Volume 23 No. 7. July 1993 1116 Journal of Gemmology

THE GEMMOLOGICAL ASSOCIATION AND GEM TESTING LABORATORY OF GREAT BRITAIN OFFICERS AND COUNCIL Past Presidents: Sir Henry Miers, MA, D.Sc., FRS Sir William Bragg, OM, KBE, FRS Dr. G.F. Herbert Smith, CBE, MA, D.Sc. Sir Lawrence Bragg, CH, OBE, MC, B.Sc, FRS Sir Frank Claringbull, Ph.D., F.Inst.P., FGS Vice-Presidents: R. K. Mitchell, FGA A.E. Farn, FGA D.G. Kent, FGA E. M. Bruton, FGA, DGA Council of Management CR. Cavey, FGA T.J. Davidson, FGA N.W. Deeks, FGA E.A. Jobbins, B.Sc, C.Eng., FIMM, FGA I. Thomson, FGA V.P. Watson, FGA, DGA R.R. Harding, B.Sc., D.Phil., FGA, C. Geol. Members' Council A. J. Allnutt, M.Sc, G.H. Jones, B.Sc, Ph.D., P. G. Read, C.Eng., Ph.D., FGA FGA MIEE, MIERE, FGA, DGA P. J. E. Daly, B.Sc, FGA J. Kessler I. Roberts, FGA P. Dwyer-Hickey, FGA, G. Monnickendam R. Shepherd DGA L. Music R. Velden R. Fuller, FGA, DGA J.B. Nelson, Ph.D., FGS, D. Warren B. Jackson, FGA F. Inst. P., C.Phys., FGA CH. Winter, FGA, DGA

Branch Chairmen: Midlands Branch: D.M. Larcher, FBHI, FGA, DGA North-West Branch: I. Knight, FGA, DGA Examiners: A. J. Allnutt, M.Sc, Ph.D., FGA G. H. Jones, B.Sc, Ph.D., FGA L. Bartlett, B.Sc, M.Phil., FGA, DGA D. G. Kent, FGA E. M. Bruton, FGA, DGA R. D. Ross, B.Sc, FGA C R. Cavey, FGA P. Sadler, B.Sc, FGS, FGA, DGA S. Coelho, B.Sc, FGA, DGA E. Stern, FGA, DGA A.T. Collins, B.Sc, Ph.D Prof. I.Sunagawa, D.Sc. B. Jackson, FGA C Woodward, B.Sc, FGA, DGA E. A. Jobbins, B.Sc, C Eng., FIMM, FGA

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

The Getnmological Association and Gem Testing Laboratory of Great Britain 27 Greville Street, London EC1N 8SU Telephone: 071-404 3334 Fax: 071-404 8843 ^Journal of Gemmology

VOLUME 23 NUMBER SEVEN JULY 1993

Cover Picture A series of cut zircons; the heat-treated stones are from Indo-China and weigh 21.32 ct (colourless), 33.34 ct (blue) and 27.58 ct (brownish-orange). They have been on exhibition for many decades and have not changed colour. The other stones are from Sri Lanka and are not treated; they weigh 9.85 ct (green) and 12.34 ct ('red'). All are on exhibition in the former Geological Museum, London. Photo E.A. Jobbins.

ISSN: 0022-1252 386 J. Gemm, 1993, 23,

GAGTL ANNUAL CONFERENCE 24 October 1993

Great Western Royal Hotel, Paddington, London

Inclusions The theme of the Annual Conference this year is Inclusions' and we are pleased to announce that Dr E. Gübelin will deliver the keynote lecture. This will include newly discovered inclusions in gemstones and also a discussion on treated diamonds. The theme will be continued with reports of recent work on Burmese and Vietnamese rubies and sapphires by Alan Jobbins, also of the range of Montana sapphires, treated and untreated, by Michael O'Donoghue. Both speakers have made recent visits to these producing areas. Other items include lectures by Philip Sadler, who will outline the part played by gems in his investigations as a forensic scientist, and by Stephen Kennedy who will be talking about pearls and pearl fishing in the Arabian Gulf. Throughout the day delegates will have the opportunity to view displays and participate in practical demonstrations.

GAGTL Open Day The conference will be followed on Monday 25 October by an Open Day at the GAGTL Gem Tutorial Centre.

For further details and a booking form please contact: Miss Linda Shreeves at GAGTL on 071 404 3334 (Fax 071 404 8843) J. Gemm., 1993,23,7 387

Zircon: a study of material donated by Mr W.C. Buckingham from various localities (mainly Indo-China) Edinburgh Gemmological Group1

Introduction selected material. The latter was mostly marked as In 1988 Mr W.C. Buckingham, FGA, donated having been worked on by Basil Anderson. his fine collection of rough and preformed zircons Ten stones were randomly selected from each to the Gemmological Association of Great Britain. packet. These constituted the samples. To help These zircons were to be made available to FGAs investigations and RI measurements windows for research purposes, provided researchers com­ were polished on the stones. The descriptions and plied with stipulated criteria namely: results are set out in Table I. l.the rough specimens originate from various localities, mostly Indo-China, and the research Optical Data and Specific Gravity might be directed towards determining any Refractive indices were measured using a variation in properties from the different Rayner Diamond Table Refractometer with localities. However, other research topics West's Solution as the contact liquid. Difficulties would be considered; arose because of the liquid's viscous nature and 2.having carried out the research programme, toxicity. Table II details results, each of which is the Fellow must present the results in the form the sample average. Samples 2, 5, 7 and 12, had of a paper which would, in the opinion of the been heat-treated once. Samples 3, 4, 8, 10 and Editor, be worthy of publication in The Journal 11 had been heat-treated twice. Samples 1, 6 and of Gemmology. 9 were untreated. Apart from samples 4, 5 and 12, This paper outlines investigations directed all fell within the range for high zircon (1.925 - towards determining possible variation in proper­ 1.984). ties of the zircons. Specific gravity was determined by hydrostatic There were 12 packets of zircons which, in toto, weighing. Anomalous specific gravity readings weighed 1420.4 grams and a further 36.9 grams of were queried and it was noted that the results had

Table I: Location and appearance of zircons tested

Packet No. Mine & location Notes 1 Looi mine, Kha district Natural state as found 2 Looi mine, Kha district Blue-coloured after initial heating 3 Looi mine, Kha district Bleached white after second heating 4 Looi mine, Kha district Tending to golden after initial heating

5 Hau Tek mine, Kha district Finest. Only white after initial heating

6 Various, Champasak district White stones after full heating 7 Various, Champasak district Pre-heated to facilitate inspection for cracks and inclusions before main heating 8 Various, Champasak district As above (packet 7) after final heating 9 Pailin district Natural colour as found. Produces only white after heating 10 Looi mine, Kha district After heating roughly shaped for faceting 11 Looi mine, Kha district Bleached white after heating: roughly shaped for faceting 12 Various, Champasak district After heating roughly shaped for faceting

© Copyright the Gemmological Association ISSN: 0022-1252 (.j.j Table II: Properties of zircons from various localities in Indo-china 00 00

Mine! Sample Colour RI DR SG Dichroism SWUV LWUV Phosphor- Heat- Observed absorption spectrum District No. escence treated

LooilKha I strong gold 1.923-1.983 0.060 4.670 gold - None None None No General absorption of the red and blue/violet. Two specimens displayed light gold an absorption line near 660 nrn,

LooilKha 2 mid blue 1.923-1. 969 0.046 4.719 blue - None None None Yes Produced absorption lines in the red at 590nm and single line or pair at colourless 653 nm. Four examples showed a line at 525nm.

Looi/Kha 3 colourless 1.923-1.984 0.061 4.657 nil None Mustard None Yes Pairs of absorption lines at 653 nm and a single line at 600 nm. In 80% of the packet there was a line at 525 nm present.

Looi/Kha 4 golden I. 922-1. 982 0.060 4.555 nil Mustard None None Yes General absorption of the red, but also showed a vague line at 653 nm. There was also a general absorption of the blue/violet.

Looi/Kha 10 blue I. 922-1. 973 0.051 4.615 sky blue- None None None Yes 600 nm line and pairs or single lines at 653 nm with further absorption colourless lines at 525 nm.

LooilKha 11 colourless 1.922-1. 979 0.056 4.593 nil Mustard Mustard None Yes Persistent absorption line at 600 nm. There was also a single or double line at 5'50 nrn, 500 nm and in 5 cases a single line at 490 nm.

Hau TeklKha 5 gold tinged 1.922-1.982 0.060 4.45 nil Orange Orange None Yes Showed a line or group oflines at 653 nm, 600 nrn, and 5 stones showed white a line at 525 nm. There was also a general absorption of the blue/violet.

Various 6 red 1.922-1. 982 0.060 4.679 red - Dull None None No No distinct absorption lines although there was general absorption of Champasak light red orange the blue/violet.

Various 7 orangy-white 1.922-1.982 0.060 4.695 nil None Orange None Yes Line at 653 nm and, in four specimens, general absorption of the Champasak blue/violet.

Various 8 colourless 1 .923-1.983 0.060 4.654 nil None Orange None Yes General absorption of the blue/violet region. All specimens showed a Champasak doublet at 653 nm, a single line at 660 nm and a single line at 640 nm. In addition, all samples gave a single line 600 nm in the orange and a line at 550 nm. All specimens showed a line in the green area at 525 nm but four stones showed multiple lines in that region. Two stones displayed a doublet in the blue at 475 nm while four others only showed a single line.

Various 12 colourless 1.922-1. 982 0.060 4.334 nil Orange Orange None Yes General absorption of the blue/violet region. A distinctive line at 653 nm Champasak could be seen in most specimens as well as additional lines in the red. All samples displayed a line at 600 nm in the orange and most stones showed a line at 580 nm in the yellow region. All stones gave a line at 630 nm with a few stones giving additional lines in that area. With the exception of one specimen all samples showed lines in the blue region at 465 and 470nm.

Various Pailin 9 pale brown 1.921-1.982 0.061 4.649 pale brown- Orange Orange None No No visible spectrum faint brown J. Gemm, 1993, 23, 7 389

Some of the heat treated stones had a skin that phosphoresced bright yellow. When this was removed by grinding no phosphorescence was observed. The skin was attributed to the surface fusion of phosphorescent material during heat treatment. These results are similar to those recorded by Anderson (1964) and Webster (1983); the varying intensity of the fluorescence influencing the colour tone.

Spectroscope results The assignment of a band or line to an exact wavelength is not possible, given the variable res­ olution of the prism spectroscope. The Map 1. Location of zircon mines (after Anderson, 1990). wavelengths cited in Table II are, therefore, a combination of accurately measured values been influenced, primarily, by the presence of reported by Anderson (1964), Webster (1983) adhering matrix or, to a minor extent, by inclu­ and O'Donoghue (1988) and those estimated by sions. The results were within the general range the Edinburgh Gemmological Group. The results for both high and intermediate zircons. are set out in Table II. Heat treatment did not materially affect the Zircons are known to possess some of the most refractive index or specific gravity of the stones. varied absorption spectra of all gemstones. The most persistent line is in the red at 653.5nm and Fluorescence and phosphorescent effects the number of lines increases with the uranium The samples were examined in long-wave ultra­ content. In his study of Ceylon (Sri Lanka) zircons violet light (LWUV) and short-wave ultraviolet Anderson (1964) noted that the breakdown of the light (SWUV) to determine any fluorescent and/or crystal structure can be clearly followed by the phosphorescent effects. The results are compared gradual deterioration of the uranium absorption with those in the literature and recorded in Table bands. Sharp lines displayed by normal, fully crys­ II. tallized zircon are replaced by weaker and vaguer Locality and amount of heat treatment were the development of the same bands until, with com­ only known variables. The Looi mine zircons gave plete structural breakdown, metamict zircon mixed results. Untreated stones (sample 1) showed displays merely a vague band in the red near no fluorescence . After initial heat treatment 650nm sometimes accompanied by a narrow band stones that turned blue (samples 2 and 10) did not in the green at 520nm. The latter band is not seen fluoresce, whilst those that turned yellow fluo­ in normal zircon. Heat treatment of intermediate resced mustard under SWUV (sample 4). Stones zircons will enhance the sharpness of the spectrum that had been heat-treated twice, thereby render­ lines. Samples 8, 11 and 12 exhibited similarities ing them colourless (samples 3 and 11), fluoresced to the anomalous spectrum produced by heat- mustard under LWUV, whilst sample 11 also flu­ treated low zircons (Anderson, 1990). oresced mustard under SWUV. The effects of heat treatment and fluorescence are clearly linked. Infrared spectra of zircon The other Kha district stones (sample 5) were Variation in the infrared spectrum of zircon cor­ recorded as turning colourless after a single heat relates directly with the degree of ordering of the treatment. These fluoresced orange under both atomic lattice. High zircons, which are well- long- and short-wave UV. ordered, display several sharp absorption bands Champasak district stones also showed a link (Figure 1). The three strong, sharp absorptions at between fluorescence and heat treatment. 434, 386, and 318cm1 represent crystal lattice Untreated stones did not fluoresce whilst those vibration while those at 980 and 902cm1 represent 4 heat-treated once (sample 7) or twice (samples 8 stretching modes of the [Si04] " anion and at 1 4 and 12) fluoresced orange under LWUV. Only 610cm , a bending mode of the [Si04] ~ anion. sample 12 showed additional orange fluorescence Metamict stones, which have poor ordering, under SWUV. display two broad absorption curves (Figure 1). Untreated Pailin district stones showed an All IR spectra were consistent with a well- orange fluorescence in both long- and short-wave ordered atomic structure. There were, however, UV. small but significant differences between the 390390 J.J. Gemm.,Gemm., 1993,1993, 23,23, 7

100.0 (Figure(Figure 2).2). ThisThis waswas attributedattributed toto crystalcrystal latticelattice absorptionabsorption effectseffects resultingresulting fromfrom enhancedenhanced order­order­ inging followingfollowing heatheat treatment.treatment. TheThe subtlesubtle 80.0 absorptionsabsorptions occurredoccurred atat 330,330, 320,320, 308,308, 294294 andand 284cm·!.284cm1. ConfirmationConfirmation ofof heatheat treatmenttreatment ofof colourless,colourless, blueblue andand redred zirconzircon isis notnot normallynormally Q) u attempted,attempted, itit beinbeingg automaticallyautomatically assumedassumed thatthat c ...,ru 60.0 suchsuch materialmaterial hashas beenbeen heat-treatedheat-treated (Nassau,(Nassau, ..., 1984).1984). TheThe IRIR spectrumspectrum ofof zirconzircon providesprovides con­con­ .r< E firmatoryfirmatory evidenceevidence ofof heatheat treatmenttreatment inin thethe Ul C absenceabsence ofof thethe anomalousanomalous visiblevisible spectrumspectrum ru 40.0 '- describeddescribed byby AndersonAnderson (1990).(1990). I- Ci~ InclusionsInclusions 20.0 TensionTension fracturesfractures formform thethe majormajor internalinternal featurefeature ofof allall thethe zircons.zircons. InIn manymany casescases thesethese werewere filled withwith secondarysecondary ironiron oxideoxide stainingstaining which,which, inin oneone specimenspecimen wherewhere thethe stainingstaining reachedreached thethe 0.0 1400 1000 600 200 surfacesurface andand couldcould bebe removed,removed, wawass identifiedidentified byby em- l X-rayX-ray diffractiondiffraction asas goethite.goethite. CurvedCurved andand healinghealing fracturesfractures werewere alsoalso common.common. Fig.Fig. 1.1. 1.1. InfraredInfrared spectrumspectrum ofof zircozirconn withwith wellwell crystallizedcrystallized atomicatomic structure.structure. ColourColour zoningzoning parallelparallel toto ththee prismprism facesfaces {I{100 OO}} 2.2. MetamictMetamict zirconzircon spectrumspectrum constructedconstructed fromfrom examplesexamples inin andand {010}{010} waswas onlyonly rarelyrarely seenseen (Figure(Figure 3)3) andand thethe literature.literature. onlyonly inin untreateduntreated stones.stones. spectraspectra ofof untreateduntreated andand heat-treatedheat-treated stones.stones. A darkdark brownbrown inclusioninclusion extendingextending toto thethe surfacesurface BetweenBetween 340cm·!340cm1 andand 260cm·!260cm1 heat-treatedheat-treated proved,proved, onon X-rayX-ray analysis,analysis, toto bebe ferrianferrian spinelspinel stonesstones showedshowed a seriesseries ofof subtlesubtle absorptionsabsorptions ofof (specimen(specimen 2/10)2/10) (Figure(Figure 4).4). A specimenspecimen fromfrom thethe variablevariable intensityintensity superimposedsuperimposed uponupon thethe funda­funda­ LooiLooi minemine waswas brokenbroken inin orderorder toto exposeexpose a similarsimilar mentalmental absorptionsabsorptions seenseen inin untreateduntreated stonesstones opaqueopaque inclusion.inclusion. Unexpectedly,Unexpectedly, thisthis revealedrevealed a

Fig.Fig. 2.2. InfraredInfrared spectraspectra ofof:: 1.1. heat-treatedheat-treated zirconzircon fromfrom thethe LooiLooi Mine;Mine; 2.2. untreateduntreated zirconzircon fromfrom thethe LooiLooi mine.mine. 79.2

69.5

59.8

~ 50.1 c ...,ru ..., .~ 40.4 U1 c ru '- I- 30.7

21.0

11 .3

1.6 1200 1010 810 610 410 210 em -1 J. Gemm, 1993, 23, 7 391

Fig. 3. Colour zoning intersecting at 90°. Fig. 4. Distorted crystal of ferrian spinel in highly fractured blue zircon.

cavity the walls of which were covered by a dark coating. Inside, partially filling the cavity, was a dark grey mineral debris* (Figure 5). Spot analy­ ses of the debris gave varying ratios of iron, aluminium and silicon which could not be assigned to any particular mineral species. Several grains (lOOjom to 150|im) contained only zirco­ nium and therefore thought to be baddeleyite (Zr02). The baddeleyite occurs close to the zircon host and suggests a possible reaction phe­ nomenon. High magnification of the dark-grey mineral debris revealed a sponge-like matrix,the voids of which contained light coloured partial- spheres

Fig. 5. Scanning electron microscope (SEM) photograph of debris- Fig. 6. Scanning electron microscope (SEM) photograph of the filled cavity in fractured zircon. groundmass showing sponge-like form with white spheres. 392 J. Gemm., 1993, 23, 7

Table III: Analyses of inclusion material before refining views on fluorescence as a poten­ tial locality or heat treatment indicator. Partial-spheres Spongiform matrix Whilst the extent of heat treatment on the Indo­ China samples clearly influenced the absorption Si02 13.12 47.65 spectra (colourless stones showing the strongest Ti02 00.98 03.16 spectra), no correlation between spectra and loca­ Zr02 00.00 00.00 tion could be established. There was no A1203 13.69 37.69 discernible difference in the absorption spectra Cr203 00.05 00.23 between the Indo-China zircons and those FeO* 62.49 08.89 described by Anderson (1964) from Sri Lanka.. CaO 00.18 00.69 Infrared spectra could not be used to prove­ K20 00.05 00.21 nance the zircons although its use in heat P205 09.15 01.41 treatment determination may prove useful. CI 00.28 00.07 It was not possible to assign particular inclu­ -o=c\ 0.06 0.02 sions to any specific locality. Total 99.93 99.98 Acknowledgements * The valeimc e state of iron is assumed be 2+ The authors would like to thank Mr W. C. Buckingham and the Gemmological Association cordierite and minerals in the cordierite-sekani- and Gem Testing Laboratory of Great Britain for allowing us to work on the specimens and their naite [Mg2Al4Si5018-(Fe,Mg)2Al4Si5018] series respectively. The partial spheres could not be patience during the course of this study. Thanks identified with confidence. The frothy, sponge­ are also due to Mr Paul Wilthew of the like appearance of the dark grey matter suggested Conservation and Analytical Research Laboratory the emission of gases. This supports the view that of the National Museums of Scotland for all SEM there has been a reaction between the inclusion and analytical work. Karl Bank is thanked for his and the host zircon probably brought about by contributions at an early stage in the work. thermal decomposition during heat treatment. The elements present in ferrian spinel and zircon Note 1. The Edinburgh Gemmological Group (EGG) is an are also those contained in baddeleyite and informal group of FGAs who meet to discuss and cordierite-sekaninaite. Such reaction features investigate gemmological topics. The EGG members who (Figure 7) can show bubbles around the inclusion. collaborated in the preparation of this paper are: James Other inclusions were black, distorted hexago­ 'Mac' Heatlie, Yvonne Holton, Brian Jackson, Alistir Tait, nal plates of biotite and apatite crystals. Euan Taylor, James Walker, Margery Watson and Tom Watson. Conclusions References Application of the various tests failed to estab­ Anderson, B.W., 1964. Gem testing. 7th edn. Butterworths, lish the existence of locality specific criteria. London. Whilst there is evidence to support a correlation Anderson, B.W., 1990. Gem testing. 10th edn., revised by E.A. between fluorescence, locality and degree of heat Jobbins. Butterworths, London. treatment, the anomalies dictate that caution Nassau, K., 1984. Gemstone enhancement. Butterworths, should be exercised. Fluorescence should be used London. O'Donoghue, M., 1988. Gemstones. Chapman and Hall, neither as a clear-cut test for locality assignment London. nor, because of the anomaly shown by sample 9 Webster, R., 1983. Gems. 4th edn., revised by B.W. Anderson. under LWUV, as categorical evidence of heat Butterworths, London. treatment. Fluorescent effects of zircons from other localities would also have to be examined [Manuscript received 1 January 1993] J. Gemm., 1993, 23, 7 393

Flux-grown synthetic rubies from Russia Dr Ulrich Herrn and Prof. Dr Hermann Bank German Gemmological Association, Idar-Oberstein, Germany

Introduction crystal habit, weighs 22.6 ct. and has a dark red Russia and some other states of the former colour. Soviet Union are well known as producers of various synthetic stones, e.g. synthetic amethyst, Crystallographic description emerald, alexandrite, spinel and diamond. The type 1 synthetic ruby crystal (tabular pris­ Synthetic ruby was first mentioned by the authors matic) shows a well-developed second-order in 1990. The dark red synthetic material (Figure hexagonal prism a{\ 120) and less distinct positive 1) showed an aggregate-like, grained texture with rhombohedron r(1011) and basal pinacoid few homogeneous parts which are facetable. The c(0001). largest piece of rough weighed 30 ct. The rhombohedral type 2 synthetic ruby shows Microscopical studies yielded black bubble-like well-developed crystal faces with the positive residues of the flux (Figure 2). rhombohedron r(10Ïl), second-order hexagonal The existence of synthetic rubies of Russian prism a(l 120), second-order hexagonal bipyramid production permitted the supposition that gem n(2243) and basal pinacoid c(0001). quality material would come up very soon. Finally in 1992, the first cut synthetic rubies from Russia Chemical composition were observed. Peretti and Smith (1993a) men­ Chemical analyses carried out by EDAX-eds tioned faceted specimens up to 1. 69 ct. and system fitted on a scanning electron-microscope reported that the synthetic rubies were hydrother- proved the two synthetic ruby crystals from Russia mally-grown. A detailed description of that to contain aluminium oxide and chromium oxide material together with the chemical and physical as main components. The tabular prismatic type properties was published by the same authors 1 synthetic crystal shows 99.72 wt. % A1203 and (Peretti and Smith, 1993b). Also in 1992, the 0.28 wt. % Cr203 and the rhomhohedral type 2 authors of this article saw a faceted synthetic ruby synthetic ruby 98.48 wt. % A1203 and 1.52 wt. % said to be flux-grown from Russia and in January Cr203. 1993 they received two rough crystals of synthetic ruby. The supplier, a colleague from the Academy Refractive indices, birefringence and of Sciences of Novosibirsk, where the synthetic density specimens are produced, stated that the synthetic Using a standard gemmological refractometer, rubies were produced by using a flux technique. the refractive indices have heen determined for The present article summarizes the properties of both type 1 and type 2 synthetic ruby: type 1 : these flux-grown synthetic rubies of Russian pro­ ne= 1.760 and nQ= 1.768; type 2: ne= 1.762 and duction and emphasizes the important n0= 1.770. The birefringence of both specimens is distinguishing features from natural rubies. 0.008. The optic sign is uniaxial negative. The density has been measured by using a General appearance hydrostatic balance. The data determined vary The two rough crystals of synthetic ruby are between 3.98 and 4.01 g/cm3. It must be remem­ quite different in visual appearance in both crystal bered that the inclusions (flux residues) habit and colour. substantially influence the values of the density. Type 1 (Figure 3) has an elongated, tabular prismatic habit and weighs 63.8 ct. The colour is Absorption spectrum and pleochroism pale red with a high homogeneity. The synthetic ruby crystals of Russian produc­ Type 2 (Figure 4) possesses a rhombohedral tion show typical absorption spectra of Cr3*. The

© Copyright the Gemmological Association ISSN: 0022-1252 394 J. Gemm, 1993, 23, 7

Fig.l. Aggregate-like, polycrystalline synthetic ruby from Russia, first described in 1990 (weight of the large piece 28 ct).

Fig. 4. Rhombohedral synthetic ruby crystal of Russian production Fig.2. Black, bubble-like flux residues in the polycrystalline synthetic (type 2), weighing 22.6 ct. Russian ruby material. x20.

Fig.3. Elongated, tabular prismatic synthetic ruby crystal (type 1) from Russia, weighing 68.8 ct. J. Gemm., 1993, 23, 7 395

Fig.5. Black, opaque flux residues in a synthetic ruby from Russia. Fig. 6. The flux residues of Figure 5 under darkfield illumination. xlO.

Fig.7. Flux residues in a synthetic ruby from Russia. xl5. Fig.8. Yellow residues of the lithium tungstate flux at the surface of the type 2 synthetic ruby crystal from Russia. xlO.

Fig.9. Cavities filled by flux residues. x20. Fig. 10. Tiny triangular platelet as a residue from the crucible (probably platinum). x30. 396 J. Gemm, 1993, 23, 7

Table 1: Properties of flux-grown synthetic rubies from Russia

Typel Type 2

Crystal habit Tabular Rhombohedral

Chemical A1203 99.72 98.48 composition (wt.%) Cr203 0.28 1.52

Colour Pale red Dark red

Pleochroism 0 Violet-red Purplish-red e Yellowish-red Orange-red

Absorption Typical Cr3+ -spectrum spectrum Cr3+-absorption line: 692 nm Cr3+-absorption bands maxima: E // c: 545 and 409 nm Elc: 554 and 400 nm

Refractive ne 1.760 1.762 indices no 1.768 1.770 Birefringence 0.008 0.008

Density (g/cm3) 3.98 4.01

UV luminescence long-wave UV Strong red short-wave UV Weak red

Internal features Black, opaque residues of the flux (tungsten oxide has been determined as a component of the flux by chemical analyses), cavities partly filled with a flux bubble (the flux material has contracted during the cooling of the synthetic ruby crystals), small triangular residues from the crucible (probably platinum), distinct growth structures.

