Volume 21 / No. 3 / 1988

Volume 21 No.3 July 1988 TheJournal of Gemmology

GEMMOLOGICAL ASSOCIATION OF GREAT BRITAIN OFFICERS AND COUNCIL

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

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

^Members of the Executive Committee

Branch Chairmen: Midlands Branch: J. Leek, FGA North-West Branch: R. Perrett, FGA South Yorkshire & District Branch: G. A. Massie, FGA

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

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

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

VOLUME 21 NUMBER THREE JULY 1988

Cover Picture Boat-shaped etch figures on a first order prism face of a green beryl crystal from the Soviet Union. The c-axis runs in the long direction. Nomarski Differential Interference Contrast. 80x. (See 'Etch figures on beryl', p. 142) Photograph by John I. Koivula.

ISSN: 0022-1252 130 J. Gemm., 1988, 21, 3

Douglas Wheeler

It is with deep regret that we report the death on Saturday 7 May 1988 of Douglas Wheeler, former Assistant Secretary of the Gemmological Associa tion of Great Britain and Deputy Secretary of the National Association of Goldsmiths. Douglas was born on 15 May 1922 in East Ham, London, and joined the staff of the G A and NAG in 1936 at the age of 14. He served both associations continuously except for a period of five years in HM Forces. On his 19th birthday he volunteered for the RAF and after flying training in Canada saw active service in Europe. He was commissioned at 21. Douglas returned to civilian life in 1946 and rejoined the Associations, working alongside the late Gordon Andrews and his brother, the late Harry Wheeler, both of whom had also returned from the services. He studied at Chelsea Polytechnic as an evening class student and became an FGA in 1948. He was appointed Assistant Secretary for the G A in 1973 and Deputy Secretary of the NAG in 1976. Douglas retired from business in November 1983. He said at that time that he had greatly enjoyed his years with the two Associations and had been lucky in the people he had met and worked with. He looked forward to a new life of retirement in Norfolk. He leaves his wife, Kathleen, two sons, Michael and Stephen and grandchildren.

NotesNotes fromfrom thethe LaboratoryLaboratory - 1U2

Kenneth Scarratt, FGAFGA

TheThe GemGem TestingTesting LaboratoryLaboratory ofof GreatGreat Britain,Britain, 2727 GrevilleGreville Street,Street, London,London, ECINEC1N 8SU8SU

TheThe LennixLennix syntheticsynthetic emerald.emerald, 3nan updateupdate determinedetermine thethe SGsSGs ooff thesethese crystalscrystals a liquiliquidd waswas FamFarn firstfirst describeddescribed ththee LenniLennixx syntheticsynthetic emeremer mixedmixed inin whichwhich aann inclusioinclusionn frefreee anandd colourlesscolourless aldald inin 19801980 (Fam,(Farn, 1980)1980) followinfollowingg a giftgift in*197in 19799 ofof a quartzquartz waswas suspendedsuspended atat roomroom temperature.. WhenWhen numbenumberr ofof samplesample crystalscrystals toto ththee Laboratory.Laboratory. LittleLittle thethe LenniLennixx crystalscrystals werewere placeplacedd intointo ththee samesame liquidliquid hashas beebeenn seenseen ofof thithiss syntheticsynthetic inin ththee markemarkett sincesince withwith ththee quartzquartz 'marker''marker' eaceachh behavedbehaved inin thethe samesame Farn'Farn'ss firsfirstt reportreport,, however,however, lastlast yearyear a furtherfurther giftgift ooff wawayy aass thethe quartz,quartz, ie.i.e. atat roomroom temperaturetemperature theythey threethree crystalscrystals waswas madmadee toto thethe LaboratoryLaboratory byby werweree suspendedsuspended iinn ththee samesame position,position, asas ththee tempertemper SzemesSzemes AttHaAttila ofof Enterprise Fran~aiseFrançaise de de Fabrication Fabrication atureature waswas graduallgraduallyy raisedraised thetheyy slowlyslowly sanksank atat thethe D'emeraude de CullureCulture (Figure(Figure 1)1) andand anotheranother samesame ratratee asas andand withwith thethe quartzquartz markermarker,, anandd asas thethe descriptiondescription (Graziani,(Graziani, elet al., 1987)1987) waswas publishedpublished inin temperaturetemperature waswas loweredlowered theythey slowlyslowly floatedfloated toto thethe GemsGemsàf & Gemology.GemDlogy. surfacesurface atat thethe samesame ratratee andand withwith ththee quartzquartz marker.marker.

