem iiss immersedimmersed inin a liquidliquid whosewhose RIRI isis thethe mostmost efficientefficient LEDLED availableavailable emittedemitted itsits peakpeak closeclose toto thatthat ofof thethe gem,gem, thethe valuevalue ofof A inin thethe energyenergy iinn thethe nearnear infra-redinfra-red atat aroundaround 830nm,830nm, thisthis numeratonumeratorr sectionsection ofof thethe FresnelFresnel equationequation alsoalso favouredfavoured thethe instrument'sinstrument's abilityability toto separateseparate approachesapproaches thatthat ofof n,n, andand thethe resultanresultantt reflectivityreflectivity diamonddiamond fromfrom strontiumstrontium titanate.titanate. DespiteDespite thethe factfact fromfrom thethe surfacesurface ofof thethe gemgem fallsfalls towardstowards zero.zero. InIn thatthat atat thethe sodiumsodium wavelengthwavelength ofof 589.3nm589.3nm thethe thethe casecase ofof ththee immersionimmersion microscopmicroscopee thithiss reducesreduces refractivrefractivee indicesindices ofof thesethese twotwo materialsmaterials areare veryvery thethe amountamount ofof unwanteunwantedd surfacesurface reflectionsreflections fromfrom close,close, atat 830nm830nm thethe largelarge differencedifference inin theirtheir disper­disper­ ththee facetsfacets ofof a polishedpolished gemgem andand allowsallows moremore lightlight toto sionssions makesmakes theirtheir effectiveeffective RIsRIs easilyeasily separatedseparated byby enterenter ththee stone.stone. TheThe samesame circumstancecircumstance explainsexplains thethe reflectivityreflectivity meter.meter. whywhy a gemstonegemstone sometimessometimes 'disappears''disappears' inin a heavyheavy SinceSince thethe introductiointroductionn inin 19751975 ofof thethe first com­com­ 3 4 liquidliquid whosewhose RIRI isis closeclose toto thatthat ofof thethe gem,gem, andand thisthis mercialmercial reflectivityreflectivity meter ',4 (the(the 'Gemeter' -- FigureFigure 1),1), therethere havehave beenbeen manymany versionsversions ofof varyingvarying sophistication.sophistication. PerhapsPerhaps thethe simplestsimplest ofof thesethese waswas 5 * ForFor absoluteabsolute measurement.measurement. (When(When makingmaking comparativecomparative measurementsmeasurements thethe HannemanHanneman 'Jeweler's'Jeweler's Eye'S.Eye' . OOff ththee moremore com­com­ usinusingg a gemmologicalgemmological reflectivitreflectivityy metermeter,, ththee relationshiprelationship isis sufficientlysufficiently plexplex models,models, therethere havhavee beenbeen threethree whicwhichh illustrateillustrate closeclose toto identifyidentify anisotropicanisotropic andand isotropicisotropic gems.gems. ForFor practicapracticall reasonreasonss ofof construction,construction, tht"the incidentincident angleangle toto ththee normanormall inin mosmostt gemgem reflectivityreflectivity thethe extentextent toto whicwhichh a simplesimple conceptconcept cancan bebe metersmeters isis aroundaround 2020 degrees.)degrees.) developed.developed.

© CopyrightCopyright thethe GemmologicalGemmological AssociationAssociation |IISS~:0022-1252 ISSN: 0022-1252 9898 J.J. Gemm.,Gemm., 1990,221990, 22,, 22

FigFig.. 1.1. GemeterGemeter,, ththee firsfirstt commerciacommerciall reflectivitreflectivityy metermeter.. ThThee totopp sectiosectionn ooff itss metemeterr scalscalee iiss calibratecalibratedd iinn RRII valuevaluess 1.1.44 ttoo 2.72.7.. PrintePrintedd letterletterss oonn ththee lowelowerr portioportionn ooff ththee scalscalee indicatindicatee ththee metemeterr readingss foforr somsomee ooff ththee principaprincipall gemgemss ((QQ foforr quartzquartz,, Z foforr zirconzircon,, D foforr diamonddiamond,, etc.)etc. )..

ThThee first ooff thesthesee wawass ththe'e 'Marti Martinn GeGemm Analyser,6Analyser'6 (Figur(Figuree 22)) whicwhichh introduceintroducedd pulsepulsedd infra-reinfra-redd illuillu­­ mination/detectiomination/detectionn (Figur(Figuree 33)) aass a meansmeans ofof combat­combat­ iningg ththee effeceffectt ooff spuriouspuriouss lighlightt enterinenteringg ththee bacbackk ooff ththee stonstonee undeunderr testtest.. ThThee nexnextt majomajorr innovatioinnovationn wawass ththee ''Gemexpert'Gemexpert,7 (Figur(Figuree 44)) whicwhichh useusedd a microcomputemicrocomputerr ttoo storstoree ththee reflectivitiereflectivitiess ooff gemgemss anandd identifidentifyy thethemm bbyy namnamee oonn aann alpha-numerialpha-numericc LCLCDD displadisplayy panelpanel.. MMyy owownn contributiocontributionn ttoo ththee developmendevelopmentt ooff ththee reflectivitreflectivityy metemeterr wawass ththee RayneRaynerr 'DiamondScan,g'DiamondScan'8 (Figur(Figuree 4)4).. ThiThiss iiss a reflectivity probprobee usinusingg aann LEDLED displadisplayy foforr ththee identificatioidentificationn ooff diamondiamondd anandd ititss simulantssimulants,, andand,, aass fafarr aass I aamm awareaware,, ththee onlonlyy versioversionn ttoo ususee fibre opticopticss ttoo achievachievee incidenincidentt illuminatioilluminationn aatt normanormall ttoo ththee gem'gem'ss surface.surface. ThThee refractometerrefractometer,, whicwhichh exploitexploitss ththee criticacriticall anglanglee resultinresultingg frofromm ththee opticaopticall contaccontactt betweebetweenn ththee surfacsurfacee ooff ititss prisprismm anandd thathatt ooff ththee gegemm undeunderr testtest,, alsalsoo reliereliess partlpartlyy oonn reflectioreflectionn foforr ititss operationoperation,, aass iitt iiss ththee lighlightt strikinstrikingg thithiss surfacsurfacee aatt angleangless greategreaterr Fig. 2. ThThee MartiMartinn GeGemm AnalyseAnalyserr wawass ththee firsfirstt reflectivityreflectivity than the critical angle that is reflected back into the metemeterr ttoo ususee pulsepulsedd infra-reinfra-redd illuminatioilluminationn whicwhichh than the critical angle that is reflected back into the minimizeminimizedd ththee effeceffectt ooff ambienambientt lighlightt enterinenteringg prisprismm ttoo illuminatilluminatee ththee brighbrightt sectiosectionn ooff ththee scalescale.. througthroughh ththee rearearr ooff ththee stonstonee undeunderr testtest.. HoweverHowever,, thertheree araree twtwoo otheotherr practicapracticall aspectaspectss ooff ththee J. Gemm., 1990,22,2 99

.^^Gemstone i f

Amplifier Voltage Pulse LED 1 ->- •rJPQ»- and Pulse Regulator Generator Driver | Demodulator \iLEDi J + t Detector Y T 9V battery Level ] y Meter f 5 Volt Ref. Stabilizer | Driver

Y Meter

4 rr 77 vl Fig. 3. Block diagram of Martin Gem Analyser circuit, showing a method of pulsing the infra-red LED and decoding the resultant reflectivity signal from the photo-detector. critical angle of a gemstone, both of which are connected with reflection. The most important of these concerns the lapid­ ary and diamond polisher, who determines the angles and proportions of a gemstone to achieve an optimum total internal reflection of light rays entering its crown facets. The critical angle of a gem is related to its refractive index as follows :- Critical angle = the angle whose sine = RI of rarer medium RI of denser medium With air as the rare medium, critical angle = arc. sine 1 RI of gemstone

For diamond the critical angle is 24.43 degrees (compared with 40.33 degrees for quartz). Rays of light entering the crown facets to meet the pavilion facets at angles greater than this will be totally internally reflected (rays 1 in Figure 6), but those rays meeting the pavilion facets at less than this angle will be refracted out of the pavilion (ray 2 in Figure 6). However, if the pavilion facets of a gemstone become coated with grease (or, as frequently hap­ pens, with soap!) the RI of the medium surrounding the pavilion increases, typically to 1.6. Diamond, with its affinity for grease, is particularly vulnerable in this respect and such a coating would result in an increase in the critical angle to around 41 degrees, with the consequent loss of rays through the pavilion facets and a reduction in the stone's overall brilliance. Fig. 4. The GfD Gemexpert contained a microprocessor To complete this brief survey of inter-related which enabled it to display the name of the gem reflectivity phenomena, I will mention one that is of under test on its LCD panel. 101000 JJ.. Gemm.Gemm.,, 1990,22,1990,22,22

FigFig.. 55.. ThThee RayneRaynerr DiamondScaDiamondScann useusedd fibrfibree opticopticss ttoo producproducee aann 0.75mO.75mmm diametediameterr infra-reinfra-redd beabeamm aatt normanormall ttoo ththee testestt surfacesurface.. FoForr larglargee stonestoness iitt coulcouldd bbee fittefittedd witwithh aann enendd cacapp whicwhichh provideprovidedd aa flatflat referencreferencee faceface..

Fig.. 77.. ThThee lateslatestt versioversionn ooff a Brewster-anglBrewster-anglee refractometerefractometerr developedevelopedd bbyy ththee authorauthor.. ThThee instrumeninstrumentt useusess a smalsmalll polarizepolarizedd laserlaser.. ThThee reflectereflectedd rarayy frofromm ththee gegemm undeunderr testestt iiss displayedisplayedd oonn ththee nulnulll metemeterr iinn ththee centrecentre;; ththee laselaserr beabeamm anglanglee iiss adjusteadjustedd (b(byy meanmeanss ooff ththee knurleknurledd edgedgee controcontroll aatt ththee totopp leftleft)) foforr aa minimuminimumm readingreading,, anandd ththee resultanresultantt RRII readinreadingg iiss displayedisplayedd oonn ththee LELEDD panepanell metemeterr oonn ththee rightright.. JJ.. Gemm.,Gemm., 1990,22,21990, 22,2 101011

,,/2 }l /' A /DIAMOND I 34°30' ~---T------r'--~ ; ,1 =24.43° I

, 2~ f

I ft--l \ 'VI

\ \ QUARTZ

Fig.Fig. 6.6. ShowingShowing hohoww thethe brilliancbrilliancee ofof a polishedpolished gemgem (in(in termsterms ofof totaltotal internalinternal reflection)reflection) dependsdepends onon itsits cutcut whicwhichh inin turnturn isis dictateddictated bbyy thethe criticalcritical angleangle ofof thethe gem.gem. RayRay 2 inin ththee toptop illustrationillustration indicatesindicates howhow lightlight raysrays enteringentering thethe conecone ofof thethe criticalcritical angleangle areare refractedrefracted outout ofof thethe pavilion.pavilion. TheThe lowerlower illustrationillustration showsshows howhow thethe pavilionpavilion ofof a quartzquartz gemgem hahass toto bebe cutcut deeperdeeper toto achieveachieve a similarsimilar totaltotal internainternall reflectioreflectionn (for(for rarayy I)1) asas shownshown inin thethe diamonddiamond aboveabove it.it. 101022 JJ.. Gemm.Gemm.,, 19901990,22,2, 22, 2