Cr3+ absorption line is located at 692 nm. The synthetic ruby crystals (Figure 8) proved the flux pleochroic absorption bands are in the green and to contain tungsten as a main component. violet spectral range and possess maxima at 554 According to information from the producer, the and 400 nm for Elc and 545 and 409 nm for E//c. synthetic rubies are produced in a lithium The pleochroism is distinct: violet-red (o) and tungstate melt (Li20-W03) at temperatures of yellowish-red (e) for type 1 and purplish-red (o) 1100°C . Flux residues are also found as residual and orange-red (e) for type 2. fillings of cavities (Figure 9). Triangular residues of the crucible material (probably platinum) are Ultraviolet luminescence also found as typical inclusions of flux-grown syn­ When exposed to ultraviolet (UV) radiation the thetic rubies (Figure 10). synthetic ruby crystals both show strong red fluo­ rescence under longwave-UV and weak red under References short-wave UV. Henn, U., Bank, H., 1990. Synthetic Ruby, probably from USSR. ICA Laboratory Alert No. 30. Internal features Peretti, H.A., Smith, C.P., 1993a. Hydrothermal Synthetic Rubies. ICA Laboratory Alert No. 66 . Microscopic investigations showed black, Peretti, H.A., Smith, C.P., 1993b, A New Type of Synthetic opaque residues of the flux (Figures 5,6,7). Ruby on the Market: Offered as Hydrothermal Rubies Chemical analyses of residues at the surface of the from Novosibirsk. Aust. Gemmol. 18, 149-156. F.G.AF.G.A.. youyourr kekeyy ttoo ththee fascinatinfascinatingg worlworldd ooff GemmologGemmologyy

ThThee GemmologicaGemmological l ThThee GemmologicaGemmologicall AssociatioAssociationn anandd GeGemm AssociationAssociationss courscoursee TestinTestingg LaboratorLaboratoryy o off hahass beebeenn speciallspeciallyy GreaGreatt BritaiBritanin hahass beebeenn compilecompiledd intintoo aa serieseriess activelactiveyly involveinvolvedd inin ooff teachin teachingg modulemoduless the very beginning of that are both readable the very beginning of that are both readable Gemmology as an and lavishly Gemmology as an and lavishly independent science. illustrated. independent science. illustrated. Tod ay, the Together they AssociationToday, the takes provideTogethe a r they Associatiopride in itsn takes providcomprehe a ensive step­ pridinternationae in its l comprehensivby-step guide eto step the- internationareputation las a learned by-stefascinap tiguidng worlde to th ofe reputatiosociety dedicatedn as a learne to d i fascinatingemmologyg worl andd oanf societthe promotioy dedicaten ofd to gemmologopportunityy tano dearn an thgemmologicale promotion o f opportunitthe covetedy tionitials earn gemmologicaeducation andl the thFGAe covete - Fellowd initial of thes educatiospread ofn and the FGA-FelloGemmologwical o f the spreagemmologd of ical GemmologicaAssociation. l gemmologicaknowledge. l AssociationTo find out. more knowledgeThe Associations. Gemmological Association completeTo find ou thte morcoupoe n Gemmological Association coveTheted Association Fellowships is and Gem Testing Laboratory completbelow aend th wee coupowill n covetea markd ofFellowshi excellencep is and Gem Testing Laboratory beloimmedw aniated wlye forward will aonly mar bestowedk of excellenc upone Of Great Britain immediatelthe Associatioy forwarns d onlmembersy bestowe, whod upo n Of Great Britain thprospectuse Association givings memberssuccessfully, wh undertakeo the Associations full details of this uniprospectuque coursse. givin g successfullwritten andy praundertakctical eDiploma the Association examinastions. full details of this unique course. writte1-n an-d practica----l Diplom- a- examinations- - - --. ------, To GAGTL Education Department, 27 Greville Street, London ECl N 8SU I rI TPolease GAGT sendL Educatio details nand Department application, 2 7form Grevill fore t heStreet Dip, lomaLondo inn GemmologyECl N 8SU Course. I Please send details and application form for the Diploma in Gemmology Course. I Name: I I Name: I I Address: I

I Add ress: I I I I I I Telephone: GEM; _ _ _ .-J L Telephone: .GEM; 398 J. Gemm, 1993, 23, 7

Notes from the Gem and Pearl Testing Laboratory, Bahrain - 2 A. Bubshait, FGA, and N.P.G. Sturman, FGA, DGA

Pressed amber distant vision) and when a hot point was used In our first Bahrain Laboratory notes (in extremely carefully, it gave off a characteristic Scarratt, 1992, 223-4) we made reference briefly resinous odour. However, unlike the necklace in to characteristic strain patterns normally associ­ our first report, when examined between crossed ated with some forms of pressed amber. The strain polars the cabochon displayed strain patterns patterns referred to were those sometimes typical of some forms of pressed amber (Figure 2). observed between crossed polars and typical of Microscopic examination revealed clear bound­ materials subjected to some form of internal struc­ aries between some of the individual amber pieces tural strain. making up the cabochon and the fluorescence Interestingly, shortly after the publication of this exhibited under short wave ultra-violet light, article, a yellow heart-shaped cabochon (Figure 1) although weak, was a patchy chalky whitish green was submitted for a verbal opinion. The proper­ colour. On closer examination the uneven fluo­ ties of the cabochon indicated that it was amber: rescence appeared to be related to the different it floated in brine, had an RI of 1.54 (direct and fluorescent characteristics of the amber pieces within the cabochon. Fig. 1. The pressed amber cabochon. Surface colour enhanced amber A string of 'worry beads' comprising 45 spheri­ cal, one cylindrically-shaped and two disc-shaped yellow brown beads was submitted recently with a request to check that the beads were amber. The usual testing procedures used on materials sus­ pected of being amber all indicated that samples from the beads were amber, but the colour of the beads looked 'odd' when examined through the microscope. This oddity took the form of trans­ parent lighter yellow patches of various sizes, scattered across the mainly darker orangish brown surface of the beads (Figure 3). These lighter areas

Fig. 2. The interference colours exhibited by the cabochon seen in , Fig. 3. One of the lighter yellow areas acting as a 'window' to reveal Fig. 1, when examined through a polariscope. the underlying colour of the beads.

© Copyright the Gemmological Association ISSN: 0022-1252 J. Gemm, 1993,23,7 399

spicuous area. Not only did the underlying colour of this particular area turn out to be light yellow, but when this previously dull orange fluorescent area was examined with UV light once more, a strong whitish-blue fluorescence was observed. It would appear that the body colour of the beads, in both this necklace and that described in the previ­ ous 'Note' (1992), is pale yellow and gives rise to whitish- blue fluorescence. The greenish-brown fluorescence of the more strongly coloured areas in the faceted bead necklace and the orange fluo­ rescence of the necklace just described, probably Fig. 4. The spangles observed in some beads. indicate either slightly different starting materials appeared to resemble gaps in an uneven coating of or different degrees of heating. some type (rather like a decorator painting a wall Numerous spangles seen in some of the beads but missing small areas), but no signs of any (Figure 4) are typical of some examples of clarified coating could be detected. Higher magnification amber (Fraquet, 1987) and add credence to the showed that many of the lighter areas were slightly idea that the beads have been heat-treated. raised above the surface. In order to check that these areas were not due to spots of some separate Surface cavity filled natural rubies substance which had been dropped onto the Today, gemmologists are not only faced with surface and solidified, we very carefully levelled identifying a wide range of gemstones, but also a one with a knife. This showed that the underlying wide range of treatments used to improve the colour was still a lighter yellow and that the raised colour, clarity and, hence, the apparent value of area was not formed from another substance. As these stones. an extra check, the underlying area revealed by the One of the most frequently encountered treat­ knife and the top of another raised area which had ments is the artificial filling of cavities and fractures not been examined previously were lightly in natural rubies and, to a lesser extent, natural sap­ touched with a thermal probe. Both gave a phires (Hughes, 1990). Figures 5 and 6 show the resinous odour typical of amber. type of filling that the gemmologist needs to be At this point we began to note the similarities aware of. These features were observed in two between these beads and those examined in our natural Thai rubies that were mounted in a necklace first 'Note from the Bahrain Laboratory5 (in containing 32 oval faceted rubies of approximately Scarratt, 1992, 223-4). In UV radiation the darker 0.60 - 0.70ct each. Three more rubies in the neck­ coloured surface areas of the beads fluoresced a lace revealed narrow fillings in deeper fractures. weak chalky orange, whilst the small lighter yellow Stones with shallow filled surface cavities may be areas within the darker body showed a distinct repolished to remove the material, but if, as in this moderate to strong whitish/blue fluorescence. case, any of the material present is in a deep fracture Pursuing this relationship between colour and flu­ or feather the potential of the stone is not so good, orescence further, we gently scraped away the as no amount of repolishing will remove all the darker surface colour of one bead in a small incon­ material.

Fig. 6. Surface-reaching fracture in another ruby showing that part of Fig. 5. The larger filled surface cavity in a ruby. the stone (top right) is filled. 400 J. Gemm., 1993, 23, 7

Waxed filled cavities in coral the late 1950s, those dealing in natural pearls have 'Worry beads' are a part of Bahraini life and as had to be wary of this type of cultured pearl. such are used as a fashion accessory. Because of These rows show just how careful dealers have to their popularity we inevitably see a large number be, especially with the improved techniques used pass through the Laboratory for examination. to culture pearls today. Nowadays, most of the Figure 7 shows some 'worry beads that were non-nucleated cultured pearls no longer have a tested recently. The concentric/radial branch-like 'Rice-Crispie' shape, hitherto so characteristic of structure of the beads and the other gemmologi- the freshwater culturing method, and many pearls cal properties proved them to be coral, but what resulting from freshwater and marine culturing was more interesting was that some cavities and methods may closely resemble natural pearls in surface-reaching fractures appeared to have been external appearance. filled. The material filling the surface features Although these mixed rows are not the first to became very apparent under reflected light have been tested by the Bahrain Laboratory, they (Figure 8), as the lustre of the filler was notably have proved to be the most mixed seen to date. In different from the surrounding coral. In addition most previous rows we have examined, the non- to the difference in lustre, some filled areas con­ nucleated cultured pearls have been small to tained one or more bubbles, were easily marked medium sized, whereas the non-nucleated cul­ with a metal pointer and flowed when a hot-point tured pearls illustrated in Figure 9 are of was placed near them. All this evidence led us to numerous sizes, including many that are large. We believe that the material used to fill the cavities know of no commercial cultured pearl farming in was probably wax that had been used in part to the Gulf so, although the natural pearls may well improve the surface appearance of the beads by have a Gulf origin, the non-nucleated cultured hiding the cavities. pearls must come from elsewhere.

Nineteen rows of mixed natural and non- Two pearls with interesting drill-holes nucleated cultured pearls In February 1993 a customer brought us two button-shaped pearls for testing. It was not their radiographic structure that interested us, but rather how they were drilled. The drilling methods used on each pearl were different, as the radio­ graph in Figure 10 shows. One showed the 4Chinese-drilling' method where two part-drilled holes are angled to meet one another to form a 'curved' drill-hole and the other showed a very large part-drilled hole in the base with a separate

Fig. 10. Radiograph and diagram of the two pearls showing the drilling methods applied to each. 15 minutes exposure, short development.

Fig. 9. Nineteen rows of pearls containing a mixture of non- nucleated cultured pearls and natural pearls.

Nineteen graduated single rows of pearls were Decently submitted for a sample test and the largest pearls (up to 8.0 mm) are shown in Figure 9. We were informed that the pearls were thought to come from the Gulf and, since being found, had been sent to India for drilling, sorting and string­ ing. Gulf pearls have been sent to India to be incorporated in Bombay bunches for hundreds of years, so this account came as no surprise. The pearls were duly tested, and, when the radiographs of the pearls were examined, it became clear that the rows contained a mixture of natural and non- nucleated cultured pearls. Ever since the introduction of non-nucleated cultured pearls in J. Gemm., 1993, 23, 7 401

Fig. 7. The coral 'worry beads'.

drill-hole at right angles, running across the diam­ Scarratt, K., 1992. Notes from the Laboratory - 16. J. Gemm., eter of the pearl. 23, 4, 215-24. Both methods of drilling are often associated Taburiaux, J., 1985. Pearls, their origin, treatment and identification. NAG Press, Ipswich, Suffolk. p. 204. with natural pearls and, in our experience, a pearl with either form of drilling often proves to be [Manuscript received 7 March 1993] natural. That this is not always the case is demon­ strated by the pearl with the "T" drilling which proved to be cultured. Such drilling clues, there­ fore, cannot be taken as proof of identity. Chinese-drilling was so named because the Chinese often drilled pearls in this way for use as buttons and decorations on Mandarins' clothes Q. Taburiaux, 1985).

Acknowledgements The authors acknowledge with thanks the assis­ tance of both the Bahrain and London Laboratory staff.

References Hughes, R.W., 1990. Corundum. Butterworth-Heinemann, Fig. 8. The difference in surface lustre seen when a filled area is London. pp. 118-19. examined by reflected light. Note the dull lustre of the soft Fraquet, H., 1987. Amber. Butterworths, London. p. 69. wax and the brighter lustre of the coral. 402402 J.J. Gemm.,Gemm., 1993,1993, 23,23, 7

EmeralEmeraldd mineralizationmineralization ofof Barang,Barang, BajauBajaurr Agency,Agency, PakistaPakistann S. ShahidShahidHussain,M.Sc., Hussain, M.Sc., DIC, DIC, MS,* MS,* M.N. M.N. Chaudhry,Chaudhry, B.Sc. (Hon.), Ph.D.,** and HamidHamid Dawood, Dawood, M.Sc.* M.Sc.*

* PakistanPakistan MuseumMuseum ofof NaturalNatural History,History, Islamabad,Islamabad, PakistanPakistan **** InstituteInstitute ofof Geology,Geology, UniversityUniversity ofof thethe Punjab,Punjab, Lahore,Lahore, PakistanPakistan

AbstractAbstract emeraldemerald mineminess inin 1984.1984. ThisThis isis thethe firstfirst accountaccount ofof emeraldemerald mineralizationmineralization A briefbrief accountaccount ofof thethe geologygeology andand emeraldemerald fromfrom Barang,Barang, BajaurBajaur Agency,Agency, NWNW PakistanPakistan.. EmeraldEmerald mineralizatiomineralizationn ofof AmankotAmankot minesmines inin Bajaur AgencyAgency mineralizatiomineralizationn isis associatedassociated witwithh talctalc carbonatecarbonate hosthost ooff iiss givengiven belowbelow.. ththee IndusIndus suturesuture ophioliticophiolitic melangemelange.. TheThe mineralizationmineralization isis pneumatolyticpneumatolytic andand hydrothermal,hydrothermal, latelate toto postpost tectonictectonic GeologGeologyy andand petrographpetrographyy ofof ththee hosthost rocksrocks ofof anandd structurallystructurally controlled.controlled. ForFor thethe firstfirst timtimee itit isis beinbeingg recognizerecognizedd andand proposeproposedd thathatt ththee sourcesource ofof berylliumberyllium emeraldemerald bearinbearingg fluidsfluids responsiblresponsiblee forfor emeraldemerald mineralizationmineralization ThThee geologicalgeological mapmap ofof ththee areaarea iiss givengiven asas FigureFigure areare ththee TertiaryTertiary minorminor granitesgranites ofof S-typeS-type occurringoccurring inin thethe 2.2. TheThe lithostratigraphiclithostratigraphic sequencesequence andand broabroadd tecto­tecto­ area.area. ThiThiss isis contrarycontrary ttoo ththee alreadyalready heldheld viewviewss thatthat ninicc unitunitss ofof ththee areaarea areare asas follows:follows: berylliuberylliumm fluidsfluids emanatedemanated fromfrom a trenctrenchh oror arcarc source.source. KohistanKohistan sequencesequence AmphiboliteAmphibolite,, etc.etc. CretaceousCretaceous ThThee colourcolour ofof BarangBarang emeraldemerald varievariess fromfrom lightlight bluishbluish­- greengreen ttoo deepdeep greengreen andand ththee crystalscrystals rangerange fromfrom minuteminute ----- MainMain MantleMantle ThrustThrust (MMT,(MMT, IndusIndus suture)suture) ------ttoo 2.2.5cm Scm.. ThiThiss paperpaper forfor ththee firstfirst timtimee presentpresentss celcelll InduInduss suturesuture TalcTalc carbonatecarbonate dimension of emerald from Pakistan by using an adv­advancedmelangmelange e UltramaficsUltramafics ancedcomputer computer program program and and four four cycles cycles of ofrefinement. refinement. GabbroGabbro CretaceousCretaceous GreenGreen schist/stoneschist/stone ttoo IntroductionIntroduction AmphibolitAmphibolitee PalaeocenePalaeocene MetasedimentsMetasediments A varietyvariety ofof gemstonesgemstones includingincluding emerald,emerald, ruby,ruby, pinpinkk anandd goldengolden topaztopaz,, bi-coloubi-colourr tourmalintourmalinee andand ------— ------ThrusThrustt ------aquamarineaquamarine areare beingbeing mineminedd iinn northernnorthern Pakistan,Pakistan, IndianIndian PlatPlatee CarbonatitCarbonatitee TertiaryTertiary MinorMinor S-typeS-type GraniteGranite mostlmostlyy bbyy ththee publicpublic sector.sector. AmongstAmongst themthem,, ththee toptop qualityquality SwatSwat emeraldsemeralds areare consideredconsidered ttoo bebe amongamong GraphiticGraphitic schistschist ththee besbestt inin ththee worldworld.. FoForr lonlongg thesthesee hahadd beebeenn soldsold Garnetiferous-Garnetiferous- inin ththee worldworld marketmarket asas 'Afghanistan''Afghanistan' emeralds.emeralds. TheThe calcareouscalcareous rocrockk PrecambrianPrecambrian recent efforts of the Gemstone Corporation of Quartzite/quartz-Quartzite/quartz- recent efforts of the Gemstone Corporation of micmicaa schistschist PakistanPakistan havhavee introducedintroduced thithiss emeraldemerald inin ththee worldworld markemarkett andand becausbecausee ofof itsits propertiesproperties itit isis iinn greatgreat GraniGranit tee gneissgneiss ProterozoicProterozoic demanddemand nowadays.nowadays. TheThe mainmain emerald-producingemerald-producing areasareas iinn ththee SwatSwat TalTalcc carbonatecarbonate blockblockss whicwhichh hoshostt emeraldemerald miner­miner­ districtdistrict areare MingoraMingora (Giibelin,(Gübelin, 1968,1968, 1982;1982; Jan,Jan, alizationalization inin BarangBarang,, BajauBajaurr AgencyAgency,, areare partpart ofof thethe 1968,1968, JanJan et ai.,a/., 1981;1981;Kazmi^a/. Kazmi et ai.,, 1984,1984,1986 1986)) andand InduInduss suturesuture melangemelange whicwhichh marksmarks ththee lineline ooff GujarGujar KiliKili (Hussain(Hussain et ai.,ai, 1982).1982). KhazanaKhazana (Shamo­(Shamo- closureclosure ofof ththee Tethys.Tethys. ThisThis tectonitectonicc melangmelangee occursoccurs zazaii area)area) isis a newlynewly discovereddiscovered localitylocality inin Swat,Swat, thethe betweebetweenn thethe IndianIndian platplatee composedcomposed mainlymainly ofof potentiapotentiall ofof whicwhichh isis stillstill toto bbee ascertained.ascertained. PrecambrianPrecambrian metasedimentsmetasediments andand S-typeS-type granitegranite EmeraldEmerald fromfrom AmankotAmankot,, BajaurBajaur AgencyAgency (longi­(longi­ gneissesgneisses cutcut atat placesplaces bbyy TertiaryTertiary garnetgarnet andand tudtudee 71071° 36.68'36.68' andand latitudelatitude 34°34° 39.25')39.25'),, hahass beenbeen tourmalintourmalinee bearingbearing leucogranitesleucogranites ofof S-typeS-type andand producedproduced bbyy thethe localslocals sincesince earlyearly 1970s.1970s. TheThe associatedassociated beryberyll bearinbearingg pegmatitepegmatitess ttoo thethe southsouth locationlocation ofof thethe areaarea isis givengiven inin FigurFiguree 1.1. BecauseBecause ooff andand ththee KohistanKohistan islandisland arcarc complexcomplex ofof Creto­Creto- ththee tribatriball andand hostilehostile attitudeattitude ofof ththee localslocals,, nono TertiaryTertiary ageage ttoo ththee north.north. outsideroutsider couldcould visitvisit ththee mininminingg areasareas ofof thithiss agencyagency A generalgeneral north-southnorth-south stretchingstretching IndusIndus suturesuture andand henchencee nothinnothingg was reportedreported aboutabout thethe naturenature ofof ophioliticophiolitic melangemelange comprisingcomprising lenseslenses andand blockblockss ooff thesthesee deposits.deposits. AfterAfter protracteprotractedd efforts,efforts, itit becamebecame greenstone,greenstone, taltalcc carbonate,carbonate, gabbro,gabbro, serpentinizedserpentinized possiblpossiblee toto carrycarry outout investigationsinvestigations ofof ththee AmankotAmankot peridotiteperidotite,, amphibolite,amphibolite, calcareouscalcareous rocrockk andand

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. Alluvlum------~I ~ Ga bbro ------,...... -;<1Quol.2...2!.J m,car tzscnitel.,Ouartzst--...... I:;r-\/~Marb . l em. - m- - uo- - ~ ~ . IV""'VVI Undifferent,ated ~G " l " s ~ Granite ______.. ___ ~Green schlst/stone " ~ metasediments - --~ ranI e gne ls -- ---i.....!...... !j ~Undifferentiated rmlGQrnetlferous ~R d ~"""/ I Talc Ca r bonatE'---'-~ m e l ange zone.----LJ:!lJcalcareous tock .. - ~ oa ------...... - .-

Car b ona tI't e ------llWlllllJITTmTTTnA mp hObI 0 II' t e -.. -.. - -~~Graphit i c schist .. 1===:.:.1 River / stream--~---~

FigFig.. 22.. GeologicalGeological mapmap ofof Barang-Barang-TurghaTurghaoo areaarea,, NWFP,NWFP, PakiPakistanstan.. metachertmetachert hashas beenbeen brieflybneily describeddescribed byby HussainHussain etet (Figure(Figure 22)).. TowardsTowards thethe northnorth itit isis truncatedtruncated byby ai.al (1984(1984)).. IndusIndus suturesuture oror MainMain MantleMantle ThrustThrust ((MMT)MMT). . TheThe larger larger outcropsoutcrops ofof talctalc carbonate, carbonate, greenstonegreenstone OphioliticOphtolitic melangemelange hashas beenbeen emplacedemplaced alongalong aa andand gabbrogabbro melangemelange havehave beenbeen shownshown onon thethe mapmap numbernumber ofof faultsfaults whichwhich areare usuallyusually markedmarked byby ((FigurFiguree 22)).. TheThe melangemelange with with smallersmaller unmappableunmappable talcosetalcose rocks.rocks . blocksblocks hashas beenbeen shownshown asas undifferentiated undifferentiated melangemelange RocksRocks ofof thethe melangemelange zonezone havehave anan angularangular J. Gemm., 1993, 23, 7 405 relationship with overlying older calcareous schists. Emerald mineralization The rock fragments or blocks in the melange zone About an 80 metre wide zone in talc carbonates to vary in size usually from a few metres to thousands the north of Amankot village has emerald miner­ of metres across. These rocks have been subjected alization. The talcose rocks are emplaced along a to deformation resulting in the formation of tight fault within graphitic schists. folds, fractures and faults. Talc carbonate rocks The Amankot mineralized area consists of three which host emerald mineralization are described emerald mines over a linear extension of about below. The other rock types in the melange have 0.80km. The emerald mineralization noted in these been excluded since they are not directly related to mines is described below: the emerald mineralization. 1. Hydrothermal veins, consisting mainly of quartz with a small quantity of carbonates, in places Talc Carbonate Rocks contain emerald crystals. Talcose rocks adjacent to Field and laboratory studies indicate that these these veins are also mineralized. The quality of this rocks are the altered ultrabasics. They occur as emerald, especially in the host talc carbonates, is the lenses, patches and sheets of various sizes and are best. The emerald crystals are usually well de­ composed of talc, carbonates (mainly magnesite), veloped, inclusion free and have good transparency. quartz, actinolite, iron ore, etc. 2. Tourmalinized meta-cherts overlying the miner­ The schistosed zones are talc-rich and exhibit alized talc carbonates are cut by pneumatolytic/ tight drag folding. Talc carbonate schists contain hydrothermal veins. Sometimes these veins contain almost equal quantities of talc and carbonate. small sized, poor to medium quality emerald crys­ Soapstone is also associated with talc carbonate tals. The host tourmalinized meta-cherts may also schist. Massive rocks are carbonate (dominantly be mineralized with the same quality emeralds. magnesite) with a small quantity of talc. These are 3. Silicification of the talc carbonates has taken well jointed and contain abundant quartz and place over smaller areas up to a few metres across. calcite veins. Lenses and nodular quartz veins and Occasionally these contain sporadic emerald crys­ stockwork are sometimes lined by chlorite and tals. The quality of these emeralds is also not good. fuchsite. 4. Sheared zones are developed along the faults in Talcosed rocks may contain phacoids (concor­ talc carbonate rocks. Hydrothermal veins have dant lenses) of green schist. Actinolite is developed filled some of these weak zones. Within such zones in talc carbonates at their contacts with metasedi- emerald crystals are found in pockets as well as ments. At these places talc carbonates appear to be disseminations. metasomatically altered. This is indicated by the presence of feldspar which is not strongly altered. Optics and chemistry of emerald Some of the altered bodies are highly feldspathic The colour of emerald crystals of Amankot area is with chlorite, actinolite, muscovite and quartz as bluish-green, green, grass green and deep green. accessory or minor minerals. These patches are up Some crystals are light greenish-blue with green to a few metres across in size. edges. Transparency varies from poor to excellent. Emerald mineralization is found in talc carbonate High quality emeralds of the Amankot area are rocks towards the north of Amankot. Silicification bluish-green, clear and transparent. of these rocks is observed and emerald has been Single crystals are usually well developed, hex­ mineralized in the silicified parts. These quartz agonal and may have small sized inclusions. The schorl and somewhat feldspathized quartz schorl size of emerald varies from 1mm to a maximum of rocks are closely associated with the talc carbonates 2.5cm in the longer dimension. The largest stones in the mine area of Amankot. The silicified and weigh up to 150 carats. metasomatized areas (quartz-schorl-feldspar and The RIs of Amankot emeralds are higher than quartz-schorl rocks) may contain tiny beryl crys­ those of pure beryl due to a high quantity of iron tals. and chromium. The values are comparable to the In Barang-Turghao area both S-type Proterozoic emeralds of Bucha, NW Pakistan (Rafiq et al., granite gneiss and younger anatectites (Tertiary in 1985) but higher than those of Mingora emeralds, age and associated with the Himalayan orogeny) are Swat, due to higher FeO. present. The small acid minor bodies of Tertiary age Absorption bands and refractive indices of one are late to post tectonic. beryl and two emerald crystals from Amankot are Kot granite gneiss and Agra-Turghao granite listed in Table I, together with similar data for gneiss of the surrounding area are S-type. Both Bucha (Mohmand) beryl and emeralds (Rafiq et al., these bodies have younger (Tertiary) acid minor 1985) as well as Mingora (Swat) emerald (Gübelin, bodies. They also include beryl- and tourmaline- 1982). The RI values were determined by immer­ bearing pegmatites. The beryl is bluish-green in sion method on powdered grains. The listed values colour. are accurate to ± 0.002. The absorption spectra of 406 J. Gemm, 1993, 23, 7

emeralds contain distinct chromium absorption as the host rock in case of Barang is talc-carbonate. lines in the red region at 682.7-683.9 nm for beryl Schrader (1983) has suggested that the green and 682.5-683.8 nm for emeralds. There are also colour in emeralds may be due to Cr, Mn, Ni, V and weak broad bands for Fe absorption for both beryl Fe. A comparison of the chemical analyses of and emeralds in the yellow region between 585-584 emerald of the Amankot area with beryl of the same nm. These are due to significant Fe contents. area shows that the values of Mn, Fe, Ni and V are Optically the emeralds of Amankot area, Bajaur similar. The only colouring factor may, therefore, be Agency, are very similar to the Bucha emeralds, Cr. This fact has been pointed out by Rafiq and Jan Mohmand Agency, reported by Rafiq and Jan (1985) for Bucha emeralds. (1985). Cell dimensions of bluish-green emerald from Two chemical analyses of Amankot emeralds and Amankot (analysis 3 in Table I) were determined. one analysis of beryl for the same area are given in The diffraction pattern was obtained on Ragaku Table II. In addition to major elements, the amounts automated powder X-ray diffractometer (Model of Cr203, MnO, CuO and NiO have also been D-MAX/IIA). The cell dimensions were calculated determined. For the sake of comparison the analy­ by using the advanced programme of Benoit (1987). ses of Amankot, Bucha (Rafiq et ai, 1985) and Swat Four cycles of refinement were used. The cell emeralds (Gübelin, 1982; Schrader, 1983) and dimensions are: Barang emeralds and green vanadium beryls of a= 9.2548 ± 0.0036 Gandao (Snee et al., 1989; Hammerstrom, 1989) c= 9.1905 ±0.0075 have been arranged as Table II. This is the first determination of cell parameters The analyses of Barang and Gandao emeralds of emeralds from Pakistan using an advanced have been discussed by Snee et al. (1989) and computer program. Hammerstrom (1989). However, they have wrongly grouped these analyses with Mohmand as constitut­ ing a single district. This grouping is erroneous Paragenesis since host rocks in the case of Barang (Bajaur Talc carbonates host emerald mineralization not Agency) are different from that of Gandao only in Barang, Bajaur Agency (this account), but (Mohmand Agency) and the two deposits are also in Mingora, Swat (Gübelin, 1968, 1982; Jan, separated by a considerable distance. The main 1968; Janetal., 1981, and Kazmi era/., 1984,1986). Mohmand deposit occurs in meta-limestone where­ Talc carbonates also host emerald mineralization in

Table I: Physical properties of Amankot, Bucha and Swat emeralds Specimen Absorption Strength of absorption Chelsea Colour Refractive Indices Inclusions (in nm) Filter e (0 Light pale green beryl 682.7 Weak to moderate Light brownish-red 1.576 1.586 Fluid inclusions (Amankot) 683.9 Weak broad bands mica and Fe-oxides 585.0 Bluish-green emeralds 682.6 Strong Deep brownish-red 1.592 1.604 Fluid inclusions, (Amankot) 683.8 talc fibres, mica 584.0 Weak broad bands plates, Fe-oxides 682.5 1.592 1.604 683.7 585.0 Light green 682.8 Weak to moderate Light brownish-red 1.575 1.583 Fluid inclusions, beryl (Bucha)* 683.9 Weak broad bands feathers of Fe- 585.0 oxides, siderite, tremolite/mica Bluish-green 682.8 Strong Dark brownish-red 1.590 1.600 Fluid inclusions, emerald (Bucha)* 683.9 talc fibres, mica 585.0 plates Emerald (Swat)** 683-680 Strong red to pink 1.588 1.595 Two phase inclusions, 662, 646, to to colour banding and 637 Distinct to strong 1.593 1.600 zoning, calcite, dolomite 477, 472 Weak 472 * Rafiq and Jan, 1985 ** Swat emerald values cover the range for seven stones (for details, see Gübelin, 1983) J. Gemm., 1993, 23, 7 407