Fig.. 11.. LenniLennixx synthetisyntheticc emeralemeraldd crystals.. FigFig.. 22.. CrystaCrystall aggregateaggregatess anandd needle-likneedle-likee inclusioninclusionss iinn ththee LenniLcn nixx synthetisyntheticc emeraldemerald.. ThThee threthreee crystalcrystalss recentlrecentlyy donatedonatedd weigweighh 0.810.81,, ThiThiss indicateindicatess aann SSGG ooff 2.62.655 (somewha(somewhatt belobeloww ththee 0.710.71,, anandd 0.80.822 ctct,, ththee 0.80.811 cctstonet stone measurinmeasuringg 4.34-4.34- valuvaluee thathatt iiss normallnormallyy expecteexpectedd ooff a naturalnatural emerald)emerald) 5.65.666 x 2.82.844 mmmm.. AlAlll fluoresce reredd whewhenn irradiatedirradiated whicwhichh iiss alsalsoo consistenconsistentt witwithh ththee findingfindingss ooff bothboth witwithh eitheeitherr long-wavlong-wavee oorr short-wavshort-wavee ultravioleultraviolett rayrayss FarFaron (2.65(2.65)) anandd GrazianiGraziani,, et af.al. (2.65-2.66).(2.65-2.66). anandd alsalsoo X-rayX-rayss (diffractio(diffractionn tubetube,, MMoo targetargett aatt 4400 kkVV ThThee inclusioninclusionss anandd growtgrowthh featurefeaturess araree similasimilarr ttoo anandd 1155 mA)rnA).. FollowinFollowingg ththee slicinslicingg anandd polishinpolishingg ooff thosthosee ooff ththee originaoriginall 19719799 samplessamples,, iinn thathatt ththee ththee 0.80.811 cClt specimespecimenn refractivrefractivee indeindexx measurementsmeasurements LenniLennixx synthetisyntheticc emeralemeraldd iiss botbothh heavilheavilyy includeincludedd ooff 1.561-1.561.561-1.5655 werweree madmadee anandd thesthesee araree botbothh anandd zonedzoned.. AAss ononee hahass comcomee ttoo expecexpectt a synthetisyntheticc consistenconsistentt witwithh flufluxx growgrownn synthetisyntheticc emeraldemeraldss iinn emeralemeraldd ttoo bbee ooff a highighh qualitqualityy (a(att leasleastt iinn termteooss ooff generagenerall anandd similasimilarr ttoo thosthosee reportereportedd bbyy FarFaron clarityclarity)) ththee facetefacetedd LenniLennixx synthetisyntheticc emeralemeraldd poseposess (1.562-1.566(1.562-1. 566)) anandd GrazianiGraziani,, etal.er al. (1.559-1.562)(1.559-1. 562).. a threathreatt ttoo ththee over-confidentover-confident.. WheWhenn examineexaminedd iinn IIt t iiss ofteoftenn difficuldifficultt ttoo obtaiobtainn accurataccuratee resultresultss whewhenn ththee directiodirectionn alonalongg ththee c axiaxiss (Figur(Figuree 22)) a multitudmultitudee determinindetenniningg ththee SGSGss ooff stonestoness iinn ththee sizsizee rangrangee ooff ooff smal smalll crystacrystall aggregateaggregatess araree seeseenn whicwhichh araree similasimilarr thesthesee crystalcrystalss iiff ththee hydrostatihydrostaticc methomethodd iiss usedused.. TToo ttoo thosthosee describedescribedd bbyy FarFamn (Farn(Farn,, 19801980.. FigureFiguress 55

FACE B

Fig.Fig. 4.4. LineLine dr-dwingdrawing sshowinhowingg thethe directiondirection inin whichwhich thethe O.!l10.81 c[ct LennixLennix 'yotsyntheti heticc erneemeral raidd was sawnsawn (A(A) •an mld popolished Ii,hed. .

FigFig.. 33.. CrystaCry,[all aggregateaggregatess anantid zoninzoningg iinn ththee LenniLennixx synthetisynTheticc Fig.. 55.. ZoninZon ing g iinn ththee LenniLcnnixx synthetisy n t heticc emeralderne raid., emerald..

rigFig. . 66. . 'Tw'Twoo phase'inclusion phase' inclusionss i inn ththee LenniLennixx syntheti synihe(icc emeraldemerald.. FigFig.. 77.. 'Tw'Twoo phasepha,e'' anandd otheotherr needle-likneedle·likee inclusioninclusionss iinn ththee LenniLennixx synthetisyntheticc emeraldemerald. . J. Gernm., 1988,21,3 133

and 6) and a clearly visible zoned structure can be The filling of cavities and feathers in ruby observed within a limited area close to the edge of Rubies in which cavities have been filled with the crystal. This zoning running 'parallel' with the glass are no longer an uncommon sight in the outer shape of the crystal can be seen in Figure 3. Laboratory. However, upon sorting through a par Upon looking into these crystals one gains the cel of rubies recently wecame across two interesting impression that a large 'seed' is contained within. In forms of filling. The first was a plastic filling and order that this might be further investigated the was observed in several cabochon-cut rubies (Fi 0.81 ct specimen was sliced and polished in the gure 9) and the second was a fracture that had been direction indicated by Figure 4. Figure S is taken filled (at least partially) with glass (Figures 10 and through face 'B' of Figure 4, and this clearly reveals II). This latter type of infilling could be somewhat two distinct growth periods. The first characterized more difficult to detect than the 'normal' cavity by a layered colourless or near-colourless and green infilling as the finished product looks, at first area which forms the greater part of the crystal and glance, to be similar to a 'normal' feather. the second by an outerskin which is layered roughly Inclusions in heat treated corundwn parallel with the four sides of the crystal. As A heat treated sapphire recently submitted for observed with the crystals reported on in 1980, examination displayed, in transmitted light, the not these later crystals contain large two- and some uncommon sight of an altered guest mineral and times three-phase inclusions (some of which show a associated tension halo (Figure 12). In reflected distinct red colour), Figure 6. However, also con light though, this inclusion revealed its 'hi-tech' tained within the more recent crystals are multi origins by bearing a closeresemblance to a 'compact tudes of small needle-like inclusions, Figures 2 and disc' (Figure 13). 7. The absorption spectrum is typical of that to be The two penny pieces test expected from 'emerald: As can be seen in Figure 8, An interesting book was loaned to us recently by the Lennix synthetic emerald transmits ultraviolet R. J. Bridges, its title being, Familiar Lessons on down to 27S nm, Mineralogy and Geology. It is the 'twelfth edition' 24' •

Lennix synthetic emerald

0·41 I 275 Nanometres 850 Fig. 8. Absorption spectrum of Lennix synthetic emerald. The curve was obtained using a Pye Unieam PU 8800103 UV/visible spectrophotometer (Basil Anderson model) with a speed of I nm/s and a bandwidth of O. 5 nm at room temperature. The path length was 2.54 mm. 134 J. Gemm., 1988,21,3

Fig. 9. Plastic infill in a cabochon-cut ruby. Fig. 10. Partially glass-filled feather in a natural ruby.