particulaparticularr interesinterestt ttoo mmee - ththee Brewster-anglBrewster-anglee ooff finallfinallyy ablablee ttoo translattranslatee mmyy simplsimplee opticaopticall modemodell 12 polarisationpolarisation.. ThiThiss iiss ththee anglanglee aatt whicwhichh onlonlyy thosthosee intintoo aann elecronielecronicc version 12.. rayrayss whoswhosee planplanee ooff polarizatiopolarizationn coincidecoincidess witwithh ththee WitWithh ththee assistancassistancee f ththee RayneRaynerr OpticaOpticall ComCom­­ planplanee ooff ththee reflectinreflectingg surfacsurfacee obeobeyy ththee lawlawss ooff panypany,, thithiss lateslatestt examplexamplee ooff ththee exploitatioexploitationn ooff reflectionreflection.. reflectioreflectionn iinn ththee aiaidd ooff gemmologgemmologyy hahass beebeenn dede­­ AAnn historihistoricc applicatioapplicationn ooff thithiss phenomenonphenomenon velopevelopedd intintoo aann instrumeninstrumentt witwithh aann RRII measurinmeasuringg occurreoccurredd iinn aann earlearlyy polariscopepolariscope,, whicwhichh useusedd a platplatee rangrangee ooff 1.1.44 ttoo 3.3.33 anandd witwithh ththee abilitabilityy ttoo measurmeasuree ooff glasglasss tiltetiltedd aatt ththee Brewster-anglBrewster-anglee ttoo produceproduce doubldoublee refractiorefractionn frofromm 0.00.011 upwardupwardss (Figur(Figuree 7)7).. polarizepolarizedd lightlight.. Naturally-occurrinNaturally-occurringg polarizepolarizedd lighlightt iiss alsalsoo propro­­ duceducedd aass ththee resulresultt ooff ththee Brewster-anglBrewster-anglee ooff polar­polar­ izationization.. IItt iiss generategeneratedd frofromm horizontahorizontall surfacessurfaces sucsuchh aass waterwater,, anandd ititss glarglaree cacann bbee reducereducedd bbyy meanmeanss ooff vertically-polarizevertically-polarizedd susunn glassesglasses.. OOff mormoree relevancrelevancee ttoo gemmologgemmologyy iiss ththee lalaww ReferenceReferencess relating the Brewster-angle of polarization of a 1I.. HannemanHanneman,, W.w.,, 19781978.. ThThee rolrolee ooff reflectivitreflectivityy iinn gemmologygemmology.. relating the Brewster-angle of polarization of a Journal of Gemmology, XVIXVI,, 22,109-21., 109-21. materiamateriall ttoo ititss refractivrefractivee indexindex.. Brewster'Brewster'ss lalaww statestatess 22.. TrumperTrumper,, L.C.L.e.,, 19591959.. MeasuremenMeasurementt ooff refractivrefractivee indeindexx bbyy thathatt completcompletee polarizatiopolarizationn ooff lighlightt reflectereflectedd fromfrom reflectionreflection.. Journal of Gemmology, VIIVII,, 22,129., 129. ththee surfacsurfacee ooff a densedenserr mediumediumm occuroccurss whewhenn iitt iiss 33.. WebsterWebster,, R.R.,, 19751975.. ReporReportt oonn a neneww electronielectronicc refractometer.refractometer. normal (i.e., at right angles) to its associated Journal of Gemmology, XIVXIV,, 66,, 281-8281-8.. normal (i.e., at right angles) to its associated 44.. WebsterWebster,, R.R.,, 1975.1975. A reporreportt oonn ththee GemeteGemeterr '75'75.. Journal of refracterefractedd rarayy iinn thathatt mediummedium.. FroFromm thisthis,, thethe Gemmology, XIVXIV,, 88,, 378-81.378-81. relationshirelationshipp betweebetweenn a material'material'ss Brewster-angleBrewster-angle 55.. WebsterWebs~er,, R.R.,, 1976.1976. ThThee 'Jeweler''Jeweler'ss Eye,Eye,:: A reportreport.. Journal of anandd ititss RRII cacann bbee formulateformulated:-d :- Gemmology, XVXV,, 11,, 19-2419-24.. 66.. ReadRead,, P.G.P.G.,, 1978.1978. ThThee MartiMartinn MGA-MGA-I1 GeGemm AnalyserAnalyser:: A RRII ooff reflectinreflectingg materiamateriall = tatann ooff ititss Brewster-angleBrewster-angle reportreport.. Journal of Gemmology, XVIXVI,, 1I,, 50-450-4.. ThThee firsfirstt persopersonn ttoo makmakee ususee ooff thithiss relationshiprelationship 77.. ReadRead,, EG.P.G.,, 19841984.. ThThee GfGfDD GemexpertGemexpert.. Gem InstrumentInstrument ttoo measurmeasuree ththee refractivrefractivee indeindexx ooff a gemstongemstonee wawass Digest,Vol.1 Vol.l,, No.5No.5,, 66-766-7.. 99 B.B.w.W Anderson ,, whwhoo iinn 19411941 useusedd ththee newlynewly 88.. ReadRead,, P.G.P.G.,, 1985.1985. ThThee RayneRaynerr DiamondScaDiamondScann --A A testestt report.report. introduceintroducedd PolaroiPolaroidd filtefilterr sheesheett ttoo confirconfirmm thethe Journal of Gemmology, XIXXIX,, 66,, 521,7521,7.. 99.. AndersonAnderson,, B.W.B.w.,, 19411941.. BrewsteBrewsterr angleangle.. Gemmologist, X,X, practicalitpracticalityy ooff thithiss methodmethod.. Thirty-eighThirty-eightt yearyearss laterlater 61-361-3.. 1lO0 I totooo builbuiltt anan experimentalexperimental refractometer usingusing 10. Read,Read, P.G., P.G., 1979. 1979. An An experimental experimental Brewster-angle Brewster-angle refractometer, refracto­ ththee Brewster-anglBrewster-anglee phenomenophenomenonn (a(ann eveevenn simplersimpler Journalmeter, of Gemmology,Journal of Gemmology, XVI, 8, 537-41. XVI, 8, 537-41. instrumentinstrument wawass proposeproposedd inin ththee samesame yeayearr bbyy R.M.R.M. 1111.. YuYu,, R.M.R.M.,, 19791979.. ThThee Brewster-anglBrewster-anglee refractometerrefractometer.. Gems&Gems & 11 Gemology, Winter,Winter, 245-7.245-7. YuYu ofof HongHong KongKong Universityll).University ). WhenWhen a relativelyrelatively 12. Read, P.G., P.G., 1988. 1988. Further Further development development of the ofBrewster-angle the Brewster­ low-coslow-costt polarizepolarizedd laserlaser becambecamee availableavailable I waswas refractometer.angle refractometer. Journal of Gemmology,Journal of Gemmology, XXI, 1, 36-9. XXI, 1,36-9. J. Gemm., 1990, 22,2 103

Gemmological Abstracts

AKIZUKI, A., 1989. Growth structure and crystal stone was reçut to 31.4 ct (32.24 metric carats) to symmetry of grossular garnets from the Jeffrey eliminate some internal black spots. After a compli­ mine, Asbestos, Quebec, Canada. American cated history, described in detail by the author (and Mineralogist, 74, 859-64,4 figs. updated in this article subsequent to the publication Orange garnets from the Jeffrey mine, Asbestos, of his book Famous diamonds in 1987), a 31.5 ct pink Quebec, Canada, may show non-cubic symmetry diamond believed to be the Agra was purchased for and birefringence. Study of the ordered atomic 82,000 francs at a Paris auction in 1909. It is now in arrangements show that the symmetry is monocli- private ownership. P. G. R. nic. Some colourless and green grossular crystals show orthorhombic symmetry though some parts BANK, H., HENN, U., 1989. Changierender Taaffeit are strained. These findings do not apply to all aus Sri Lanka. (Colour-changing taaffeite from grossular garnets from this locality. M.O'D. Sri Lanka.) Zeitschrift der Deutschen Gemmologis- chen Gesellschaft, 38, 2/3, 89-94, 5 figs (1 in ARANYAKANENI, P., 1989. Amphoe Bo Phloi. A colour), graph, bibl. New Thai sapphire deposit. Wahroongai News, The taaffeite from Sri Lanka weighed 12.23 ct 23,7,7-12. and showed a colour change from reddish to blue. Reprinted from The Great Mine of Thailand, RI 1.724-1.720, DR 0.004, SG 3.61. The absorption published by SAP Mining Co. Ltd, this is a long spectrum showed typical bands caused by Fe2+ and account of a new deposit on a hillside about 40km is characterized by absorption minima in the red from Kanchanaburi which is itself about 130km and blue range and an intense maximum in the west of Bangkok. Sapphires are found in basalt, green. E.S. some of which is columnar. Alluvial deposits con­ centrate the sapphire but are often found as hard BANK, H., HENN, U., 1989. Farbloser, klar dur­ conglomerates. The paper is concerned almost chsichtiger, geschliffener Sellait aus Brasilien. entirely with geological provenance and the occurr­ (Colourless, clear transparent, cut sellaite from ence of the sapphire-bearing load and gives little Brazil.) Zeitschrift der Deutschen Gemmologischen indication of quality, sizes and quantities found. Gesellschaft, 38,4,143-5,2 figs, bibl. But deposits are apparently mined with some The faceted, cut, colourless, transparent speci­ enthusiasm so the find is probably an important one mens were said to come from the Brumado mine in in an area already known for its sapphires. [On a Bahia, Brazil. RI 1.378-1.390, DR 0.12, SG 3.15. personal note, abstractor is fairly certain that Kan­ Microscopic examination showed multiple growth chanaburi relates closely to 'Kanburi', one of the tubes, flat, irregularly shaped cavities with liquid many terrible prisoner-of-war camps on the route of gaseous filling, as well as three-phase inclusions. the Burma/Siam railway along the River Kwai. He Sellaite is a magnesium fluoride. E. S. missed those camps by the skin of his teeth in 1943 and was shipped up to northern Japan instead. But a BANK, H., HENN, U., 1989. Gemmologische Kur­ great many good friends died on that appalling zinformationen. Schleifwürdiger, transparenter railway.] R.K.M. blauer Saphir aus Kenia. Zeitschrift der Deutschen Gemmologischen Gesellschaft, 38, 2/3,105-6, bibl. BALFOUR, I., 1989. Famous diamonds of the world, Describes a cuttable, transparent, blue sapphire XLII. The Agra. Indiaqua, 54, (1989/3), 171-5. from Lodwar on Lake Turkana in Kenya. There The Agra diamond, a light pink cushion-cut was lamellar twinning and distinct growth struc­ stone weighing 41.25ct, was said to have been worn tures. E.S. in the turban of the first Mogul ruler, Babur. The city of Agra, from which the gem takes its name, BANK, H., HENN U., 1989. Gemmologische Kur­ was founded by the Mogul emperors as their capital zinformationen. Ein ungewöhnlicher Granat aus and is the site of the Taj Mahal. Ostafrika. Zeitschrift der Deutschen Gemmologis­ In 1844 a diamond thought to be the Agra was chen Gesellschaft, 38, 4,161-4, 2 figs, bibl. acquired by the Duke of Brunswick. Later, this Describes an unusual orange-brown garnet from 104 J. Gemm., 1990, 22, 2

East Africa weighing 64.47 ct. RI 1.739, SG 3.74, 100,19-21,4 figs (2 in colour). found to be a pyrope-spessartine mixed crystal Cathodoluminescence was able to distinguish a containing grossular as well as almandine. E. S. De Beérs synthetic diamond from natural diamond, YAG and zircon, giving a strong characteristic BANK, H., HENN, U., PETSCH, E., 1989. Gemmolo- emission line at 520nm. M. O'D. gische Kurzinformationen. Spinelle aus dem Umba-Tal, Tansania. Zeitschrift der Deutschen BIRMINGHAM, J.C., 1989. Mourning jewellery. Au­ Gemmologischen Gesellschaft, 38, 4, 166-8, 1 flg., stralian Gemmologist, 17, 3, 82-4,4 figs. bibl. A brief history of memorial jewellery through the Deals with spinels from the Umba Valley in ages. R.K.M. Tanzania. The spinels were of pink, red, orangish- red and bluish-violet colour, RI 1.713-1.718, SG BORELLI, A., 1988. A brief note on problematical between 3.54-3.69. Colouring matter determined by yellow-brown diamond. La Gemmologia, 13, 3/4, spectroscopy. E.S. 27-32,6 figs in colour. A brilliant-cut stone of yellow to yellowish-brown BANK, H., HENN, IL, SCHMIDT, S.TH., 1989. colour with zoning along possible crystal faces was Gemmologische Kurzinformationen. Hochlich- identified as natural diamond. No trace was seen of tbrechender Rubin aus Malawi. Zeitschrift der absorption in the 594nm region though lines were Deutschen Gemmologischen Gesellschaft, 38, 2/3, observed at 478 and 415.5nm, though the latter was 106-8,1 table, bibl. difficult to detect. Under LWUV the stone showed a Describes a ruby from Malawi, RI 1.770-1.780, strong bluish-white to nearly white fluorescence DR 0.01, SG 4.05. The stone was found about 50 and a persistent yellow phosphorescence. Under miles south of Lake Nyasa. E. S. SWUV the stone gave a medium intensity bluish- white to pale yellow. M. O' D. BANK, H., PLATEN, H.V., AMARASINGHE, A.G.B., 1989. Gemmologische Kurzinformationen. BRACEWELL, H., 1989. Wave Hill prehnite. Austra­ Saphirblauer, durchsichtiger Sapphirin aus Sri lian Gemmologist, 17,4,127-8, 7 figs in colour. Lanka. Zeitschrift der Deutschen Gemmologischen Gives details of prehnite bearing areas near Gesellschaft, 38, 2/3,103-5,4 tables, bibl. Kalkaring, south of Darwin. Colours white, Describes a sapphire-blue, transparent stone through green, yellowish-green and yellow; SG from Sri Lanka which was identified as sapphirine. about 2.87; RI 1.614-1.637, quite variable; H 6-7; RI 1.704-1.711. E.S. fluorescence under LUV dull brown; absorption band vague at 440nm; some material is facetable. BEATTIE, R., 1989. Personalities behind the gem R.K.M. world: Kokichi Mikimoto 1858-1956 [1954?]. Wahroongai News, 23,6, 27-30. BROWN, G., 1989. Dayboro variscite. Australian A concise biography based on Eunson's book The Gemmologist, 17, 3, 98-100,4 figs in colour. Pearl King, about the first successful producer of Once thought to be bluish-green turquoise, this spherical cultured pearls. Born in humble circumst­ hydrated aluminium phosphate is now identified as ances only five years after Commodore Peary landed variscite, found at nicely named Mt Scrubbytop, in Japan, forcing that country out of the feudal Queensland, it occurs in thin veins and, more rarely, system and into the modern world, Mikimoto by in nodules in a blackish chert. H 4, SG 2.4, RI 1.56, sheer hard work and dedicated purpose throughout all appreciably lower than turquoise constants. his long life eventually achieved what has to be seen Chalky green fluorescence in LUV. No absorption as a major advance in the world of gems. R. K.M. bands. R.K.M.