Table II: Analyses of beryls, emeralds and green vanadium beryls from Pakistan. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Si02 63.74 _ 62.41 63.05 _ _ 64.2 63.7 _ N.D. _ 63.8 N.D. 63.1 62.1 63.2 Ti02 0.04 - 0.03 0.02 - - - - - 0.12 <0.02 <0.07 0.13 <0.05 0.01 0.02 A1203 13.28 _ 15.26 14.20 - - 14.8 13.7 - 14.5 14.8 14.5 14.7 12.7 14.1 14.0 Cr203 0.10 0.27 0.85 0.76 0.83 0.66 0.8 1.4 0.2 - 0.03 0.03 - 0.45 0.17 0.04 Fe203 2.52 2.25 2.47 2.18 2.10 0.9 0.4 1.4 0.7 - 1.6 1.4 - 1.2 0.94 1.40 BeO 12.95 _ 12.08 13.07 ------11.41 - 10.96 - - MnO 0.08 0.10 0.10 0.10 0.10 - 0.0 0.1 0.002 - - - - - 0.02 0.00 MgO 1.26 2.18 2.15 2.34 1.91 2.6 2.7 2.4 0.6 2.0 2.4 2.2 s 2.5 4.8 2.77 2.14 CaO 0.69 _ 0.41 0.34 - - - - - 0.3 <0.04 0.53 <0.3 0.13 0.02 - Na20 2.29 1.87 1.91 1.82 2.14 2.1 2.1 1.9 2.0 2.30 2.49 - 2.22 - 2.19 1.75 K20 0.18 0.27 0.16 0.13 0.08 ------<0.5 - <0.04 0.02 0.03 CuO 0.18 0.41 0.21 0.19 0.11 ------NiO 0.04 0.04 0.05 0.06 0.02 - - - <0.02 0.00 ------V 0.04 - 0.06 0.04 - - 0.1 - >0.05 - 1.33 0.53 0.02 0.04 0.02 0.66 Sc=0.14 ( asV2O3)0asV 203) + H20 1.70 - 1.50 1.67 - - - - - H2CT 0.14 - 0.11 0.08 - - - - - 1. Light pale green beryl from Kot, Malakand Agency 2. Light green beryl from Bucha, Mohmand Agency. Analyst M. TahirShah (Rafiq and Jan 1985) 3 & 4. Bluish-green emerald from Amankot area, Bajaur Agency 5. Deep bluish-green emerald from Bucha, Mohmand Agency. Analyst M. TahirShah (Rafiq and Jan, 1985) 6. Emerald from Mingora, Swat. Analyst M. Weibel (Giibelin, 1982) 7 & 8. Microprobe analyses of two emeralds from (Swat?) Pakistan, (Hänni, 1982) 9. Neutron activation analysis of emerald from (Swat?) Pakistan. Average oxide values calculated from element percentages of two samples by Rafiq and Jan (1985) from Schrader (1983) 10 & 13. Neutron activation analyses of emeralds from Barang (Snee et al., 1989) 11. Neutron activation analysis of green vanadium beryl from Gandao (Snee et al., 1989) 12. & 14. Induced coupled Argon Plasma-Atomic Emission Spectrometry analyses of green vanadium beryl from Gandao and of emerald from Barang respectively (Snee et al., 1989) 15 & 16. Microprobe analyses of emerald from Barang and of green vanadium beryl from Gandao respectively (Hammerstrom, 1989)

Gujar Kili, Makad and Charbagh areas of Swat addition there are minor post tectonic granite (Hussain, 1982). bodies of S-type as well as I-type. Kot granite gneiss Giibelin (1982) suggested a dolomitic host for and Agra-Turghao granite gneiss are S-type. Both emerald mineralization in Mingora, Swat. However, have younger Tertiary minor acid bodies including detailed petrological and geochemical studies of talc some beryl-bearing pegmatites. The Kot granite carbonates and associated ultramafics from Indus gneiss is an extension of Malakand granite gneiss suture melanges in Swat area clearly show that the studied by Chaudhry et al. (1974, 1976) and talc carbonate rocks are strongly carbonatized ser- Hamidullah^a/. (1986). pentinites and serpentinized peridotites. Chaudhry The younger magmatic phases show blue beryl et al. (1980) and Jan et al. (1968, 1980, 1981) also mineralization and some tourmalinization. The considered talc carbonate rocks as derivatives from Selai Patti amphibole bearing granite gneiss and an igneous (ultramafic) parentage. associated minor acid bodies are as yet not known to Prior to this presentation no direct evidence was contain beryl mineralization or tourmaline of their available to relate emerald mineralization to its own. It is, therefore, not possible to relate emerald source. Jan et al. (1981) ruled out the possibility mineralization with amphibole bearing granite/ that a granite source may have been responsible for granodiorite or equivalent gneisses (arc related). emerald mineralization. They suggested the trench The emerald mineralization in the talc carbonates related fluids as a possible source of Be responsible of the melange zone is characterized by its associa­ for emerald mineralization in talc carbonates and tion with post obduction pneumatolytic and hyd­ related ultrabasic blocks of the Mingora melange. rothermal activity. This activity is manifested by They ruled out a granite source of Be on the silicification and development of emerald and tour­ grounds that while the emerald host of Shangla- maline. Blue tinges and bluish-green colour of Mingora (talc carbonates and related rocks) are emerald are common. But green and grass green Mesozoic, the associated granites are Palaeozoic. colours also occur. In the Barang-Turghao area the granites and It is important to note that blue or bluish-green granite gneisses are predominantly S-type, garnet beryl is also mineralized in acid minor bodies and (at places) tourmaline bearing granite gneisses associated with Kot granite gneiss and Agra- and amphibole bearing (I-type) granite gneisses. In Turghao granite gneiss. The emerald mineralization 408408 J.J. Gemm.,Gemm, 1993,1993, 23,235 77

can,can, therefore,therefore, bebe relatedrelated toto postpost obductionobduction TertiaryTertiary Giibelin,Gübelin, E.J.,E.J., 1982.1982. GemstonesGemstones ofof Pakistan:Pakistan: Emerald,Emerald, rubyruby andand pneumatolyticpneumatolytic phasesphases relatedrelated toto acidacid magmatism.magmatism. spinel.spinel. Gems and Gemology, 18,18, 123-9.123-9. Hamidullah,Hamidullah, S.,S., Jabeen,Jabeen, N.,N., Bilqees,Bilqees, R.,R., Jamil,Jamil, K.,K., 1986.1986. ThisThis TertiaryTertiary acidacid minorminor magmatismmagmatism isis associatedassociated GeologyGeology andand petrologypetrology ofof thethe MalakandMalakand granitegranite gneissgneiss andand withwith thethe S-typeS-type granitegranite gneissesgneisses andand isis a productproduct ofof metasedimentarymetasedimentary complex.complex. Geol. Bull. Univ. Peshawar, 19,19, anatexisanatexis relatedrelated toto thethe thrustthrust stackingstacking andand crustalcrustal 61-76.61-76. thickeningthickening atat thethe leadingleading edgeedge ofof thethe Indo-PakIndo-Pak Hammerstrom,Hammerstrom, ].M.,J.M., 1989.1989. MineralMineral chemistrychemistry ofof emeralds:emeralds: anan shield just south of the melange zone containing talc electronelectron microprobemicroprobe study.study. In:In: Emeralds of Pakistan: geology, shield just south of the melange zone containing talc gemology and genesis (Eds.(Eds. Kazmi,Kazmi, A.H.,A.H., andand Snee,Snee, L.W.).L.W). carbonates,carbonates, somesome ofof whichwhich areare mineralizedmineralized bbyy VanVan NostrandNostrand Reinholq,Reinhol, NewNew York.York. 125-50.125-50. emerald.emerald. GhazanfarGhazanfar et al.al. (1986) (1986 )and and Chaudhry Chaudhry et et al. al. Hanni,Hänni, H.A.,H.A., 1982.1982. A contributioncontribution toto thethe separabilityseparability ofof naturalnatural (1987,1990)(1987, 1990) havehave discusseddiscussed thethe TertiaryTertiary anatexisanatexis atat andand syntheticsynthetic emeralds.].emeralds. J. Gemm., 18,18, 138-44.138-44. thethe leadingleading edgeedge ofof thethe Indo-PakIndo-Pak plateplate (just(just southsouth ofof Hunt, E.C., E.C., Stanton, Stanton, R.E., R.E., Wells, Wells, R.A., R.A., 1960. 1960. Field Field determination determina­ tionof beryllium of beryllium in soil forin soilgeochemical for geochemical prospecting. prospecting. Inst. Inst. thethe IndusIndus suturesuture melange)melange).. Min. Metall., 641,641, 361-9.361-9. ItIt isis inin thesethese zoneszones thatthat youngeryounger Be-BBe-B bearingbearing Hussain,Hussain, S.S.,S.S., Khan,Khan, T,T., Dawood,Dawood, H.,H., Khan,Khan, 1.,1982.I., 1982. CharbaghCharbagh minorminor acidacid bodiesbodies (mainly(mainly pegmatites)pegmatites) areare present.present. AlpuraiAlpurai ExplorationExploration Project.Project. GemstoneGemstone CorporationCorporation ofof HereHere melangemelange ultrabasicsultrabasics (bearing(bearing Cr)Cr) andand TertiaryTertiary Pakistan,Pakistan, Peshawar.Peshawar. Unpub. Report. 125p.125p. Hussain,Hussain, S.S.,S.S., Khan,Khan, T.,T., Dawood,Dawood, H.,H., Khan,Khan, 1.,1984.I., 1984. A notenote onon anatectitesanatectites (Be-B)(Be-B) interactinteract toto givegive riserise toto emeraldemerald Kot-PrangKot-Prang Ghar Gharmelange melange and associated and associated mineral occurrences. mineral occurr­ mineralization.mineralization. ences. Geol. Bull. Univ. Peshawar, 17,61-8.17, 61-8. EmeraldEmerald mineralizationmineralization isis therefore,therefore, regardedregarded Hussain, S.S., S.S., Chaudhry, Chaudhry, M.N., M.N., Dawood, Dawood, H., Anwar, H., Anwar, J., 1989. J., 1989. mainlymainly asas aa productproduct oftheof the interaction interaction ofofBe-B-Si-AI Be-B-Si-Al GeologyGeology andand emeraldemerald mineralizationmineralization inin Barang-Barang-TurghaTurghaoo area,area, BajaurBajaur Agency,Agency, Pakistan.Pakistan. Kashmir Journal of Geology, 6 & 7,7, pneumatolytipneumatolyticc activityactivity associatedassociated withwith thethe emplace­emplace­ 87-102.87-102. mentment ofof nearlynearly pospostt obductionobduction youngeryounger granitesgranites Jan,Jan, M.Q.,M.Q., 1968.1968. PetrographyPetrography ofof ththee emeraldemerald bearingbearing rocksrocks ofof (Tertiary)(Tertiary) describeddescribed earlier.earlier. ThisThis mineralizationmineralization iiss MingoraMingora (Swat(Swat State)State) andand PrangPrang GharGhar (Mohman(Mohmandd Agency),Agency), structurallystructurally controlled,controlled, postpost obductionobduction andand mosmostt WestWest Pakistan.Pakistan. Geol. Bull. Univ. Peshawar, 3,3, 10-11.10-11. Jan,Jan, M.Q., M.Q., 1980. 1980. Petrology Petrology of of thethe obducted mafic mafic and and ultramafic ultrama­ probablyprobably latelate toto postpost tectonic.tectonic. ChromiumChromium hashas beebeenn ficmetamorphites metamorphites from thefrom southern the southern part of the part Kohistan of the Kohistan impartedimparted byby thethe hosthost talctalc carbonatescarbonates whichwhich araree islandisland arcarc sequence.sequence. Geol. Bull. Univ. Peshawar, 13,95-107.13, 95-107. themselvesthemselves alteredaltered ultraultrabasics basics.. Jan,Jan, M.Q.,M.Q., Kamal,Kamal, M.,M., Khan,Khan, M.I.,M.I., 1981.1981. TectoniTectonicc controlcontrol overover emeraldemerald mineralizatiomineralizationn inin Swat.Swat. Geol. Bull. Univ. Peshawar, 14,101-9.14, 101-9. ReferencesReferences Kakar,Kakar, S.S.K. K.,, BadshahBadshah,, M.M.S. S.,, Khan,Khan, J.,J., 1971.1971. TheThe geologygeology ooff Ashraf, M., M., Chaudhry, Chaudhry, M.N., M.N., Hussain, Hussain, S.S., S.S.,1987. 1987.Mineralization Mineraliza­ JandulJandul valley,valley, WesternWestern Dir.Dir. Geol. Bull. Univ. Peshawar, 6,6, tion associatedassociated withwith thethe alkalinealkaline rocksrocks andand carbonatitescarbonatites inin 54-73.54-73. NWFP, Pakistan.Pakistan. Kashmir Kashmir]our. Jour. Geol., Geol., 5, 51-4.5, 51-4. Kazmi,Kazmi, A.H.,A.H., Lawrence,Lawrence, R.D.,R.D., DawoodDawood,, H.,H., Snee,Snee, L.W,L.W., BadshahBadshah,, M.S.M.S.,, 1979.1979. GeologGeologyy ooff BajauBajaurr anandd northernorthernn parpartt ooff HussainHussain,, S.S.,S.S., 1984.1984. GeologGeologyy ooff ththee InduInduss sutursuturee zonzonee iinn thethe MohmandMohmand.. Geol. Bull. Pesh. Univ., 11,11, 163-79163-79.. Mingora-ShanglMingora-Shanglaa areareaa ooff SwatSwat.. Geol. Bull. Univ. Peshawar, Benoit, P.H., P.H., 1987. 1987. Adaptation Adaptation to microcomputerto microcomputer of the of Appleman the Apple­ 17,127-44.17, 127-44. man EvanEvanss prograprogramm foforr indexinindexingg anandd leasleastt squarsquaree refinementrefinement KazmiKazmi,, A.H.A.H.,, LawrenceLawrence,, R.D.R.D.,, AnwarAnwar,, J.J.,, Snee,Snee, L.W.L. W,, Hussain,Hussain, ooff powdepowderr diffractiodiffractionn datdataa foforr uniunitt celcelll dimensions.dimensions. Amer. S.S.S.S.,, 1986.1986. MingorMingoraa emeralemeraldd depositdepositss (Pakistan)(Pakistan):: suturesuture MinMin.,., 72 72,1018-19., 1018-19. associateassociatedd gegemm mineralizationmineralization.. Econ.Eean. Geol., 81,81, 2022-82022-8.. BeusBeus,, A.A.A.A.,, 1966.1966. Geochemistry of beryllium and genetical type of KazmiKazmi,, A.H.A.H.,, 1983.1983. ReporReportt oonn ththee economieconomicc geologgeologyy andand beryllium deposits. FreemanFreeman,, SanSan FranciscoFrancisco,, CACA.. p.287p.287.. developmendevelopmentt prospectprospectss ooff SwatSwat emeralemeraldd minesmines,, Mingora:Mingora: ButtButt,, K.A.K.A.,, ShahShah,, Z.Z.,, 1985.1985. DiscoverDiscoveryy ooff blubluee beryberyll frofromm Hanamm PakistanPakistan,, GemstonGemstonee Corp.Corp.,, Unpub. report, 105p.105p. granite and and its its implication implication on onthe thegenesis genesis of emerald of emerald mineralization miner­ LLee BasBas,, M.J.M.J.,, MianMian,, I.I.,, RexRex,, D.CD.C.. AgAgee anandd naturnaturee ooff carbonatitecarbonatite alization iinn SwaSwatt districtdistrict.. Geol. Bull. Univ. Peshawar, 1818,, emplacemenemplacementt iinn nortnorthh PakistanPakistan.. Geol. Rundschau. (I(Inn press)press).. 75-81. Maluski,Maluski, H.F., H.F., Matte, Matte, P.,P., 1984.1984. Age of alpinealpine tectonometamorphic tectonometamor­ ChaudhryChaudhry,, M.N.M.N.,, AshrafAshraf,, M.M.,, HussainHussain,, S.S.S.S.,, 1980.1980. PreliminaryPreliminary eventsphic events in the northin the western north westernHimalaya Himalaya (N. Pakistan) (N. byPakistan) by studstudyy ooff nickenickell mineralizatiomineralizationn iinn ththee SwatSwat districtdistrict,, NWFP,NWFP, ththee 40Ar/39A40Ar/39Arr methodmethod.. Tectonic, 33,, 1-18.1-18. PakistanPakistan.. Contr. Geol. Pakistan. 1,9-26.1, 9-26. RafiqRafiq,, M.M.,, JanJan,, M.Q.M.Q.,, 1983.1983. A discoverdiscoveryy ooff emeralemeraldd neanearr Bucha,Bucha, ChaudhryChaudhry,, M.N.M.N.,, GhazanfarGhazanfar,, M.M.,, 1987.1987. GeologyGeology,, structurstructuree andand MohmanMohmandd AgencyAgency.. Geol. Bull. Univ. Peshawar, 16,16, 168168.. geomorphology of of upper upper Kaghan Kaghan valley, valley, Northwest Northwest Himalaya, Hima­ RafiqRafiq,, M.M.,, JanJan,, M.Q.M.Q.,, 19851985.. EmeralEmeraldd anandd greegreenn beryberyll fromfrom Pakistan.laya, Pakistan.Geol. Bull. Geol. Univ. Bull. Punjab., Univ. 22 ,Punjab., 13-57. 22,13-57. 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ObservationsObservations ofof redred berylberyl crystalscrystals fromfrom thethe WahWah WaWahh mountains,mountains, UtahUtah Masahiro H Hosaka, osaka, Ph.D., Ph.D., FGA FGA*, *, Kiyomi Kiyomi Tubokawa* Tubokawa* Toshio Hatushika** Hatushika** and and Hisao Hisao Yamashita Yamashitaf †

* InstituteInstitute ofof GemmologyGemmology andand JewelleryJewellery ArtsArts ofof YamYamanashi an as hi,, TokojichoTokojicho 1955-1,1955-1, Kofu,Kofu, 400,400, JapanJapan **Faculty** Faculty Engineering,Engineering, YamanashiYamanashi University,University, TakedaTakeda 4,4, Kofu,Kofu, 400,400, JapanJapan tYamanshi†Yamanshi IndustrialIndustrial TechnologyTechnology Centre,Centre, SatoyoshiSatoyoshi 3-9-4,3-9-4, Kofu,Kofu, 400,400, JapanJapan

AbstractAbstract enoughenough toto measuremeasure thethe ESRESR spectrumspectrum withoutwithout Physical,Physical, opticaloptical andand otherother propertiepropertiess ofof redred berylberyl crushing,crushing, thethe weightweight beinbeingg 0.200-0.3000.200-0.300 ct.ct. TheThe crystalscrystals fromfrom thethe WahWah WahWah mountains,mountains, Utah,Utah, werweree otherother propertiesproperties werewere asas follows:follows: studiedstudied usingusing spectroscopy,spectroscopy, electronelectron spinspin resonanceresonance SGSG 2.63-2.722.63-2.72 usingusing specific­specific- (ESR)(ESR) andand usualusual instrumentsinstruments ofof identification.identification. gravitygravity bottlebottle RIRI E8=1.561-1.565,0 = 1.561-1.565,w) = 1.1. IntroductionIntroduction 1.567-1.5711.567-1.571 TheThe colour-causingcolour-causing elementelement andand mineralogicalmineralogical BirefringenceBirefringence 0.0040.004 datdataa ofof redred beryberyll fromfrom WahWah WahWah mountains,mountains, Utah,Utah, PleochroismPleochroism OrangeOrange red-purplishred-purplish redred hashas alreadyalready beenbeen reportedreported (Nassau(Nassau et ai.,al., 1968;1968; UVUV fluorescencefluorescence InertInert toto LWandLW and SWSW ShigleyShigley et ai.,al., 1984).1984). BothBoth thethe MnMn++2 ioionn (Nassau(Nassau et ChelseaChelsea colourcolour filterfilter InertInert ai.,al., 1968)1968) andand thethe Mn+Mn+33 ionion (Shigley(Shigley et aI.,al., 1984)1984) ContentContent ofof MnMn andand FeFe 0.23wt%and0.23 wt% and 1.3wt%1.3 wt% havehave beenbeen suggestedsuggested asas thethe originorigin ofof thethe colour.colour. InIn respectivelyrespectively byby atomicatomic thisthis report,report, thethe nearnear infra-redinfra-red spectrumspectrum duedue toto absorptionabsorption analysisanalysis vibrationsvibrations ofof thethe H200 inin rvpeType I andand TypeType IIII sitessites (Wood(Wood et ai.,al., 1967)1967) inin a berylberyl crystalcrystal withwith spectraspectra inin InclusionsInclusions ththee visiblevisible regionregion andand ESRESR spectrumspectrum forfor observingobserving LiquidLiquid inclusions,inclusions, minuteminute fracturesfractures andand blackblack ththee valencevalence statestate ofof manganesemanganese havehave beenbeen measuredmeasured solidsolid inclusionsinclusions werewere observedobserved underunder thethe micro­micro­ withwith thethe otherother gemmologicalgemmological characteristics.characteristics. scope.scope. FigureFigure 1 showsshows X-rayX-ray lineline profileprofiless ofof FeFe KexKa andand MnMn KexKa forfor thethe solidsolid inclusioninclusion whichwhich appearedappeared 2.2. ResultsResults andand discussiondiscussion onon thethe surfacesurface ofof a beryberyll bbyy EPMA.EPMA. ThisThis analysisanalysis TheThe specimensspecimens testedtested werewere transparent,transparent, oneone foundfound thethe inclusioninclusion toto bebe blacblackk bixbyitbixbyitee [(Mn,[(Mn, Fe)2Fe) havinhavingg a modifiedmodified brilliant-cubrilliant-cutt style,style, anandd werweree largelarge 2 0 ], o33]. Fig.Fig. I.1. A componentcomponent imageimage andand X·rayX-ray lineline profilesprofiles ofof FFee KexKa andand MnMn KexKa forfor thethe solidsolid inclusioinclusionn thatthat appearedappeared onon thethe SpectroscopySpectroscopy surfacesurface ofof a roughrough redred beryl.beryl. BlackBlack barbar onon thethe leftleft sidsidee FiguresFigures 2A,2A, 2B,2B, showsshows thethe absorptionabsorption spectraspectra ooff representsrepresents 100/Lm.100/urn. UtahUtah facetedfaceted redred beryl,beryl, naturalnatural ColombianColombian emeraldemerald andand RussianRussian hydrothermally-grownhydrothermally-grown syntheticsynthetic emerald.emerald. TheThe absorptionabsorption peakspeaks ofof naturalnatural Col­Col­ ombia.nombian emeraldemerald assignedassigned toto one,one, twotwo andand threethree vibrationvibration modesmodes ofof H20 molecularmolecular inin thethe Type-IType-I sitesite oror thethe Type-IIType-II sitesite areare observedobserved FigureFigure 2A,2A, spec­spec­ trumtrum bb,, atat 953,953, 1145,1145, 1398,1398, 1460,1460, 1833,1833, 1897,1897, 19581958 andand aboveabove 20020000 cm'.cm1. OfOf thethe absorptionabsorptionss shownshown inin FigureFigure 2A,2A, spectrumspectrum bb,, thethe strongstrong peakpeak ofof 18971897 cm"cm-'1 isis associatedassociated withwith H200 inin thethe Type-IIType-II site,site, andand thethe otherother toto H20 inin thethe Type-IType-I sitesite oror freefree HH2200 molecularmolecular (Wood(Wood et ai.,ai, 1967).1967). AccordingAccording toto WoodWood andand Nassau,Nassau, H20 ofof thethe Type-IType-I sitesite hashas two-foldtwo-fold symmetricalsymmetrical axesaxes perpendiculaperpendicularr toto thethe c-axisc-axis ooff emeraldemerald crystalscrystals andand hashas nono alkalialkali ionsions nearbynearby.. OnOn thethe otherother hand,hand, H20 inin thethe Type-IIType-II sitesite hashas two-foldtwo-fold symmetricalsymmetrical axesaxes parallelparallel toto thethe c-axisc-axis andand hashas alkalialkali

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ionionss adjacentadjacent toto H20.0. TheThe formform ooff thethe wholewhole foforr thethe fieldfield perpendiculaperpendicularr toto ththee hexagonahexagonall axisaxis.. A absorptionabsorption spectrumspectrum ofof redred beryberyll (Figure(Figure 2A,2A, sharpsharp spectrumspectrum lineline (Fe3+)(Fe3+) anandd wave-likewave-like spectraspectra spectrumspectrum c)c) waswas similarsimilar ttoo thathatt ooff thethe naturalnatural werewere obtained,obtained, bubutt 'hyperfin'hyperfinee splitting'splitting' duduee ttoo thethe +22 ColombianColombian emeraldemerald,, inin whichwhich bothboth typestypes ofHzOof H20 areare MnMn+ ioionn (S=5/2)(S=5/2) was nonott observedobserved.. HoweverHowever,, thethe included,included, althougalthoughh thethe absorptioabsorptionn ofof redred berylberyl Mn4 +"2 ionion coulcouldd bbee expectedexpected toto existexist iinn ththee reredd beryl,beryl, havinhavingg ititss centrcentree atat aboutabout 19001900 cm-cm1I iiss veryvery weakweak andand becausbecausee oonn thethe basibasiss ooff thethe ESRESR data,data, iinn whichwhich broabroadd iinn comparisocomparisonn withwith thathatt ooff naturanaturall ColombianColombian 'hyperfine'hyperfine splitting'splitting' duduee ttoo MnMn++22 ioionn was observedobserved emerald.emerald. ConsequentlyConsequently,, thethe reredd beryberyll hashas botbothh typestypes iinn synthesizedsynthesized pinpinkk beryberyll crystalcrystalss (Flamini(Flamini et al.,al., 2+ ofof H20.0. InIn ththee RussianRussian hydrothermally-grownhydrothermally-grown 1986),1986), iitt iiss consideredconsidered thatthat MnMn2+ ioionn oughtought toto givegive emeraldemerald,, FigureFigure 2A,2A, spectrumspectrum a,a, ththee quantityquantity ooff pink-repink-redd colourcolourss toto naturalnatural reredd berylberyl crystals.crystals. ThusThus Type-IIType-II waterwater mighmightt bebe mormoree thathann ththee Type-Type-II water,water, ththee apparenapparentt absencabsencee ooff distincdistinctt 'hyperfine'hyperfine splitting'splitting' asas iinn thethe casecase ooff naturalnatural ColombiaColombiann emeraldemerald.. TheThe iinn ourour naturanaturall reredd berylberyl,, whicwhichh includeincludess 0.20.233 wt%wt% varietyvariety anandd amountamount ofof alkalalkalii ionion adjacenadjacentt ttoo Type-IIType-II manganesmanganesee ionion,, maymay bbee attributedattributed ttoo ththee interfer­interfer­ 3+ H22O0 couldcould bbee stronglystrongly influencedinfluenced byby thethe surround­surround­ encencee ofof thethe Fe3+Fe ESRESR spectrumspectrum withwith ththee ESRESR iningg environmentenvironment iinn whichwhich thethe respectiverespective crystalscrystals spectrumspectrum ooff MnMn2+.2+. TheThe ESESRR spectrumspectrum ooff MnMn2+2+ isis havehave beenbeen growngrown.. ItIt hahass beebeenn reportedreported thatthat a probablprobablyy concealeconcealedd byby ththee wave-likwave-likee spectraspectra onon considerablconsiderablee amountamount ooff iroironn isis containecontainedd iinn UtahUtah botbothh sidessides oofthef the FeFe3+3+ lineline (3325G(3325G region,region, gg== 1.1.980) 980).. reredd beryberyll (Wood(Wood et al., 1967;1967; ShigleyShigley et al., 1984)1984).. TheThe contencontentt ofof iroironn ioionn iinn thithiss redred beryberyll waswas 1. 33 wt%wt% AcknowledgementAcknowledgementss aass alreadalreadyy shownshown aboveabove.. TheThe ironiron ionion hashas thethe TheThe authorsauthors wiswishh ttoo thankthank DDrr TT.. Miyata,Miyata, InstituteInstitute absorptionabsorptionss inin ththee visiblevisible regionregion.. IInn thethe spectrumspectrum ooff ooff GemmologyGemmology & JewelrJewelryy ArtsArts ooff YamanashYamanashii andand UtaUtahh redred berylberyl shownshown inin FigurFiguree 2B,2B, spectrumspectrum c,c, thethe MrMr Ogawa,Ogawa, ToyoToyo CommunicationCommunication EquipmentEquipment CoCo.. twotwo broadbroad bandbandss ooff 373700 andand 424266 nnmm correspondcorrespond toto Ltd.Ltd. foforr helpfulhelpful suggestions.suggestions. ththee atlsorptionsabsorptions duedue toto thethe iroironn ionion.. TheseThese areare assigneassignedd toto Fe+Fe+3 ioionn iinn octahedraloctahedral sitessites inin berylberyl ReferenceReferencess crystalcrystalss (Wood(Wood et al., 1968).1968). ThThee samesame absorptionabsorption NassauNassau,, K.K.,, WoodWood,, D.L.D.L.,, 1968.1968. AnAn examinationexamination ooff redred berylberyl bandbandss werweree observedobserved inin ththee visiblevisible regioregionn ooff RussianRussian fromfrom UtahUtah.. Amer. Mineral., 53,53, 801-6801-6.. hydrothermally-growhydrothermally-grownn emeraldemerald spectrumspectrum (Figure(Figure Shigley,Shigley, J.E.J.E.,, FoordFoord,, E.E.E.E.,, 1984.1984. Gem-qualitGem-qualityy reredd beryberylfroml from thethe WaWahh WaWahh mountains,mountains, UtahUtah.. Gems & Gemology, XX,XX, 4,4, 2B,2B, spectrumspectrum a).a). ThThee reredd iiss causedcaused bbyy a broadbroad 208-21.208-21. absorptioabsorptionn bandband ofof 540-560540-560 nmnm anandd a fairlfairlyy broadbroad Wood,Wood, D.L.,D.L., NassauNassau,, K.K.,, 1967.1967. Infra-reInfra-redd spectraspectra ofof foreignforeign absorptionabsorption banbandd inin ththee vicinityvicinity ooff 484800 nm.nm. moleculesmolecules iinn berylberyl.. J. Chemical Physics, 47,2220-8.47, 2220-8. WoodWood,, D.L.D.L.,, NassauNassau,, K.,K., 1968.1968. TheThe characterizationcharacterization ofof berylberyl andand emerald emerald by visible by visible and infra-red and infra-red absorption absorption spectroscopy. spectros­ ESESRR spectrumspectrum copy. Amer. Mineral., 53,777-800.53, 777-800. Flamini, A., A., Gastaldi, Gastaldi, L., L., Viticoli, Viticoli, S., 1986.S., 1986. Crystal Crystal growth growth and and FigurFiguree 3 showsshows thethe ESRESR spectrumspectrum (a(att -169°C)— 169°C )of of characterizatiocharacterizationn ofof beryberyll dopeddoped withwith transitiotransitionn metametall ions.ions. ththee reredd beryberyll frofromm ththee WaWahh WahWah mountains,mountains, Utah,Utah, Mat.Mal. Res. Bull.,21 21,1-6., 1-6. 412 J. Gemm, 1993, 23, 7