Fig. 11. Partially glass-filled feather in a natural ruby.

Fig. 12. Altered inclusion and tension halo in a heat treated Fig. 13. Altered inclusion and tension halo in a heat treated sapphire, transmitted light. sapphire, reflected light. J. Gemm., 1988,21,3 135

and is dated 1830. There are a number of interesting 'tests' described (many of which cannot be recom mended today), one of which is described as follows '... if the substance be small, place it betwixt twopenny pieces, and strongly press them with the thumb and finger, when, if it is not a diamond, it will break and be reduced to powder;...' Apart from its intended use as currency, we have heard of many uses for the humble penny and now we have yet another.

ANICS, synthetically grown beryl During the International Gemmological Confer ence held in Brazil in September/October 1987, the author was given a group of four synthetic beryl crystals. They were given via Dr Miyata of the Fig. 14. ANICS synthetic beryl group. Institute of Gem & Jewellery Art, Kofu, Japan, by Naosuke Adachi of the manufacturing company, Adachi New Industrial Co. Ltd, of Osaka, Japan. The method of growth is by chemical vapour figures largely agree with those obtained on the deposition and the following types of material are specimens in Figure 14, although the SG obtained said to be produced: emerald, reddish beryl, sky on the violet/mauve sample was a little less, at blue beryl, pink beryl, violet beryl, yellowish-green approximately 2.64, than that quoted by the manu beryl, colourless beryl and watermelon beryl. It is facturer of 2.67, and the refractive indices of the reported (Yagi and Adachi, 1979) that the doping 'watermelon' specimen differed fractionally, at agents involved in producing these colours are: Co, 1.560-1.563, to those obtained by Koivula. The Mn, Ni, Cu, Nd, Ag, Ti, Fe, Ce, Cr and their colour in three of the specimens is clearly zoned and combinations. the most common inclusions are twisted 'veil-like' The four stones given are red, violet/mauve, sky feathers and diffuse clouds. blue, and 'watermelon' with a mauvish centre and green skin (Figure 14). The latter weighs 0.64 ct and 'Fluorolith' its dimensions are 7.7 x 3.5 x 2.8 mm. The Every now and then peculiar 'fashion stones' 'watermelon' type, which closely resembles tourma appear on the market such as the 'mood stones' of line, has been described by Koivula (1986) as about a decade ago. A short time ago we were given having a specific gravity of 2.66 and refractive the two stones in Figure 15 and were told that they indices of 1.559 and 1.564. The company give the were being marketed as 'fluorolith'. They are in mean refractive indices and specific gravity for each teresting in that they phosphoresce quite strongly type as: emerald 1.57 and 2.63-2.70, reddish 1.568 and for a considerable length of time, after exposure and 2.66, sky blue 1.575 and 2.67, pink 1.569 and to light. Figure 16 shows this green phosphoresc 2.66, and violet 1.573 and 2.67 respectively. These ence after exposure to an optical fibre light.

Fig. 15. Two cabochons of 'Fluorolith'. Fig. 16. The two cabochons of Figure 15 phosphorescing after exposure to light. 136 J. Gemm., 1988,21,3

Fig. 17. Kyocera synthetic blue sapphire. Fig. 21. Platinum wire and seed in the Kyocera synthetic emerald crystal of Figure 19.

Kyocera synthetics weighing 1.20 ct, had indices of 1.562-1.565. The The Laboratory has obtained through the UK SG for the emerald-cut stone was found to be 2.64 offices of the Kyocera Corporation an up-to-date and that of the crystal 2.66. Using a prism-type range of their synthetic stones. This includes: blue hand-held spectroscope, in all cases a strong chro sapphire, white and black 'opal', emerald, star ruby, mium spectrum was seen. Under long-wave ultra alexandrite and alexandrite cat's-eye (Figures 17, violet light the stone's fluorescence is a very weak 18, 19, and 20). orange-red or it is inert and under short-wave The emerald crystal seen in Figure 19 weighs ultraviolet the fluorescence is a dull or weak orange- 22.15 ct and measures 13.19 x 16.37 x 10.05 mm. red. When viewed through a Chelsea colour filter The seed is clearly visible in the crystal and a the stones appear a strong red and under an intense platinum wire can be seen looped through it (Figure light, such as that provided by the optical fibre type, 21). Twisted and veil-like feathers, typical of synth they glow a bright red (Figure 23). etic emeralds in general, are present within the The star ruby (Figure 20) is a nicely proportioned crystal, however, little in terms of the 'usual' oval cabochon of 1.42 ct which when observed with inclusions are present in one of the faceted stones. a prism-type hand-held spectroscope displays the This is a 1.22 ct emerald-cut stone measuring 7.01 x normal chromium spectrum for ruby. Its SG and RI 6.04 x 4.35 mm and those inclusions present consist (distant vision) are also within the range for corun of many needles (Figure 22) running parallel to the dum. The star is formed from a mass of silk-like optic axis - which is perpendicular to the table facet. inclusions (Figure 24) which in themselves could The refractive indices for this emerald-cut stone are prove deceptive but the 'smoky' or 'flame-like' 1.560-1.565 but another brilliant-cut stone structures so often seen in the surface areas of

Fig. 24. The silk-like inclusions responsible for the star effect Fig. 26. Zoning in a Kyocera synthetic alexandrite. in the Kyocera synthetic star ruby. J, Gemm., 1988,21,3 137