BERK, M., 1989. New from New England. Lapidary BROWN, G., 1989. Kauri gum revisited. Wahroongai Journal, 43, 8,44-8,2 figs in colour. News, 23,10,21-8,4 figs and sketches. Amethyst has recently been found at locations in An excellent account of a comparatively unconsi­ Maine and New Hampshire, USA. M.O'D. dered New Zealand gem material, based at least in part on the work of the GANZ study group. Found BILLE, C, CHAPOULE, R., DORBES, J., SCHVOER- only in the north of North Island, the gum can be ER, M., 1989. Reconnaissance d'un diamant de either fossil, possibly of great age, or recent. Kauri synthèse De Beers parmi d'autres gemmes grâce trees are still thriving so can be bled for the gum a la cathodoluminescence. (Recognition of a De even today. This paper covers history, mode of Beers synthetic diamond from others thanks to occurrence, prospecting and 'mining', plus gemmo- cathodoluminescence.) Revue de Gemmologie, logical and other testing. SG 1.03 to 1.09, increasing J. Gemm., 1990, 22, 2 105 with age; RI 1.54; young gum is more soluble in BUZAS, Z., 1989. Interessante Einschlüsse in mex- ether than amber, but this decreases with age of the icanischem Opal. (Interesting inclusions in Mex­ gem; alcohol is perhaps a better solvent but again it ican opal.) Lapis, 14,10,27-8,2 figs in colour. will not distinguish ancient fossil kauri gum Quartz crystals are reported as inclusions in opal (perhaps 30m years old) from amber (similar age?); from Queretaro, Mexico. M. O'D. UV fluorescence is variable and very similar to that of amber. Crazed surface is much more common in CAMPBELL, I.C.C., 1989. Visual structural differ­ young kauri gum, but can occur in amber. General ences between elephant ivory, bone and vegetable conclusion is that it would be hard to distinguish ivory. South African Gemmologist, 3, 3, 20-7, 17 between the better fossil qualities of kauri gum and figs (11 in colour). amber. R.K.M. Scrapings of elephant ivory, bovine bone, veget­ able ivory and walrus tusk are examined and BROWN, G., BRACEWELL, H., 1989. Yundamindera photomicrographs illustrated. M. O'D. 'fire'opal. Australian Gemmologist, 17, 3, 101-3, 8 figs in colour. CAMPBELL, I.C.C., KLEYENSTÜBER, A.S.E., 1989. Yellowish-brown to amber common opal is found An alexandrite of apparent Hematita origin. at this attractively named semi-desert locality in South African Gemmologist, 3, 4, 8-11, 7 figs in Western Australia. SG about 2, RI 1.42, inclusions: colour. flow structures and dendrites, no play of colour, but An alexandrite reported to have come from the an attractive gem which 'deserves greater promo­ Hematita deposits in Brazil showed quartz and tion'. R.K.M. kaolin traces on electron microprobe analysis, sug­ gested a pegmatitic origin. The traces appear to BROWN, G., KELLY, S.M.B., SNOW, J., 1989. have come from inclusions breaking the surface. Russian hydrothermally-grown emerald. Austra­ M.O'D. lian Gemmologist, 17, 3,103-5,6 figs in colour. These synthetic emeralds are generally eye-clean CASSEDANNE, J.P., 1989. Diamonds in Brazil. but microscope reveals characteristic phenakite Mineralogical Record, 20, 5, 325-36,16 figs. based 'dagger' inclusions, partly healed cracks, The paper gives a history of the working and wavey growth patterning, occasional brassy metallic discovery of diamond in Brazil. By the end of the needles. Colour dark bluish-green; Chelsea filter 1700s Brazil was the world's leading diamond gives green; inert to UV; dichroism blue and green. producer, only yielding this place to South Africa in RI 1.571-1.579, DR 0.009, SG 2.76. Investigators the nineteenth century. Typical crystal forms are report that 680nm fluorescent doublet was no seen illustrated and there is a map of the diamond- [but it is listed in their table of properties]. Physical bearing areas. A table lists some of the major properties overlap those of natural emerald, so diamonds found in Brazil. M. O'D. inclusions are vital for identification. R. K. M. CASSEDANNE, J.-P., 1989. Découverte d'un BROWN, G., SNOW, J., 1989. Some observations on nouveau gîte d'émeraude. Revue de Gemmologie, helenite. Australian Gemmologist, 17, 3, 88-90, 5 98, 3-4, 7 figs (lin colour). figs in colour. Emerald is reported from a ravine called Riacho do Mamao, Fazenda Paioli (Capoeirana), in the An American olive-green glass said to be made municipality of Nova Era. The area is about 90km from 'pure' volcanic ash from the Mt St Helen's ENE from Belo Horizonte, Minas Gerais, Brazil. eruption in Washington State in 1980, some speci­ The established Belmont emerald mine is only mens from pure ash and some from ash 'diluted' about 10km distant from the new site. Stones with glass. Discs of the latter are cut from rods spun examined have SG 2.660, RI 1.577-1.584, with DR from highly viscous glass and retain marked con­ 0.007. There is no luminescence nor radioactivity. centric lamellae. SG 2.448, RI 1.508, grains of Pleochroism is greenish-blue/pale yellowish-green possible ash, bubbles and swirls were seen. R. K. M. and crystals consisting of broken prisms with signs of corrosion and frequently colour-zoned are found BURT, D.M., 1989. Vector representation of tour­ in schists close to pegmatite bodies. Two-phase maline compositions. American Mineralogist, 74, inclusions are reported but no mineral inclusions. 826-39, 21 figs. Instead of the traditional triangular method of M.O'D. representing tourmaline group composition, a vec­ tor method is proposed. This method has been used CASSEDANNE, J., 1989. Maricota, un nouveau gise­ successfully for the mica and amphibole mineral ment d'andalousite (Minas Gerais, Brésil). (Mari­ groups. M.O'D. cota, a new location for andalusite, Minas Gérais, 106 J. Gemm., 1990, 22, 2

Brazil.) Revue de Gemmologie, 100, 7-9, 6 figs in ties of gem emerald very similar in quality and colour. properties to stones from the Belmont mine 10 Green and rose-coloured andalusite is reported kilometres away. Most are light bluish-green in from a new location named Maricota in the Fazenda colour and some best described as green beryl. RI of Lageadâo, 40km north-east of Araçuai and 10km ten stones tested varied slightly around 1.577- west of Itinga, in the north-east of the Brazilian state 1.583. SG about 2.71. Some had been oiled. No red of Minas Gérais. The colour of faceted stones is or pink through emerald filter; two-and three-phase olive-green to yellowish-green and rose colour. inclusions seen, but unlike the jagged-edged cavi­ Pleochroism gives a pale olive green to a violet-red. ties in Colombian stones; biotite and calcite or The material is found in quartz. M.O'D. dolomite were identified; inclusions plentiful but fewer than in the Belmont stones and identical in COZAR, J.S., 1989. Determination de rasgos de type. Chemical composition was also consistent tratamiento, en topacios azules irradiados, por with those stones. R. K. M. espectroscopia gamma de alta resolution. (Deter­ mination of signs of treatment in irradiated blue EPSTEIN, D.S., 1989. Brazilian trio. Lapidary Jour­ topaz, using high-resolution gamma-ray spec­ nal, 43, 8, 22-8,4 figs in colour. troscopy.) Boletin del Instituto Gemmologogico Three amethyst-producing areas in Brazil are Espanol, 31, 8-18, 7 figs in colour. described, Maraba, Pau D'Arco and Rio Grande do Gamma-ray spectroscopy is at present the only Sul. Differences in the product are discussed. way to detect treatment of gemstones by ionizing M.O'D. radiations, if these have stimulated activation. De­ tails of the methodology are given. M.O'D. FRAZIER, S., FRAZIER, A., 1989. Phantoms. Lapid­ ary Journal, 43,9,66-80, 3 figs in colour. CROWNINGSHIELD, R., 1989. Grading the Hope The development of phantom crystals, mostly in diamond. Gems& Gemology, 25, 2,91-4, 5 figsi n quartz, is discussed. M.O'D. colour. A modern assessment of the world's most famous FRAZIER, S., FRAZIER, A., 1989. Inter-Agate. blue diamond by a team from the New York Lab Lapidary Journal, 43,5,28-42,5 figs (3 in colour). found it to be a 'fancy dark greyish-blue', weighing The agate deposits in the Idar-Oberstein area of 45.52 ct, of VVS clarity. No fluorescence in LUV West Germany are described with a note on their and possibly faint fluorescence in SUV, followed by strong red phosphorescence after SUV. R.K.M. FRITSCH, E., CONNER, L., KOIVULA, J.I., 1989. A preliminary gemologkal study of synthetic di­ DAWIDOWICZ, T., 1989. L'influence des inclusions amond thin films. Gems& Gemology, 25,2,84-90, sur la structure cristalline. (The influence of 7 figs in colour. inclusions on crystal structure.) Revue de Gemmo­ The past two decades have seen diamond or logie, 100, 23-4. diamond-like carbon (DLC) films grown onto The paper gives a brief account of crystalline surfaces by a chemical vapour deposition technique defects and their influence on spectrographic test­ from carbo-hydrate gases. DCLs seem easier and it ing methods. M. O'D. is thought such films might be used on gems to increase resistance to wear. They are mostly poly- DUBOIS-FOURNIER, J., LENAIN, B., LE MAGUER, crystalline but Sumitomo have experimented with D., 1989. La microspectrofluorescence et ses producing single crystal diamond on synthetic applications en gemmologie. (Microspectrof­ diamond [to increase size?. luorescence and its gemmological applications.) Other possible gemmological uses to improve Revue de Gemmologie, 100, 15-18, 10 figs (1 in diamond simulants, or add a diamond surface to colour). softer gems are discussed. The films seem to be Microspectrofluorescence is used to detect ele­ detectable with little trouble, and so far there do not ments in gemstones - in this case, in corundum. appear to be any commercially diamond-coated Fluorescence spectra are measured and illustrated gems on the market. R. K. M. and compared with those given by the Verneuil product. M.O'D. FRYER, C.W., (ED.), CROWNINGSHIELD, R., HUR- EPSTEIN, D.S., 1989. The Capoeirana emerald WIT, K.N., KANE, R.E., HARGETT, D., 1989. deposit near Nova Era, Minas Gérais, Brazil. Gem Trade Lab notes. Gems & Gemology, 25, 3, Gemsäf Gemology, 25, 3,150-8,12 figs in colour. 171-6,15 figs in colour. Discovered in 1988 this mine is yielding quanti­ 'Black onyx' seal stones from Hong Kong were J. Gemm., 1990, 22, 2 107 identified as glass; SG 2.51 and RI 1.53 suggest an oured black and grey cultured pearls grown in the effort to get near to chalcedony constants; H 5.5 to 6 large black-lipped oyster P Margaritifera, in the was low. lagoons of the Tuomotu Archipelago and the Gam- A 2.68 ct 'Old Mine' diamond with a concave bier Islands; in |French Polynesia. These large pearls table facet probably dated from 1910 when J.L.Go- have better lustre and iridescence than most natural nard patented the cut, to 'increase brilliancy'; it black pearls, and supercede black-stained cultured does reduce table reflection. A flat six-sided lozenge pearls which dominated this market until the of diamond had a central Latin cross machine- 1960s. P Margaritifera was overfished for shell last engraved and painted black; today the engraving century and natural black pearls became rare. would be simpler by laser. Facet edges of diamonds Today the oyster is farmed and cosseted, and the in a bracelet were abraded, evidentally what used to shell a bi-product of a multi-million dollar produc­ be known as 'paper-worn'. [This happened when a tion of fine pearls. Largest recorded specimen, stone-paper of diamonds was carried around in the 20.8mm diameter, is illustrated. pocket of a dealer for a long time; the diamonds did Bead nucleus and mantle tissue are inserted in the did the damage, not the paper.] A diamond brooch gonad (reproductive gland) of the oyster rather than had five dead iridescent green beetles set in it for in the mantle. Bead sometimes ejected and a 'keshi' added colour [a minor Victorian fashion]. (tissue-nucleated) black pearl may result. R. K. M. Necklace pearls chipped at one end of the drill-hole had been drilled through from the oppo­ GOUPIL, V., 1989. Les évangéliaires précieux. (The site end, instead of half way from each side. A precious gospels.) Revue de Gemmologie, 98, yellowish 'demi-pearP is illustrated, one end nac­ 11-19, 8 figs (6 in colour). reous, the other dull and pitted; why is not known. Discusses the jewelled bindings of 9th-10th cen­ Pinkish cultured pearls often show traces of dye tury versions of the Gospels. M.O'D. around the string hole; one is illustrated with a red clot alongside the hole. GRIFFIN, W.L., COUSENS, D.R., RYAN, CG., SIE, A star ruby illustrated is thought to be an early S.H. SUTER, G.F., 1989. Ni in chrome pyrope synthetic one and resembles a purplish-red natural garnets: a new geothermometer. Contributions to star stone; strings of minute gas bubbles looking Mineralogy and Petrology, 103, 199-202, 2 figs. like silk, and curved striae were seen. A tanzanite The positioning of nickel between chrome had an unexplained iridescent coating which did pyrope and olivine found in garnet-peridotite xeno- not affect tanzanite RIs. It was easily removed by an liths from kimberlites is found to be strongly ink eraser. [Hair lacquer deposited accidentally temperature-dependent and allows an estimation of while holding hair in place with the ring hand? Such the temperature of formation for single pyrope coatings usually come off with paint stripper!] grains such as those found as diamond inclusions. R.K.M. M.O'D. HÄNNI, H.A., 1989. Les feldspaths. (The feld­ GENDRON, F., 1989. Le jade en Meso-Amérique, spars.) Revue de Gemmologie, 101,19-20, 3 figs in symbole de pureté et de vie. (Jade in Central colour. America, symbol of purity and of life.) Revue de A brief introduction to the ornamental varieties Gemmologie, 98, 5-10, 6 figs (3 in colour). of the feldspar mineral group. M.O'D. The article gives an historical review of the uses of jade in the civilizations of Central America. Useful names and categories are distinguished. HÄNNI, H.A., 1989. Irisierendes natürliches Glas M.O'D. aus Mexiko. (Iridescent natural glass from Mex­ ico.) Zeitschrift der Deutschen Gemmologischen GODOVIKOV, A.A., BULGAK, L.V., 1989. (Fers- Gesellschaft, 38, 2/3, 51-62, 9 figs (2 in colour), 2 man.) Lapis, 14, 10, 11-17, 11 figs (8 in colour). tables, bibl. [In Russian.] An English version of this paper appeared in The collections of the A.E. Fersman Mineralogic- Journal ofGemmology, 21,8,488-95. E. S. al Museum in Moscow are described. Among the specimens illustrated are outstanding examples of HÄNNI, H.A., WEIBEL, M., 1989. Ursache des emerald and alexandrite. M. O'D. Katzenaugen-Effekts bei erhitzten Zirkonen aus Sri Lanka. (Cause of cat's-eye effect in heated GOEBEL, M., DIRLAM, D.M., 1989. Polynesian zircons from Sri Lanka.) Zeitschrift der Deutschen black pearls. Gems& Gemology, 25, 3,130-48, 23 Gemmologischen Gesellschaft, 38, 2/3, 95-101, 5 figs in colour. figs (2 in colour), bibl. Superbly illustrated account of naturally col­ After heat treatment, certain zircons from Sri 108 J. Gemm., 1990, 22, 2