An examination of garnets from the Sinai Peninsula, Egypt Robert C. Kammerling, John I. Koivula and Gustave P. Calderon GIA Gem Trade Laboratory, Inc., Santa Monica, California, USA

Abstract garnets was found in place on the head of a Dark brownish-red garnets reported to be from the woman buried at Abydos and dating to the time of Sinai Peninsula, Egypt, were identified as almandine- the Naqada II culture (c. 3200 BC). This gem spessartine, based upon their gemmological properties, material was most popular during the Middle chemistry and current criteria for distinguishing between Kingdom (c. 2133-1786 BC) (Andrews, 1991), the different gem garnets. possibly due to intensive exploitation of Sinai mineral deposits during this period. In the Cairo Introduction Museum is a gold collar inlaid with several species Although garnets occur in a great range of of gemstone, one of which is garnet. It is part of a colours, those of a predominantly red hue are no parure of the Princess Khnumet who was buried doubt the best known. Such garnets may be essen­ in the vicinity of the pyramid of Ammenemes II tially pyrope or almandine, or they may be (early Xllth Dynasty) (Aldred, 1978). pyrope-almandine or almandine-spessartine mix­ tures (Stockton and Manson, 1985). Among the Background to study sources for one or more of these gems are Austria, Australia, Brazil, Canada, Czechoslovakia, India, Madagascar, Russia, Sri Lanka, United Kingdom (Scotland), USA, Zambia and Zimbabwe (Webster, 1983); Argentina, Japan, Norway, Sweden and Uruguay (Arem, 1987); Afghanistan (Bowersox, 1985); China (Keller and Wang, 1986); Tanzania (Jobbins, 1978); Mexico, Myanmar (Burma), Pakistan, Thailand and Greenland (Rouse, 1986). A review of the miner­ alogy of garnets can be found in Deer et al. (1982). Egypt has also been a source of red garnets. Pliny mentions 'carbuncles'-a gem name now thought to have referred to garnets coming from an area near Thebes, although Rouse (1986) Fig. 1. These garnets, reportedly from the Sinai Peninsula of Egypt, states this may be a reference to a trading station are part of a 36-bead necklace. Photo by Maha Smith- rather than a mining area. It is known that garnets DeMaggio. have been recovered near Aswan in Upper Egypt, at the same locality from which the ancient While on a trip to Egypt in late 1991, one of the Egyptians obtained much of their amethyst. Other authors (RCK) visited a gem dealer in Luxor Egyptian sources are in the Eastern Desert inland who displayed a necklace of dark brownish-red from Quseir and northeast of Qena (Andrews, beads represented as garnets (Figure 1). These 1991). More relevant to this report, larger stones- were said to have been recovered from the more appropriate for fashioning as gems- came south-central area of the Sinai Peninsula, 'two from Western Sinai (Aldred, 1978). These mountains over from Gebel Musa' (Mt. Sinai). reports, however, do not classify the garnets using According to the merchant, his father obtained current gemmological criteria. the garnets at the mine site several years before, but the exact location was no longer known It is also known that garnets were used by the (unsuccessful efforts had been made to relocate ancient Egyptians for personal adornment. the source). The necklace was subsequently Garnets were fashioned for jewellery use as early acquired for gemmological examination. as the Predynastic Period; a diadem that includes

© Copyright the Gemmological Association ISSN: 0022-1252 J. Gemm., 1993, 23, 7 413

Fig. 2. What appear to be apatite crystals were noted in many of the Fig. 3. Black opaque inclusions with the appearance of ilmenite were garnets in this investigation. Photomicrograph by John 1. also detected in many of the garnets described herein. Koivula. SOx. Photomicrographby John I. Koivula. SOx.

Fig. 4. EDXRF analysis detected the presence of both iron and manganese in the garnets in this study. Analysis performed by Sam Muhlmeister using a Spectrace 5000 X-ray unit (tube voltage 20 KV, tube current O.15mA, atmosphere-vacuum, aluminium filter, livetime 100 seconds.

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Gemmological examination Chemistry Description: Energy-dispersive X-ray fluorescence (EDXRF) A necklace consisting of 36 off-round drilled analysis was carried out by the GIA Research beads ranging in diameter from approximately Department using a Spectrace 5000 X-ray unit. 12.3 to 13.0 mm. This revealed aluminium and silicon as major components, a high iron content with lesser Colour/appearance: amounts of manganese, and traces of calcium and In reflected light, the beads were very dark yttrium (Figure 4). This chemistry is consistent brown (almost black) and nearly opaque due to with that of garnets in the almandine-spessartine their very dark colouration. In strong transmitted solid solution series (see Deer et al.> 1982). light, however, they were brownish-red and trans­ parent. Conclusion Based on the gemmological properties and Microscopic features: using the criteria established by Stockton and Magnification revealed numerous partially Manson (1985), the garnets in the necklace were healed fractures located throughout all of the identified as almandine-spessartine. The chemical beads. Crystalline inclusions were also noted and analysis, showing a significant iron component as visually identified as apatite (Figure 2) and well as lesser amounts of manganese, further sub­ ilmenite (Figure 3) which are known to occur in stantiates this identification. garnets of this type (Gübelin and Koivula, 1986). References Refractive index: Aldred, C., 1978. Jewels of the Pharaohs, Egyptian jewelry of the Spot refractive index readings were taken using Dynastic period, abridged edition, Ballantine Books, New York, USA. a Duplex II refractometer and white light source. Andrews, C., 1991. Ancient Egyptian jewelry, Harry N. This produced readings from approximately 1.81 Abrams, Inc., New York. to over-the-limits of the instrument. Arem, J.E., 1987. Color encyclopedia of gemstones, second edn. Van Nostrand Reinhold, New York. Chelsea Filter reaction: Bowersox, G., 1985. A status report on gemstones from The beads appeared yellowish-green. Afghanistan. Gems Gemol., 21, 4, 192-204. Deer, W.A., Howie, R.A., Zussman, J., 1982. Rock-forming minerals, Vol. 1A orthosilicates, second edn. Longman Ultraviolet luminescence: Group Ltd., Harlow. All of the beads were inert to both long- and Gübelin, E.J., Koivula, J.I., 1986. Photoatlas of inclusions in short-wave ultraviolet radiation when examined gemstones. ABC Edition, Zurich. with 4-watt UV light sources. Jobbins, E.A., 1978. Studies of a gem garnet suite from the Umba river, Tanzania, J. Gemm., 16, 3, 161-71. Keller, P., Wang, F., 1986. A survey of the gemstone Absorption spectrum: resources of China, Gems Gemol., 22, 1, 3-13. Examination was carried out using both a Beck Rouse, J.D., 1986. Garnet. Butterworths, London. prism spectroscope mounted on a GIA GEM Stockton, C.M., Manson, D.V., 1985. A proposed new Instruments spectroscope illuminator base and a classification for gem-quality garnets. Gems Gemol., 21, 4, GIA GEM DIS CAN diffraction-grating spectro­ 205-18. scope unit. This revealed absorption bands at Webster, R., 1983. Gems, their sources, descriptions and identification, Fourth edn. revised by B.W. Anderson. approximately 410, 430, 460, 500, 525, and 575 Butterworths, London. nm. [Manuscript received 19 December 1992] J. Gemm., 1993, 23, 7 415

Gemstone enhancement - detection of polymer treated jadeite A. Hodgkinson Glasgow, Scotland

During a discussion in 1992 with Emmanuel a droplet of concentrated hydrochloric acid. Fritsch and Ken Scarratt,1 was privileged to learn Touch the acid down as a standing droplet on the of a forthcoming paper on the treatment and jadeite surface, previously wiped clean. It is advis­ detection of jadeite which had been enhanced able to add a second or even a third droplet to using a polymer impregnation process (Fritsch et sustain the acid supply. al, 1992). Figure 2 shows a 20mm jadeite drilled bead The paper divides jadeite into three categories specimen known to have been fashioned at least used in Hong Kong: thirty years ago. (A) jadeite which has not been treated other than The applied acid droplet can just be seen across by traditional surface waxing; the edge of the window reflection. Down the (B) jadeite, the sub-surface of which has been centre of the specimen, it can be seen that the acid filled by polymer impregnation. The process has reappeared at the surface of an internal frac­ is preceded by bleaching by immersion in ture and away from the original applied droplet. acid; Figure 3 shows a close-up of the acid weeping (C) jadeite which has been impregnated by a from below to accentuate two internal fractures staining process. which form a diagonal cross. The evidence took The paper examines the detection of the 'B' some two to three minutes to surface. It is evident treatment via various visual clues, and concludes that in untreated jadeite ('A' type) the acid is that identification is positively achieved by drawn under the surface by the capillary action of infrared spectroscopic confirmation of the the jadeite's cryptocrystalline grain boundaries polymer used. and/or open fractures. Where there are no evident I was delighted to be able to lend to Dr Fritsch fractures, a 'perspiration' aureole of acid is seen three transparencies which showed how the basi­ surrounding the droplet several minutes after the cally equipped gemmologist could tackle and acid application. identify such bleached jadeite using an acid testing When the acid is placed on a specimen of technique. The test procedure is described in my bleached 'B' type jadeite. the acid sits on the forthcoming book, but sufficient interest was surface until it evaporates and cannot reappear aroused during lectures in Hong Kong, Canada elsewherel since the polymer has in fact sealed the and Tucson, to relate the procedure in slightly micro-porous structure. more detail. My photographs appeared to be at odds with Figure 1 shows a trio of: the findings of the GIA Lab which had observed (a) an untreated slice of green and white jadeite no such diagnostic response. I discussed the dis­ (note the brownish outer skin due to natural crepancy with Fritsch by telephone and he kindly iron staining), forwarded one of the GIA specimens which had (b) a slice which has been acid bleached and not responded to their own acid tests. polymer filled (note the absence of iron dis­ At first the GIA specimen resisted the coloration); and hydrochloric acid, but I determined this was due (c) a cabochon fashioned from the (b) material. in part to the fine grain texture of the translucent To carry out the test technique, position the white jadeite specimen. I could see the first glis­ specimen so that it presents a flat (or near to flat) tening response of the acid on the pyroxene but portion uppermost - Blu-tak always makes a good not sufficient to capture by camera. I added a anchorage. Use the head of a new domestic pin second and third drop of acid at one minute inter- (held by tongs or a similar tool) to dip and retrieve vals on the same spot and slowly the acid

© Copyright the Gemmological Association ISSN: 0022-1252 416 J. Gemrn., 1993, 23, 7

Fig. 1. From left to right: (a) untreated green and white jadeite with Fig. 2. A 30 year old untreated jadeite bead showing an applied acid a brown iron-stained skin; (b) jadeite which has been droplet across the edge of the window reflection and near the bleached and polymer-resin treated; (c) a cabochon fashioned centre of the specimen, also droplets which have re-appeared from the polymer-impregnated material. at the surface of an internal fracture.

Fig. 3. Close-up of the acid droplets which have migrated up along Fig. 4. Cabochon of stained jadeite ('C type) made from more two internal fractures in untreated jadeite. porous material. The centrally applied acid drop has sweated profusely over a surrounding aureole which covers the whole surface of the cabochon.

Fig. 5. Stained jadeite with an acid drop on the surface; the drop acts Fig. 6. Traces of the initial mauve stain agent in a green stained as a lens and reveals the staining pattern more clearly. jadeite. JJ.J.. Gemm.,Gemm, 1993,1993, 23,23, 7 414177

reappearereappearedd elsewhereelsewhere,, butbut ththethee effecteffect waswas some­some­ accesaccesss bbyy theththee stainstain agencyagency.. AAss a result,result, theththee dropdrop ofof whatwhat thwartedthwarted bbyy theththee decorativdecorativee groovinggrooving whichwhich hydrochlorihydrochloricc aciacidd quicklyquickly revealsrevealrevealss ththethee naturnaturee ofof patternedpatterned ththee carvedcarved lealeaff designdesign ofof ththee surfacesurface asas suchsuch a porouporouss materialmaterial aass itit sweatssweats profuselprofuselyy iinn a shownshown bbyy FritschFritsch et al. (1992).(1992). surroundingsurrounding aureole,aureole, iniinn thithiss casecase coverincoveringg thethe A furtherfurther telephonetelephontelephonee conversationconversation pointepointedd tottoo wholwholee undersideunderside ofof theththee cabochon.cabochon. opposinopposingg resultresultsresultss untiluntil I happenedhappened ttotoo asaskk thethe tem­tem­ PolymePolymerr treatmenttreatmentreatmentt ofof stainedstained jadeitjadeitee woulwouldd nono peraturperaturee iinn LosLos Angeles.Angeles. ThThee 100°FIOO°F+IOO°F++ temperaturetemperature doubdoubtt sealseal andand prevenpreventt suchsuch a resultresult,, bubutt itit iisiss rel­rel­ witwithh airair conditioningconditioning contrastecontrastedd withwith thethe temper­temper­ ativelyatively easyeasy toto spotspot ththee stainingstaining ooff jadeitejadeite.jadeite.. TheThe atatee ScottishScottish climatclimatee inin whichwhich I wawass domiciledomiciledd andand waxinwaxingg ooff jadeitjadeitee iiss a longlong standingstanding practicpracticeee toto thethe discrepancdiscrepancyy waswas explainedexplained byby thethe rapidrapid evap­evap­ presenpresentt ththee besbestt polishepolishedd surfacesurface (lustre).(lustre). ItIt waswas orationoration atat higherhigher temperaturestemperatures witwithh airair foundfound thatthat eveevenn freshlfreshlyy waxewaxedd jadeitjadeitee diddid notnot conditioning.conditioning. I alsoalso foundfound mixedmixed resultsresults iinn HongHong interfereinterfere withwith ththee abovabovee aciacidd tests.tests. KongKong withwith theitheirr ubiquitouubiquitouss aiairr conditioning.conditioning. InIn ththee courscoursee ooff aciacidd testintestingg ththee stainedstained jadeitejadeite DrDr W.W. HannemanHanneman ofof CaliforniaCalifornia wawass quicquickk toto typetype 'C','C, ththee appliedapplied dropledroplett ofof aciacidd acteactedd asas a lenslens poinpointt ououtt aann inexpensiveinexpensive solutionsolution (doesn't(doesn't hehe whicwhichh resolveresolvedd ththee stainstain agencieagenciess moremore distinctlydistinctly always!).always!). PlacePlace a glassglass celcelll oror disdishh oveoverr ththee speci­speci­ (se(seee FigureFigure 5).5). A waterwater dropletdroplet doesdoes ththee samesame ooff menmen subsequentsubsequent ttoo thethe aciacidd dropdrop application,application, andand course,course, aass alsoalso doesdoes a lOX10X lens.lens. includeinclude undeunderr thethe glassglass a smallsmall receptaclreceptaclee oror waterwater TheThe greegreenn stainingstaining ofof jadeitjadeitee isis actuallactuallyy a two­two- ttoo maintainmaintain normanormall conditions.conditions. parpartt process,process, thethe earlierearlier parpartt ofteoftenn involvininvolvingg a A furtherfurther confirmationconfirmation ofof anan untreateuntreatedd surfacesurface purplpurplee stainingstaining agentagent.. SometimesSometimes ththee purplepurple stainstain alsoalso camecame ttoo light.light. AfterAfter ththee concentratedconcentrated isis stillstill iinn evidenceevidence afteafterr thethe final stainingstaining processprocess hydrochlorichydrochloric aciacidd hahadd satsat oonn ththee untreateduntreated surfacesurface (see(see FigureFigurFigUree 6).6)6).. (type(type 'A''A' jadeitejadeite)) foforr severalseveral minutes,minutes, ththee actioactionn ofof I trusttrust thisthis willwill bebe foundfound toto bebe a helpfulhelpful adjunctadjunct wipinwipingg awayaway thethe aciacidd dropledroplett withwith a whitewhite tissuetissue ttoo ththee mainmain papepaperr researchedresearched anandd reportedreported inin suchsuch revealerevealedd a brownbrown iroironn stain,stain, thoughthough thithiss waswas notnot detaildetail bbyy DrDr EmmanuelEmmanuel FritscFritschh anandd hihiss colleagues.colleagues. apparenapparentt toto thethe eyeeye inin thethe dropledroplett itselfitself.. SuchSuch stainingstaining wouldwould bebe removedremoved aass parpartt ofof ththee deepdeep ReferenceReference cleansincleansingg acidacid actioactionn priopriorr toto polymepolymerr treatmenttreatment FritschFritsch,,, E.E.,, elet at.,ai.,al., 1992.1992. IdentificationIdentification ofof bleachebleableachedchedd andand polympolymerpolymeerr ooff typetype 'B'B'' jadeite.jadeite. impregnatedimpregnateimpregnated iadeiteiadeite.. Gems Gemol., 28,28, 3,176-87.3,3, 176-87. FigurFiguree 4 showsshows a greegreenn stainedstained jadeitejadeite.. ThThee 'C''C typetype reliereliess oonn a mormoree porousporous typtypee ooff jadeitjadeitee toto gaingain [[ManuscriptManuscript receivedrreceivedeceived 1919 March March 1993]1993]

SPECIALSPECIAL LONDONLONDON LECTURELECTURELECTURE PROFESSORPROFESSOPROFESSORR I.I. SUNAGAWASUNAGAWASUNAGAWA TheThe DistinctionDistinctionDistinction ofofof Natural NaturalNatural fromfromfrom SyntheticSyntheticSynthetic DiamondsDiamondsDiamonds

onon MondayMondaMondayy 181818 OctoberOctoberOctober 199319931993 atatat 6.306.306.30 pmppmm -- 8.008.008.00 pmpmpm

ToTo bebe heldheld ataatt GAGTL,GAGTL,GAGTL, 2nd2n2ndd Floor,FloorFloor,, 272727 GrevilleGrevilleGreville Street,Street,Street, London,LondonLondon,, ECINEECINC IN 8SU8SU8SU

TicketsTickets -- £3£3.5£3.50.500 MembersMembersMembers £7.00£7.00 MemberMember andandand GuestGuest £5.00£5.00 Non-Members £5.00 Non-Members Please contact:-contact:- Please contact: - Miss L.L. ShreevesShreeves MissGAGTLGAGTL L. Shreeve s 27 GreviGrevilleGAGTlle StreetLStreet London27 Grevill ECINe Stree 8SU8SUt Tel: 071-4043334 Fax: 071-404 8843 Tel: 071-404Londo 3334 n EC INFax: 8S U071-4048843 Tel: 071-404 3334 Fax: 071-404 8843 418 J. Gemm., 1993, 23, 7

Microscopic estimation of refractive index using a dial test indicator and a personal equation T. Farrimond University of Waikato, Hamilton, New Zealand

Abstract achieving this, particularly if the microscope is Fitting a dial test indicator to a microscope and its use adapted to use a dial test indicator (DTI). With combined with a personal equation, enables reasonably care it is possible to obtain a reasonably good eval­ accurate measures of RI to be made in mounted and uation of the RI of a gemstone using the unmounted stones: some examples are given. microscope in place of the refractometer. A modification is shown of engineers' digital calipers which facilitate the measurement of depth in mounted For this, the relatively inexpensive biological stones. microscope is ideal. It is preferable to have a mechanical stage so that the stone may be moved It is often useful to know the approximate value laterally with its table still remaining parallel to the for the refractive index of a gemstone before using microscope stage. However, if the microscope the refractometer, particularly for stones with RIs does not have a mechanical stage, adjustment of in the region of 1.8 and above. The measurement position can still be accomplished manually if care of real and apparent depth provides a quick way of is taken not to touch the stone but only the slide on which it is mounted. The DTI method is both Fig. 1. Dial test indicator 0.50mm, XO.Olmm. more convenient and more accurate than using a vernier scale mounted to the microscope. The gauge used in this report has a range from 0 to 50mm with scale divisions of 0.01mm. This allows estimations of a fifth part of a scale division (i.e. to an accuracy of about 0.002mm). The gauge is easy to read; a dial size should be selected which enables it to fit comfortably on the microscope (in this case the dial shown in Figure 1 measures 70mm in diameter). A simple brass mounting bracket with two locat­ ing screws may be constructed as shown in Figure 2. It is bored to take the stem of the gauge which is located by means of a 3mm grub screw. The vertical position of the gauge is adjusted by sliding it up or down in the bracket so that when its probe is touching the stage, the dial shows a mid-scale reading with the microscope in focus. This ensures that as the stage is raised or lowered, con­ tinuous readings are obtained on the gauge. Once set in position the gauge becomes an integral part of the microscope and may be used for making a variety of measurements. When focusing on a gemstone mounted with its table uppermost, it is safer to focus on the culet first; subsequent focus­ ing may then be accomplished without the risk of damage to the objective. When focusing on the dome of a cabochon (via its base) care is needed to check that the 'surface details' focused on are not dust specks on the substage condenser.

© Copyright the Gemmological Association ISSN: 0022-1252 J.. Gemm.Gemm.,, 19931993,, 2323,, 7 414199

MovinMovingg ththee condensecondenserr downwarddownwardss slightlyslightly removeremovess ththee problem.problem. A usefuusefull accessoraccessoryy showshownn iinn FigureFiguress 3 anandd 44,, iiss a smallsmall platplatee abouaboutt ththee sizsizee ofof a microscopmicroscopee slideslide (7(755 x 25mm25mm)) madmadee ooff 1.l.66 oorr 2m2mmm thicthickk alu­alu­ miniuminiumm sheetsheet.. ThiThiss hahass a serieseriess ooff holeholess ooff differendifferentt sizesizess drilledrilledd iinn iitt ttoo accommodataccommodatee stonesstones ooff differendifferentt diametersdiameters.. A slislitt iiss cucutt ttoo taktakee a gem­gem- stonstonee mountemountedd iinn a ringring.. ThiThiss slislitt iiss alsalsoo ideaideall forfor mountinmountingg trap-cutrap-cutt stonestoness anandd cabochons.. TheThe stonestoness shoulshouldd bbee checkecheckedd ttoo ensurensuree thathatt theirtheir tabletabless liliee paralleparallell ttoo ththee microscopmicroscopee stage.. ThThee followinfollowingg resultresultss werweree obtaineobtainedd usingusing a 0.520.52 ctct rounroundd facetedfaceted pyroppyropee garnet.garnet. MeasurementMeasurementss werweree repeaterepeatedd 1010 timetimess anandd RIsRIs calculatecalculatedd aass follows:follows: DeptDepthh ooff stonestone =RIRI ApparenApparentt deptdepthh ooff stonestone

MeaMeann RRII (x(x)) = 1.77l.7722 StandarStandardd deviatiodeviationn ooff thethe n 1 samplsamplee (tir(8 -,)) =0.009=0.009

ThThee maximumaximumm anandd minimuminimumm valuevaluess ooff ththee tenten readingreadingss werweree 1.7871.787 andand 1l.. 756756 respectivelyrespectively.. TheThe valuevalue ofof RRII forfor ththee garnet,garnet, obtainedobtained bbyy a refrac­refrac- tometertometer,, waswas 1.756.1.756.

AsAs itit stands,stands, thethe methodmethod givesgives a reasonablyreasonably goodgood Fig.Fig. 2.2. Probe ofof mountedmounted dialdial testestt indicatorindicator (DTI(DTI)) inin contactcontact witwithh sstagetage.. approximationapproximation ofof thethe stone'sstone' s RIRI bubutt itsits accuracyaccuracy maymay bebe improved.improved. TheThe valuesvalues obtainedobtained varyvary withwith ObtainedObtained valuevalue ofRIof RI 1.1. 772772 (10(10 readings)readings) thethe techniquetechnique usedused inin focusingfocusing onon thethe tabletable andand TrueTrue valuevalue ofRIof RI l.1.75 7566 culetculet soso thathatt somesome practicpracticee isis neededneeded toto ensureensure errorerror = 0.0160.016 over-estimationover-estimation consistency.consistency. IndividualsIndividuals willwill havehave theirtheir ownown method,method, resultingresulting inin possiblepossible over-estimationover-estimation oror AsAs a percentagpercentagee ofof thethe truetrue value,value, thisthis isis under-estimatiounder-estimationn and,and, jusjustt asas astronomersastronomers usedused a 0.016^^ xlOO=09x 100 = 0.9%0/. , personalpersonal equationequation forfor measuringmeasuring thethe transittransit ofof a 1.756 . 0, star,star, soso anan equationequation maymay bebe calculatedcalculated forfor thethe over-estimationover-estimation whichwhich shouldshould bebe correctedcorrected inin allall microscope.microscope. InIn thisthis case,case, thethe personalpersonal equationequation isis measurements.measurements. foundfound asas follows:follows: Fig.Fig. 3.3. MMounteountedd stonestone heldheld inin slotslot ofof slide.slide. Fig.Fig. 4.4. UnmountedUnmounted stostonene, euletculet down,down, inin slot.slot. 420 J. Gemm., 1993, 23, 7

Fig. 5. Electronic calipers with attached, odd-leg 2mm diameter pins.