Kyocera Synthetic alexandrite

~ l'=!: j ...e rJ) ,.Q ~

001 I ]90 nanometres tI:lO~.

Fig. 15. Absorption spectrum of the synthetic alexandrite crystal. The curve was obtained using a Pye Unicam PU 8800/03 UV/visible spectrophotometer (Basil Andersom model) with a speed of I nm/s and a bandwidth of 0.5 nm at worn temperature. The path length was 6.5 mm. synthetic starcorundum give away the origin of this The faceted synthetic blue sapphire in Figure 17 material. has refractive indices of 1.760-1.768, but the colour Figure 18 shows the synthetic alexandrite and distribution of the uncut material is most distinctive synthetic alexandrite cars-eye produced by (Figures 28 and 29). Bubbles are also present. Kyocera. The uncut alexandrite specimen weighs The Kyocera opal product is similar in its 18.13 ct and measures 17.02 x 13.30 x 6.53 mm and structural characteristics to the Gilson material, i.e, the cabochon-cut eat's-eye weighs 0.97 ct. The a chicken wire or mesh-like structure is clearly refractive indices obtained from the round faceted visible in both the black and white material (see stone are 1.740-1.748, and the absorption spectrum Schmetzer and Henn, 1987). of the crystal is reproduced in Figure 25. The uncut synthetic alexandrite has easily visible growth structures which at first glance may appear [Q be 'curved lines: However, as the angle of view is Acknowledgements changed slightly, it can be seen [hat they are in fact It is with pleasure that the author acknowledges angular(Figure 26), and similar growth features can the assistance of all the members of staff at the Gem be seen in [he round faceted stone. The eat's-eye Testing Laboratory of Great Britain in compiling cabochon has a dear 'fibrous' structure (Figure 27) these 'Notes: In particular, S. 1. Kennedy, I. which is dissimilar to that seen in the natural Shenker and N. Sturman, provided much informa material (see Kane 1987). The uncut eat's-eye tion concerning the Kyocera synthetics. The fluoro material has similar structures but many bubbles lith was shown to us by E. A. Thomson Gems, who are present close to the surface. continue, as always, to provide the Laboratory with 138 J. Gemm., 1988,21,3

Fig. 18. Kyocera synthetic alexandrite and synthetic alexan Fig. 19. Kyocera synthetic emerald crystal. drite cat's eye.

Fig. 20. Kyocera synthetic star ruby. Fig. 22. Needle-like inclusions in the Kyocera synthetic emerald.

Fig. 23. Kyocera synthetic emerald glowing red in the light Fig. 27. 'Fibrous-type' structure in a Kyocera synthetic alex produced from an optical fibre light unit. andrite cat's-eye. J. Gemm., 1988,21,3 139

Fig. 28. Colour distribution in a Kyocera synthetic blue sap phire crystal. valuable information for which we are most grate ful. We owe a debt of thanks to Szemes Attila of Enterprise Française de Fabrication D'emeraude de Culture, for the Lennix synthetic emerald specimens and to Naosuke Adachi of Adachi New Industrial Co. Ltd, of Osaka, Japan for the ANICS synthetic beryl specimens and state further, that we wish some other manufacturers of synthetic gem mate rials could find their way to being as generous. Our thanks also go to R. J. Bridges for the loan of Fig. 29. Colour distribution in a Kyocera synthetic blue sap Familiar Lessons on Mineralogy and Geology. phire crystal.

References Schmetzer, K., Henn, U., 1987. Synthetic or imitation? An Farn, A. E., 1980. Notes from the Laboratory, Journal of investigation of the products of the Kyocera Corporation Gemmology, XVII, 2, 73-80. that show a Play of Colour, Gems & Gemology, 23, 3, 148-51. Graziani, G., Gübelin, E., Martini. M., 1987. The Lennix Yagi, I., Adachi, N., 1979. Syntheses of emerald and other synthetic emerald, Gems&Gems & Gemology, 23, 3, 140-7. colour varieties of beryl minerals. Journal of the Gemological Kane, R. E., 1987. Inamori synthetic cat's-eye alexandrite, Gems Society of Japan, 6, 3, 3 (67). & Gemology, 23, 3, 158-62. Koivula, J. 1986. Gem News, Gems& Gemology, 22, 1, 55. [Manuscript received 10 May 1988] 140 J. Gemm., 1988,21,3