Lanka showed a cat's-eye effect. The oriented HOCHLEITNER, R., 1989. Die Sonderausstellung inclusions which caused the chatoyancy are very des Fersman-Museums in München. (Special fine fissures crystallographically orientated parallel exhibition of the Fersman Museum in Munich.) to the c-axis, apparently in the (100) and (010) Lapis, 14, 12,25-7,6 figs (4 in colour). planes. Prismatic crystals were found in the centre Fine specimens from the Fersman Mineralogical of the disc-shaped fissures (diameter approximately Museum in Moscow on exhibition in Munich 5 microns), probably thermally decomposed apa­ included a red crystal of topaz from the Sanarka tite. E.S. River, Ural Mountains and two specimens from Mursinka, a blue topaz and a greenish-yellow beryl. HARDER, H., 1990. Spinell-attraktive, aber wenig M.O'D. bekannte Edelstine. (Spinel, attractive but little- known gemstone.) Aufschluss, 41,13-25, 7 figsi n HODGKINSON, A., 1989. Visual optics. Australian colour. Gemmologist, 17,4,137-8,4 figs in colour. The gem variety of spinel is less well-known than A brief résumé of Hodgkinson's direct vision its beauty warrants. The paper gives physical, testing as applied to diamond and some of its chemical and geological details of the spinel miner­ imitations, a skill calling for careful assessment of als, grouping the red stones according to their tiny spectra which needs to be used with caution. resemblance to ruby, pyrope and almandine. Blue R.K.M. spinel is compared to sapphire and some stones are compared to padparadscha. M.O'D. HOLZHEY, G., 1989. Untersuchung einer Opal- Imitation. (Investigation of an opal imitation.) HENN, U., BANK, H., BANK, F.H., 1989. Gemmo- Zeitschrift der Deutschen Gemmologischen Gesell­ logische Kurzinformationen. Orangefarbene schaft, 38, 4, 139-42, 4 figs (3 in colour), 1 table, Korunde aus Malawi. Zeitschrift der Deutschen bibl. Gemmologischen Gesellschaft, 38, 4, 164-6, 1 fig., The stone investigated was of unknown origin, a bibl. cabochon weighing 0.48 ct, 10 x 7 mm. It did not A note on orange coloured corundums from look polished, but probably pressed or cast. The Malawi. RI 1.763-1.773, DR 0.008, SG 3.97-3.98. colourful stone was found to be glass, but could not Lamellar twinning, healing cracks, and double be identified with any previously known imitation. refractive, rounded inclusions were observed. E. S. E.S.

HICKS, W.H., 1989. Editorial appreciation. Austra­ HUGHES, R.W., 1989. Talkin' 'bout gem-testing lian Gemmologist, 17,4,139,1 fig. instruments. Australian Gemmologist, 17, 4, 159- Bill Hicks illustrates a photo-copying attachment 64. supplied by Jack Snow in answer to a dire editorial A long and rather flippant diatribe which attacks need. R.K.M. in humorous terms several instrument manufactur­ ers, either disguised by a pseudonym or named, for Hiss, D.A., 1989. Geuda transforms Sri Lanka's bad design, unreliable construction and other off­ 'City of gems'. Jewelers' Circular Keystone, Octo­ ences. I find myself puzzled that having found one ber 1989,244-7, 5 figs in colour. table spectrometer quite unsatisfactory Mr Hughes The geuda sapphire industry in which colourless apparently went on and requested three more of corundum is heated to give a fine blue has revived them. some of the fortunes of Sri Lanka's gem merchants. In the matter of spares, he says 'The frequency of M.O'D. bulb failure will be in direct proportion to the HLAING, T., 1989. The characteristics of Burmese importance of that bulb, and in inverse proportion spinel. Australian Gemmologist, 17, 3,84-7, 3 figs. to the ease of getting spares. Those bulbs which fail Part of a thesis which made a detailed study of most often will be located in totally inaccessible spinel from the Mogok area. Notes that Burma is locations within the instrument, and will be exotic now called Myanmar [which will take some getting items containing radon gas encased in a hollowed used to!]. R.K.M. out taaffeite chamber, utilizing the pubic hair of a now-extinct homosexual Amazonian flea as the HOCHLEITNER, R., 1989. Blauer Euklas aus Zim­ filament. The bulb is available only from an obscure babwe. (Blue euclase from Zimbabwe.) Lapis, 14, black magic shop in Burundi, and no, they don't 10,24-7, 7 figs (5 in colour). accept American Express.'- and more in that vein. A sapphire-blue variety of euclase is reported This is patently fiction and serves no real purpose if from south west of Miami in Zimbabwe, Central this gentleman has genuine complaints about in­ Africa. The mineral occurs in a pegmatite. M. O'D. strument design or supply. J. Gemm., 1990, 22, 2 109

[I am left wondering whether this long and This edition of the magazine is a memorial to Jack amusing paper is intended to be taken seriously, or Snow, one of the most active exponents of gemmolo- whether it has been written simply as a humorous gy in Australia for many years, who died last June. exercise. If the former, then it does itself a disservice Ms Kelly describes Jack's dedicated tuition when in including the fictitious invention extracted.] she had problems with this rather difficult instru­ More is promised. R. K. M. ment. R.K.M.

HUNSTIGER, C, 1989. Darstellung und Vergleich KOIVULA, J.I., 1989. Geofingerprints. Lapidary primärer Rubinvorkommen in metamorphen Journal, 43,6, 20-35, 6 figs in colour. Muttergesteinen. Pétrographie und Phasenpetro- An introduction to the study and classification of logie. Teil I. (Description and comparison of inclusions in gemstones, with a list of references. primary ruby occurrences in metamorphic rock. M.O'D. Petrography and phase petrology. Part I.) Zeits­ chrift der Deutschen Gemmologischen Gesellschaft, KELLY, S.M.B., BROWN, G., 1989. Synthetic peric- 38,4,113-38, 8 figs (3 in colour) 8 tables, bibl. lase. Australian Gemmologist, 17, 3, 90-2, 5 figs, The formation of ruby requires relative accu­ some in colour. mulation of A1202 compared to SiC>2 plus some Offered as 'natural sapphire', this material had H chromium to produce the red colour. During 5.5 and cubic cleavage, SG 3.57, RI 1.73, single and metamorphism corundum is formed from diaspore, an included bubble. Identified as the magnesium or can be changed from muscovite or margarite into oxide, periclase, and had been manufactured in feldspar + vapour + corundum. This article deals Austria. After some months polished surfaces be­ with rubies in amphibolites: Fiskenaesset in Green­ came dulled by hydration which gave a whitish land, Kittilae in Finnish Lapland, Valle d'Arbedo in efflorescence, probably brucite. R. K. M. Switzerland and also north of Locarno in Switzer­ land, Chantel in France, Longido in Tanzania and KOIVULA, J.I., 1989. The hidden beauties of gem- the Harts Range in Australia. The mineral analysis stones:-Artistry through the microscope. Austra­ of corundum carrying amphibolites are compared. lian Gemmologist, 17,4,139-42,10 figs in colour. E.S. Some quite remarkable pictures of gem surfaces and inclusions contributed by one of the greatest KAMMERLING, R.C., KOIVULA, J. I., 1989. Thermal specialist photographers of such things as a photo­ alteration of inclusions in 'rutilated' topaz. Gems essay in memory of Jack Snow. R. K.M. & Gemology, 25, 3,165-7, 3 figs in colour. Colourless faceted topaz with acicular inclusions KOIVULA, J.I., FRITSCH, E., 1989. The growth of has been offered as 'rutilated'. Needles identified as Brazil-twinned synthetic quartz and the potential dislocation channels stained with limonite. Heat for synthetic amethyst twinned on the Brazil law. altered the yellowish-brown limonite to dark red Gems& Gemology, 25, 3,159-64, 8 figs in colour. hematite and inclusions became more prominent. Natural amethyst is interpenetrantly twinned on The dark red colour is regarded as proof of heat what is known as the Brazil law, which is evinced by treatment. R.K.M. interrupted spectral rings seen between crossed polarizers, a feature which has been regarded as KARWOWSKI, L., DORDA, J., 1986. The mineral- proof of natural origin. But quartz is being synthe­ forming environment of 'Marmaros diamonds'. sized with this twinned habit and test can no longer Mineralogia Polonica, 17,1, 3-16, 21 figs. be considered reliable. There is no proof that 'Marmaros diamonds' are euhedral, transparent commercial amethyst growers are yet exploiting and generally colourless quartz crystals found at a this, but the quartz is easy to grow and Brazil number of locations in the Flysch Carpathians, twinned synthetic amethysts may be expected. Poland. Thermo-and barometric study of the fluid R.K.M. inclusions contained in the crystals revealed a KOIVULA, J. I., KAMMERLING, R.C., 1989. Gemmo- chloroform content which appears to indicate that logical properties of emerald from Nova Era, the principal components of the mineral-forming Minas Gérais, Brazil. South African Gemmologist, fluids were aliphatic hydrocarbons. Other hydro­ 3, 4,20-5,4 figs in colour. carbons are found in minor amounts. M. O'D. Emeralds are found in a biotite-phlogopite-mica schist at the Nova Era mine, Minas Gérais, Brazil. KELLY, S.M.B., 1989. Using the spectroscope. A Ten faceted stones were tested and showed prop­ personal assessment of the contribution to gem- erties in the established range for emerald. Two-and mology of J.J. Snow, FGAA, FGA. Australian three-phase inclusions and fine acicular growth Gemmologist, 17,4,118-19. tubes parallel to the c-axis were observed. M.O'D. 110 J. Gemm., 1990, 22, 2