Applying this correction factor to the measure­ other 10mm. The electronic calipers give readings ment of the RI of a trap-cut 2.6ct synthetic yellow to an accuracy of 0.01mm with values displayed sapphire gave the following values: digitally and the calipers may still be used after modification for normal measurements since they Microscope value of RI 1.780 (average of are self-zeroing. 3 readings) Second-hand electronic calipers may sometimes Take off 0. 9% (Personal Error) 0.016 be found which have a problem (due to wear) with This gives the RI as 1.764 accurate self-zeroing in the closed position. When pins are attached so that closure occurs at a point This is within the published range 14mm greater than before, the problem disap­ o + e 1.761-1.774 pears as the worn area is not now being used. The second-hand Mitutoyo calipers which were mod­ Other uses of the gauge included the measure­ ified cost the equivalent of just under £17. To ment of the depth of an inclusion inside a stone, measure the depth of an unmounted stone opti­ also the determination of the size of the inclusion cally may be most easily accomplished by placing (applying, of course, the appropriate correction for the stone with its table down over a small hole in the optical effect of 'shallowness' caused by the RI the aluminium slide. Sufficient illumination is of the stone). When testing ring-mounted stones, usually available from the substage condenser so it is usually possible to use the transmitted light that after focusing on the culet and taking a from the sub-stage condenser, but for some rings reading, the slide may be moved laterally to bring side lighting may be needed. In most cases it is an adjacent hole into view and a second reading easier to measure the true depth of the mounted obtained by focusing on the machining marks stones using a Leveridge type gauge. around the hole. It is possible to modify (or have modified) engi­ Some examples of RIs obtained on different neers' electronic calipers as shown in Figure 5, by stones are as follows: grinding down the tips of the calipers and mount­ (a) This sample was a ring with an 8.8ct ing two 2mm diameter pins, one 4mm long, the yellowish-green synthetic sapphire. Physical J. Gemm, 1993, 23, 7 421

depth determined by using calipers was cabochon, at the deepest portion of the apex. 5.98mm. Three apparent depth readings Readings should be continued until consistent showed a variability of 3.368, 3.360 and values are obtained. If the microscope is binocu­ 3.360 (At 100X magnification). Taking the lar, the appropriate eyepiece should be carefully average as 3.3626 gives an RI of 1.778. adjusted to ensure that both left and right views Subtracting the personal equation factor of show identical sharpness. If polarizing filters are 0.9% gives an RI of 1.762. fitted in the oculars (as in this microscope) they (b) In the case of a 9.7ct mounted red should be rotated, in the case of a biréfringent tourmaline, 8.38 mm deep, internal detail stone, to show only one image (the same image in was less clear, therefore a magnification of both oculars). Objectives with 4X and 10X mag­ only 40X was used. Based on three readings nification combined with a 10X eyepiece usually and after applying the correction factor of give sufficient clearance between objective and 0.9% the RI value was 1.628. stone (15 and 7mm respectively) at magnifications (c) A 1.5ct diamond, mounted in a ring, gave of 40 and 100 times. When testing a cabochon three readings with an average apparent which is mounted dome downwards in the slit on depth of 1.740. The physical depth was the microscope slide, its centre can be ascertained 4.29mm. The calculated RI value less the by viewing the dark edges of the slit, which appear 0.9% correction factor gave a value of 2.42. as two curved lines. The centre is at the point (d) A synthetic ruby cabochon, depth 6.36 mm, where the two lines are closest together and also viewed with transmitted light, the dome of symmetrically positioned in the microscope field. the cabochon facing the substage condenser It could be advantageous to construct specific cor­ (stone mounted in the slit on the aluminium rection factors for different sizes and shapes of slide). A few specks of dust on both surfaces stones and also for the various magnifications aid the observations. Apparent depth values used. In this way, the microscope becomes a con­ at 40X magnification are 3.575 and 3.577. venient tool for the measurement of refractive RI value = 1.778-0.016= 1.762 indices without any restriction on the magnitude It is necessary in making all the above observa­ of the RI. tions to focus on the same details each time, selecting a point in the centre of the stone and focusing via the table, or base in the case of the [Manuscript received 3 December 1992] 422 J. Gemm, 1993,23,7

Towards a mathematical gemmology. Thinking in terms of ratios makes a difference Martin A. Schell, AG, FGA PO Box 1103, Yogyakarta 55011, Indonesia

Abstract This article explains Monsieur Poirot's qualita­ The author analyses the separation of light rays in tive observation in quantitative terms, thereby doubling and 'fire' in terms of Snell's Law, and shows revealing a fresh approach to understanding the that the amount of separation varies inversely with the amount of doubling that we see in gems that have product of the highest and lowest RIs. Doubling strength high birefringence. The same analysis is then and a new index that the author calls 'dispersing strength' are therefore recommended as being more applied to our observation of dispersion and a new accurate than birefringence and dispersion, respectively, type of index is presented to quantify our under­ whenever gemmologists wish to quantitatively discuss standing of a gem's ability to split white light into visual effects based on divergent light rays. Finally, fresh the colours of the rainbow. insight is given into the problem of colour fringes appearing during readings of a refractometer in white Background concept light, with the author suggesting that a comparison of the When a ray of light travels from a rarefied gem/hemicylinder critical angles in violet and red light is medium (such as air) into a denser medium (such more useful than a comparison of the respective dispersions as a gemstone), it generally undergoes several of gem and hemicylinder. changes: it slows down, it bends towards the 'normal' (an imaginary line perpendicular to the Introduction interface) and sometimes it splits. The refractive One of the simplest observations that a gem­ index (RI) of a gem is the ratio of the speed of light mology student learns to make is the recognition in air to the speed of light in the gem. The higher of the doubled images of the back facets of a cut the refractive index, the more the light slows gemstone. This 'doubling' effect is positive proof down. that a stone is doubly refractive (DR), and there­ Snell's Law states that there is a fixed relation­ fore it is a useful test for separating diamond from ship between the angle at which a light ray strikes some of its simulants. an object's surface and the angle at which the light Gemmology instructors typically explain that ray is bent ('refracted') while it travels through the the amount of doubling depends on two factors: object. Measuring both the incident and refracted the path length of the light inside the gem and the angles outward from the normal, Willebrord Snell gem's birefringence. Birefringence is the difference (1591 - 1626) determined their relationship to be: between the highest and lowest RIs of a DR mate­ rial. Subtracting the two RIs is generally assumed (1) sinz to indicate the amount of separation between the —:— = n where n is the object's refractive index two images: a gem which has high birefringence sinr ' (e.g. zircon or peridot) will show more doubling than a gem which has low birefringence (e.g. topaz Therefore, the higher the refractive index, the or quartz), if all other factors are equal. more sharply a light ray is bent when it enters the However, in the ninth edition of Gem Testing, B. object. W. Anderson added a parenthetical comment to When an incident ray of light splits into two rays his discussion on the doubling effect of gems that inside a gem (double refraction), each ray slows have high birefringence: 'J-P- Poirot, Director of and bends by a different amount. As a result, it the Paris gem-testing laboratory, has made the becomes necessary to refer to two refractive important observation that for a given birefrin­ indices. Subtracting the lowest RI reading from gence the doubling effect is more marked in stones the highest RI reading gives us the gem's birefrin­ of low RI than in those of high index' (Anderson, gence. 1980). Isaac Newton discovered that a material's RI

© Copyright the Gemmological Association ISSN: 0022-1252 J. Gemm., 1993, 23, 7 423

varies according to the wavelength ofthe incident light. Each of the component wavelengths of white light slows and bends by a different amount. Because the sides of a prism are not parallel, we are able to see the colours of the spectrum dis­ tinctly as they each bend by their characteristic amount. The variation of RI with wavelength is called dispersion. The numerical value of dispersion is usually given as the difference between the RI of the Fraunhofer B line (686.7 nm) in the red part Air of the spectrum and the RI of the Fraunhofer G Gem line (430.8 nm) in the violet part ofthe spectrum. Do the simple subtractions involved in deter­ mining a gem's birefringence and dispersion describe any quantity that is mathematically meaningful? Generally speaking, the answer is 'no".' Only by looking closely at Snell's Law can we accurately relate a gem's birefringence and dis­ persion to the separation of light rays that we B observe in doubling and prismatic effects. Snell's Law views RI not as a single piece of data (i.e. A speed of light in a gem) but rather as a relationship Fig. 1. Splitting of an incident light ray between measurements (i.e. a fixed ratio between two sines at all possible angles of refraction). refracted rays A and B can be expressed as b - a. Separation, as perceived by the eye and as We can derive an exact formula for this divergence depicted in drawings of light ray paths, depends by using Snell's Law (with the RIs of A and B rep­ entirely upon angular separation and path length. resented as na and nb' respectively): Angular separation depends on the angle of inci­ sml dence and the refractive indices, while path length therefore is determined by the size and cut of the gem as (2) na = sma well as the facet and angle through which the gem is viewed. Of all these factors, only the refractive and similarly: indices are related to the nature of the gem mate­ rial itself - the RIs are what we are referring to sini . sini n =-- therefore slnb =-­ when we say 'diamond has a lot of fire' or 'peridot b sinb nb shows strong doubling'. The formula for an exact calculation of diver­ Another Approach gence is therefore: Although double refraction is the splitting of a single incident ray while dispersion is the separa­ . sini . sml (3) b - a = arcsm -­ - arcsm-­ tion of an infinite number of superimposed incident nb n a rays (i.e. the various wavelengths of white light), the two phenomena are mathematically equivalent; However, a closeapproximation of divergence can from one angle of incidence come two (or more) be found by simplifying the exact formula, based angles of refraction. on the fact that the divergence of rays is nearly In both dispersion and birefringence, the always very small. (The dispersion of diamond angular separation is the arithmetic difference and the birefringence of high zircon each produce between the angle of refraction of one ray and the an angular separation that is less than 1°.) angle of refraction of another ray. Thus, an exact According to Maclaurin's theorem, the rela­ answer to 'How much divergence is there between tionship between a small angle and its sine is the two rays?' can be achieved by subtracting the nearly linear (Jenkins and White, 1976). two angles of refraction. Subtracting the two RIs Therefore, we can make a reasonable approxima­ gives only a rough approximation ofthe divergence. tion of a small angular separation by replacing the quantity b - a with the quantity sinb - sina. The In Figure 1, the angular separation between formula then becomes: 424244 J.J. Gemm.Gemm.,, 1993,1993, 2323,, 7

. b', . sinisim sinisim .. (1. 1 1K ) TableTable 1:1: BirefringenceBirefringence andand doublingdoubling strengthstrength (4(4)) b - a '"; SInsin e - SInasina "'--~ -- ~'" SIn.sin.lV (-— -­ nnbK - nanQ ! nnbK na GeGemm LowestLowest HighestHighest BirefringenceBirefringence DoublingDoubling RIRI RIRI StrengthStrength AsAs cancan bbee seenseen fromfrom formulaformulaee 3 anandd 4,4, thethe SynSyn RutileRutile 2.612.6166 2.90 2.9033 0.280.2877 0.03780.0378 angularangular separationseparation betweebetweenn twotwo refracterefractedd raysrays CalcitCalcitee 1.4861.486 1.6581.658 0.170.1722 0.0690.06988 variesvaries directldirectlyy withwith theitheirr anglanglee ooff incidence.incidence. SphenSphenee 1.9001.900 2.052.0500 0.150.1500 0.0380.03855 Discussions that compare materials of different Discussions that compare materials of different HighHigh ZirconZircon 1.9251.925 1.9841.984 0.0590.059 0.01550.0155 opticaloptical densitdensityy inin termsterms ofof theitheirr refractinrefractingg powerpower DioptasDioptasee 1.6551.655 1.7081.708 0.050.0533 0.01870.0187 generallygenerally assumassumee a constanconstantt anglanglee ofof incidenceincidence.. IfIf wwee thereforthereforee removremovee ththee quantitquantityy sinisini fromfrom BenitoitBenitoitee 1.7571.757 1.8041.804 0.040.0477 0.0140.01488 formulaformula 44,, wwee arrivarrivee aatt ththee followinfollowingg formulaformula SinhaliteSinhalite 1.6681.668 1.7071.707 0.030.0399 0.0130.01377 whichwhich providesprovides uuss withwith a highlhighlyy accurataccuratee indeindexx ofof PeridoPeridott 1.6541.654 1.6901.690 0.0360.036 0.0120.01299 ththee 'divergin'divergingg powerpower'' ooff ananyy mineralmineral (relative(relative toto DiopsideDiopside 1.6751.675 1.7011.701 0.0260.026 0.0090.00911 otheotherr mineralmineralss ooff knownknown RI):RI) : TourmalineTourmaline 1.6241.624 1.6441.644 0.020.0200 0.0070.00755 SpodumeneSpodumene 1.6601.660 1.6761.676 0.010.0166 0.0050.00588 (5)(5) divergindivergingg powepowerr ~ ~ —^ ^- QuartzQuartz 1.5441.544 1.5531.553 0.0090.009 0.00380.0038 TopaTopazz 1.6191.619 1.6271.627 0.0080.008 0.00300.0030 nb na na x nb CorundumCorundum 1.7621.762 1.7701.770 0.0080.008 0.00260.0026 DoublingDoubling StrengthStrength TheThe doublindoublingg strengthstrength ofof a gemgem isis understoodunderstood TableTable 2a2a:: DoublDoublee refractiorefractionn inin calcitecalcite asas thethe degredegreee toto whichwhich ththee gegemm materialmaterial producesproduces IncidentIncident RefracteRefractedd RefracteRefractedd AngulaAngularr a doublingdoubling ofof thethe imagesimages ofof itsits backback facetsfacets (relative(relative angleangle angleangle ooff anglanglee ofof separationseparation toto otherother gemgemss illuminatedilluminated aatt thethe samesame angleangle ofof o-rayo-ray e-raye-ray 2 incidencincidencee anandd viewedviewed witwithh equalequal pathpath length).2length). 15°15° 8.98°8.98° 10.03°10.03° 1.05°1.05° HowHow doedoess formulaformula 5 comparecompare withwith birefrin­birefrin­ 3030°° 17.55°17.55° 19.66°19.66° 2.11 °° gencegence inin determinindeterminingg doublindoublingg strength?strength? TheThe 45°45° 25.24°25.24° 28.41 °° 3.17°0 quantitquantityy nana - nbnb cacann bbee recognizerecognizedd aass ththee birefrin­birefrin­ 6060°° 31.49°31.49° 35.65 35.65°° 4.16°4.16° gence, which formula 5 states must be divided by gence, which formula 5 states must be divided by 7575°° 35.6335.63°° 40.54°40.54° 4.914.91°° thethe quantityquantity nana x nnbb (the(the producproductt ofof thethe gem'sgem's higheshighestt anandd loweslowestt refractivrefractivee indicesindices)) toto givgivee a Table 2b: Double refraction in sphene closclosee approximationapproximation ofof thethe doublindoublingg strength.strength. InIn Table 2b: Double refraction in sphene otheotherr words,words, ththee doublingdoubling strengthstrength produceproducedd bbyy a IncidenIncidentt RefractedRefracted RefractedRefracted AngulaAngularr givegivenn birefringencbirefringencee variesvaries inverselinverselyy witwithh thethe twotwo anglanglee anglanglee anglanglee separationseparation forforn naa fofornyr riy RIRIss (i.e.(i.e. roughly inin inverseinverse proportionproportion toto thethe squaresquare 3 15°15° 7.83°7.83° 7.25°7.25° 0.50.58°8 ofof thethe meameann RI). 3 3030°° 15.26° 14.12°14.12° 1.14°1.14 TableTable 1 comparecomparess ththee birefringencebirefringence ofof 1414 15.26° commocommonn gegemm materialsmaterials withwith theitheirr doublingdoubling 45°45° 21.85°21.85° 20.18°20.18° 1.6T1.67 strengthstrength aass derivedderived frofromm formulaformula 5.5. TheThe doublingdoubling 6060°° 27.12°27.12° 24.99°24.99° 2.12.13°3 strengthsstrengths ofof twotwo gemgemss can bbee comparedcompared linearly:linearly: 75°75° 30.5630.56°° 28.11°28.11° 2.42.45°5 thethe factfact thatthat calcitecalcite hahass abouaboutt l.81.8 timetimess thethe dou­dou­ blinblingg strengthstrength ooff sphenesphene meansmeans thathatt ththee angularangular TableTable 2c:2c: ComparisoComparisonn ofof calcitcalcitee andand sphenesphene separationseparation betweebetweenn thethe twotwo raysrays ooff ththee formeformerr wilwilll IncidentIncident AngulaAngularr AngulaAngularr RatioRatio ooff bebe approximatelyapproximately 1.l.88 timestimes thethe sizesize ooff thethe angularangular anglanglee separatioseparationn separatioseparationn separationsseparations inin calcitcalcitee inin sphenesphene (calcite/sphene)(calcite/sphene) separationseparation betweenbetween ththee twtwoo raysrays ooff ththee lattelatterr forfor anyany givengiven anglanglee ooff incidencincidencee (see(see TableTabless 2a,2a, 2b2b 15°15° 1.05°1.05° 0.580.58°° 1.811.81 : 1 andand 2c)2c).. 30°30° 2.112.11°° 1.14°1.14° 1.851.85 : 1 FormulaFormula 5 explainexplainss whywhy calcitecalcite showsshows 8585 perper 4545°° 3.173.17°° 1.6T1.67° 1.90:1.90 1 cencentt more doublindoublingg thathann syntheticsynthetic rutile,rutile, eveneven 60°60° 4.16°4.16° 2.132.13°° I.1.9 955 : 1 thougthoughh calcite'scalcite's birefringencbirefringencee isis onlyonly 6060 peperr centcent 7575°° 4.91 °° 2.45°2.45° 2.02.00:0 1I asas large.large. SimilarlySimilarly,, wewe finfindd thathatt ththee doublingdoubling strengthstrength ooff syntheticsynthetic rutilerutile iiss less thathann thatthat ofof DispersingDispersing strengthstrength sphene,sphene, despitedespite ititss birefringencbirefringencee beingbeing nearlnearlyy twicetwice FormulFormulaa 5 cancan alsalsoo bbee usedused toto clarifyclarify ourour under­under­ asas muchmuch asas sphene's.sphene's. ComparedCompared toto zirconzircon,, peridotperidot standingstanding ofof dispersiondispersion iinn a gem.gem. TheThe firefire thatthat wewe hahass 6611 peperr cencentt ofof ththee birefringencbirefringencee anandd 8383 perper seesee iinn a diamondiamondd isis a resulresultt ofof itsits cutcut (crown(crown heightheight centcent ooff ththee doublindoublingg strength.strength. DioptasDioptasee hashas lowerlower andand crowcrownn angle)angle) anandd caratcarat weightweight (path(path length).length). birefringencbirefringencee thathann zircozirconn bubutt higher doublingdoubling HoweverHowever,, whenwhen wwee comparecompare a diamonddiamond withwith otherother strength.strength. gemgemss ofof similarsimilar sizesize anandd idealideal cutcut,, theitheirr differencesdifferences J. Gfimm., 1993, 23, 7 425

in fire depend entirely on their ability to produce (including natural zircon) will be avid enough to angular separation between the various wave­ calculate their dispersing strength from formula 5. lengths undergoing refractions. As explained above, formula 5 gives a close Dispersion on a hemicylinder approximation for angular separation-better than The problem of colour fringes at the shadow simple subtraction of RIs. Making a distinction edge when reading a refractometer in white light analogous to the contrast between doubling is due to a 'difference' in dispersion between the strength and birefringence, we can use formula 5 gem and the refractometer's hemicylinder. What to calculate a 'dispersing strength' which is more is the difference? Again, it is not a simple subtrac­ accurate than simple dispersion. tion. Table 3 compares the dispersion of five SR Recall that the shadow edge is determined by gems with their dispersing strength as derived the critical angle between the hemicylinder and from formula 5. Estimates had to be made for the the gem. The critical angle is directly related to the red and violet RIs, because all of the numerous ratio between the RI of the hemicylinder (nhemi) reference sources available to me list net disper­ and the RI of the gem (ngem): sion without indicating the actual B and G RIs (except for diamond). (6) critical angle = arcsin —^—- The dispersing strength of strontium titanate is n about 4 times that of diamond, a fact stated in hemi numerous gemmological texts. In comparing these The appearance of colour fringes at the shadow two gems, dispersing strength gives nearly the edge means that the critical angle between hemi­ same answer as dispersion, because the RIs are so cylinder and gem varies slightly for different close. wavelengths of light. Therefore, the influence of However, as the RI decreases, a given dispersion dispersion on the sharpness of a refractometer acquires more dispersing strength. Thus, com­ reading should be calculated by comparing the pared to diamond, cubic zirconia's dispersion is critical angle in red light to the critical angle in 36 per cent higher but its dispersing strength is 69 violet light. If the two critical angles are nearly per cent higher. GGG's dispersion is only 2 per equal, the effect of dispersion will be almost nil cent higher than diamond's, but its dispersing (i.e. colour fringes will be difficult or impossible to strength is 54 per cent higher. The fire of GGG is see). thus closer to that of CZ than to that of diamond. To minimize the colour fringes, we need to Furthermore, the dispersing strength of YAG is produce a situation that can be expressed as greater than that of diamond (approximately follows: 0.0083 vs 0.0075). I suggest that the reason a ngemR ngemV piece of YAG does not show as much fire as a (7) arcsin ~ arcsin diamond is because the ideal proportions for nhemiR nhemiV diamond simulants have not been calculated with as much precision as Tolkowsky and others Formula 7 is approximately equivalent to: devoted to the cutting of the diamond. If cut to its own specific ideal proportions, YAG could show ngemR ngemV as much fire as diamond.4 (8) « nhemiR nhemiV Table 3: Dispersion and dispersing strength Therefore, the important consideration in deter­ mining the effect of dispersion on colour fringes is Gem Red (B) Violet (G) Dispersion Dispersing division, not subtraction. That is, we should not be RI RI strength comparing the dispersion of the gem (ngemV - Strontium 2.36 (est.) 2.55 (est.) 0.190 0.0316 ngemR) and the dispersion of the hemicylinder Titanate (nhemiV " nhemiR)' but ramer the ratio between the Cubic 2.14 (est.) 2.20 (est.) 0.060 0.0127 two RIs in red light and the ratio between the two Zirconia RIs in violet light. GGG 1.950 (est.) 1.995 (est.) 0.045 0.0116 For example, an ideal ('colour-fringe free') Diamond 2.407 2.451 0.044 0.0075 shadow edge would be present on a hemicylinder that has n = 1.92 and n = 1.88 (dispersion = YAG 1.820 (est.) 1.848 (est.) 0.028 0.0083 v R 0.040) if the gem being tested has nv = 1.550 and I hope that a reader who has access to the exact nR = 1.518 (dispersion = 0.032) B and G RIs for the various diamond simulants 426426 JJ.. Gemm.,Gernrn., 1993,1993, 23,23, 7

IInn thithiss case,case, thicknessthickness iiss constant,constant, thethe differencdifferencee inin speedspeed causescauses a 'retardation''retardation' (i.e(i.e lag)lag) betweenbetween thethe twotwo rays.rays. TheThe exactexact distancedistance ooff ananyy retardationretardation correspondcorrespondss toto nngemRgemR = 0.80740.8074 anandd nngemVgemV = 0.80730.8073.. oneone ofof 'Newton's'Newton's colours',colours', whichwhich araree shownshown inin nhemiRnhemiR nhemiVnhemiV sequencesequence oonn a Michel-LevyMichel-Levy chartchart (Hurlbu(Hurlbutt andand KleinKlein,, 1977).1977). A mineral'mineral'ss birefringencbirefringencee cacann bebe ThThee 'match''match' iiss thereforetherefore nearlynearly perfecperfectt (assum­(assum­ estimateestimatedd fromfrom ththee chartchart,, accordingaccording ttoo thethe inging thathatt ththee ratiratioo remainsremains ththee samesame foforr alalll ooff thethe followingfollowing formulaformula (Phillips(Phillips,, 1971):1971): wavelengthswavelengths betweebetweenn redred anandd violet)violet),, despitdespitee thethe retardatioretardationn = thicknesthicknesss x birefringence.birefringence. 'difference'difference'' betweebetweenn ththee dispersiondispersion ooff thethe hemi­hemi- 2 RecallingRecalling thethe formulaformula thatthat isis thethe basisbasis forfor thethe DucDue dede ChaulnesChaulnes methomethodd (Webster(Webster,, 1983),1983), itit shouldshould bebe cylindercylinder (0.040)(0.040) anandd thethe dispersiondispersion ofof ththee gemgem notenotedd thatthat ththee doubleddoubled imageimagess ddoo nonott liliee iinn thethe (0.032)(0.032).. samesame planeplane.. BecauseBecause ththee twtwoo raysrays havhavee differentdifferent RIsRls,, thethe twtwoo facefacett imageimagess produceproducedd bbyy themthem havehave ConclusionConclusion differendifferentt apparenapparentt depths.depths. ThThee formulaeformulae presentepresente~d inin thithiss articlarticlee areare notnot 3 TheThe termterm 'mean'mean RI'RI' isis commonlycommonly encounteredencountered inin 'news'news'' ttoo thosthosee whwhoo araree acquaintedacquainted witwithh thethe fieldfield mineralogymineralogy texts.texts. ItIt shouldshould bbee recognizerecognizedd asas anan ofof opticsoptics.. OldOld mineralogmineralogyy textbookstextbooks suchsuch asas abstracabstractt concepconceptt thatthat doedoess notnot havhavee a specificspecific Dana'sDana's A Textbook of Mineralogy containcontain numer­numer­ relationshiprelationship withwith crystalcrystal structure.structure. ForFor example,example, ououss formulaformulaee thatthat araree fafarr mormoree complexcomplex thanthan thosethose averaginaveragingg ththee highesthighest anandd lowestlowest RlsRIs ooff a biaxialbiaxial stonestone generallygenerally doesdoes not givgivee ththee betbetaa RI.RI. ooff thithiss articlearticle.. IndeedIndeed,, manymany mathematicalmathematical analy­analy­ UsinUsingg 'mea'meann RI'RI' iinn thethe formulaformula forfor doublingdoubling ses of optical phenomena dating back to the ses of optical phenomena dating back to the strengthstrength increaseincreasess thethe numbernumber ooff stepssteps involvedinvolved inin nineteentnineteenthh centurycentury remairemainn valivalidd (e.g(e.g.. thethe opticaloptical thethe calculatiocalculationn anandd givesgives resultresultss thatthat areare slightlyslightly tootoo indicatriindicatrixx wawass presentepresentedd bbyy L.L. FletcherFletcher inin 1892).1892). loloww iinn casecasess ooff veryvery highighh birefringencebirefringence:: syntheticsynthetic Therefore,Therefore, thisthis articlearticle iiss notnot aboutabout thethe discoverydiscovery rutilerutile = .0377.0377 andand calcitcalcitee = .0696.0696 (compar(comparee thesethese ofof a neneww formulaformula.. Rather,Rather, itit isis aboutabout thethe applica­applica­ figures withwith thethe correspondincorrespondingg figures iinn TableTable 1).1). tiontion ooff oldold formulaformulass ttoo a newnew fieldfield ooff sciencescience calledcalled 4 TheThe amountamount ofof firefire thatthat oneone seessees inin a well-cutwell-cut 'gemmology''gemmology'.. I aamm writinwritingg ttoo encouragencouragee gemmol­gemmol- diamondiamondd dependdependss onon botbothh ththee crowcrownn anglanglee anandd thethe ogistogistss ttoo getget inin stepstep witwithh ththee mathematicalmathematical crowcrownn height.height. AnAn idealideal crowcrownn anglanglee maximizemaximizess thethe 'fannin'fanningg outout'' ooff ththee variousvarious wavelengthwavelengthss whewhenn theythey conceptconceptss thathatt opticaopticall mineralogistsmineralogists havhavee beenbeen exitexit thethe gemgem (i.e.(i.e. ththee spectralspectral colourscolours araree easiereasier toto usinusingg forfor ththee paspastt hundredhundred years.years. seesee becausbecausee theirtheir rayrayss areare spreadspread more).more). A largelarge ThThee simplesimple subtractionsubtraction involveinvolvedd iinn determiningdetermining crowcrownn heighheightt increasesincreases ththee sizesize ofof ththee crowcrownn facetsfacets birefringencbirefringencee andand dispersiodispersionn isis,, toto puputt itit bluntly,bluntly, a relativrelativee ttoo ththee tabltablee (i.e.(i.e. iitt increasesincreases ththee proportion ooff simplisticsimplistic approach.approach. AAss a rulrulee ofof thumb,thumb, wwee cancan internallinternallyy reflectereflectedd lighlightt thathatt hahass itsits componentcomponent saysay thatthat whewhenn ththee birefringencebirefringence oorr dispersiondispersion wavelengthwavelengthss spreadspread enoughenough toto bebe easileasilyy seen)seen) equalequalss aatt leastleast 2 peperr centcent ofof a gem'sgem's RIRI,, a gem­gem- (Pagel-Theisen,(Pagel-Theisen, 1989).1989). mologist'smologist's interpretatiointerpretationn ofof visuavisuall observationsobservations (i.e(i.e.. angularangular separations)separations) willwill becomebecome distorteddistorted ReferenceReferencess AndersonAnderson,, B.WB.W.. Gem testing, 9t9thh edn,edn, p.5p.511 (1980)(1980) anandd 10th10th unlesunlesss hehe oorr sheshe hashas beebeenn trainedtrained toto thinkthink inin termsterms ednedn (1990)(1990) p.4p.433 onon Poirot.Poirot. ofof ratiosratios (doublin(doublingg strengthstrength anandd dispersingdispersing HurlbutHurlbut,, C.SC.S.. andand KleinKlein,, C.,C., 1977.1977. Manual of mineralogy 19th19th strength)strength) ratheratherr thanthan differences.differences. edn,edn, p.206p.206 onon Michel-Levy.Michel-Levy. JenkinsJenkins,, F.AF.A.. andand WhiteWhite,, E.E.,, 1976.1976. Fundamentals of optics, 4th4th edn,edn, pp.pp. 150-1150-1 onon Maclaurin'sMaclaurin's theorem.theorem. NoteNotess Pagel-TheisenPagel-Theisen,, V.V.,, 1989.1989. Diamond grading ABC, 9t9thh edn,edn, 1 The subtraction of Rls meaningful when a 1 The subtraction of RIs isis meaningful when a pp.145-6pp. 145-6 onon dispersion.dispersion. mineralogistmineralogist estimateestimatess birefringencbirefringencee fromfrom thethe Phillips,Phillips, F.C.,F.C., 1971.1971. Mineral optics: principles and techniques, observatioobservationn ooff interferencinterferencee colourscolours iinn a specimenspecimen ooff pppp.. 91-291-2 oonn retardationretardation,, chartchart ooff interferenceinterference colourscolours foldsfolds knownknown thickness.thickness. HereHere itit iiss usefuusefull toto vievieww thethe ououtt afterafter p.1p.100 00.. differencdifferencee betweebetweenn highhigh andand loloww RlsRIs asas thethe Webster,Webster, R.,1983.R.,1983. Gems, 4t4thh ednedn,, p.71p.7144 onon refractometerrefractometer differendifferentt speedsspeeds ooff thethe twotwo rays.rays. WheWhenn thethe coloucolourr fringesfringes,, p.72p.7244 onon dede ChaulnesChaulnes fonnula.formula. J. Gemm., 1993, 23, 6 427