The 10x lens

A.E. Farn, FGA

Seaford, East Sussex, BN25 3HP

It was not entirely inappropriate that the July/ In the old days our opposite number was the October Journal arrived on Remembrance Day, 11 Service Public du Contrôle des Diamants, Perles November 1988. I was encouraged by the editorial Fines, et Pierres Précieuses de la Chambre de which indicated that there was room for some Commerce et d'Industrie de Paris. We of course lighter material other than the 'meat'of the Journal's were The Laboratory of the Diamond, Pearl and highly scientific content which it quotes as 'tackling Precious Stone Trade Section of The London gemmological education at the frontiers'. I noted Chamber of Commerce. Mademoiselle Dina Level and was particularly warmed by the nostalgia is possibly one of the longest serving members of expressed in the Editorial for the Louis Kornitzer the Paris Laboratory. She started in 1929 and retired style of writing. Kornitzer certainly holds a special in July 1969 completing 40 years of service for place in the dealer/traveller world of gemstones. His which she received the Médaille d'or du Travail, the style reveals a deep appreciation and love of gem- gold medal of industry. She is also Présidente stones. He was, however, a man who earned his d'Honneur Association Française de Gemmologie living by buying and selling gems. Without this and an Honorary Fellow of The Gemmological commercial appreciation and profit motive our Association of Great Britain. She is now retired world of gemmology would be less well provided from the Paris Laboratory but not from the world of for. gemmology. In her earlier days she was a welcome Fortunately for students of gemmology stones visitor to our laboratory. We enjoyed her enthusias which are heavily included or indeed flawed are tic and truly gallic reactions to the luminescent relatively cheap and provide ideal material upon effects in the X-ray viewing chamber and other which to practise. optical phenomena. In these retirement days there is time for reflec At one time not many gemmologists had seen tion, retrospection and a reading of papers previous adequately displayed the fluted or 'organ pipe' ly published, plus periodicals to peruse. Having group of bright red lines in the spectrum of natural moved house and home several times recently in red spinel. When we demonstrated this effect to fairly rapid succession I am somewhat geared to Dina Level many years ago we used a small clearing out and generally reducing the accumula colourless glass bottle packed tight with hundreds tion of old papers, periodicals and the like. of tiny octahedral crystals of red spinel. A flask of When these occasions occur I start with deter copper sulphate solution served to cool and concen mination and enthusiasm to discard some of the trate the beam of light on to the microscope. The papers and books, but they all suddenly acquire spectroscope sat on top of an old brass microscope interest and importance. Very few are jettisoned, at used solely as a light gathering source. Basil Ander worst they are 'relegated'. My industry soon grinds son, well over six feet tall, looked comfortably down to a halt, held up by my immersion in an absorbing through the mounted spectroscope, but as Dina is article by Basil Anderson, or one of his informative petite, we stood her on a strong low stool for better yet entertaining letters. These 'pearls of wisdom', viewing. Success was achieved, but on viewing this evoke memories of the old days, the old lab and old extremely fascinating sight for her first time Dina friends. The Journal editorial, in like manner, nearly came over backwards with delighted reac directed my thoughts to one of the most delightful tion. She has a very genuine love and appreciation writers of the gemmological scene. Someone who for the many beautiful inclusions and optical effects revels in the structures of gemstones and who has seen in natural, synthetic and imitation stones. over many years explored the interiors of gemstones Mile Level has written many fascinating articles with a poetic eye. for the 'Revue française de gemmologie' in a lively

but learned manner. Her appearance on National Examination by progressive magnification with the Television literally swept audiences off their feet microscope revealed furrow-like scratches all over; with her exuberant enthusiasm for the hidden some appear to come from within. Polishing has cut beauties of gemstones. across and sectioned some furrows. Intersecting In a report of her talk on television, the writer lines in the interior have a star-like effect with clear uses as a heading Dina's own words, 'Pierre tu vas rounded green centres. The material is slightly me dire quelque chose' (gemstone you are going to translucent. The chevron or star effect is unlike that tell me something); quoting and translating loose of any natural material, or even purpurine glass. subtle nuances such as the intimate 'tu' for a gem. It Eventually an analysis proved it to be lead glass is difficult to convey the feeling expressed by Dina which was surprising considering its low refractive Level. These are the kind of papers which stop me index of 1.54. when I start to tidy up. They can be easily Where the high power of the microscope failed assimilated by readers who may enjoy a break from Mile Level succeeded - with a detailed examination the heavier 'meat', mentioned in the Journal's using a lOx lens. She was looking for 'the natural editorial. signature of the artificial' - a bubble. A lOx lens is In an article entitled 'Les Mystères de la Coupe more manoeuvrable than a microscope. Dina Level Verte, racine d'émeraude ou?' Mlle Level gives a found a small milky bubble typical of glass and then description of an oval green cup on show in the two more. She finishes her discussion and describes Louvre Museum, Paris. It is exhibited among the the deception afforded by the cup; it is no less 'Agates' of Monseigneur le Dauphin. It has an oval interesting because of the material, in itself rare, its bowl, baluster stem and oval foot, all three pieces manufacture unknown. She writes of the cup's own being of the same material. It has simple classic soliloquy, 'for a century and a half you have lines and has an overall lightly scratched appear described me as prime d'émeraude^ then prase (with ance. The foot and stem are ornamented by twisted reservations), then prase again. Almost a century enamelled cordons of gold. Three earlier inventor after, the year of grace 1973, is the year of my ies in 1723, 1791 and 1876 gave precise details but disgrace. What would Monseigneur le Dauphin failed to agree on the correct nature of the material. have said?' Dina Level apologises to the cup saying The first entry in 1723 stated, prime d'émeraude; this 'excuse me little cup for upsetting you; gemmology is old style French used wrongly for prase, fluor or thanks you for allowing the examination and the jade. According to M. J.P. Poirot, Director of the sight in your furbelows of those precious "pearls" - Paris Laboratory, Prime d'émeraude is untranslat your bubbles'. able. The second description in 1791 described the Mile Level writes of, and talks to gems; she cup as prase but with an interior crystallization not delves with delight into the world of moss, needles, yet determined. Both descriptions stated that the doubling, dichroism and shatter marks; she is poet, cup had been repaired (cassée et remastiquée). The enthusiast and scientist. As a respite from the third description of 1896 described the cup as prase heavier going, hers is the kind of gemmology that and attributed it to the reign of Henri IV, but made stops me in my tracks. no mention of included crystallization. Members of the Société Française de Gemmo- References logie were able to make a detailed examination of Level, D., 1973. Les mystères de la Coupe Verte, racine the cup and produced the following details. Softer d'émeraude prase ou? Revue de Gemmologie, 35, 8-9. than quartz, old conchoidal fractures, inert to ultra violet rays and inert through the Chelsea Filter. [Manuscript received 26 January 1988] 142 J. Gemm., 1988,21,3

Etch figures on beryl

John I. Koivula

Gemological Institute of America, 1660 Stewart Street, Santa Monica, California 90404, USA