KOIVULA, J.I., KAMMERLING, R.C., 1989. A gem- joining Max Resources of New Zealand to explore mological study of 'Opalite' and 'Opal Essence'. for diamonds near Darwin, Australia. Australian Gemmologist, 17, 3, 93-8, 5 figs, some in colour. Coloured stones Two names for the same 'new' plastic opal which Plumbago Mining have opened an amethyst mine seemed to be identical to earlier plastic imitation at Sweden, Maine, New England. Same company opals. A needle pressed lightly onto these 'stones' are reopening the Mt Mica tourmaline mine, also in dented them readily; very warm to touch; hot Maine. Sceptre amethyst is reported from Malawi. needle gave acrid smell; the plastic was hydropho­ The Bolivian amethyst-citrine mine is reported bic and a drop of water placed on it formed a closed but 'poached?' material is still readily avail­ hemispheric bead; natural or synthetic opal are able. Fine quality large aquamarines are coming hydrophilic and water spreads rapidly across the from Madras State, India; blasting and heat damage surface. Low SG 1.15 to 1.25, RI 1.51, H 2.5 and the spoils much of the material; 41 ct specimen ex­ usual microscopic features should identify. But in a amined had graining due to strain but colour was setting the se can deceive. R. K. M. exceptional and not due to heating. A cave in the Namib desert is yielding 'chandeliers' of quartz KOIVULA, J.I., KAMMERLING, R.C., 1989. An crystals, one formation was estimated to weigh 13 investigation of three imitation opalized shells. tons. Rough Santa Terezinha de Goias emeralds, Australian Gemmologist, 17, 4, 148-52, 10 figs in Brazil, are being heated moderately with Opticon, a colour. synthetic sealant; a further report is in preparation. It is fitting that these shells should be discussed A large bi-colour yellow and green water-worn in the Australian Gemmologist for they originated in sapphire from Anakie, Queensland, is illustrated. that country and were undoubtedly made to de­ Kanchanaburi, Thailand, sapphires are often ceive. heat treated, resultant colour sleepy or a greyish The shells looked entirely wrong with large blue rather like similarly treated stones from Sri angular chunks of boulder opal conforming in some Lanka; pin points of dark blue 'ink-drops' occur as strange way to the required outlines of the fossil inclusions; untreated stones have fine dust-like silk shapes, not at all like the normal homogeneous (as in Burmese sapphires) or long needles (as in Sri opalized shell. Examination showed a mixture of Lankan); boehmite and apatite crystals also in­ opal, opal breccia, and iron-stone held in a plastic cluded. Undersea searches inspired by Thai Gov­ matrix and either moulded or ground to shape. ernment and UN Development Department are They were too well polished, and had spherical seeking corundum, titanium, zirconium and gold in bubbles trapped in the binding material. Hardness, the Gulf of Thailand; they have already found tin hot needle and water spot tests all confirmed plastic. under the Andaman Sea. Paraiba, Brazil, is produc­ Spot RIs of about 1.55 were obtained from each of ing some exceptional colour blue and green tourma­ them. Opal portions fluoresced bluish-white under lines, mostly under one carat but largest seen was LUV, other parts were inert, some gas bubbles also 15.18ct. fluoresced. It seems another chapter has been added to the opal story. [A deception to look out for!] Pearls R.K.M. A large cultured blister pearl was seen in a fresh-water mussel shell represented the goddess KOIVULA, J.I., KAMMERLING, R.C., 1989. Gem Kwan Yin; insert was probably carved shell or news. Gems& Gemology, 25, 3, 177-84, 12 figs in plastic and X-ray did not detect it. colour. Diamond Synthetics and Simulants CSO report diamond sales of $2 317 billion, 'Jadeite' concentric mobile sphere balls seen in a highest ever for a six month period. Diamond Guangzhou (Canton) factory were mostly bowenite, cutting seen at Foshan, Guangzhau Province, Chi­ with a few of low-grade jadeite; workers insisted na, used jam peg dops more normal for coloured that all were 'jade', confirming that this word has stones; no mechanical dops seen and each stone was broader application in Chinese. 'Opalized fossil' worked short time only, to avoid cement softening. shells from Australia were found to be composite Argyle officials, Australia, deny recruiting Indian made from opal, boulder opal and iron-stone matrix diamond cutters to train cutters in China. Economic cemented with a plastic, moulded or ground to viability of a kimberlite intersection is being tested shape. R.K.M. near Prince Albert, Saskatchewan. Australians are exploring possibilities of kimberlite pipes in Wis­ KOIVULA, J.I., KAMMERLING, R.C., 1989. Ex­ consin and Michigan. A De Beers subsidiary is amination of a gem spinel crystal from the Pamir J. Gemm., 1990,22,2 111

Mountains. Zeitschrift der Deutschen Gemmologis- thirds correct results, including a number in which chen Gesellschaft, 38, 2/3, 85-8, 3 figs in colour, a multiple choice of answers was offered. The bibl. narrow tolerances of the program plus the use of The gem quality pink spinel crystal examined broad SG ranges provided by flotation methods of came from the Pamir mountain range in the south of testing probably increased the failure rate. Micros­ the USSR, almost parallel to the northern border of copic and spectroscopic tests were not included. Pakistan and the Wakhan Corridor belonging to Spot RIs were too approximate. Criticism suggests Afghanistan. RI 1.711, SG 3.55. Inclusions are that the program could not be used for examination described. E.S. purposes. [Examinations are to test gemmological interpretation by the student. A computer could KORITNING, S., 1989. Achate aus dem Harz. (Agate hardly do that.] from the Harz.) Aufschluss, 40,349-59,12 figs (10 Peter Read, the originator of 'Gemdata', replies in colour). and intends further modifications which may in­ Fine agates are described from the Harz region of crease its efficiency. Editorial comment makes West and East Germany. M.O'D. further suggestions. [One can see weaknesses in the method of assessment as well as in the program LARSSON, T., 1989. Adelstenar bland Fältspaterna. itself, and is left wondering whether the computor (Feldspar gemstones.) Gem Bulletinen, 2, [un­ offers any real improvement over old fashioned paged] 1 fig. brain-power and gemmological 'nous'?] R.K.M. Varieties of the feldspar mineral group with gem or ornamental application are described. M. O'D. MCKAY, D.J., O'DONOGHUE, M., 1989. Compute­ rized information services. In: WOOD, D.N., HARDY, J.E., HARVEY, A.P., (EDS), Information LIEBER, W., 1989. Smithsonit von der Kelly Mine, Sources in the Earth Sciences, 78-133. New Mexico, USA. (Smithsonite from the Kelly Available earth science databases are listed and Mine, New Mexico, USA.) Lapis, 14,10,29-31,6 critically discussed. (Author's abstract) M.O'D. figs (4 in colour). Fine bluish-green smithsonite from the classic MITCHELL, R.K., 1989. Some thoughts on snuff- source of the Kelly Mine, Socorro County, New bottles. Australian Gemmologist, 17, 4, 129-31, 1 Mexico, USA, is described. The mineral is found in fig. in colour. the Magdalena Range. M.O'D. An attempt to list the many materials used to make these collectable Chinese items, and to de­ LIEBER, W., 1989. Broken Hill. Lapis, 14, 5,11-29, scribe the methods of fashioning. Inspired by a 38 figs (26 in colour). stray question in a 1982 examination paper. The survey of the mineralization of Broken Hill, (Author's abstract) R.K.M. New South Wales, Australia, contains details of the occurrence and photographs of transparent crystals of rhodonite which is usually found on galena. MIYAMOTO, M., AKAISHI, M., OHSAWA, T., M.O'D. YAMAOKA, S., FUKUNAGA, O., 1989. Morpholo­ gy and formation process of diamond from glassy LINTON, T., BROWN, G., 1989. Economic micro­ carbon. Journal of Crystal Growth, 97, 731-8, 9 scopes for gemmologists. Australian Gemmologist, figs. 17,4,120-1 and 156-8, 5 figs. Glassy carbon was used as a starting material for Describes the SZM-1 Stereozoom microscope, diamond formation with a catalyst metal. The A$665; the SZM-2 Stereozoom microscope with hydrogen present in the starting carbon greatly phototube; the SM-4G Stereoscopic microscope affects the diamond formation and for this to take (Chinese) at A$355; the SMS-10 Stereoscopic place the hydrogen content has to be between 1200 microscope at A$150 and the EK-1 Fibre optic cold and 2200ppm. Using an iron-rich catalyst a charac­ light illuminator, A$563. Other microscopes are teristic needle-like diamond was formed. M.O'D. briefly mentioned. Prices are tax-exclusive and in any case would not apply in Britain. R. K. M. MÖLLER, R., 1989. Filatelia y gemas. (Philately and gems.) Gemologia, 30, 81/82,17-20,10 figs. MCCAUGHTRY, G., 1989. An evaluation of the Some examples of the use of gemstones on 'Gemdata' gem identification program. READ, P. stamps are given. M. O'D. Comments on the evaluation of'Gemdata'. Edito­ rial comment. Australian Gemmologist, 17, 3, NASSAU, K., 1989. Amethyst and citrine. Lapidary 107-9. Journal, 43, 8, 30-4, 5 figs (4 in colour). Assessment based on test reports by one student The transformation of amethyst into citrine by were used,and 'Gemdata' gave approximately two- heat treatment and the conversion of citrine into 112 J. Gemm., 1990, 22, 2 amethyst by irradiation are discussed. M. O'D. of the Chrysoprase variety of quartz. M. O'D.

O'DONOGHUE, M., 1989. Secondary literature: bibliographies, abstracts and indexes. In: WOOD, READ, P., 1989. A synthetic by any other name. D.N., HARDY, J.E., HARVEY, A.P., (EDS), In­ Australian Gemmologist, YJ, 4, 153-6, 4 figs, some formation Sources in the Earth Sciences, 6A-11. in colour. Bibliographies, indexes and abstracts in the earth 'Synthetic' is a word which carries a stigma when science field are listed and critically discussed. connected with gems and Mr Read discusses the (Author's abstract) M.O'D. urge among some manufacturers to find ways around its use when describing their products. In Britain a synthetic is a synthetic and must be so PILATI, T., GRAMACCIOLI, CM., Sosso, F., 1988. Identification of gemstones by single-crystal X- described, but in some other countries the rules are ray diffractometer. La Gemmologia, 13, 3/4, 19- less exacting and there appear to be ways round the 25. problem. Thus Chatham in the US is, after con­ Distinction between quartz and scapolite, topaz siderable litigation, legally allowed to call his stones and danburite and sinhalite and olivine are made by 'created emeralds', while the Australian Tool emer­ the single-crystal X-ray diffractometer. The techni­ ald', although very similar to the Biron synthetic que is applicable both to crystals and to faceted emerald, is to be described as 'refined natural stones. M.O'D. emerald recrystallized under hydrothermal condi­ tions'. The Knischka synthetic rubies are advertised as PLATONOV, A.N., TARAN, M.N., KLYAKHIN, K., 'Knischka-created-rubies' and are produced by KLYAKHIN, V.A., 1989. On two colour types of 3+ what is called a 'luxury synthetic process', because it Mn -bearing beryls. Zeitschrift der Deutschen takes about a year to produce the stones. Gemmologischen Gesellschaft, 38,4,147-54,5 figs, In many cases such semantics are backed by 1 table, bibl. 3+ claims that the product in question is practically Two types of Mn coloured natural beryls are indistinguishable from the natural stone except by investigated. Differences in absorption spectra, sophisticated methods of analysis; indeed the best thermal stability of colour and behaviour under examples are often so good that their very purity irradiation are caused by differing crystal field 3+ and superb colour can themselves arouse suspicions symmetry of the Mn ions in the beryl structure. of synthesis. In most cases they can in fact be The difference between morganite and pink beryl 3 + identified as synthetic fairly simply and must, in the as caused by Mn distortion is discussed. E. S. UK at least, be sold as such. The other common factor seems to be that once the repugnant term PONAHLO, J., 1989. Mikrospektralphotometrie der 'synthetic' has been eliminated, the prices tend to Edelstein-Kathodolumineszenz. (Microspectro- rise dramatically. photometry of gemstone cathodoluminescence.) The writer finally makes the point that these Zeitschrift der Deutschen Gemmologischen Gesell­ evasions may not be so serious at the point of first schaft, 38, 2/3, 63-84, 27 figs (17 in colour), 2 sale but that they could become much more prob­ tables, bibl. lematical when a stone is inherited or sold on The author explains the use of microspectro- through several owners long after the initial transac­ photometry of cathodoluminescence of gemstones tion was completed. R. K. M. as a method of distinguishing between natural and synthetic stones. The method can be used on luminescing gemstones and ornamental stones. ROBERT, D., 1989. Synthèses de l'émeraude. The necessary apparatus is described in detail, as (Syntheses of emerald.) Revue de Gemmologie, are the CL-spectra of rubies, emeralds, padparads- 100,4-6,4 figs in colour. chahs, alexandrites, diamonds and lapis lazuli. The The paper forms the first part of a series in which method has a number of advantages: results are emerald syntheses are described. This part deals easily compared, parcels can be examined as well as with some hydrothermal and the Chatam product. single stones, it can be applied to all stones with Characteristic inclusions are illustrated. M.O'D. usable CL bands, although also weakly luminescent material can be tested and differences between ROBERT, D., 1989. Synthèses de l'émeraude. 2nd natural and synthetic stones can be explored. E. S. part. Revue de Gemmologie, 101, 5-7, 2 figs in colour. POUGH, F.H., 1989. Chrysoprase. Lapidary Jour­ The productions of Lens, Gilson and Lechleitner nal, 43,9, 20-4,1 fig. in colour. are reviewed with notes on Soviet and Japanese A short account of the mineralogy and properties material. M.O'D. J. Gemm., 1990,22, 2 113