Gemmological Abstracts

BANK, H., 1992. Demonstrationsobjekt had been tumbled to a water-worn appearance. 'Gemmologische Brosche' als pädagogisches More elaborate fakes were also found; synthetic Anschauungsmaterial. ('Gemmological material shaped to crystal habit with quench- brooch' as educational material.) Zeitschrift cracking and lateral striation to increase der Deutschen Gemmologischen Gesellschaft 41, deception, often heat-treated to reduce curved 2/3, 101-5, 1 photograph, bibl. striae, oiled or waxed, impregnated with blue- The brooch contains twenty-one gemstones, dye, or infilled with fragments of real stones. all somewhat deviating from 'normal' colour. Dr Many natural stones painted with red nail Bank had this brooch made up to demonstrate varnish. Composites of either ruby or sapphire to students the difficulties of determining the could contain both natural and synthetic gem materials in set pieces. E.S. material. When cut, most of these are easily identified BENNETT, D., KEELING, J.L., 1992. Imitation by conventional gemmological testing, but the lapis lazuli, charoite and azurite malachite. rough parcels are much more difficult and it is Australian Gemmologist, 18, 3, 83-5, 6 figs. advisable to polish a 'window' before arriving at Rough specimens obtained at Loxton a final decision. Gemboree, South Australia, are described. Adulterated sapphire rough could be tested Cabochons were cut from these. In general one for the absence of a 450nm band in the synthetic needs imagination to associate these materials material spectrum. with the natural stones they are supposed to Natural rubies share inclusion types with imitate [natural charoite is violet or lilac in those from Burma, with additional features of colour, not Royal blue as the imitation, and not blue zoning, pyrrhotite rods (brassy or black), or orange-brown as in the natural stone, colourless rods of calcite, orange rutile, fine illustrated]. Described as not very attractive, bluish clouds of rutile needles and flux-like intended for cheap jewellery only. SEM showed masses of orange norstrandite. them to be made of powdered barite and Writers say that to survive, the Vietnam ruby gibbsite plus colouring in an organic cement and sapphire industry must eliminate these containing perspex. R.K.M. practices at once. [Otherwise parcels from these sources may be rejected as untrustworthy.] BROWN, G., 1992. The elephant and its ivory. Some fakes were crude but surprisingly Wahroongai News, 26, 10, 19-16, 18 figs. ingenuous. An interesting listing of elephant species A valuable paper! R.K.M. (proboscidae) from the Eocene era to the present day, illustrated by photocopies of line CAVENEY, R.J., 1992. De Beers Diamond drawings including mammoths, mastodons and Research Laboratory Report 1992. Indiaqua earlier fossil species, some of which might well Annual 1992/3, 275-7, 9 photos in colour. be represented in cfossil' ivories extant today. The main gem interest in this report is a brief R.K.M. account of the cutting of the shield-shaped 273 Centenary diamond. The diamond was cut, BROWN, G., BEATTIE, R., 1992. Vietnamese under conditions of high-level security, in the ruby fakes: a problem requiring urgent DRL premises, scientists and engineers of the solution. Australian Gemmologist, 18, 4, 108- laboratory developing the necessary specialized 14, 36 figs. equipment. This included the scaife and special Arrival of good quality rubies from Luc Yen dops fed with a liquid coolant. A thermocouple and other Vietnam localities in 1990 occasioned attached to the stone monitored its temperature much excitement, but many parcels, whether during cutting and, with the aid of a rough or cut, were and still are, heavily sophisticated control system, ensured that the adulterated with stones from other sources, or gem was not subjected to any abnormal or with fragmented Verrieuil type synthetics which sudden forces or to thermal variations. 428428 JJ.. Gemm.,Gemm., 1993,1993, 2323,, 7

IInn thethe MineraMinerall ProcessinProcessingg DivisionDivision,, workwork BrieBrieff descriptiodescriptionn ofof a finfinee emerald,emerald, a garnetgarnet progresseprogressedd duringduring thethe yeayearr oonn thethe developmentdevelopment andand aann agateagate plate,plate, withwith otheotherr gemsgems,, formingforming ooff a fullfullyy integratedintegrated sorthousesorthouse foforr diamonddiamond partpart ofof thethe ImperiaImperiall TreasureTreasuress ooff ththee Hapsburgs,Hapsburgs, recoveryrecovery.. NeNeww designdesignss ooff X-raX-rayy machine,machine, opticsoptics helheldd inin thethe HofburgHotburg,, ViennaVienna.. M.O'D.M.O'D. andand ejectoejectorr technologietechnologiess werewere introducedintroduced ttoo improvimprovee ththee efficiencyefficiency ooff sorting.sorting. P.G.RP.G.R. DUCHAMP,DUCHAMP, M.M.,, 1992.1992. DeuDeuxx sommetssommets ddee llaa gravuregravure sursur cristacristall dede rocheroche:: leless portraitportraitss ddee COENRAADSCOENRAADS,, R.R.RR,, 1992.1992. SapphireSapphire anandd rubiesrubies l'amiral'amirall ddee RuyterRuyter etet dede l'empereul'empereurr LeopoldLeopold associateassociatedd witwithh volcanicvolcanic provincesprovinces:: inclusionsinclusions 1erler.. Revue de gemmologie, 113,113, 5-7,5-7, 3 photosphotos andand surfacesurface featuresfeatures throwthrow lighlightt onon theirtheir (1(1 inin colour).colour). origin.origin. Australian Gemmologist, 18,18, 33,, 70-8,70-8, 1111 TwoTwo celebratecelebratedd engravedengraved rockrock crystalcrystal figsfigs,, 1 map.map . portraitportraitss areare described.described. M.O'D.M.O'D. LikLikee manmanyy otheotherr sourcessources worldwideworldwide,, ththee alluviaalluviall sapphiressapphires ofof NeNeww England,England, NSWNSW,, araree ooff FM-TGMS-MSAFM-TGMS-MSA SymposiumSymposium onon garnetgarnet,, 19931993.. volcanicvolcanic originorigin,, inin thithiss casecase fromfrom ththee CentralCentral [Short[Short paperpaperss fromfrom ththee Symposium].Symposium], ProvinceProvince region.region. ThThee paperpaper describesdescribes thesthesee anandd Mineralogical record, 2424,, 61-8,61-8, 4 photosphotos iinn otherother fields,fields, crystacrystall habithabit,, inclusions,inclusions, miningmining colourcolour,, 1313 figs.figs. methodmethodss andand manymany otherother mattermatterss iinn considerableconsiderable ThThee shortshort paperpaperss covercover:: nomenclaturnomenclaturee anandd detail.detail. RK.M.R.K.M. classificationclassification ofof garnets;garnets; ththee causescauses ooff coloucolourr iinn garnetsgarnets;; crystalcrystal structures,structures, chemistrychemistry anandd COLDHAMCOLDHAM,, T.C.,T.C., 1992.1992. TheThe AustralianAustralian sapphiresapphire propertiepropertiess ooff garnets;garnets; inclusioninclusionss iinn garnets;garnets; industry.industry. Australian Gemmologist, 18,18, 4,4, 104-7.104-7. geologicageologicall occurrencoccurrencee ofof mineralmineralss inin thethe garnetgarnet A historyhistory ofof sapphiresapphire miningmining andand processingprocessing group;group; chemicachemicall anandd physicalphysical propertiepropertiess ooff iinn QueenslanQueenslandd anandd NeNeww SouthSouth Wales,Wales, withwith vanadium-vanadium-,, chromium-,chromium-, andand iron-bearingiron-bearing problemproblemss anandd possiblepossible future.future. RK.M.R.K.M. garnets;garnets; garnetsgarnets iinn architecturalarchitectural paintspaints;; garnetsgarnets inin ththee gem-bearinggem-bearing pegmatitepegmatite dikedikess ooff SanSan DiegoDiego COOPERCOOPER,, M.P.M.P.,, 1993.1993. LetterLetter fromfrom Europe.Europe. CountyCounty,, CaliforniaCalifornia;; garnetgarnetss ofof MagneMagnett cove,cove, Mineralogical Record, 24,24 ,3, 3 , 231-7,231-7, 88 photosphotos (5(5 Arkansas;Arkansas; a neneww garnetgarnet localitylocality iinn Connecticut;Connecticut; iinn colour).colour). ththee McBridMcBridee propertpropertyy [Hull[Hull County,County, Quebec]Quebec].. EuropeaEuropeann mineraminerall showsshows durinduringg 19931993 havehave M.O'DM.O'D.. featurefeaturedd transparentransparentt gem-qualitygem-quality greegreenn zoisitezoisite frofromm PakistaPakistann (one(one crystacrystall aatt leastleast displayingdisplaying FRITSCHFRITSCH,, E.E.,, MUHLMEISTERMUHLMEISTER,, S.,S., BIRKNER,BIRKNER, A.,A., pronouncepronouncedd dichroism)dichroism);; veryvery largelarge spessartinespessartine 1992.1992. A preliminarypreliminary spectroscopicspectroscopic studystudy ooff crystalscrystals frofromm ththee ShagarShagar valley,valley, PakistanPakistan;; gemgem­- ththee BiroBironn syntheticsynthetic pinpinkk titaniutitaniumm beryl.beryl. qualitqualityy emeraldemerald crystalscrystals fromfrom NigeriaNigeria;; finefine deep­deep- Australian Gemmologist, 18,18, 33,, 81-2,81-2, 3 figs.figs. colouredcoloured aquamarineaquamarine crystalcrystalss frofromm JosJos,, NigeriaNigeria UUVV visiblvisiblee andand infraredinfrared werweree used,used, givinggiving (the(the reportereporterr feelsfeels thathatt thethe deepdeep colourcolour iiss similarsimilar resultresultss ttoo thosethose forfor otheotherr BironBiron syntheticsynthetic natural).natural). M.O'D.M.O'D. berylsberyls.. G.G. BrowBrownn hahass saidsaid thatthat thisthis materiamateriall iiss easilyeasily identifieidentifiedd bbyy normalnormal gemmologicalgemmological tests.tests. DISSANAYAKE,DlSSANAYAKE, C.B.,C.B., RUPASINGHERUPASINGHE,, M.S.M.S.,, RK.M.R.K.M. DHARMARATNDHARMARATNEE T.T.,, 1992.1992. FluorineFluorine hydrochemistryhydrochemistry iinn a topaz-rictopaz-richh areaarea inin SrSrii GODOVIKOV,GODOVIKOV, A.A.A.A.,, BULGAK,BULGAK, L.V.L.V.,, 1993.1993. DieDie LankaLanka.. ZeitschriftZeitschriJt der DeutschenDeutschen MalchanskerMalchansker Elbait-LagerstättElbait-Lagerstattee imim russischenrussischen Gemmologischen GesellschaJt,Gesellschaft, 41,41, 2/3,2/3, 111-16,111-16, TransbaikalienTransbaikalien.. Lapis, 18,18, 1,1, 13-15,13-15, 5 photosphotos 2 maps,maps, 1 table,table, bibl.bibl. iinn colour,colour, 1 map.map . HalogenHalogenss areare oftenoften useusedd iinn geochemicalgeochemical Gem-qualitGem-qualityy pinpinkk andand greengreen elbaiteelbaite iiss foundfound exploratioexplorationn foforr mineraminerall depositsdeposits.. FluorineFluorine,, ththee inin ththee MalchanskMalchansk pegmatitepegmatitess inin RussianRussian mosmostt reactivreactivee ofof ththee halogens,halogens, isis usefuluseful foforr ththee Transbaikalia.Transbaikalia. AAnn interestininterestingg featurefeature ooff somesome ooff exploratioexplorationn ooff F-bearinF-bearingg gemgem mineralsminerals suchsuch aass ththee tourmalinetourmaline isis ththee highighh contencontentt ofof Bi22003;; ththee topaztopaz,, fluorspafluorsparr anandd tourmaline.tourmaline. A studystudy ofof ththee MalchansMalchanskk pegmatitepegmatitess containcontain severalseveral bismuthbismuth ElaherElaheraa gemgem depositsdeposits inin SriSri LankLankaa showsshows thatthat compounds.compounds. M.O'D.M.O'D. ththee geochemistrgeochemistryy ofof F inin ground-wateground-waterr couldcould bbee usedused ttoo locatelocate areaareass ooff F-bearinF-bearingg gegemm materials.materials. HANNAFORDHANNAFORD,, R,R., 1992.1992. TheThe carat:carat: ththee unitunit ooff E.SE.S.. weightweight.. Australian Gemmologist, 18,18, 44,, 117-18,117-18, 1I fig. usedused asas covercover design.design. DOMENECH,DOMENECH, M.V.,M.V., 1992.1992. LesLes gemmesgemmes singularssingulars AAnn antiqueantique scalescale boughboughtt bbyy MMrr HannafordHannaford dedell TresorTresor ImperialImperial dede Viena.Viena. Gemologia, 3434,, forfor golgoldd weighingweighing hadhad aann incompletincompletee setset ooff 89,89, 4-84-8,, 3 photophotoss inin colour.colour. weightweightss iinn oldold EnglisEnglishh fractionafractionall caratcaratss whichwhich J.J. Gemm.,Gemm., 1993,1993, 23,23, 77 429429

meansmeans thethe scalescale iiss forfor gemsgems andand mustmust predatepredate hydrothermalhydrothermal methodmethod areare thethe absorptionabsorption spectraspectra 1914,1914, whenwhen thethe BritishBritish ratifiedratified ththee newnew weight.weight. andand somesome microscopicmicroscopic features.features. TheseThese ddoo notno t HeHe quotesquotes HerbertHerbert Smith'sSmith's Gemstones inin whichwhich appearappear inin allall examples,examples, asas thethe productsproducts areare veryvery thethe varyingvarying gramgram valuesvalues worldwideworldwide areare given.given. cleanclean andand onlyonly sometimessometimes leaveleave tracestraces ofof their their SuchSuch fractionsfractions werewere recordedrecorded separatelyseparately andand notnot productionproduction processes.processes. E.SE.S.. addedadded together.together. [Abstracter[Abstracter hashas a MoeMoe diamonddiamond gaugegauge bookletbooklet whichwhich quotesquotes weightweightss similarly.]similarly.] HENN,HENN, U.,U., BANK,BANK, H.,H., 1992.1992. AquamarineAquamarine ausaus TheThe EnglishEnglish caratcarat waswas 0.20530.2053 gramsgrams untiluntil 19141914 Mo<;ambique.Moçambique. (Aquamarine(Aquamarine fromfrom whenwhen thethe standardstandard caratcarat ofof 0.2000.200 gramsgrams waswas Mozambique).Mozambique). ZeitschriftZeitschriJt der DeutschenDeutschen adopted.adopted. [The[The makermaker ofof thethe scalescale isis quotedquoted aass Gemmologischen GesellschaJt,Gesellschaft, 41,41, 2/3,2/3, 107-10,107-10, DeDe Crave,Crave, butbut I suspectsuspect thatthat thisthis isis inin factfact DDee 1 photograph,photograph, 11 graph,graph, bib!.bibl. Grave,Grave, a wellwell knownknown makermaker inin VictorianVictorian times.]times.] AquamarinesAquamarines ofof finefine colourcolour (Santa(Santa Maria)Maria) RK.M.R.K.M. werewere foundfound inin thethe sixtiessixties inin primaryprimary depositsdeposits aatt MocubaMocuba inin Mozambique.Mozambique. RIRI 1.572-1.580,1.572-1.580, ttoo HANNI,HÄNNI, H.A.,H.A. , 1992.1992 . ConsiderationsConsidérations 1.582-1.589,1.582-1.589, DRDR 0.009.0.009. SGSG 2.70-2.73.2.70-2.73. ThThee terminologiquesterminologiques auau sujetsujet desdes emeraudesémeraudes dduu colourcolour isis causedcaused bbyy Fe.Fe. MicroscopicMicroscopic studiesstudies NigeriaNigeria dede couleurcouleur bleu-vert.bleu-vert. Revue dede showshow tinytiny fluidfluid inclusionsinclusions andand hollowhollow tubes.tubes. gemmologie, 113,113, 2-4,2-4, 1 photphotoo andand 3 figs iinn AnalysisAnalysis showsshows thethe ironiron contentcontent toto bebe betweenbetween colour.colour. 2.06-2.552.06-2.55 weightweight % FeO.FeO. E.SE.S.. Bluish-greenBluish-green emeraldsemeralds fromfrom NigeriNigeriaa offeroffer aa problemproblem inin nomenclature.nomenclature. However,However, a CCrr HENN,HENN, U.,U., BANK,BANK, H.,H., 1992.1992. GemmologischeGemmologische absorptionabsorption lineline cancan bebe seenseen atat 683nm683nm andand ththee Kurzinformationen.Kurzinformationen. (Short(Short gemmologicalgemmological stonesstones thusthus fulfilfulfil thethe Cr-contentCr-content criteriacriteria foforr notes.)notes.) ZeitschriftZeitschriJt der DeutschenDeutschen emeraldemerald despitedespite theirtheir strongstrong blubluee component.component. Gemmologischen GesellschaJt,Gesellschaft, 41,41, 2/3,2/3, 63-7,63-7, 66 M.O'D.M.O'D. photographs.photographs. A DeDe BeersBeers syntheticsynthetic diamonddiamond ofof 0.43ct0.43ct iiss HARDER,HARDER, H.,H., 1992.1992. Rauchmondsteine,Rauchmondsteine, eineeine discussed.discussed. ItIt isis a yellow,yellow, ofof TypeType Ib,lb, fluorescentfluorescent neueneue Mondstein-Varietat.Mondstein-Varietät. (Smoky(Smoky underunder long-long- bubutt inertinert underunder short-waveshort-wave UV.UV. moonstonesmoonstones,, a newnew moonstonemoonstone variety.)variety.) UnderUnder thethe microscopemicroscope oneone couldcould seesee definitedefinite ZeitschriJtZeitschrift der Deutschen GemmologischenGemmologischen colourcolour zoning,zoning, hollowhollow tubestubes whichwhich werewere ththee GesellschaJt,Gesellschaft, 41,41, 2/3,2/3, 69-84,69-84, 8 photographsphotographs,, 3 remnantsremnants ofof thethe catalystcatalyst andand somesome veryvery finefine tables,tables, 1 maps,maps, 1 schematicschematic drawing,drawing, bib!.bibl. clouding.clouding. UnderneathUnderneath thethe colourlesscolourless andand whitewhite InIn NovemberNovember 19911991 somesome cutcut blackblack diamondsdiamonds moonstonesmoonstones nearnear Implube,Implube, easteast ofof RatnapuraRatnapura iinn werewere offeredoffered inin thethe tradetrade whichwhich turneturnedd outout toto bbee SriSri Lanka,Lanka, 'smoky'smoky moonstones'moonstones' havehave recentlyrecently radio-active;radio-active; highhigh radiatioradiationn mademade thesethese stonesstones beenbeen found.found. TheyThey exhibitexhibit a flashflash ofof blueblue oror whitewhite unsafe.unsafe. ThisThis alsoalso appliedapplied toto somesome radio-activeradio-active frofromm a dardarkk body.body. TheThe blue,blue, semi-bluesemi-blue anandd blubluee topazes.topazes. AccordingAccording ttoo GermanGerman law,law, stonesstones whitewhite moonstonesmoonstones havehave differentdifferent alkalialkali contents.contents. whichwhich havehave beenbeen treatedtreated andand exceedexceed certaincertain TheThe whitewhite qualityquality isis richerricher inin potassiumpotassium,, ththee limitslimits ofof radio-activityradio-activity cannotcannot bebe traded.traded. blueblue inin sodium.sodium. IInn thethe toptop blueblue moremore thanthan halfhalf ofof TheThe articlearticle thenthen dealsdeals withwith somesome syntheticsynthetic thethe alkalialkali positiopositionn inin thethe latticelattice ofof thethe feldsparfeldspar iiss zinczinc oxideoxide fromfrom Poland,Poland, colourlesscolourless beryberyll crystalscrystals occupiedoccupied byby sodium,sodium, soso itit isis moremore ofof anan albitealbite coveredcovered withwith syntheticsynthetic emeraldemerald film, greengreen glassglass 2Z+ thanthan anan orthoclase.orthoclase. A higherhigher Fe + contentcontent isis thethe fromfrom ZambiaZambia tradedtraded asas emeraldemerald crystalcrystal andand aa chemicalchemical reasonreason forfor thethe smokysmoky moonstonemoonstone facetedfaceted cutcut tourmalinetourmaline fromfrom BrazilBrazil withwith ththee qualityquality whichwhich makesmakes thethe blueblue shineshine betterbetter visible.visible. zoningzoning atat rightright anglesangles toto thethe c-axis;c-axis; thethe pinkpink E.S.E.S. colourcolour wawass causedcaused byby Mn3+ andand thethe yellowyellow bbyy Mn2+.Mn2+. HENN,HENN, U.,U., 1992.1992. UberÜber diedie diagnostischendiagnostischen A greengreen materialmaterial withwith brownbrown specksspecks wawass MerkmaleMerkmale vonvon synthetischensynthetischen AlexandritenAlexandriten foundfound inin NewNew SouthSouth Wales;Wales; itit isis a mixturemixture ooff ausaus derder GemeinschaftGemeinschaft UnabhangigerUnabhängiger StaatenStaaten plagioclaseplagioclase andand jadeitejadeite andand can can bebe used used asa san a n (GUS).(GUS). (About(About thethe diagnosticdiagnostic characteristicscharacteristics ornamentalornamental stonestone calledcalled 'nunderite''nunderite'.. E.SE.S.. ofof syntheticsynthetic alexandritesalexandrites fromfrom thethe formerformer SovietSoviet IndependentIndependent States.)States.) ZeitschriftZeitschriJt der HLAING,HLAING, U.T.,U.T., 1992.1992. MyanmarMyanmar jadejade:: anan update.update. Deutschen Gemmologischen Gesellschajt,Gesellschaft, 41, 41 ,2/3, 2/3 , Australian Gemmologist, 18,18, 3,3, 79-80,79-80, 4 figs. 85-93,85-93, 1010 photomicrographs,photomicrographs, 2 graphs,graphs, 11 DealsDeals withwith legendlegend ofof jadjadee discoverydiscovery inin thethe table,table, bib!.bibl. thirteenththirteenth century,century, althoughalthough regularregular tradetrade dididd TheThe identificationidentification ofof thethe syntheticsynthetic notnot startstart untiluntil latlatee inin thethe eighteentheighteenth century.century. alexandritesalexandrites producedproduced byby flux-pullingflux-pulling oorr NaturaNaturall resourcesresources andand gemsgems arear eState State owned,owned , 434300 ].J. Gemm.Gemm.,, 1993,1993, 23,23, 77

bubutt exploitedexploited jointljointlyy withwith privatprivatee companies.companies. habitshabits withwith trapezohedrotrapezohedronn predominantpredominant,, usuallyusually FinesFinestt gemsgems araree soldsold abroadabroad bbyy MyanmarMyanmar GemsGems heavilheavilyy striated.striated. R.K.M.R.K.M. EnterpriseEnterprise ttoo brinbringg foreignforeign currency,currency, bubutt smugglingsmuggling hahass ledled ttoo a jadjadee centrcentree iinn Bangkok,Bangkok, KoiVULAKOIVULA,, J.I.J.I., , 1992.1992. TheThe gemmologicalgemmological Thailand.Thailand. SalesSales havehave improveimprovedd sincesince jadeitjadeitee wawass propertiepropertiess ofof extraterrestrialextraterrestrial peridotsperidots.. SouthSouth sawnsawn ttoo disclosdisclosee ititss quality.quality. RK.M.R.K.M. African Gemmologist, 6,6, 10-16,10-16, 5 photophotoss iinn colour.colour. HOLZHEY,HOLZHEY, G.,G., 1992.1992. PraktischePraktische GemmologieGemmologie TransparenTransparentt toto translucenttranslucent nodulesnodules ooff peridotperidot aamm BeispielBeispiel historischerhistorischer Pretiosen.Pretiosen. (Practical(Practical havehave beebeenn founfoundd inin pallasitespalla sites,, meteoritemeteoritess withwith aa gemmologgemmologyy aass applieappliedd ttoo historicalhistorical sculpture.)sculpture.) metallimetallicc networnetworkk ooff nickenickell andand ironiron.. PropertiesProperties Zeitschrift der Deutschen GemmologischenGemmologischen areare withiwithinn ththee rangerange forfor gegemm peridotperidot bubutt stonesstones Gesellschaft, 4141,, 2/32/3,, 95-10095-100,, 3 photographs,photographs, showshow acicularacicular inclusioninclusionss causedcaused possiblypossibly bbyy bib!.bibl. stress-stress- andand heat-causeheat-causedd exsolutionexsolution.. M.O'D.M.O'D. TheThe sculpturesculpture discusseddiscussed iiss a silver-giltsilver-gilt elephanelephantt producedproduced bbyy thethe goldsmitgoldsmithh andand jewellerjeweller LASNIERLASNIER,, B.B.,, POIROTPOIROT,, J-P.,J-P., SMITH,SMITH, D.C.D.C.,, 1992.1992. J.MJ.M.. DinglingeDinglingerr iinn DresdeDresdenn iinn ththee firstfirst quartequarterr ooff IntercroissancesIntercroissances ddee jadéitjadeitee ddee differentesdifférentes ththee 18th18th century.century. TheThe dimensionsdimensions araree 17.517.5 x 1212 compositionscompositions dandanss leless jadejadess révéléereveleess paparr cm,cm, heightheight 13.513.5 cmcm;; itit iiss listedlisted iinn thethe inventoryinventory cathodoluminescencecathodoluminescence.. Revue de gemmologie,gemmologie, ofof 17251725 ofof thethe 'Gruene'Gruenenn Gewoelbe'Gewoelbe'.. ThThee saddlesaddle 113,8-11,5113, 8-11, 5 photophotoss iinn colourcolour,, 4 figs. ooff ththee elephantelephant iiss studdedstudded withwith precioupreciouss stones,stones, ZoneZonedd cathodoluminescenccathodoluminescencee cancan bbee seenseen iinn 2211 emeralemeraldd cabQchonscabochons,, bubutt onlyonly 2222 ofof ththee 4411 crystalscrystals ofof jadeitjadeitee andand provideprovidess a meanmeanss ooff rose-cutrose-cut stonesstones areare diamonds,diamonds, ththee remainderremainder araree distinguishingdistinguishing compositionalcompositional variations.variations. rockrock crystacrystall oorr colourlesscolourless topaztopaz.. ThThee qualitqualityy ooff M.O'D.M.O'D. ththee emeraldemeraldss isis variablevariable.. E.SE.S.. LIEBER,LIEBER, W.,W., 1993.1993. FarbzoneFarbzonenn inin Kristallen:Kristallen: HUTTON,HUTTON, D.R,D.R., TROUPTROUP,, G.J.G.].,, 1992.1992. MagneticMagnetic BeobachtungeBeobachtungenn imim MineralreichMineralreich.. Lapis, 18,18, 1,1 , resonancresonancee spectrumspectrum ooff TorringtoTorringtonn emerald.emerald. 29-4829-48,, 1515 photophotoss inin colour.colour. Australian Gemmologist, 18,18, 3,3, 89-90,89-90, 2 figs. AmonAmongg ththee exampleexampless ofof zonezonedd mineralsminerals AnAn investigationinvestigation ofof electron-spinelectron-spin resonanceresonance ooff discusseddiscussed areare rocrockk crystalcrystal,, amethystamethyst anandd emeraldemerald fromfrom anotheranother AustralianAustralian locality,locality, tourmalinetourmaline;; ththee paperpaper includesincludes a discussiondiscussion ooff identifyingidentifying a greatlygreatly reducereducedd contentcontent ooff chemicalchemical reasonreasonss forfor thethe phenomenonphenomenon.. M.O'D.M.O'D. vanadiumvanadium iinn comparisocomparisonn witwithh stonesstones fromfrom PoonaPoona oror withwith ColombiaColombiann emeraldemerald.. ComparisonComparison LINTON,LINTON, T.T.,, BROWNBROWN,, G.G.,, 1992.1992. HofeHoferr gemstonegemstone witwithh BiroBironn syntheticsynthetic emeraldemerald alsoalso made.made. colorcardcolorcard.. Australian Gemmologist, 18,18, 44,, 122-122- RK.M.R.K.M. 4,4, 1 fig.fig. DespitDespitee itsits namename thisthis iiss intendeintendedd ttoo determinedetermine JACKOWSKA-POLEWCZAK,JACKOWSKA-POLEWCZAK, A.,A., 1991.1991. KamienieKamienie ththee coloucolourr temperaturetemperature ooff lighlightt availableavailable iinn szlachetneszlachetne i ozdobnozdobnee Madagaskaru.Madagaskaru. whichwhich ttoo judgjudgee stones.stones. ItIt doedoess notnot definedefine ththee MineralogiaMineralogiapolonica, polonica, 2222,, 3,3, 79-8779-87,1, 1 map.map . colourcolour ofof stones.stones. RK.M.R.K.M. GeGemm mineralmineralss areare describeddescribed andand briefbrief geologicageologicall anandd mininminingg detaildetailss araree givegivenn foforr MENZIESMENZIES,, M.A.M.A.,, BOGGS,BOGGS, R.C.RC.,, 1993.1993. MineralsMinerals Madagascar.Madagascar. M.O'D.M.O'D. ooff ththee SawtoothSawtooth batholithbatholith,, Idaho.Idaho. Mineralogical Record, 24,24, 3,3, 185-202,185-202, 2200 JANOSZCZYKJANOSZCZYK,, B.B.,, 1992.1992. ProbleProblemm otrzymywaniaotrzymywania photophotoss (6(6 iinn colour),colour), 1 map.map . syntetycznycsyntetycznychh opalopalii szlachetnychszlachetnych.. Mineralogia AmonAmongg thethe mineralmineralss foundfound iinn miaroliticmiarolitic polonica, 23,23, 1,1, 89-93.89-93. cavitiescavities anandd pegmatitepegmatite dikedikess iinn thethe granitegranite ofof thethe SomeSome considerationsconsiderations ooff thethe GilsoGilsonn syntheticsynthetic SawtoothSawtooth batholitbatholithh inin south-centralsouth-central IdahIdahoo araree opaopall araree offeredoffered witwithh theorietheoriess onon ththee possiblepossible gem-qualitygem-quality aquamarineaquamarine anandd colourlescolourlesss topaz.topaz. methodmethodss ooff manufacturemanufacture.. M.O'D.M.O'D. SmallerSmaller crystalscrystals ooff spessartinespessartine araree alsoalso reported.reported. SomeSome aquamarineaquamarine crystalcrystalss reachreach oveoverr 10cm10cm inin KEELING,KEELING, J.L.J.L.,, FLINTFLINT,, R.B.RB.,, 1992.1992. AlmandineAlmandine lengthlength.. M.O'D.M.O'D. garnegarnett crystalscrystals frofromm thethe PrydzPrydz BayBay area,area, AntarcticaAntarctica.. Australian Gemmologist, 18,18, 3,3, 85-85- PASTERNAKPASTERNAK,, A.A.,, 1993.1993. RockRock star.star. ES, ththee 8,8, 8 figs,figs, 2 maps.maps. Evening Standard magazinemagazine,, JunJunee 1993,1993, 22 RedRed toto brownish-rebrownish-redd almandinalmandinee crystalcrystal photophotoss iinn colour.colour. fragmentfragmentss foundfound onon VikoVikoyy Island,Island, nearnear Davis,Davis, Reporter'Reporter'ss interviewinterview withwith LondonLondon merchantmerchant werewere examinedexamined andand foundfound toto bbee ofof expectedexpected LaurenceLaurence Graff.Graff. M.O'D.M.O'D. JJ.. Gemm.,Gemm, 1993,1993, 2323,, 77 431431