If one closely examines the corroded looking Abstract surfaces of a solution-etched beryl crystal, the The surface features of several natural solution-etched apparently haphazard irregular appearance gives beryl crystals were photomicrographically way to a delightful array of geometric patterns documented using Nomarski Differential Interference known to mineralogists as etch figures. Contrast microscopy (Brightman, 1982). The observed These etch figures, decorating the surfaces of the etch figures are characteristic for the mineral beryl and can be useful in the identification of even badly corroded solution-attacked beryl, reflect the internal sym crystals. metry of the crystal's underlying structure. But the three-dimensional structural framework of beryl Solution etched beryl varies with direction in the crystal. So it follows that When examining rough crystals of the mineral crystal faces which are identical would display beryl it will be noticed that the condition of the similar etch figures. And, those etch features would individual faces on those crystals varies greatly be visibly different from the etch figures found on from crystal to crystal, and even from face to face on dissimilar faces. Therefore each facial plane (or the same crystal. While some entire crystals, or crystal form) on a solution-etched beryl would have separate faces on certain crystals, will appear to be its own set of characteristic etch figures. mirror smooth, others will be quite obviously pitted In his excellent book, Emerald and Other Beryls or corroded looking. This apparent corrosion, or (1981) John Sinkankas illustrates, through a series etching, is the result of dissolution or the dissolving of black-and-white line drawings, some of the away of previously formed crystal faces. possible etch figures that have been observed on the Dissolution is a term that can be applied to any various faces of beryl. He shows twenty two solution-etched crystal. Natural crystals, such as different figures for the prism faces alone. While beryl, that grow in solution, are always susceptible another eighteen drawings serve to show some of to solution etching or dissolution should the chemi the patterns that have been found and described on cal environment change sufficiently. the pyramidal and pinacoidal faces.

Fig. 1. Rectangular etch figures on a first order prism face of a Fig. 2. Triangular etch patterns on a first order bypyramid of a Brazilian aquamarine. Nomarski Differential Interfer Brazilian aquamarine Nomarski Differential Interfer ence Contrast. The c-axis runs in the long direction. ence Contrast. 80x. 80x.

Fig. 3. Shield-shaped etch figures on a second order bypyramid Fig. 4. Hexagonal solution cavities on the basal pinacoid of an of a Brazilian goshenite. Nomarski Differential In aquamarine from Brazil. The c-axis is perpendicular to terference Contrast. 80x. the image. Nomarski Differential Interference Con trast. 80x.

It would be beyond the scope of this article, and explore the dissolution hallmarks of beryl. the budget of most journals, to provide colour photomicrographs depicting all the etch figures References illustrated by Sinkankas in Emerald and Other Brightman, R. F., 1982. Surface Topography of gem crystals. Beryls. So only the most common etch figures Australian Gemmologist, 14, 11, 301-4. observed on the prism (Cover Photomicrograph and Sinkankas, J., 1981. Emerald and Other Beryls, Chilton Book Company, Radnor, Pennsylvania. Figure 1), pyramid (Figures 2 and 3) and pinacoid faces (Figure 4) are shown. It is hoped that these few colourful photomicro- graphic images will excite others to microscopically [Manuscript received 3 March 1988]

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Gemmological Association of Great Britain Saint Dunstan's House, Carey Lane, London EC2V 8AB Telephone: 01-726 4374 Fax: 01-726 4837 Cables: Geminst, London EC2 J.J. Gemra.Gemm.,, 1988,21,31988,21,3 145145

CharacterizatioCharacterizationn ofof RussiaRussiann hydrothermally-grownhydrothermally-grown synthetisyntheticc emeraldsemeralds

Dr Karl SchmelZerSchmelzer

InstitutInstitutee ofof MineralogMineralogyy andand PetrograpPetrographh , UniversityUniversity ofof HeidelbergHeidelberg,, WestWest GermanyGermany