ROMBOUTS, L., 1987. Geology and evaluation of the gischen Gesellschaft, 38,4,155-60,1 map, 3 tables, Guinean diamond deposits. Annales de la Société bibl. Géologique de Belgique, 110,1,214-59, 5 maps. Survey of emerald production in Colombia in Nineteen Cretaceous kimberlite pipes, classified early 1989. Coscuez could not be visited for security into three types, with area surfaces from 1100 up to reasons. Yacopi was producing, but mainly light 95 000 m2, and alluvial diamond deposits are located green crystals, well formed and transparent. Penas in Upper Guinea, in the area bounded by Kissi- Biancas is situated in a district controlled by dougou, Kerouane and Macenata. The kimberlites, guerillas. Gachala is being cleaned and prepared for which seem all diamond-bearing, are intruded into working. Production from Chivor varies a lot, both the Archaean craton of the Guinea Rise and are in quality and quantity. Buenavista is at the moment closely related to the break-up of Gondwana. About not being worked. Difficulties in export of emeralds 1700 diamonds, ^ 10 ct, were examined for their and other gem materials is also discussed. E. S. crystallography and colour. Octahedra, dodeca- hedra and their twins are best represented, while cubes are very rare. White and yellow colours SERGUNENKOV, B.B., 1989. (Gem scapolite from predominate over brown, grey and green. In the the Tarakuloma Ridge (the Pamirs).) Zapiski alluvial deposits of the Gbenko-Banankoro area, 93 Vses, Min, Obshch., 118, 4, 84-90. (Russian with per cent of the stones are of gem quality. R. V.T. English abstract.) Gem scapolites of lilac and other colours occur in RUSTIONI, M., BERTONI, S., 1988. BGO, a new secondary cavities in granite pegmatites cutting material of gemmological interest? La Gemmolo- marbles in this area. They are dipyres of composi­ gia, 13, 3/4, 7-17,4 figs (2 in colour). tion Mei8—Me37. Their lilac colour is related to 3+ Bismuth germanium oxide is described and its Mn 6 and electron centres SO~3. IR spectra are ornamental potential discussed. Grown by heat presented. The blocky crystals have faces {010}, exchange, Bridgman or pulling techniques it has a {110}, {120}, {111}. {011} and {001}, with surface hardness of 5, SG 7.12 and RI2.10. It crystallizes in sculpture including hillocks and pits at the outlets the cubic system. With a dispersion of 0.050 it of acicular channels oriented along c. These chan­ might be considered as a possible diamond substi­ nels are hollow or contain dispersed material. tute, were it not for the low hardness. [The Refractive indices and cell dimensions are reported; abstractor commented on BGO several years ago in a scapolite with composition Mei8 has e 1.536, co Synthetic Crystals Newsletter and also observed its 1.541, a 12.070, c 7.583 Â. R.A.H. high degree of brittleness. M.O'D. SNOW, J. J., 1989. The use of the Figure-O-Scope in SCHMETZER, K., 1989. Im hydrothermal verfahren gemmology. Australian Gemmologist, 17,4,122-6, hergestellter synthetischer Aquamarin aus der 9 figs, some in colour. UdSSR. (Hydrothermally-grown synthetic A reprint from a 1979 issue in which Jack Snow aquamarine from the USSR.) Goldschmiede und described the simplified conoscope that he de­ Uhrmacher Zeitung, 9-89, 139-41, 12 figs in signed to facilitate observation of interference fi­ colour. gures in biréfringent stones. R.K.M. Aquamarine is now manufactured by the hyd­ rothermal growth process in the USSR. Constants given are SG 2.69, RI 1.583 and 1.575 with DR SNOW, J., BROWN, G., 1989. Inamori stones'rough 0.008. A variety of different types of inclusion is (some observations and speculations). Australian found and some are illustrated. M. O'D. Gemmologist, 17,4,132-5,9 figs in colour. A résumé of observations on the synthetic gem SCHÜPBACH, T., 1989. Ein interessanter Quarz- products of the Kyocera Corporation, discussing Epidotfund aus dem Val Punteglias. (An interest­ aspects of bubble inclusions and other identifying ing quartz-epidote find from the Val Punteglias.) features. Synthetic corundum, alexandrite and opal Schweizer Strahler, 8, 8, 353-65, 9 figs (7 in are dealt with. Some illustrations seem not to colour). convey what the captions suggest they should. Have Gem quality crystals of quartz and green epidote a couple of them got mixed? A useful paper! have been found in the Val Punteglias, Switzerland. R.K.M. M.OT). THEMELIS, T., 1989. Clues to identity. Lapidary SCHWARZ, D., 1989. Smaragdabbau in Kolumbien: Journal, 43, 6, 36-40, 2 figs in colour. Neue Aspekte. (Emerald mining in Colombia: A short note on the use of inclusions as gem new aspects.) Zeitschrift der Deutschen Gemmolo- testing tools. M.O'D. 114 J. Gemm., 1990, 22, 2

THEMELIS, T., 1989. Some inclusions in Umba 821-5,4 figs. corundums. Lapidary Journal, 43, 8, 19,2 figs in One natural and two synthetic opals were tested colour. for electrical conductivity with a complex impe­ Among inclusions noted in corundum from the dance analysis. The conductivity of the synthetic Umba region of East Africa are apatite, rutile, material is lower and its activation enthalpy higher. boehmite and graphite. M. O'D. This may be due to the lower concentration of Na+ charge carriers. The dielectric constant of the THEMELIS, T., 1989. Longido. Lapidary Journal, synthetic opal is anisotropic and is dominated by 43,9,49-50, 3 figs (2 in colour). the presence of water. M.O'D. The Longido mine is located near the settlement of Mdara in northern Tanzania and is celebrated for ZEITNER, J.C., 1989. Thunder Bay. Lapidary Jour­ ruby crystals in green zoisite. After a lengthy nal, 43, 8, 36-42, 3 figs (2 in colour). cessation of mining limited operations have recom­ A large deposit of amethyst is found at Thunder menced. M.O'D. Bay, Ontario, Canada, on the northern shore of Lake Superior. The deposit has been worked for WANG, F., Guo, J., 1989. Chicken-blood stone amethyst since the early seventeenth century. from China. Gems & Gemology, 25, 3, 168-70, 3 M.O'D. figs in colour. This Chinese Cretaceous or Jurassic rock of ANON. 1989. Diamond sorting made easy. Industrial volcanic origin is found at Changhua, Zhejiang Diamond Review, 49, 6,265-6, 5 figs. Province, and at Balinyouqi in Inner Mongolia. The Examination of large quantities of diamonds or fine-grained dickite-kaolinite and quartz mixture is jewellery under a loupe or miscroscope is extremely known as chicken-blood stone, a material prized for time consuming. A new microscope system (the carving for many centuries. Once incorrectly called Sortoscope) is described which is suitable for the pyrophyllite, it may be white, yellow, green or grey, examination of polished gem diamonds, precious with patches, clouds or spots of bright to dark red of stones, pearls and finished jewellery, but can also be cinnabar, the redder the higher the value. SG varies used for examining uncut gem and industrial 2.6 to 3.0; H 3; RI for background material ('dong') diamonds. The acrylic glass slides suitable for about 1.55-1.56; microgranular; very easy to carve. examining diamonds have an 84.5° notch on the top side and are slightly recessed on the underside; the R.K.M. diamaonds are scattered on the notch and examined WIERSEMA, B., 1989. Spotlight on Scripps. Lapid­ with the aid of stereozoom optics using dark-field ary Journal, 43, 5,20-6,4 figs (3 in colour). optic fibre lighting. To inspect an individual di­ The newly-opened Scripps Hall of Mineralogy at amond more closely, it can be rolled about its own the San Diego Museum of Natural History is axis while simultaneously pulling the slide. The described. M.O'D. position of the diamond is not changed with tweezers but with a fine retouching brush, which is also used to remove dust particles. R. A. H. WILSON, A. F., 1989. The use of isotopes in explora­ tion for gemstones. Australian Gemmologist, 17,4, ANON. 1989. Debex's diamond recovery plants 142-6. double for andalusite. Indiaqua, 54, 3, 59-60, 5 A detailed account of the use of isotopes of figs in colour. radio-active elements such as uranium, thorium, rubidium and potassium to determine 'age signa­ This article, in the form of a press release, tures' of host rocks in order to assess gem bearing describes the use of a dense medium separation potentials and save expensive exploration of barren plant (DBS) designed by Van Eck and Lurie and pegmatites. manufactured in South Africa by Debex (Pty) for A totally different approach uses stable, non- the recovery of industrial andalusite in the North­ radio-active isotopes of oxygen, carbon, hydrogen ern Transvaal area of South Africa. Unlike the rare or sulphur to assess physical conditions of mineral gem quality andalusite, this aluminium silicate is formations, while potassium/argon ageing can also used in high-grade refractories and ceramics. When be assessed. heated to a sufficiently high temperature it changes to mullite which is in demand for its high melting Methods and applications are explained together point, good electrical and thermal insulating prop­ with some examples. An important and highly erties, low coefficient of expansion and high resist­ technical paper which puts modern prospecting and ance to mechanical and thermal shock. The mineral mining into a new and very intriguing light. R. K.M. is used in refractories for furnaces, oil and gas fire Xu, M.Y., JAIN, H., NOTIS, M.R., 1989. Electrical boxes, combustion funnels, spark plugs, enamel properties of opal. American Mineralogist, 74, and chinaware. E G. R. J. Gemm., 1990,22,2 115

Book reviews

CHAUVET, M., 1989. Frédéric Cailliaud. Editions agate in ornament. It is good to have established ACL-Crocus. pp.371. Illus. in black-and-white sites mentioned - many of the locations quoted by and in colour. F 295. Matthew Heddle in the Mineralogy of Scotland have This book was written by a Nantais, to com­ never been identified. M. O'D. memorate the bicentenary of one of Nantes' famous sons: the naturalist and egyptologist Frédéric Cail­ liaud (1787-1869). The author painstakingly re­ traces the expeditions of his compatriot in Egypt MOREL, B., 1988. The French crown jewels. Fonds and the Sudan, covering the period 1815-1822. Mercator, Antwerp, pp.417. Illus. in colour. Although primarily of interest to the student of £60.00. egyptology, it will be remembered that M. Cailliaud This sumptuous book gives the history of the also held the position of mineralogist to the Khe­ French crown jewels from the earliest times to their dive, Mehemet Ali, and in this connection chapters final incorporation into the collections of the 3 and 5 - dealing with Cailliaud's rediscovery of the Louvre. It should be noted that the articles used as ancient 'lost' emerald mines of Zabara and Gebel coronation regalia did not form part of the crown Sikait - are of particular, and historic, interest to the jewels in the same way as in England, and for this gemmologist. Illustrations are from original prints reason this particular group of artefacts is treated of the period complemented by present-day photo­ separately in the first section of the book. The graphs and there is a fold-out map of the country. crown jewels proper were the result of the establish­ N.C. ment by Francois I of a national collection of jewels and although they have been dispersed more than LEVINE, G., VOOKLES, L.L., 1986. The jeweler's once many have been recovered. The book in fact eye. Hudson River Museum, Yonkers, New York. covers ten centuries of French history as well as pp.111. Illus. in black-and-white and in colour. describing the manufacture and history of the Price on application. pieces themselves. After the opening section de­ The catalogue illustrates and describes a collec­ scribing the artefacts of the coronation ceremonies tion of nineteenth century jewellery in the collec­ the book goes on to discuss the collection founded tion of Nancy and Gilbert Levine. A preliminary by Francois I on 15 June 1530 and its development. essay discusses the social setting of nineteenth This takes up sixteen chapters and is a chronologic­ century jewellery and is followed by the catalogue al account ending with the acquisition by the itself in which the majority of the pieces are Louvre of some pieces long dispersed from the illustrated in colour. The catalogue is followed by an collection. Despite the price of the book (by no essay on the culture of beauty. This is a well- means excessive for what you get) it is very well produced catalogue with good quality photographs worth buying if you have the smallest interest in fine and interesting essays. M. O'D. historical jewellery. The illustrations are of high quality and there are useful bibliographies of a topic MACPHERSON, H.G., 1989. Agates. Natural History which has not been covered in detail since the Museum, London, and National Museums of nineteenth century and a lot has happened since Scotland, Edinburgh, pp.72. Illus. in colour. then. M.O'D. £5.95. This is a most welcome short guide to agates with particular reference to specimens found in the STRASSER, A., 1989. Die Minerale Salzburgs. (The British Isles. As might be expected, most of the sites minerals of Salzburg.) Published by the author: are in Scotland. There is a discussion of the types of Salzburg, pp.348. Illus. in black-and-white and rock in which agates are found and of why they are in colour. Price on application. there; this is followed by a description of agate Notes on beryl and phenakite deposits can be structure and coloration. Most of the book is found in this excellent guide to the minerals of the devoted to descriptions of fine British specimens Salzburg area of Austria which includes a first-class and there are also notes on cutting and on the use of bibliography. M.O'D. 116 J. Gemm., 1990, 22, 2

Proceedings of the Gemmological Association of Great Britain and Association Notices