PETERSEN,PETERSEN, O.V.,O.V., SECHER,SÉCHER, K.,K., 1993.1993. TheThe uraniumuranium zircozirconn suggestssuggests thathatt conditionsconditions maymay mineralmineralss ooff Greenland.Greenland. Mineralogical Record, havhavee beebeenn appropriatappropriatee foforr ththee emplacementemplacement ooff 24,2,4-67.24, 2, 4-67. 7676 photosphotos (colou(colourr anandd black-and­black-and- diamondiferoudiamondiferouss materiamateriall durinduringg thisthis period.period. white),white), 6 mapsmaps,, 2222 figs. RA.H.R.A.H. AmongAmong ththee mineralmineralss ooff GreenlanGreenlandd withwith ornamentalornamental applicationapplication areare tugtupite,tugtupite, sphene,sphene, SAADI,SAADI, lA.,J.A., GRASSO,GRASSO, J.C.J.C.,, 1992.1992. RhodochrositeRhodochrosite garnetgarnet,, rubrubyy anandd sapphirinesapphirine thougthoughh fefeww cacann bbee frofromm ArgentinaArgentina.. Australian Gemmologist, 18,18, 4,4, countedcounted gegemm qualityquality aparapartt fromfrom ththee firstfirst twotwo 125-32,26125-32, 26 figs. named.named. TheThe paperpaper iiss a welcomwelcomee andand exhaustiveexhaustive DescribesDescribes ththee CapillitasCapillitas minesmines,, whichwhich yieldyield up-to-dateup-to-date descriptivedescriptive summarysummary ooff oneone ooff thethe thithiss beautifulbeautiful pinpinkk toto reredd ornamentalornamental mineral,mineral, iinn world'world'ss majomajorr mineralizemineralizedd areasareas.. M.O'D.M.O'D. considerablconsiderablee detail.detail. IInn a regionregion producingproducing muchmuch superlativesuperlative material,material, itit seemsseems thathatt thethe OrtizOrtiz minemine PLASZYNSKA,PLASZYNSKA, M.M.,, 1992.1992. SomeSome remarksremarks onon thethe iiss totopp inin quality,quality, somesome ooff whicwhichh woulwouldd appeaappearr ttoo applicationapplicationss ooff BalticBaltic ambeamberr todaytoday anandd inin bbee facetable.facetable. ThThee majormajor outpuoutputt iiss slabbedslabbed foforr ancienancientt anandd medievamedievall times.times. MineralogiaMineralogia decorativedecorative use,use, carvecarvedd oorr usedused forfor cabochons.cabochons. polonica, 2323,, 2,2, 75-6.75-6. RK.M.R.K.M. A briefbrief accountaccount ofof ththee ususee ofof amberamber throughthrough ththee ages.ages. M.O'D.M.O'D. SCHUBNEL,SCHUBNEL, H-J.H-J.,, 1992.1992. LesLes gemmegemmess etet I'histoirel'histoire dede llaa mineralogieminéralogie dede LouisLouis XIIXIIII aà CharleCharless XX.. POIROTPOIROT,, J-P.,J-P., 1992.1992. AmbreAmbre naturelnaturel,, ambreambre Revue de gemmologie, 113,113, 14-18,14-18, 1414 photophotoss ((77 pressépresse,, ambreambre synthetique.synthétique. Revue dede inin colour).colour). gemmologie, 113,113, 25-625-6,, 1 photphotoo iinn colourcolour,, 11 MineraMinerall anandd gemgem collectioncollectionss atat thethe MuseumMuséum fig. NationaNationall d'Histoird'Histoiree NaturelleNaturelle,, ParisParis,, reflectreflect ththee A briebrieff resumeresume ofof thethe variouvariouss typestypes ofof amberamber collectingcollecting activitiesactivities ofof severalseveral FrencFrenchh kings.kings. TheThe andand amberamber simulantssimulants withwith detaildetailss ooff somesome threethree mainmain collectioncollectionss araree ththee JardinJardin dudu RoyRoy manufacturinmanufacturingg processeprocessess wherwheree appropriate.appropriate. (1626-1730)(1626-1730) witwithh anan emphasiemphasiss onon thethe medicinalmedicinal M.O'D.M.O'D. useuse ofof minerals;minerals; ththee CabineCabinett RoyaRoyall d'Histoired'Histoire NaturelleNaturelle,, (1739-1793),(1739-1793), displayedisplayedd inin 9999 READREAD,, P.G.P.G.,, 1993.1993. DiamondDiamondss iinn thethe desert.desert. showcasesshowcases andand LeLe MuséuMuseumm NationaNationall d'Histoired'Histoire Canadian Jeweller, ApriAprill 1993,1993, 27-8,27-8, 1 photophoto NaturellNaturellee (179(17933 ttoo ththee present)present).. ApproximatelyApproximately inin colour.colour. 243,000243,000 specimensspecimens araree nownow iinn thethe collections.collections. CoversCovers thethe historyhistory ofof thethe discoverdiscoveryy ooff M.O'D.M.O'D. diamondsdiamonds alonalongg ththee NamibiaNamibiann coastacoastall deserdesertt iinn whawhatt waswas thenthen GermanGerman SouthSouth WesWestt AfricaAfrica,, ttoo THOMAS,THOMAS, A.E.A.E.,, THOMAS,THOMAS, CA.C.A.,, 1992.1992. GarnetsGarnets thethe developmendevelopmentt ooff ththee CDCDMM miningmining operationoperation ofof ththee alluvialalluvial diamondiamondd diggings,diggings, ptpt 22.. SouthSouth afteafterr WorlWorldd WarWar I anandd ititss incorporatioincorporationn intointo thethe African gemmologist, 66,, 3,3, 5-9,5-9, 3 photophotoss iinn DeDe BeerBeerss group.group. (Author'S(Author's abstract)abstract) P.G.RP.G.R. colourcolour.. GarnetsGarnets fromfrom twtwoo areaareass areare examinedexamined anandd ROBERT,ROBERT, D.D.,, 1992.1992. LaLa coloratiocolorationn artificiellartificiellee dduu describedescribedd witwithh detailsdetails givegivenn ofof theitheirr weight,weight, bérylberyl.. Revue de gemmologie, 113,113, 23-4,23-4, 4 colourcolour,, RIRI,, SG,SG, fluorescence,fluorescence, absorptionabsorption photosphotos inin colourcolour,, 1 fig.fig. spectrumspectrum andand inclusions.inclusions. TheThe twtwoo areaareass areare:: VariousVarious waysways ofof colouringcolouring berylberyl areare brieflybriefly diggingsdiggings iinn thethe VaalVaal RiverRiver catchmentcatchment fromfrom described.described. M.O'D.M.O'D. BoskuilBoskuil througthroughh BloemhofBloemhof andand ChristianChristianaa ttoo WarrentonWarrenton iinn ththee westernwestern TransvaalTransvaal;; anandd anan areaarea ROBERTSONROBERTSON,, A.D.C.A.D.C.,, SUTHERLAND,SUTHERLAND, F.L.,F.L., 1992.1992. iinn thethe northernnorthern CapCapee betweebetweenn Schmidtsdrift,Schmidtsdrift, PossiblPossiblee originoriginss anandd agesages foforr sapphiresapphire anandd Douglas,Douglas, Higg'Higg'ss HopHopee andand Prieska,Prieska, includinincludingg thethe diamondiamondd fromfrom thethe centralcentral QueenslandQueensland gemgem confluenceconfluence ofof ththee OrangOrangee anandd VaaVaall Rivers.Rivers. fields.fields. Records of the Australian Museum,Museum, AttemptsAttempts araree mademade toto placplacee ththee stonesstones oonn aa Suppl.,Suppl, 15,15, 45-5445-54,, 1 mapmap,, 1 photo.photo. garnetgarnet colourcolour scale.scale. M.O'D.M.O'D. MiningMining ooff sapphiresapphire hashas beebeenn carriecarriedd outout forfo r overover 100100 yearyearss inin thisthis areaarea,, ththee classicclassic grainsgrains ofof sapphiresapphire reputedlyreputedly derivederivedd frofromm thethe localocall basalt.basalt. VOYNICKVOYNICK,, S.,S., 1993.1993. SyntheticSynthetic gemstones:gemstones: highhigh NeNeww workwork hahass shown,shown, however,however, thathatt ththee fashionfashion,, higherhigher techtech.. Compressed air, 98,98, 44,, 8-8- sapphiressapphires originateoriginate iinn pyroclastipyroclasticc rocksrocks andand araree 15,15, 9 photophotoss iinn colour.colour. associatedassociated withwith zirconszircons.. TheThe zirconzirconss araree ofof twotwo A briefbrief resumresumee ofof ththee ususee ofof man-mademan-made types:types: olderolder low-uraniulow-uraniumm zircozirconn anandd youngeryounger crystalcrystalss aass gemstonesgemstones withwith notesnotes oonn thethe problemsproblems high-uraniumhigh-uranium zircon.zircon. TheThe occurrenceoccurrence ofof low- low- ofof identification.identification. M.M.O'D O'D.. 432432 J.J. Gemm.,Gemm, 1993,1993, 23,23, 7

WILLIAMSON,WILLIAMSON, L.L.,, 1992.1992. A newnew theorytheory ofof archaicarchaic Association.Association. ItIt startsstarts withwith a shortshort historyhistory andand jadesjades.. Bulletin ojof the Friends ojof Jade,Jade, 77,, 42-742-7.. aimsaims ofof thethe AssociationAssociation illustratedillustrated withwith DrawingDrawing onon thethe developmentdevelopment ofof ideographsideographs photographsphotographs ofof paspastt andand presenpresentt presidents.presidents. TheThe somesome ideaidea ofof thethe useuse ofof ChineseChinese jadjadee artefactsartefacts anniversaryanniversary wawass celebratedcelebrated withwith a two-daytwo-day cancan bebe obtained.obtained. DiagramsDiagrams areare takentaken fromfrom symposiumsymposium onon 2727 andand 2828 SeptemberSeptember 19921992 andand Karlgren,Karlgren, GrammataGrammata SericaSerica Recensa,Recensa, thethe inauguralinaugural speechspeech bbyy ProfessorProfessor DrDr BankBank isis Stockholm,Stockholm, 1957.1957. M.O'D.M.O'D. reprinted.reprinted. ThereThere werewere 2727 contributionscontributions whichwhich areare reprintedreprinted inin condensedcondensed versions,versions, bothboth inin ZHANG,ZHANG, P.,P., 1992.1992. Gem-qualityGem-quality scapolitescapolite fromfrom GermanGerman andand English.English. TheThe subjectsubject mattermatter ofof thethe SinjiangSinjiang region,region, WestWest China.China. AustralianAustralian lectureslectures waswas varied,varied, fromfrom neneww observationsobservations onon Gemmologist, 18,4,18, 4, 115-17,2115-17, 2 figs. thethe originorigin ofof tiger's-eyetiger's-eye dealingdealing mainlmainlyy withwith thethe ProspectsProspects appearappear toto bebe goodgood forfor purplishpurplish pinkpink crocidolitecrocidolite fromfrom GriqualandGriqualand West,West, toto variousvarious scapolitescapolite founfoundd iinn associationassociation withwith sphenesphene iinn thisthis productioproductionn methodsmethods ofof producingproducing syntheticssynthetics inin region,region, botbothh asas facetablefacetable andand asas cat's-eyecat's-eye Japan.Japan. AntiqueAntique RomanRoman gemstonesgemstones includingincluding material.material. R.K.M.R.K.M. mosaicsmosaics werewere discussed.discussed. TwoTwo extremelyextremely interestinginteresting lectureslectures onon diamondsdiamonds dealtdealt withwith What'sWhat's newnew inin minerals?minerals? 1993.1993. [various[various diamonddiamond andand diamond-likediamond-like thinthin filmfilm coatingscoatings authors].authors]. Mineralogical Record, 24,24, 3,3, 219-30,219-30, andand a reviewreview ofof thethe ArgyleArgyle mines.mines. OtherOther subjectssubjects 1993.1993. 3232 photosphotos (31(31 inin colour).colour). were:were: heat-treatedheat-treated pinpinkk spinelspinel fromfrom SriSri Lanka;Lanka; ShowsShows atat TucsonTucson andand PasadenaPasadena areare reviewed.reviewed. tracetrace elementselements andand conditionsconditions forfor heat-treatmentheat-treatment AmongAmong thethe gem-qualitygem-quality speciesspecies observedobserved werewere asas factorsfactors ofof thethe gemgem qualityquality ofof corundums;corundums; yellowyellow beryberyll fromfrom Skardu,Skardu, Pakistan;Pakistan; colourcolour andand causescauses ofof colourcolour inin greengreen berylsberyls andand rhodochrositerhodochrosite fromfrom thethe SweetSweet HomeHome mine,mine, theirtheir nomenclaturanomenclaturall delimitation;delimitation; polymerspolymers asas Colorado;Colorado; greengreen zoisitezoisite fromfrom Skardu;Skardu; veryvery finefine gemstone-relevantgemstone-relevant materials;materials; identificationidentification ofof etchedetched heliodorheliodor fromfrom UkrainiaUkrainia andand etchedetched fissure treatmenttreatment inin gemstones;gemstones; newnew occurrencesoccurrences sherry-colouredsherry-coloured topaztopaz fromfrom thethe samesame country;country; ofof preciousprecious stonesstones inin BohemiaBohemia (opal-(opal- hyalite,hyalite, diamonddiamond crystalscrystals fromfrom north-north- westernwestern HunanHunan aragonitearagonite andand natrolite,natrolite, smokysmoky quartz,quartz, cassiteritecassiterite province,province, China;China; alsoalso fromfrom ChinaChina werewere lightlight blueblue andand fluorite);fluorite); gemstonesgemstones inin NepalNepal;; a newnew devicedevice aquamarineaquamarine crystals;crystals; orangeorange clinohumiteclinohumite fromfrom forfor obtainingobtaining a reflectedreflected IRIR spectrum;spectrum; Kukh-i-Lal,Kukh-i-Lal, PamirPamir mountainsmountains ofof Tajikistan;Tajikistan; spectrometryspectrometry andand X-rayX-ray fluorescencefluorescence ofof brazilianitbrazilianitee fromfrom Baixo,Baixo, Guandu,Guandu, MinasMinas Gerais,Gérais, sapphires;sapphires; cathodoluminescencecathodoluminescence ofof preciousprecious Brazil;Brazil; largelarge palepale bluish-greenbluish-green datolite,datolite, alsoalso stonesstones andand minerals;minerals; fresnoite,fresnoite, a newnew syntheticsynthetic danburitedanburite andand axiniteaxinite fromfrom Dal'negorsk;Dal'negorsk; emeraldemerald ornamentaornamentall stonestone (fresnoite(fresnoite waswas foundfound inin andand alexandritealexandrite fromfrom thethe MalyshevaMalysheva mine,mine, metamorphicmetamorphic sanborite-quartzitesanborite-quartzite zonezone nearnear Takavaya,Takavaya, Urals;Urals; topaztopaz fromfrom Mursinka,Mursinka, Russia;Russia; Fresco,Fresco, California);California); firstfirst cataloguecatalogue ofof RamanRaman sillimanitesillimanite fromfrom Rakwana-Deniyara,Rakwana-Deniyara, spectraspectra ofof gemstonesgemstones;; thethe presenpresentt conditioncondition forfor SabaragamuwaSabaragamuwa province,province, SriSri LankaLanka (one(one crystalcrystal rubyruby (in(in JapanJapan andand includingincluding rubiesrubies fromfrom seenseen measuredmeasured 1.8cm);1.8cm); chrysoberylchrysoberyl twinstwins fromfrom VietnamVietnam which,which, accordingaccording ttoo thethe author,author, mightmight TeixeiraTeixeira dada Freitas,Freitas, Bahia,Bahia, BrazilBrazil andand fromfrom comecome fromfrom otheotherr localities);localities); contributionscontributions toto thethe MedeirosMedeiros NetoNeto inin thethe samesame state;state; nearnear gem­gem- crystalcrystal growthgrowth analysisanalysis ofof naturalnatural andand syntheticsynthetic qualityquality sapphirinesapphirine fromfrom Androy,Androy, MalagasyMalagasy rubies;rubies; identificationidentification ofof a dominantdominant negativenegative c Republic.Republic. M.O'D.M.O'D. rhombohedralrhombohedral 'd'd' planplanee (0112(0112)) iinn naturanaturall rubyruby;; morphologicalmorphological aspectsaspects ofof diamonds,diamonds, naturalnatural andand ANON,ANON, 1992.1992. OpalOpal theft.theft. Australian Gemmologist, synthetic,synthetic, stablestable andand metastablemetastable growth;growth; newnew 18,4,18,4, 115,115, 1 fig.fig. gemmologicalgemmological materialsmaterials analyzedanalyzed byby CISGEMCISGEM A shortshort notenote onon a splitsplit pairpair ofof redred pin-flashpin-flash (pearl,(pearl, mother-of-pearl,mother-of-pearl, doubletsdoublets andand boulderboulder opalsopals (4.5(4.5 x 3.5cm3.5cm each)each) stolenstolen fromfrom thethe imitations);imitations); beautybeauty gradesgrades ofof gemstonesgemstones (ruby,(ruby, MuseuMuseumm ofof Victoria.Victoria. FinderFinder toto inforinformm DrDr BillBill tourmalinetourmaline andand tanzanite)tanzanite);; analysisanalysis ofof BurmeseBurmese BirchBirch ofoftha thatt MuseumMuseum (010(010 61036699878).61 03 669 9878). andand ThaiThai rubiesrubies byby PIXE;PIXE; gemstonesgemstones ofof thethe R.K.M.R.K.M. SwissSwiss Alps;Alps; Embilipitiya,Embilipitiya, anan interestinginteresting gemgem deposidepositt inin SriSri LankaLanka (almandine(almandine garnetgarnet,, spinel,spinel, ZeitschriJtZeitschrift der Deutschen GemmologischenGemmologischen cordieritecordierite andand kornerupine).komerupine). TheThe contributionscontributions Gesellschajt,Gesellschaft, 1992.41,4,121-97.1992. 41, 4, 121-97. areare illustratedillustrated byby 2020 photographs,photographs, 2 maps,maps, numerous graphs and tables. E.S. ThisThis issueissue ofof thethe ZeitschrijtZeitschrift isis dedicateddedicated toto thethe numerous graphs and tables. E.S. 60th60th anniversaryanniversary ofof thethe GermanGerman GemmologicalGemmological JJ.. Gemm.,Gemm, 1993,1993, 2323,, 6 433433

BooBookk ReviewsReviews

CLARKCLARK,, A.MA.M.. 1993.1993. Hey's Mineral Index.Index. previoupreviouss editioneditionss ooff thethe presenpresentt worworkk onlonlyy thethe ChapmaChapmann & HallHall,, LondonLondon., pppp.. xixi,, [852].[852]. sixthsixth editionedition waswas usedused;; thisthis iiss nownow a rarraree bookbook £50.00£50.00.. ISBNISBN 0 414122 3995399500 4.4. andand referencesreferences havhavee beebeenn tracketrackedd dowdownn ttoo theirtheir FirstFirst a bibliographicabibliographicall notenote oonn thethe historhistoryy ofof originaloriginal appearancappearancee soso thathatt DanaDana editioneditionss 1-51-5 thithiss majormajor workwork.. ItIt begabegann liflifee inin 19501950 asas ththee firstfirst onceonce moremore havehave worworkk ttoo do.do. MostMost namnamee variantsvariants editionedition ofof An index of mineral species andand varietiesvarieties iinn GermaniGermanicc languageslanguages araree takentaken frofromm thethe veryvery arranged chemically [spine[spine titltitlee anandd familiarlyfamiliarly rarraree anandd ververyy expensiveexpensive Handbuch der knowknownn aass Chemical index to minerals].minerals]. TheThe Mineralogie series,series, establisheestablishedd bbyy CarlCarl Hintze.Hintze. secondsecond editionedition withwith ththee samesame titltitlee appeareappearedd inin DetailsDetails ooff crystalcrystal system,system, unitunit cellcell dimensions,dimensions, 1955;1955; thereafterthereafter ththee workwork wawass continuecontinuedd iinn twotwo anandd formulaformula uniunitt contentscontents [Z][Z] areare given;given; thertheree isis appendiceappendicess publishedpublished iinn 19631963 andand 1974,1974, thethe alsalsoo a two-two- oror three-partthree-part numbernumber relatedrelated ttoo thethe latterlatter witwithh P.G.P.G. EmbreyEmbrey asas co-author.co-author. ThThee mainmain previousprevious HeyHey numbersnumbers bubutt notnot identicaidenticall ttoo them.them. worworkk waswas alsoalso reprintereprintedd witwithh minorminor corrections.corrections. PDPDFF (Powder{Powder Diffraction file)file) numbernumberss areare givengiven TheThe workwork wawass compilecompiledd byby,, andand isis a memorialmemorial forfor thosethose entriesentries wherwheree ththee uniunitt cellcell datdataa araree heldheld ttoo MaMaxx HeyHey whoswhosee namename isis fittinglyfittingly inin thatthat file. commemoratecommemoratedd inin thethe presenpresentt titletitle.. ThiThiss isis oneone AAnn importantimportant neneww featurfeaturee iiss ththee inclusioninclusion ofof ooff thethe threethree oorr fourfour mineralogmineralogyy textstexts formingforming thethe typetype localitlocalityy forfor speciesspecies andand well-definedwell-defined foundationfoundation ooff allall seriousserious study.study. varieties,varieties, whenwhen thisthis isis knownknown.. GemmologistsGemmologists TheThe firstfirst twotwo editioneditionss listedlisted mineralmineralss inin mamayy likelike toto knoknoww thatthat ththee typetype localitlocalityy providesprovides chemicalchemical ordeorderr witwithh elementelementss firsfirstt anandd rarerrarer thethe specimenspecimen frofromm whichwhich ththee mineralmineral oror varietalvarietal compoundscompounds lastlast;; iitt alsalsoo includeincludedd organicorganic descriptiondescription iiss firstfirst made.made. AlthougAlthoughh somesome materialmaterialss anandd substancessubstances inadequatelyinadequately politico-geographicapolitico-geographicall changechangess havhavee beebeenn mademade characterizedcharacterized aatt ththee time.time. MineralMineral classeclassess werewere sincesince originaloriginal paperpaperss werewere written,written, thithiss boobookk stillstill assignedassigned a numbernumber withwith speciesspecies givegivenn a runningrunning managesmanages ttoo bbee up-to-dateup-to-date,, takingtaking intointo accountaccount numbenumberr withiwithinn thethe class.class. ThesThesee numbernumberss alsoalso ththee unificatiounificationn ooff GermanyGermany (but(but nonott thethe includedincluded doubtfudoubtfull speciesspecies anandd varietiesvarieties;; iitt waswas disintegrationdisintegration ooff ththee formeformerr USSUSSRR andand anandd stillstill iiss difficuldifficultt toto distinguishdistinguish betweenbetween thesethese Yugoslavia).Yugoslavia). TheThe remainderremainder ooff ththee entryentry givesgives twtwoo categoriescategories.. ThThee presenpresentt worworkk isis arrangedarranged ththee originorigin ofof ththee namename,, referencreferencee toto importantimportant alphabeticallyalphabetically butbut stillstill includesincludes ththee chemicalchemical chemicalchemical redefinitionsredefinitions thatthat havehave occurredoccurred duringduring orderorder listinglisting whicwhichh iiss givegivenn iinn a conciseconcise formform atat thethe historhistoryy ooff a species,species, synonymssynonyms andand varietalvarietal ththee enendd ofof ththee mainmain text.text. ThThee namesnames araree allall namenamess - thesethese mamayy bbee basedbased onon habithabit,, coloucolourr oror publishedpublished anandd ththee sequencesequence alsalsoo containcontainss somesome chemicachemicall differences.differences. DataData concerningconcerning unnamedunnamed ooff thethe commonecommonerr mis-spellingsmis-spellings,, somesome meteoritemeteorite speciesspecies isis notnot givengiven inin thisthis edition,edition, nonorr isis thethe anandd rocrockk namesnames whicwhichh ofteoftenn resembleresemble namenamess ofof pronunciatiopronunciationn tabletable,, sincesince thethe authorauthor admitadmitss thatthat mineralmineralss anandd somesome tradtradee namesnames wherwheree theythey eveneven inin a singlesingle laboratorlaboratoryy (an(andd eveneven moremore inin thethe resemblresemblee mineraminerall namesnames.. EacEachh entryentry containscontains fieldfield)) twotwo peoplpeoplee rarelyrarely agreagreee oonn thisthis topitopicc - thethe chemicalchemical compositioncomposition,, grougroupp namename wherewhere perhapperhapss therethere wawass somethingsomething ttoo bbee saidsaid forfor thethe applicablapplicablee [the[the groupingsgroupings araree muchmuch ththee samesame asas OxbridgeOxbridge accentaccent whenwhen shoutedshouted againsagainstt thethe wind!wind! thosthosee setset outout inin FleischeFleischerr & Mandarino'sMandarino's ThThee boobookk iiss amazingamazing valuevalue forfor itsits pricpricee andand a Glossary of mineral species. ThereThere iiss a referencereference superb,superb, long-awaitedlong-awaited workwork.. M.O'D.M.O'D. wherwheree possiblpossiblee ttoo thethe descriptiodescriptionn ooff thethe originaloriginal mineraminerall anandd referencereferencess araree alsalsoo givegivenn foforr manymany KAZMI,KAZMI, AA.. HH.. andand O'DONOGHUEO'DONOGHUE,, MM.. 1990.1990. oldold namenamess andand synonyms.synonyms. CyrillicCyrillic charactercharacterss areare Gemstones of Pakistan: Geology andand givegivenn foforr RussiaRussiann languaglanguagee namesnames,, soso ofteoftenn a Gemmology. GemstonGemstonee CorporationCorporation ofof causcausee ooff contention.contention. ItIt iiss interestinginteresting ttoo find thatthat PakistanPakistan,, PeshawarPeshawar., pp.pp. viiviiii + 146,146, 2424 blackblack citationscitations araree madmadee inin thithiss editioeditionn ttoo earlierearlier andand whitwhitee figs. 7272 coloucolourr platesplates,, 1919 tables,tables, editioneditionss ooff Dana'Dana'ss System of mineralogy;mineralogy, inin PricePrice £35.£35. 434 J. Gemm, 1993, 23, 7