AbstractAbstract chromium-vanadiumchromium-vanadium spectrumspectrum ofof emerald.emerald. BerylBeryl RussianRussian hydrothermally-growhydrothermally-grownn syntheticsynthetic emeraldsemeralds samplessamples ofof thisthis typetype revealreveal a pleochroispleochroismm ofof blueblue II|| Cc areare characterizedcharacterized witwithh respecrespectt toto chemicalchemical,, physical,physical, andand andand yellowish-greenyellowish-green ..LJ_ c,c, anandd emeraldsemeralds ofof thisthis spectroscopic properties,properties, growthgrowth structuresstructures and incluinclusions.particulaparticular r colourcolour originatingoriginating fromfrom Miku,Miku, Zambia,Zambia, sions. PhysicaPhysicall propertiesproperties sucsuchh aass specificspecific gravity,gravity, werweree first describedescribedd byby SchmetzerSchmetzer & BankBank (1980,(1980, refractiverefractive indices,indices, colourcolour anandd pleochroism,pleochroism, asas wellwell aass absorptionabsorption bandbandss iinn ththee visiblvisiblee andand infrareinfraredd regioregionn areare 1981).1981). InIn ththee paperpaper ooff ScarrauScarratt (1987),(1987), non-polarizednon-polarized causedcaused bbyy ththee extraordinaryextraordinary chemicalchemical compositiocompositionn ooff absorptionabsorption spectraspectra ooff twotwo samplessamples areare pictured,pictured, ththee samplessamples containingcontaining highighh amountsamounts ooff CrCrlO"2O3 , Fel2O03,3, whicwhichh werewere recordedrecorded atat anglesangles ofof 90°90° toto eacheach other,other, Ni2l 0O3 andand CuO.CuO. MicroscopiMicroscopicc featuresfeatures suchsuch asas growthgrowth butbut obliquobliquee toto thethe opticaloptical axiaxiss ooff ththee roughrough andand structuresstructures andand inclusioninclusionss areare duedue toto thethe experimentalexperimental facetefacetedd stone,stone, respectively.respectively. SomeSome extraordinaryextraordinary conditionsconditions ofof crystalcrystal growth.growth. InIn summary,summary, allall featurefeaturess ooff featurefeaturess ofof ththee spectraspectra areare mentioned,mentioned, butbut nono diagnosticdiagnostic valuevalue areare explainableexplainable withwith respecrespectt toto thethe explanationexplanation forfor thesthesee propertiesproperties coulcouldd bbee given.given. detailsdetails ofof synthesissynthesis applieappliedd toto thethe growtgrowthh procesprocesss ofof thisthis MicroscopicMicroscopic observationsobservations werweree describedescribedd inin allall exceptional typetype of of synthetic synthetic emerald emerald by by Russian Russian scien scientists. paperpaperss citecitedd aboveabove dealingdealing withwith informatioinformationn onon seedseed tists. AllAll propertiesproperties determinedeterminedd areare comparecomparedd withwith features ofof naturalnatural emeralds emeralds from from different different sources. sources. platesplates,, irregularirregular growtgrowthh structures,structures, reddishreddish- brownisbrownishh andand opaqueopaque plateletplateletss asas wellwell asas two-two- andand II.. IntroductionIntroduction three-phasthree-phasee inclusions.inclusions. SyntheticSynthetic emeraldsemeralds havhavee beenbeen manufacturedmanufactured iinn DuringDuring a systematicsystematic studystudy ofof absorptionabsorption spectraspectra RussiaRussia bbyy hydrothermalhydrothermal techniquestechniques sincesince 19619655 ofof naturaJ.natural anandd syntheticsynthetic emeralds,emeralds, thethe presentpresent (Emel(EmePyanov 'yanovaa et ai.,aL, 1965).1965). CommerciallyCommercially producedproduced authorauthor wawass ableable toto recordrecord ththee spectraspectra ooff somesome facetefacetedd samplessamples werewere firstfirst mentionementionedd inin gemmologemmolo- facetefacetedd samplessamples ofof RussiaRussiann syntheticsynthetic hydrothermhydrotherm gicagicall literaturliteraturee byby FryerFryer et al. (1983)(1983) andand KoivulaKoivula ally-growally-grownn crystalscrystals whichwhich werewere madmadee availableavailable asas a (1984(1984,, 1985).1985). ChemicaChemicall datdataa werweree publishedpublished byby loaloann fromfrom Prof.Prof. DrDr EE.. GiibelinGübelin ooff MeggenMeggen,, SwitzerSwitzer HofmannHofmann et al. (1985),(1985), GubelinGübelin (1986)(1986) andand LinLindd et lanlandd iinn DecemberDecember 1986.1986. ThThee firsfirstt spectroscopicspectroscopic aZ.al. (1987).(1987). IInn allall threthreee paperpaperss cited,cited, exceptionalexceptional highhigh resultsresults indicatedindicated thethe presencepresence ofof somesome absorptionabsorption iroironn contentscontents forfor berylberyl oror emeraldsemeralds betweebetweenn 3.073.07 bandsbands,, whicwhichh werewere notnot ablablee toto bbee assignedassigned ttoo thethe andand 5.325.32 wt. % Fez03Fe203 werewere mentionedmentioned.. IInn addition,addition, a knowknownn chromium,chromium, vanadiuvanadiumm anandd ironiron absorptionsabsorptions remarkablremarkablee nickenickell contentcontent ofof 0.620.62 wt. % NiNiOO waswas ofof emeraldemerald (d.(cf. LindLind etal.,et al., 1987;1987; Scarratt,Scarratt, 1987).1987). InIn founfoundd bbyy HofmanHofmannn etetal. al. (1985)(1985).. addition,addition, usingusing X-raX-rayy fluorescencfluorescencee analysis,analysis, tracestraces SpectroscopicSpectroscopic datadata werewere publishedpublished byby GubelinGübelin ofof nickenickell and,and, mosmostt surprisingly,surprisingly, coppercopper werewere foundfound (1986),(1986), LinLindd et al. (1987)(1987) andand ScarranScarratt (1987).(1987). TheThe ttoo bebe presentpresent.. FromFrom thesthesee preliminarpreliminaryy results,results, a firsfirstt authorauthor brieflybriefly mentionsmentions absorptioabsorptionn lineslines andand moremore comprehensivecomprehensive studystudy ooff chemical,chemical, physicalphysical absorptionabsorption bandbandss whichwhich araree typicatypicall forfor C~"Cr3+ inin andand spectroscopicspectroscopic propertiepropertiess asas wellwell asas microscopicmicroscopic beryl.beryl. InIn thethe paperpaper ofof LindLind et al. (1987)(1987),, thethe featuresfeatures ofof thisthis exceptionalexceptional typtypee ofof syntheticsynthetic emeremer absorptionabsorption bandbandss foundfound iinn thethe spectraspectra whichwhich werweree aldald was initiated.initiated. AllAll characteristicscharacteristics observedobserved areare inin recordedrecorded forfor severalseveral samplessamples ofof RussianRussian hydrohydro goodgood agreementagreement witwithh RussiaRussiann literatureliterature dealingdealing thermally-grownthermally-grown syntheticsynthetic emeraldsemeralds werweree assignedassigned withwith propertiepropertiess ooff hydrothermally-growhydrothermally-grownn syntheticsynthetic 3+ 3+ 2+ ttoo Cr3+,, FeH andand FeFel+ liganligandd fielfieldd transitionstransitions asas berylberyl dopeddoped withwith tracetracess ooff chromium,chromium, iron,iron, nickelnickel wellwell asas ttoo a FeFel+2+ /FeIFeH3+ charge-transfercharge-transfer absorption.absorption. andand copper.copper. InIn addition,addition, mosmostt observationsobservations areare InIn otherother wordswords,, thethe absorptionabsorption spectrumspectrum waswas interinter usefuluseful foforr determinativdeterminativee purposes,purposes, i.ei.e.. forfor a recogrecog pretedpreted ttoo bebe typicatypicall foforr emeraldsemeralds containingcontaining a nitionnition ofof samplessamples ofof unknownunknown originorigin asas wellwell asas forfor distinctdistinct aquamarineaquamarine componentcomponent inin additionaddition ttoo thethe distinctiodistinctionn ooff naturanamrall andand syntheticsynthetic emeralds.emeralds.