OBITUARIES The November 1989 issue of the latter journal John Joseph Qack) Snow 1923-1989. was published most fittingly as a memorial issue to We are deeply sorry to report the death of one of Jack Snow, and in it Geoff Tombs, GAA Patron, Queensland's leading gemmologists on 2 July 1989, described him as 'One of the quiet achievers' who after a long and courageous battle with emphysema. was known to so many as 'Practical Jack'. There is John Joseph (Jack) Snow, FGAA, FGA, was born little doubt that this kindly and clever man will be in Brisbane in 1923, the youngest son of James and greatly missed, but the hope is expressed that his Maud Snow. He had little formal education but was example will be echoed in the achievements of apprenticed as an optical mechanic after leaving future Australian gemmologists. primary school. For the remainder of his working Grahame Brown, Federal President, GAA life he was closely associated with various aspects of R. Keith Mitchell, Vice President, GAGB the optical industry. He even came into gemmology • • • as a result of his then employment as Queensland Manager for British Optical, who were the distribu­ Mrs Anne Eaton, FGA (D.1984), Lymm, tors for Rayner gemmological instruments. Cheshire, died in June 1989. Jack joined the Queensland Branch of the Austra­ Mrs Linda Hennessy, FGA (D. 1984), Wahroon- lian Gemmological Association in May 1959, ga, NSW, Australia, during 1989. according to his application, solely in order to learn something of the gemmological instruments he was Mr John G. Luder, FGA (D. 1969) of Den Haag, selling. By the end of 1960 he had obtained his The Netherlands, died in November 1989, aged 77. Fellowship Diploma for the GAA and was starting After a long and brave fight with kidney failure, the almost thirty years of devotion to gemmology. end came peacefully, and at his request he was Characteristically, he confirmed his knowledge and buried by the sea near his home. A good man and an ability by sitting and passing the Gemmological excellent gemmologist. He leaves a widow, Eli­ Association of Great Britain's examination in 1976. zabeth, and one son. His significant and valuable contribution to Austra­ lian gemmology was formally acknowledged when NEWS OF FELLOWS he was awarded Honorary Life Membership of the On 26 January 1990 Mr Michael O'Donoghue GAA in 1980. gave a lecture entitled 'Gemstones of Pakistan' to Jack Snow's contribution to gemmology was the Russell Society at the University of Lough­ considerable. At various times over the three de­ borough. cades he occupied most of the elected positions on MEMBERS' MEETINGS the Queensland Branch Council; lectured and de­ London monstrated optics, gemmological instruments and On 19 March 1990 at the Flett Theatre, Geologic­ practical gem testing to several generations of al Museum, Exhibition Road, South Kensington, students and to members of the general public; was London SW7, Mr George Bosshart, M. Sc, GG, on the GAA's Instrument Evaluation Committee; a gave an illustrated lecture entitled 'The coloration member of several Federal Executives and was a of green diamonds'. gemmological researcher of international standing. As a consequence of these many interests he Midlands Branch contributed some 45 papers to gemmological pub­ On 19 January 1990 at the Society of Friends, Dr lications world-wide as well as writing regularly for Johnson House, Colmore Circus, Birmingham, Mr the Queensland Branch publication - Wahroongai David Callaghan, FGA, gave an illustrated lecture News and for the Australian Gemmologist. entitled 'The Duchess of Windsor's jewellery'. J. Gemm., 1990, 22, 2 117

On 16 February at the Society of Friends Gwen Forge, Claude, Paris, France. Kingsley gave a lecture entitled 'History of the Fujimori, Syohei, Fukuoka-Pref, Japan. Stonbridge Glass Industry'. Fujisawa, Takako, Chiba-Pref, Japan. Galligan, Fiona L., Greenford. North West Branch Gilson, Pascale N., Brussels, Belgium. On 20 September 1989 at Church House, Hanov­ Hausier, Rebecca, Bangkok, Thailand. er Street, Liverpool 1, Val Duke gave a lecture on Hills, Margaret A., Tonbridge. the gemstone trade in Brazil. Horiguchi, Yasuhiko, Tokyo, Japan. On 18 October 1989 at Church House, David Irikura, Hisanobu, Tokyo, Japan. Callaghan, FGA, gave an illustrated lecture entitled Ishikawa, Noriko, Tokyo, Japan. The Duchess of Windsor's jewels'. Jain, Neerja, Birmingham. On 15 November at Church House, the Annual Jinbo, Kazuko, Tokyo, Japan. General Meeting was held, at which Mr William Jupp, Thomas H., London. Franks, FGA, was elected Chairman and Mrs Irene Kewell, Geoffrey, Cranbrook. Knight, FGA, re-elected Secretary. Kimura, Hiroyuki, Tokyo, Japan. On 17 January 1990 at Church House, a social Lake, Richard J., Grouville, Jersey, CI. evening was held, when members brought along Lim, Heng M., Burong, Singapore. interesting gemmological specimens. On 21 Febru­ Madhvani, Marie-Laure, Nairobi, Kenya. ary 1990 at Church House, Dr Jeff Harris gave a Mason, Alec J., Retford. lecture on colour in diamonds. Matsumoto, Masako, Osaka, Japan. On 21 March 1990 at Church House, Mr David Matsumoto, Tamio, Takyo, Japan. Callaghan, FGA, gave an illustrated lecture entitled Millot, Valerie, Paris, France. 'From gem to jewel'. Moreiras-Blanco, Damaso, Oviedo, Spain. Munakata, Yoshio, Wakayama-Pref, Japan. COUNCIL MEETING McCarthy, Edward J., Cambridge. At a meeting of the Council of the Association Nilsson, Assar, Varmdo, Sweden. held on 22 February 1990 at the Royal Automobile Oda, Mineko, Tokyo, Japan. Club, Pall Mall, London SW1, the business trans­ Pattni, Mamta C.P, Nairobi, Kenya. acted included the election to membership of the Peh, Angeline, Glasgow. following: Rigby, L. Clare, Doncaster. Sasako, Miyuki, Kanagawa-Pref, Japan. Fellowship Schmidt, Simon P, London. Chiu, Sau K.D., New Territory, Hong Kong. 1989 Shibata, Hirofumi, Osaka, Japan. Civitello, Odile, Outremont, Canada. 1989 Smith, Alan J., Alton. Cope, Andrew R.W, Nottingham. 1989 Soma, Hiroshi, Kanagawa-Pref, Japan. Ellis, Phillipa, Sydney, Australia. 1989 Suzuki, Hiroshi, Tokyo, Japan. Hawkins, Richard A., Sutton. 1989. Takeda, Mari, Tokyo, Japan. Hitchin, Peter F, Bangkok, Thailand. 1989 Takeuchi, Kumi, Chiba-Pref, Japan. Ho Kiam Fong, Steve, Singapore. 1989 Tanigawa, Sonoh, Tokyo, Japan. Lambley, Jenifer G., Brightwell cum Sotwell. 1981 Tazima, Kazumi, Tokyo, Japan. Lau, Ellen Y.Y., Hong Kong. 1989 Tsuda, Miwako, Hyogo-Pref, Japan. MacGregor, Rory, Teresopolis, Brazil. 1989 Van Opstal, W.B.M., Tilburg, The Netherlands. Nevalainen, Tuula M.L., Helsinki, Finland. 1989 Von Redlich, Anna B.A., Monza, Italy. Pette, Jan W, Arnhem, The Netherlands. 1989 Watanabe, Naoki, Tokyo, Japan. Pun, Yuk L.M., New Territory, Hong Kong. 1989 Wells, Andrew, Caterham. Rieger, Catherine J., Maidstone. 1989 Wilson, Nean E., Longniddry. Wooldridge, James M., Worcester. Ordinary Membership Yasuda, Atsuko, Tokyo, Japan. Adams, Suzanne, Sutton. Ashitaka, Nobuyoshi, Osaka, Japan. Azizollahoff, Geoffrey, London. INTERGEMLAB GROUP Bauer, La Shawn, Kingman, Kan., USA. The INTERGEMLAB Group comprises a num­ Birrell, Andrew T, London. ber of gemmologists representing internationally Clark, Susan W, London. recognized laboratories. The Group meets twice a Davis, David R., London. year to discuss gemmological problems which De Silva, Nihal G.J., Mitcham. directly effect their laboratories. The members of Echeverry, Jose FO., Bedford. the group as at January 1990 are listed below: 118 J. Gemm., 1990,22,2

France cases, reports on natural pearl necklaces based upon J.-B Poirot, Public Service for the Control of X-radiography alone may only be considered as Diamonds, Natural Pearls and Precious Stones, 'sample reports'. Amongst those pearls which re­ Chamber of Commerce of Paris, Paris. main unidentified by this method could be a Great Britain number of cultured pearls, particularly of the K. Scarratt, The Gem Testing Laboratory of Great non-nucleated variety (i.e. with organic implant). Britain, London. When the client insists upon a 'sample report' he will find the following statement on reports issued Italy by the Group: M. Superchi, CISGEM, Chamber of Commerce of 'NB This single examination by X-radiography did Milan, Milan. not prove the identity of every pearl in the The Netherlands necklace; therefore the 'pearls' must be removed PC. Zwaan, Netherlands Gem Laboratory, Leiden. from the silk for every pearl to be determined.' In the issuing of 'sample reports' each member is Switzerland operating to specific but unpublished guidelines. CA. Schiffmann, Gemmological Laboratory Gübe- The Group also warns those inexperienced in the lin, Lucerne. examination of pearls that the identification of a Following the Intergemlab Group meetings in large number of natural and non-nucleated cultured 1986, the Group announces that an Agreement has pearls cannot be relied upon from radiographs been reached between its members with regard to taken only in one direction. The Group also works the issuing of reports on pearls. to specific guidelines for reports on both cultured The Agreement is specific both with regard to the pearl necklaces and those with a mixture of natural wording used in reports and the methods of ex­ and cultured pearls. amination. In all cases, regardless of the type or TRADE FAIRS number of pearls involved, the reports issued by the The Gem and Mineral Fairs 1990, organized by member laboratories will describe the pearls both in the British Lapidary and Mineral Dealers Associa­ terms of weight and size, and sometimes state the tion, are listed below. Full details may be obtained method(s) used for examination, e.g. X-ray, from John F Turner, Glen joy, 19/21 Sun Lane, radiography, Laue diffraction and/or optical Wakefield, Yorkshire, telephone 0924 373786. methods. The units to be used in specific instances both for weight and size descriptions and the form Bristol and West of wording to be used in cases relating to various Watershed Media Centre, Canons Road, Bristol. 26 possible results have been agreed. and 27 May The Agreement has been in operation for two years and has been found to work well for each Harrogate International member. The results given in one laboratory are Crown Hotel, Harrogate. 25,26 and 27 August similar in wording to those given in another. One of the reasons why members felt it was London International necessary to draw up an agreement of this kind was Holiday Inn, Swiss Cottage, London. 20 and 21 the increase in inexperienced persons setting up October 'X-ray' equipment and declaring themselves 'pearl experts'. A number of inaccurate and/or misleading The 3rd World Gems Expo is to be held from 2 to reports have been issued by such inexperienced 5 June 1990 at the Hong Kong Convention and persons over the last few years. The Group also felt Exhibition Centre, 1 Harbour Road, Wanchai, that the trade and the public should have consistent Hong Kong. Details from co-organizers: Hong reporting from each member and most importantly Kong Diamond Bourse and Headway Trade Fairs they should be informed of the limitations of each Ltd, 9/F Sing-Ho Finance Building, 168 Gloucester method used for examination. Road, Hong Kong. An area for concern is the reporting on natural pearl necklaces by X-radiography. On rare occa­ The Bangkok Gems and Jewellery Fair 1990 is sions, using X-radiography alone, it is possible to to be held from 12 to 16 September in the Exhibi­ give a result for every pearl in a natural pearl tions Halls, Department of Export Promotion, necklace but in the majority of cases this is not Bangkok. For further information contact the Sec­ possible. The Group strongly recommend that in retariat Office of the Fair, Exporter Service Divi­ the case of natural pearl necklaces, the pearls should sion, Department of Export Promotion, 22/77 be cut from the silk to allow for each pearl to be Rachadapisek Road, Bangkok 10900, Thailand. examined and reported upon. In the vast majority of Telephone 5131909 Ext. 272,273. J. Gemm., 1990, 22, 2 119

NEW AND UPDATED PRODUCTS FROM stone appraisal identifications and gemmological THE ASSOCIATION studies, has just been released. The new version has The Association is proud to announce that it has been designed mainly in response to user requests been appointed sole UK distributor for the World and as a result of independent evaluation tests. In Map of Gem Deposits published by the Swiss addition to small modifications to gem constants, a Gemmological Society and based upon the work of new section enables crystal specimens to be identi­ Dr Edward Gübelin and his colleagues. fied from inputs for crystal system/optical charac­ The Map is said by many to be a gemmological ter, colour, transparency and SG, and is supported masterpiece and is the culmination of much inves­ by a graphics page of typical crystal habits. tigative research. It measures 92 x 128cm and has an In the polished stone section there are now information key printed in English, Spanish, Ger­ optional inputs for uniaxial/biaxial stones, for man, French, Italian and Portuguese. All maps are 'negative' readings above the range of the standard discretely overprinted with the Association's Coat of refractometer, and for extended SG tolerance limits Arms (unless otherwise requested). for the hydrostatic weighing of small stones. Crystal Such a publishing achievement is remarkable and system/optical character is now included with the will be a constant visual source of vital information, information displayed for each gemstone. When a not only for students and persons interested in list of gemstones is requested there is also a scroll gemmology and jewellery, but as a 'backdrop' for stop-continue feature which provides a page-by- window displays wherever quality gems and jewel­ page view of the data, and it is now possible to lery are exhibited. re-run a gem identification using alternative search The face side identifies deposits world-wide and a limits without having to input the test data again. colour code is used to highlight the sites of eleven GEMDATA is compiled in QuickBASIC and can major gems and various ornamental gem materials. be loaded direct from DOS on any IBM PC- The reverse side features 65 full colour illustrations compatible computer having a minimum memory of gems as well as photographs of gem deposits and of 128K. GEMDATA is supplied on either a single mining operations. 5.25 inch double-sided double-density disk or a 3.5 The whole concept of such a work has been inch disk, and comes complete with operating enthusiastically received by the world's leading instructions and gem index. Separate versions of the jewellers and gemmologists, and the following are program are available for use with colour or just two reviews: monochrome monitors. GEMDATA (Update 2) is 'A most useful display document for both cus­ available from the Gemmological Association, price tomers and staff. The Map can be used as a sales aid £90.00 (plus VAT, postage and packing). for normal business and special promotions, and I To order either of these products please use the have no hesitation in recommending this wonderful coupons on p. 126. Payment can be made by the pictorial chart to both retail jewellers and gemmo­ major credit/charge cards. To obtain a catalogue and logists. '-Richard Peplow of W.H. Peplow, Worcester, price list of instruments contact the Gemmological and Chairman of the National Association of Gold­ Association of Great Britain, Saint Dunstan's smiths House, Carey Lane, London EC2V 8AB. This modern production updates and extends the pioneer work produced by H.J.Schubnel some THE JOURNAL OF GEMMOLOGY decades ago. The map is much larger enabling more BACK NUMBERS deposits to be shown in greater detail. The series of A member of the Association has for sale a fine photographs of gem deposits on the reverse of complete set of The Journal from 1972 to 1989, as the Map provides a convenient cross section of the well as back issues of overseas journals. Enquiries to methods of mining, both primative and sophisti­ the Association, Box No. 1713. cated, used around the world. A most useful publication for teaching and for display in jewellers' CORRIGENDA shops and elsewhere.' - Alan Jobbins, Editor, the On the front inside cover, Vol. 22, No. 1, under Journal of Gemmology. 'Members elected to Council', CR. Burch, B.Sc, The map can be supplied either folded or flat. FGS, RJ.Peace, B.Sc, C.Chem, FRSC, FGA, and Your company's logo, name and address can be E.Stern, FGA, should have been included, and overprinted on the Map (minimum order 100 E.M.Bruton, FGA, omitted. The South Yorkshire copies) making it an ideal gift for valued clients. and District Branch Chairman, GA.Massie, FGA, The price for the folded map is £13.50 (£14.50 flat) should have been omitted also plus postage and packing. On p. 52 above, second column, Stig E. Sundin, The second annual update of the computer Hylkje, Norway, was omitted from the list of those program GEMDATA, developed to assist in gem- that qualified in the 1989 Preliminary Examination. 120120 JJ.. Gemm.,Gemm., 1990,22,21990,22,2