This book might easily be considered as the Metuchen NJ. pp. xxxiii, 1179, illus. in black- sister publication of the earlier work Emeralds of and-white. ISBN 0 8108 2652 6. £179.50. Pakistan, especially since A. H. Kazmi is a co­ At last gemmology has a worthy bibliography, author of both texts. Both have a geological bias, and if one single event helps a subject to come of but this work has the avowed intention of age this must be it. This is a bibliography in the stimulating budding gem geologists and jewellers sense of a catalogue raisonné rather than a list of to go out and make more gem discoveries. To books, with many old problems now at last laid this end the authors provide a twenty page to rest, freeing the student for other work and general introduction to gemstone composition, perhaps even building upon this one since the properties and distribution; this includes the use output of books and papers shows no sign of of testing instruments, cutting and polishing and lessening. the procurement of rough. A list showing The book opens with a foreword by Richard worldwide distribution of gemstones by T. Liddicoat and continues with a preface in countries is also provided. which the parameters of the book are described. The physical and geological features of It is certain that no previous bibliography exists Pakistan are described in the next chapter, and when Sinkankas began a literature search for which includes useful maps and sections his first book, published in 1955, he found that explaining the tectonic setting. The latter is used it was necessary not only to consult a very large as a basis for describing gemstones according to number of existing books for their citations but their various tectonic associations. Pakistan also to acquire many of them and, at the same emeralds are described in some detail under the time, recording their bibliographical details as 'Indus suture associated gemstones' heading and fully as possible. From these careful beginnings are compared with their synthetic counterparts. the present work has sprung; the library of books Ruby and spinel (often blue) are among the acquired now graces the Gemological Institute gems found in an extensive belt of crystalline of America. It has taken something like forty marble found in the Hunza valley and elsewhere years to bring this project to fruition. which forms part of the 'Karakoram suture During the compilation of the bibliography associated gemstones' chapter. Pegmatites are many books were consulted and recorded, widely distributed in Pakistan and this is perhaps for the last time since some were printed reflected in the variety of gemstones in the on so poor a paper that they cannot now be chapter on 'Pegmatite associated gemstones'. repaired. For this reason Sinkankas has provided The descriptions of aquamarine, tourmaline, as much detail as possible, including cloth types, feldspar, quartz, topaz and others are colours, lettering, ornamentation, bevelled edges accompanied by good colour photographs and and endpapers. Such details are also provided useful diagrams. The chapter on 'Gemstones in for most of the other entries as well so that there hydrothermal veins' deals with zircon, rutile, will always be a record in the event of disaster. agate and the notable pink topaz from Katlang The scope of the bibliography is based on size which merits a detailed description. The book and relevance of the subject- matter. Thus many concludes with a brief section on miscellaneous works are included which are peripheral to the gems and the gem market in Pakistan. There is a main study of gemstones; such books include comprehensive bibliography. works on engraved gems, regalia, gem lore and A major feature of the book is the excellent biographies, with other topics. A limit of 15 colour photography; largely the painstaking work pages was set for inclusion but shorter pieces of of Dr Edward Gübelin on the inclusions and A. importance are included. Most entries are in H. Kazmi on the mineral specimens and the English, with European languages covered to a good topographical pictures. The contents pages lesser (but still considerable) extent. Books and are reasonably informative, but there is no index. papers must be in the Roman alphabet but this It is unfortunate that Photo No. 1 of an of course includes the romanization of works in engraved emerald is the colour of a blue Cyrillic and oriental scripts. sapphire. Despite its geological bias, the book is Numbered entries are under author where very readable and should be on the shelves of possible and follow accepted bibliographical those gemmologists who are curious about the practice. The preface explains this is some detail; origins of the gemstones they admire, collect, entries may be abbreviated for short articles and test, sell or incorporate into beautiful artifacts. full when a major work is cited. In such cases the E.AJ. entry begins where possible with a brief biographical sketch of the author so that SlNKANKAS, J., 1993. Gemology. An annotated important contributors to the literature of bibliography. 2 vol. Scarecrow Press, gemmology are highlighted; such treatment is J. Gemm, 1993, 23, 7 435

especially useful for historical and classical occurrences, descriptions, inclusion figures; today's major writers will be tracked characteristics, identification and other features'. down in their turn. Among British figures are This aim has been comprehensively achieved Anderson, Webster, Herbert Smith, Blakemore, and the text must be in the hands of all Bruton and the present reviewer. gemmologists and students, although the price Physical details of the book cited are very full may seem a little high to some. The book is and enable the student to distinguish editions, described as a limited edition, so a quick re-issues and variants from one another - this is purchase may be advised. After an introduction not always easy since in the earlier part of this to corundum in which the main characteristics, century dates of publication were not always including cause of colour, are described, the given and there was no ISBN. Notes on effects of heat are outlined, to be more illustrations are also very valuable since these exhaustively covered later in the text where may vary a great deal within a particular work specimens from individual locations are which is printed more than once. Some very discussed. At this point the author is content to large books were published or re-issued for a list and describe heat and diffusion processes for particular small, wealthy group of collectors. the various colours of corundum. Fourteen Even large library catalogues do not always show different processes are considered; they include this type of thing. Those interested can look up darkening and lightening of colour, development such entries as Heber R. Bishop's The Bishop of colour change, production of asterism and collection: investigations and studies in jade, where removal of excess silk, diffusion treatment and full details of a celebrated limited circulation some experimental treatments. Next comes a work will be found. In my years as a curator at section on how inclusions may be affected by The British Museum I passed this enormous treatment, followed by general notes on two-volume book in its glass case many corundum identification. hundreds of times - now I know its contents! By chapter five the author embarks on as full However, this is not the only kind of book an account of heat treatment as can be found whose contents are described since Sinkankas anywhere. Particularly welcome are the notes on provides descriptions of the text of virtually all the types of equipment required and on the ways the monographs cited. He also gives details of in which the stones are prepared for treatment. major reviews. Much of the small detail A 70-page chapter then describes corundum by pertaining to an entry is abbreviated and a table country of origin, giving details where known of sets these out over four pages. This section is whether or not the stones are routinely treated. followed by a list of serial publications and by a The amount of detail is very large and much of it list of bibliographies and references consulted. is of the greatest use to workers not primarily These are listed alphabetically by compiler. It is interested in colour alteration as well as to those remarkable and says much for the skill of the working directly in this area. The vexed author that all this preliminary matter occupies questions of disclosure of treatment, of country only 33 pages. of origin and of value form the final chapter, At many openings title pages of important though there is a bibliography and index. As so books are reproduced; this not only makes an much of the material in this excellent book is attractive and useful break in the text but helps newly-acquired, the reader will find it a vital the student to see quickly which edition he has adjunct to existing modern books on gemstones: or wishes to know about. A superb work with much of the information will filter through quite a reasonable price for the amount of papers and bulletins supplemented where information contained and a credit to our necessary by even more up-to-date accounts science. M.O'D. since this is the most important development area of gemmological investigation. The details THEMELIS, T., 1992. The heat treatment of ruby seem to be correct; there are some misprints of and sapphire. Gemlab Inc. pp. xviii, 236, illus. names and some papers mentioned in the text in black-and-white and in colour. £65.00. are not found in the bibliography, but these are ISBN 0 940 965 10 0. not important points when so much of the The book is sub-headed 'An account of the material is new to the literature. Colour pictures, most commonly practised heat treatment which are grouped together, show interesting methods and apparatuses which alter the and hitherto unpublished examples and are of appearance of the ruby and sapphire; their good quality. M.O'D. 436 J. Gemm., 1993, 23, 6

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

GIFTS TO THE GAGTL The GAGTL is most grateful to Mr Fawcett of the Cultured Pearl Co. Ltd for the gift of a cul­ tured Mabe pearl.

NEWS OF FELLOWS Dr Roger Key, who is on secondment from the British Geological Survey, will be in Botswana for the next two years as Principal Geologist in charge of field mapping. On 25 April 1993 Peter Read gave a talk on gem instruments to students of the Queensland Branch of the Australian Gemmological Association at their headquarters in 20 Rosslyn Street, East Brisbane. He was also invited by the President, Roy Beattie, to be guest speaker at the Branch's Diploma Dinner in Brisbane on 1 May, and gave a talk on 'Diamonds and De Beers'. Before his talk he presented GAA diplomas to that year's successful Queensland candidates.

Dr E. Gübelin at GAGTL lecture

entitled 'The significance of natural and artificial inclusions in diamonds'. Those present were treated to a show of many excellent slides that Dr Gübelin used to illustrate his lecture. On 14 April 1993 Dr Jamie Nelson gave an illustrated talk on 'Light scattering effects in gem- stones'. Much of the talk dealt with recent developments in Raman scattering spectrometry. This is the ultimate laboratory tool for non­ Peter Read in Brisbane presenting a GAA Certificate to successful destructive^ characterizing those gemstone Queensland candidate Bradley Kearton. On the left is Roy Beattie, President of the Queensland branch of the Gemmological Association of inclusions which lie below the polished surface of Australia. a stone. On 27 April 1993 an illustrated talk was given MEMBERS' MEETINGS by Stephen Kennedy entitled 'Rubies in the lab­ London oratory'. The following meets were held at the GAGTL's On 11 May 1993 Christopher Cavey gave an new Gem Tutorial Centre situated on the second illustrated talk on 'Engraved gems'. floor at 27 Greville Street, London EC IN 8SU: On 14 June 1993 the Annual General Meeting On 1 April 1993 Dr E. Gübelin gave a lecture was held (a full report of which is given below) fol- J. Gemm., 1993, 23, 7 437

GAGTL GEM TUTORIAL CENTRE 27 Greville Street, London EC1N 8SU

Gems for retailers information contact Alison Sutton at the 8-9 September University of London Centre for Extra-Mural Two full days of practical experience with Studies, 26 Russell Square, London WC1B mounted stones. Investigate and test the 5DQ, or telephone Alison on 071-631 6654. stones you are likely to handle in the retail Price £50.00 environment. Discuss suitable selling and talking points with gemmologists who have an extensive knowledge of the retail jewellry DIY Laboratory trade. 30 September Price £164.50 Spend a day finding out about the basic gem testing instruments. You will be looking at the principles by which these instruments Two days of diamonds work and the results you should obtain. You 15-16 September will also be constructing some instruments of For an insight into gem diamond origins, your own. grading, simulants and treatments. Price £111.63 (includes materials) Price £223.25

Preliminary workshop Synthetics and enhancements today 12-14 October 22-23 September One-day practical tuition for Preliminary Are you aware of the various treated and students and anyone who needs a start with synthetic materials that are likely to be instruments, stones and crystals; student masquerading alongside the gemstones you discount are buying and selling? Whether you are Price£44.65; GAGTL students£31.73 valuing, repairing or dealing, can you afford to miss these two days of investigation? Price £223.35 Jade 10 November An unrivalled opportunity to handle jade, Precious stones and crystals under the guidance of Alan Jobbins and Evening course commencing 28 September Christopher Cavey. The University of London's Centre for Observe the great variety of jades, their simu­ Extra-Mural Studies will run a course of ten lants, artificial treatments and 'accidental' evening classes at the GAGTL Gem Tutorial alterations. Centre to be held on each Tuesday from Where are the limits to identification? 28 September to 30 November, Price£111.63 (includinglunch) from 6.30 to 8.30 p.m. Each week Ian Mercer, B.Sc, FGA, the GAGTL's Director of Education and a Photographing gemstones University Extra-Mural geology lecturer, will 23 November introduce a different aspect of these Spend the day in the company of Frank fascinating materials. Greenaway, one of the leading photographers The course will appeal to beginners as well as of gemstones. A rare opportunity for you to qualified gemmologists. enhance your photography. For an application form and further Price £111.63 (including materials and lunch)

ALL PRICES INCLUSIVE OF VAT AT 17.5% 438 J. Gemm, 1993, 23, 7

lowed by a Reunion of Members and a 'Bring and company before any new elections are made. Buy' sale. The Annual Report and Accounts of GAGTL for 1992 were approved and signed. Midlands Branch Messrs A. E. Farn, D.G. Kent and R.K. On 30 April 1993 at Dr Johnson House, Bull Mitchell were re-elected as Vice-Presidents and, Street, Birmingham, the Annual General Meeting in recognition of his work for the Association over was held, at which David Larcher and Gwyn many years, Mr E. Bruton elected as Vice- Green were re-elected Chairman and Secretary President. respectively. Mr I. Thomson was re-elected to the Council of On 13 June 1993 a trip to Castleton and Treak Management; the election of Mr T.J. Davidson Cliff Caverns Ollerenshaw Collection, Derbyshire, was confirmed and Mr N.W. Deeks was elected. was arranged for members. Messrs H. Levy and E.A. Thomson retired from the Members' Council. Messrs J. Kessler. G. North West Branch Monnickendam, L. Music, J.B. Nelson and P.G. On 19 May 1993 at Church House, Hanover Read were re-elected and Messrs P. Dwyer- Street, Liverpool 1, Dr J. Franks gave an illus­ Hickey and R. Shepherd elected to the Members' trated talk entitled '"Lalique" jewels, from 1992 Council. Paris Exhibition'. Messrs Hazlems Fenton were re-appointed On 16 June 1993 at Church House a 'Members Auditors. and Friends' evening was held, which included a This concluded the business of the meeting. 'Bring and Buy' sale. Retirement of David Callaghan ANNUAL GENERAL MEETING Mr Ted Thomson then gave the following vote On 14 June 1993 the Annual General Meeting of thanks to David Callaghan on his retirement as of the Gemmological Association and Gem Chairman of the GAGTL. Testing Laboratory of Great Britain was held at 27 'I stand to say a few words on your behalf on the Greville Street, London EC IN 8SU. occasion of David Callaghan's retirement from the David Callaghan chaired the meeting and Chairmanship of the GAGTL and the Council of opened by saying how pleased he was that so Management. If anyone ever deserved a long and many had attended. Although the previous AGM happy retirement from public service it is David. had been held on the second floor of 27 Greville It is quite amazing how long and comprehensive Street, David stated that this was the first to be his service is and how early he started. held in the newly completed Gem Tutorial 'David joined Hancocks as an apprentice at the Centre. The whole aspect of gemmology has now age of sixteen and has worked for them all his life become very much more involved with the so far. He took his FGA in 1958 as part of his modern synthetics and gemstone treatments now apprenticeship under the guidance of Miss Willis, appearing. The Centre is now able to offer an who inspired his love of opals. Miss Willis, inci- increasing number of courses to enable those with dently, was one of the first ladies to qualify for the an interest in gemmology, either as a hobby or FGA and is now living in Leigh-on-Sea at the ripe within the trade, to identify such gemstones. 'So it age of ninety-four. is now possible', David continued, 'to buy books 'During his career at Hancocks David has and gem testing instruments, then take a course to become an authority on gemstones, silver, high find our how to use them - all in the same build­ class jewellery and especially Victoria crosses, and ing'. has lectured worldwide on these topics. In the '60s David Callaghan then announced that he was to he became a Director of Hancocks, a Freeman of retire from the Council of Management and from the City of London, a Liveryman of the the position of Chairman at this meeting. He said Clockmakers Company, a Freeman of the Wax that he had very much enjoyed his term as Chandlers and in 1983 a Liveryman of the Chairman and thanked all those who had given Goldsmiths Company. This latter shows an him help and support over the years. It had been appreciation of his services to the trade. agreed that the Office of Chairman should not be 'He was Chairman of the Precious Stone filled immediately. Because of the changes in the Diamond and Pearl Section of the London company as a result of the merger between the Chamber of Commerce from 1977-80. At that Gemmological Association of Great Britain and time this committee was the main connection the Gem Testing Laboratory, it was decided to between the trade and Government, and had seek the opinions of members on how they see the many responsibilities in addition to running the roles of Chairman and President of the merged Laboratory. He was a sucker for punishment as he J. Gemm, 1993, 23, 7 439

FORTHCOMING MEETINGS

London Throughout 1993 there is a programme of meetings on the second floor at 27 Greville Street. Refreshments will be available from 6.00 p.m. and lectures will start at 6.30 p.m.; these will be followed by discussion and closing about 7.45 p.m. The charge for a member will be £3.50 and, as places are limited to 55, entry will be by ticket only, obtainable from GAGTL.

20 September 'Photographing minerals and gems' Frank Greenaway 6 October* 'Diamonds in the Laboratory' Eric C. Emms 18 October 'The distinction of natural from synthetic diamonds.' Professor I. Sunagawa 8 November 'Thai evening' Amanda Good and Martin Issacharoff 22 November 'CIBJO matters' - the gem trade in Europe Harry Levy 7 December* 'Pearls in the Laboratory' Ana I. Castro and Stephen Kennedy

The GAGTL Annual Conference is to be held on 24 October 1993 at the Great Western Royal Hotel, Paddington. This will be followed on 25 October by a GAGTL Open Day and the Presentation of Awards. Full details of these events are given on p. 386.

Midlands Branch

24 September 'Deep diamonds.' Dr Jeff Harris 29 October 'Rescued from the scrap box.' David Wilkins 26 November A practical demonstration of light behaviour in gemstones. Dr Jamie Nelson

The meetings will be held at Dr Johnson House, Bull Street, Birmingham. Further details from Gwyn Green on 021-445 5359.

North West Branch

15 September Jonathan Condrup from Sotheby's, London 20 October 'Minerals in the Bronze Age'. Tony Hammond 17 November Annual General Meeting

Meetings will be held at Church House, Hanover Street, Liverpool 1. Further details from Joe Azzopardi on 0270-628251.

* Please note change of date: make a note in your programme card. 440 J. Gemm., 1993, 23, 6

was also Chairman of the National Association of following: Goldsmiths from 1976-78 as well as an Examiner for the Retail Jewellers Diploma. Ordinary Membership 'I have a feeling, however, that his real love has Bastians, Indramal Chitranganie, London. always been the GA and the Laboratory. When Bray, Betty A., Abilene, Tex, USA. Doug King had to retire from the Chair of the GA Brown, Symon, Cockermouth, Cumbria. in 1980 David stepped in and since then has Cliff, Graham, Eltham, London. headed the Association with skill and enthusiasm. Everest, Andrew, London. He was instrumental in seeing through the merger Kleiser, Alwen, Holyhead, Gwynedd, Llgsidis. with the Laboratory in 1990 - which was no mean Smith, Ian Hobden, Thatcham. feat. It was very appropriate that he should lead the merged organization since his support for the At a meeting of the Council of Management Laboratory over so many years has been very sig­ held on 19 May 1993 at GAGTL, 27 Greville nificant in establishing continued development of Street, London EC IN 8SU, the business trans­ its activities and resources - both through support acted included the election of the following: from the Trade and acquisition of new instruments. In particular he did a lot of the background work to Ordinary Membership enable the Laboratory to acquire the UV-VIS spec­ Bae, Sang-Kea, Seoul, Korea. trophotometer - appropriately named the Basil Bonnyarak, Orapin, Johor Bahru, West Malaysia. Anderson spectrophotometer - in 1984. De Narvaez, Mauricio, Bogota, Colombia. 'So on behalf of his old colleagues at the Devon, Jill, Felstead. Chamber of Commerce and more especially his Howard, Stanley, Mill Hill, London. many friends and colleagues at the GAGTL, I Nolens-Verhamme, Paule, Sint Truiden, would like to thank you David for the many things Belgium. you have done for the Trade in so many facets and Wood, Victor, Ilford. would ask you to accept our gift as a small token of appreciation of your contribution and in the hope At a meeting of the Council of the Management that you will have many years of enjoyment from it'. held on Wednesday 16 June 1993 at GAGTL 27 Greville Street, London EC IN 8SU, the business MEETING OF THE TRADE LIAISON transacted included the election of the following: COMMITTEE At a meeting of the Trade Liaison Committee Fellowship held on 25 March 1993 at 27 Greville Street, Baiter, Jonathan, London. 1992. London EC IN 8SU, the business transacted included the election of the following: Ordinary Membership Booth, Diane, Cromer. Gold Laboratory Membership Branco, Rui Jose Portela Jorge, Viseu, Portugal. J. & B. Cousins & Sons Ltd., 8,9,9a Sun Street, Gangsted, Anne, Bangkok, Thailand. Canterbury, Kent. Keen, Paul, London. Graff Diamonds Ltd., 16 Greville Street, Hatton Pellas, Isabelle, London. Garden, London EC IN 8SQ. Schmid, Huldrych, Bachenbulach, Switzerland. Gruet, 52 Rue La Fayette, 75009-Paris, France. Tandjung-Teo, Liti M., London. King's Diamond Trading Company, Rm 701-5 Targiello, Barbara, Lublin, Poland. Lane Crawford House, 70 Queen's Road, Zanettin-Barbin, Fabrizia, Geneva, Switzerland. Central Hong Kong. Gold Laboratory Membership Ordinary Laboratory Membership Chatila & Sons Ltd, 22 Old Bond Street, Gold Arts, 7 Brighton Place, Brighton BN1 London W1X 3DA. 1HD. Ordinary Laboratory Membership MEETINGS OF THE COUNCIL OF Eugenios Petrides, GG, FGA, London NW3 MANAGEMENT 3AX. At a meeting of the Council of Management held on 21 April 1993 at Hancocks & Co., 1 CORRIGENDUM Burlington Gardens, London W1X 2HP, the On p. 353 above, the illustrations for Figures 29 business transacted included the election of the and 30 were transposed J. Gemm, 1993, 23, 7 441

Letters to the Editor

From Kurt Nassau, Hon. FGA duced a colour concentration layer at the surface. Were this to be the case, his process would no Dear Sir, longer be a heat or oxidation treatment but would I feel somewhat hesitant in submitting com­ become a surface diffusion process, with quite dif­ ments to no less than three of the articles in the ferent implications for disclosure. October 1992 issue of The Journal of Gemmology (Vol. 23, No. 4). Perhaps I can be excused this Yours etc., momentary excess in view of the many other Kurt Nassau issues where I have not had any comments at all! 21 December 1992 The determination of the ages of emeralds by Lebanon, NJ, USA. rubidium-strontium analysis (Vidal, Lasnier and Poirot, p. 198) is certainly an original way of dis­ From Jos Lurie tinguishing natural emeralds. If this test were to come into professional use, however, I believe that Dear Sir, it would not be too difficult to subvert. Emerald In regard to Dr Nassau's comments I wish to synthesizers could merely add controlled amounts reply as follows: of rubidium and strontium isotopes to their Dr Nassau is perfectly correct; having now care­ growth medium and so simulate any age desired fully consulted numerous works I acknowledge in their synthetic material! that in my paper 'quoin' should read 'vertex' in all In his otherwise excellent article on symmetrical cases. I regret the error but trust that my meaning polyhedra for gemstones (pp 207- 14), Lurie uses was clear. the correct term Vertex' interchangeably with the term 'quoin'. I have consulted several dictionaries Yours etc., and believe that 'quoin' is an incorrect usage. The Jos Lurie multivolume Oxford English Dictionary (1933 on to 9 March 1993 the most recent 1987 supplement), for example, School of Mines, Technikon Witwatersrand, defines 'quoin' as applying to the 'external angle of PO Box 3293, Johannesburg 2000. a wall or building' or to the 'internal angle or corner, as of a room' or an 'angle or an angular From Wang Chuanfu object', among other less relevant meanings. When an author employs an inappropriate usage Dear Sir, such as 'quoin' for 'vertex' ('an angular point, as of Many heat-treatment methods of sapphire have a triangle or polygon' in OED; plural Vertexes or been used for Chinese sapphires and many vari­ vertices), then he needs to supply justification for able factors such as temperature, time, such a usage lest he mislead others. atmosphere conditions, etc., were investigated. Finally, the author of the interesting article on Although heat-treatment method is very simple, it the electrolytic oxidation treatment of sapphires is not suitable for Chinese sapphire (containing (Wang Chuanfu, pp. 195-7) does not appear to be high content of Fe (l-5wt% Fe203)). Owing to familiar with the many variables applicable to sap­ the high content of Fe the absorption of Fe-Ti bi- phire heat treatments, such as temperature, time, particle is difficult to form a peak. and precise oxidation-reduction conditions. The Now this method has a great commercial value failure of his single attempt at heat treatment does and it is a pity that my paper only simply reports not demonstrate that his material could not be as above. changed to a desirable blue under more appropri­ ate conditions. His explanation for the observed Yours etc., colours in terms of simple Fe2+, Fe3+ and Ti3+ Wang Chuanfu absorptions also omits consideration of the most Vice Director important absorption, that of Fe-Ti charge trans­ General Research Institute for fer. Finally, he suggests that his electrolysis causes Non-Ferrous Metals, Beijing 100088, PR China. Ti to diffuse into the sapphire, without checking 15 March 1993 (or at least without reporting) whether this pro­ 442 J. Gemm, 1993, 23, 7

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FIRSFIRSTT FLOORFLOOR,, 2277 GREVILLGREVlllEE STREET,(SAFFRONSTREET;(SAFFRON HILHillL ENTRANCE)ENTRANCE),, LONDOLONDONN EClECl N 8SU8S U

TELEPHONETELEPHONE:: (071)(071140 4044 33343334 FAX:(071)404884FAX: (071 ) 404 88433

SYNTHETICSYNTHETIC INCLUSIONINCLUSIONSS ~ St. ~~, F.G.AFGA.. TRANSPARENCIETRANSPARENCIESS DealeDealerr iinn finefine,, rarraree anandd collectorscollectors'' gemstonesgemstones,, carvingcarvingss anandd mineraminerall (1(1)) 4400 slideslidess - SYNTHETISYNTHETICC EMERALDEMERALD specimensspeCImens.. (2(2)) 4400 slideslidess - SYNTHETISYNTHETICC CORUNDUMCORUNDUM SpecialisSpecialistt suppliesupplierr ooff jadejade,, fromfrom archaiarchaicc nephritnephritee ttoo imperiaimperiall jadeitejadeite.. ThesThesee setsetss includincludee exampleexampless from ththee followingfollowing producersproducers:: KYOCERA (INAMORI), RAMAURA,RAMAURA, ValuationValuationss ooff collectioncollectionss anandd ooff LENS (LENNIX),(LENNlX), LECHLEITNER, KNISCHKA, KNISCHKA, individuaindividuall itemitemss undertakenundertaken.. VACUUM VENTURES (REGENCY),(REGENCY), LINDE, LINDE, I wiswishh ttoo purchaspurchasee gegemm anandd mineraminerall USSR (VASAR), SEIKOSEIKO && others.others. collectionscollections,, engraveengravedd gemstonegemstoness (especiall(especiallyy intagliosintaglios)) anandd ololdd bookbookss EacEachh sesett £69.5£69.500 (incl(incl.. UUKK p&p)p&p).. oonn gegemm relaterelatedd subjectssubjects.. ChristopheChristopherr RR.. CaveyCavey,, F.G.A.F.G.A. SupplieSuppliedd iinn protectivprotectivee covercoverss plupluss explanatorexplanatoryy notesnotes.. OtheOtherr setsetss availablavailablee (syntheti(syntheticc & natural)natural).. UniUnitt 171777 GrayGrayss AntiquAntiquee MarketMarket 5588 DavieDaviess StreetStreet LondoLondonn WWIYl Y 1A1ARR College of THTHEE SQUARESQUARE,, FINDONANDON., ~ Collegeof W.SUSSEXW.SUSSEX., BNI4BNUOT OTFF v/ GemmologGemmologyy TelTel:: 09009033 8724021872731872402/872731 TelephoneTelephone:: 071-49071-4955 17417433 Notes for Contributors The Editors are glad to consider original is consistent with clear indication of the articles shedding new light on subjects of content of the paper. It should be followed by gemmological interest for publication in the the names (with initials) of the authors and by Journal. Articles are not normally accepted their addresses. A short abstract of 50-100 which have already been published elsewhere words should be provided. Papers may be of in English, and an article is accepted only on any length, but long papers of more than the understanding that (1) full information as 10 000 words (unless capable of division into to any previous publication (whether in parts or of exceptional importance) are English or another language) has been given, unlikely to be acceptable, whereas a short (2) it is not under consideration for publication paper of 400-500 words may achieve early elsewhere and (3) it will not be published publication. elsewhere without the consent of the Editors. Twenty fivecopie s of individual papers are Papers should be submitted in duplicate on provided on request free of charge; additional A4 paper. They should be typed with double copies may be supplied, but they must be line spacing with ample margins of at least ordered at first proof stage or earlier. 25mm all round. The title should be as brief as

ADVERTISING IN Rates per insertion, excluding THE JOURNAL OF VAT, are as follows: GEMMOLOGY Whole page £180 Half page £100 The Editors of the Journal invite Quarter page £60 advertisements from gemstone and mineral dealers, scientific Enquiries to Mrs M. Burland, instrument makers, publishers Advertising Manager, and others with interests in the Gemmological Association, gemmological, mineralogical, 27 Greville Street, lapidary and jewellery fields. London EC1N8SU. Volume 23 No. 7. July 1993

1116 Journal of Gemmology

Contents

Zircon: a study of material donated by Mr W.C. Buckingham from various localities (mainly Indo-China) Edinburgh Gemmological Group 387 Flux-grown synthetic rubies from Russia U. Henn and H. Bank 393 Notes from the Gem and Pearl Testing Laboratory, Bahrain -2 A Bubshait and N.P.G. Sturman 398 Emerald mineralization of Barang, Bajaur Agency, Pakistan 5.5. Hussain, M.N. Chaudhry and H. Dawood 402 Observations of red beryl crystals from the Wah Wah mountains, Utah M. Hosaka, K. Tubokawa, T. Hatushika and H. Yamashita 409 An examination of garnets from the Sinai Peninsula, Egypt R.C. Kammerling, J.I. Koivula and G.P. Galderon 412 Gemstone enhancement - detection of polymer-treated jadeite A. Hodgkinson 415 Microscopic estimation of refractive index using a dial test indicator and a personal equation T. Farrimond 418 Towards a mathematical gemmology. Thinking in terms of ratios makes a difference M.A. Schell 422 Gemmological Abstracts 427 Book Reviews 433 Proceedings of The Gemmological Association and Gem Testing Laboratory of Great Britain and Notices 436 Letters to the Editor 441 Copyright© 1993 The Gemmological Association and Gem Testing Laboratory of Great Britain Registered Office: Palladium House, 1-4 Argyll Street, London WlV IAD

ISSN: 0022-1252

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