LettersLetters toto ththee EditoEditorr

PromFrom K.ScarrattK.Scarratt GemGem TestingTesting LaboratoryLaboratory inin LondonLondon hadhad beenbeen The GemGem TestingTesting Laboratory Laboratory of ofGreat Great Britain Britain examiningexamining a similarsimilar groupgroup ofof blackblack diamondsdiamonds whichwhich alsoalso conductedconducted electricity.electricity. However,However, itit waswas con­con­ DearDear SirSir,, cludedcluded thatthat asas graphitegraphite (the(the blackblack appearanceappearance ofof thethe A shortshort paperpaper writtenwritten byby S.S. ScandellaScandella wawass stonesstones resulteresultedd fromfrom ththee inclusioninclusion inin ththee diamonddiamond ofof publishedpublished inin thethe JulyJuly 19891989 issueissue ofof The Journal Journal (21,(21, a blackblack materialmaterial thatthat waswas possiblypossibly graphite)graphite) con­con­ 7,7, p.411p.411)) regardinregardingg observationsobservations mademade durinduringg ththee ductedducted electricityelectricity nono safesafe conclusionconclusion witwithh regarregardd toto examinationexamination ofof a numbernumber ofof blackblack diamonds.diamonds. ThThee ththee diamonds'diamonds' TypeType couldcould bbee madmadee withouwithoutt moremore paperpaper,, inin itsits titletitle andand content,content, assumedassumed thathatt ththee detaileddetailed work.work. Indeed,Indeed, testtestss indicatedindicated thathatt ththee stonesstones inin questionquestion werewere ofof thethe TypeType lIb.lib. ThisThis stonesstones diddid notnot conductconduct inin thosthosee areasareas wherwheree ththee assumptionassumption hahadd beenbeen made,made, inin thethe main,main, fromfrom twotwo includedincluded materialmaterial diddid nonott reachreach thethe surface.surface. clearclear facts,facts, (a)(a) thatthat thethe stonesstones werewere diamond,diamond, andand (b)(b) InIn orderorder thatthat wwee mightmight clearlyclearly 'Type'Type' thesethese stones,stones, thatthat thetheyy conductedconducted electricity.electricity. thethe LaboratoryLaboratory purchasepurchasedd oneone exampleexample inin whichwhich WhilstWhilst realizingrealizing thethe difficultiesdifficulties involvedinvolved inin arriv­arriv­ therethere appearedappeared toto bebe a narronarroww tunnetunnell ofof inclusion­inclusion- inging atat a 'Type'Type' forfor whatwhat mustmust havehave beenbeen almost,almost, ifif notnot freefree diamonddiamond runninrunningg througthroughh ththee stone.stone. SoSo thathatt entirely,entirely, opaqueopaque diamonds,diamonds, oneone hahass toto questionquestion thethe visiblevisible andand infraredinfrared spectraspectra couldcould bebe obtained,obtained, ththee wisdowisdomm ofof publishinpublishingg statementsstatements thatthat areare basedbased stonestone wawass laser-cutlaser-cut andand polishedpolished toto taketake bestbest uponupon insufficientinsufficient evidence.evidence. TheThe papepaperr mademade nnoo advantageadvantage ofof thethe inclusion-freeinclusion-free area.area. TheThe resultingresulting mentionmention ofof thethe UV/visiblUV/visiblee oror IRIR absorptionabsorption characcharac­­ visiblevisible andand infraredinfrared spectraspectra (Figures(Figures 1 andand 22)) teristicsteristics ofof thethe stones,stones, eveneven thoughthough itit isis thesethese veryvery determineddetermined thethe stonestone toto bebe TypeType IaAIaA.. factorsfactors whichwhich assignassign a 'Type'Type' toto a givengiven diamond.diamond. InIn concludingconcluding wwee wouldwould likelike toto thankthank MrMr C.C . ShortlyShortly beforbeforee thethe publicatiopublicationn ooff this papepaperr thethe WelbourneWelbourne ofof thethe DiamonDiamondd TradingTrading CompanyCompany

A B oS R B A BLACKBLACK DIAMONDDIAMOND N C E

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FigFig.. 22 122 J. Gemm., 1990, 22, 2

Research Department both for his assistance in diamond full of graphite (?) would still retain the arranging for the stone to be laser-cut and polished usual tenacity and hardness of diamond. and for his comments upon the spectra. We would welcome any further suggestion!

Yours etc., Yours etc., K. Scarratt S.Scandella and C.A.Schiffmann

26 February 1990 6 March 1990 The Gem Testing Laboratory of Great Britain, 27 Gübelin Gemmological Laboratory, Denmalstrasse Greville Street, London EC1N 8SU. 2, CH-6000 Lucerne 6, Switzerland.

From R. Keith Mitchell FGA

From S.Scandella and CA.Schiffmann Dear Sir, Gübelin Gemmological Laboratory In an abstract of mine on p. 42 of the January 1990 issue of the Journal, the comment '[part of the text Dear Sir, is missing so this entry is difficult to understand]' Thank you for informing us of the letter of Mr has been printed. That comment was incorrect and Ken Scarratt referring to the testing of two black my misreading was due to slightly awkward phras­ diamonds. The remarks of Mr Scarratt are correct in ing at the beginning of the next column. I tried to showing the steps to be taken in such an analysis. cancel this at the time, but my 'phone call was On the other hand, we know that gemmology evidently too late. My apologies to the author for must often be practised under quite limiting cir­ carelessness on my part. cumstances. In this case the diamonds were opaque, Yours etc., there was no permission to slice them and they had R. Keith Mitchell to be given back within a short time. Going back to the semi-conducting behaviour of 5 March 1990 these diamonds, we don't quite see how a Type I Orpington, Kent.

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World Map of Gem Deposits The Gemmological Association is the sole UK distributor for the World Map of Gem Deposits (see pp66 and 119 for full details). To order your copies please complete the coupon below.

To: Gemmological Association of Great Britain, Saint Dunstan's House, Carey Lane, London EC2V 8AB. Please supply copy(s) of the World Map of Gem Deposits as follows: Postage and packing Rest of UK Europe World Please D Folded Map @£13.50 D£0.90 D£2.25 D£4.50 tick DFlatMap @£14.50 D£1.50 D£3.15 D£6.00 DI enclose remittance £ D OR please charge my credit/charge card (please tick) D D D D Diners Club Card No Expiry date Name i Address

Signature Date , OVERPRINTING (minimum order 100 copies): Please supply copies of the World Map of Gem Deposits overprinted as attached sample. (A proforma invoice will be sent for the full cost of Maps and overprinting). GEMDATA A computer program for gem identification The GEMDATA Package by Peter Read is available through the Gemmological Association at £90.00 plus postage, packing and VAT* (*UK only at £13.50). Postal rates are as follows: £3.50, UK and Eire; £4.00 Europe; £6.00 rest of the world. To order your Package use the form below.

To: Gemmological Association of Great Britain, Saint Dunstan's House, Carey Lane, London EC2V 8AB. Please supply copies of the GEMDATA package, with 5.25/3.5-inch disk * *I use a colour/ monochrome monitor *I enclose remittance £ /debit my credit/charge card (please tick appropriate box) D ES D S D Hi D Diners Club Card No Expiry date Name Address Telephone No.. Signature Date. *Delete as applicable J. Gemm., 1990,22,2 127 GEMDATA - UPDATE 2 A computer program for gem identification * Now available in 3.5-inch disk version *

Now available in its second updated version, GEMDATA is compiled in QuickBASIC and will run directly from MS-DOS on any IBM PC-compatible computer. It is designed to help with both appraisal identifications and gemmological studies. Optional yearly update of GEMDATA will be available. GEMDATA is supplied on either a SVi-inch double-sided, double- density disk, or a 3V£-inch disk, and contains the following two sections :- Gem 1. Gem and Crystal Identification from a databank of over 220 gems Gem 2. Gem Comparisons (side-by-side display of the constants and crystal systems of selected gems), Tables of RI and SG values, Gem Calculations (SG, reflectivity, critical angle, Brewster angle and gem weight/diameter estimation) The GEMDATA package, complete with disk, operating notes and gem index, costs £90.00 (plus postage and VAT). To order your package please use the coupon given on p. 126.

Gemmological Association of Great Britain Saint Dunstan's House, Carey Lane, London EC2V 8AB 128128 J.J. Gemm.Gemm.,, 1990,22,21990,22,2

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The Arms and Crest of the octahedra and the gem-set ring Association, conferred by a grant indicates the use of gems in of Arms made by the Kings of ornamentation. The lynx of the Arms under royal authority. crest at the top was credited, in The cross is a variation of that ancient times, with being able to in the Arms of the National see through opaque substances. Association of Goldsmiths of He represents the lapidary and Great Britain and Ireland. In the student scrutinizing every the middle is a gold jewelled aspect of gemmology. In the book representing the study of paws is one of the oldest heraldic gemmology and the emblems, an escarhuncle, to examination work ofthe represent a very brilliant jewel, Association. Above it is a top usually a ruby. The radiating arms plan of a rose-cut diamond inside suggest ligbt diffused by the a ring, suggesting the scrutiny of escarbuncle and their tips are shown gems by magnification under a lens. as jewels representing the colours of The lozenges represent uncut the spectrum.

Historical Note The Gemmological Associa tion of Grea t Canadian Gemmological Association, the Gem Britain was originally founded in 1908 as the and Mineral Society of Zimba bwe, the Education Commi ttee of the National Gemmological Association of Hong Kong, the Association of Goldsmi ths and reconstituted Gemmological Association of South Africa in 1931 as the Gemmological Association. Its and the Singapore Gemologist Society. name was extended to Gemmological TheJournal ofGemmology was first Association of Grea t Britain in 1938, and published by the Association in 1947. Itisa finally in 1944 it was incorporated in that name quarterly, published in January, April, July, under the Companies Acts as a company and October each year, and is issued free to limited by guarantee (registered in England, Fellows and Mem bers of the Association. no. 433063). Opinions expressed by au thors are not Affilia ted Associations are the necessarily endorsed by the Association. Gemmological Association of Australia, the

Notes for Contributors The Editors are glad to consider original is consistent with dear indication of the articles shedding new light on subjects of can tent of the paper. It should be followed by gemmological interest for publication in the the names (with ini tials) 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 lcnf!th, but long papers of more than the understanding that (1) full information as 10 000 words (unless capable of division into to any previous pu blication (whether in parts or of exceptional importance) are English or another language) has been given, unlikely to be accepta ble, whereas a short (2) it is not under consideration for pu blication paper of 400-500 words may achieve early elsewhere and (3) it will not be pu blished publication. elsewhere without the consent of the Editors. Twenty five copies of individual papers are Papers should be su bmi tted 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 first proof stage or earlier. 2 5mm all round. The title should be as brief as Volume 22 No. 2. April 1990

1 hcJournal of Gemmology

Contents

A contribution to the distinguishing characteristics of sapphire from Kashmir H.A. Hänni 67

An unusual agate from Guyana J. G. Gosling 76

Spectroscopic evidence for heat treatment of blue sapphires from Sri Lanka - additional data K. Schmelzer and L. Kiefert 80 Red and orange corundum (ruby and padparadscha) from Malawi U. Henri, D. Bank and F.H. Bank 83

The diamond drill used in the Cambay bead industry R. V. Karanth 91

Reflections on reflectivity P.G. Read 97

Gemmological abstracts 103

Book Reviews 115

Proceedings of the Gemmological Association of Great Britain and Association Notices 116 Letters to the Editor 120

Copyright © 1990 Gemmological Association of Great Britain Registered Office: Saint Dunstan's House, Carey Lane, London EC2V 8AB

ISSN: 022-1252

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