II. Materials and methods However, according to Russian literature, the com For the present study, 13 faceted samples of mercial production of hydrothermally-grown Russian hydrothermally-grown synthetic emeralds synthetic emerald, which was reduced to practice on were available for non-destructive investigations. jewellery plants in Sverdlovsk, Leningrad, Lvov Eleven square cut samples in the range of 0.35 to and Estonian (Lebedev, 1987), is performed at 0.52 ct in weight and about 4x5 mm in size (Figure Lvov, Ukraine, USSR (Godovikov et al, 1982). At 1) originally came to Europe as pre-shaped or cut present, hydrothermally-grown synthetic emerald samples via Hong Kong in 1986. One faceted is produced in limited amounts of nearly 1-2 kg a sample 0.88 ct in weight and 5 x 5.5 mm in size year on contract with private businessmen from the came to Great Britain in 1986 and was already USA and Canada. Only limited information about described by Scarratt (1987). Another cut sample properties of this commercially produced type of 2.34 ct in weight and 6.5 x 10 mm in size was given synthetic emerald is available to the present author to a private collector in 1979 during a visit to the from Russian literature (Godovikov et al, 1982; Institute of Geology and Geophysics, Siberian Granadchikova et al, 1983), but according to the

111

Fig. 1. Faceted Russian hydrothermally-grown synthetic emeralds. Size of samples approx. 4x5 mm {Photo by O. Medenbach, Bochum, West Germany). branch of the USSR Academy of Sciences, Novosi features of the material available for this study, birsk, USSR. growth conditions and properties of the Russian By scientists of this research institute, the com scientific research material and the commercial plete development of growth processes for hydro- Russian production are similar or almost identical. thermal synthesis of emeralds was undertaken and One important difference, i.e. the different mate complete descriptions of chemical, physical and rials used for autoclave walls, will be discussed later spectroscopic properties as well as growth struc in this article (cf. section IV). tures of this research material were published in the For the present study, all samples available were Russian language (Solntsev et al, 1976, 1978; Il'in spectroscopically examined in the range of about et al, 1980; Klyakhin, 1980; Lokhova et al, 1980; 11,500 to 32,500 cm * using a double-beam UV- Bukin^a/., 1980, 1981; Shatsky er a/., 1980, 1981; VIS spectrophotometer (Leitz-Unicam, model Klyakhin et al, 1981a,b; Solntsev, 1981a,b; SE 800). Five samples representing the complete Lebedev & Askhabov, 1984; Lebedev & Dokukin, variability of spectroscopic properties were selected 1984; Pugachev, 1984; Lebedev et al, 1986). for chemical analysis by electron microprobe ( ARL, J. Gemm., 1988,21,3 147

model SEMQ, used for main and trace elements) preparation of a KBr pressed disk for infrared and X-ray fluorescence techniques (Siemens, spectroscopy using a double-beam IR spec model SRS 300, used for trace elements). As trophotometer (Perkin-Elmer, model IR 180). internal reference materials, samples of synthetic emeralds grown by Chatham, Gilson and Lechleit- III. Results ner were included in the chemical study, and ///. / Chemical and physical properties of Russian fragments of the identical crystals were simul hydrothermally-grown synthetic emeralds taneously analyzed for colour causing trace ele Chemical data of Russian hydrothermally-grown ments by destructive techniques using inductively synthetic emeralds obtained by non-destructive coupled plasma atomic emission spectrometry (Per- techniques are presented in Tables 1 and 2. The kin-Elmer, model ICP 6000). For the determination analytical results indicate remarkably low values of of unit cell dimensions as well as for infrared MgO and Na20 compared with most sources of spectroscopy small amounts of powder were natural emeralds (Hänni 1981, 1982; Schrader, scraped from the girdle of one faceted stone. This 1983; Stockton, 1984), but surprisingly high, but powder was used in order to obtain an X-ray powder varying amounts of colour-causing trace elements diffraction pattern for the calculation of unit cell such as Cr203, Fe203, Ni203 and CuO (cf. Figure dimensions (Debye-Scherrer camera, diameter 2). The valence states and lattice positions of these 114.6 mm, FeKa radiation) as well as for the transition metal elements are determined by an

Table 1. Chemical and physical properties of Russian hydrothermally-grown synthetic emerald (sample a) Chemical properties Physical properties Chemical analysis Cations calculated Unit cell dimensions [Â] [wt.%] to Si=6 Lattice Site (refined from 20 d-values) CuO 0.10 Cu 0.007 1 ao 9.234(3) 1 tetrahedron BeO 13.58 Be 2>993 ) 3.000 Co 9.197(4)

MgO 0.04 Mg 0.005 "A Specific gravity [g/cm3] MnO <0.01 Mn A1203 16.05 Al 1.736 I dob, 2.69(1) V2O3 <0.01 V >2.021 octahedron dcalc. 2.703 Cr203 0.35 Cr 0.025 f 2 Fe203 3.00 Fe 0.207 1 Refractive indices 3 Ni203 0.72 Ni 0.048 J n0 1.580(1) Si02 65.38 Si 6.000 tetrahedron ne 1.573(1)

Li20 n.d. Li 0.x ~\ An 0.007 Na20 0.03 Na 0.005 I channel K20 0.03 K 0.004 [ 4 H20 0.98 H20 0.300J 2 100.26 n.d. not determined, but present according to infrared spectroscopy 1 calculated for 2 Be+Cu = 3.00 2 total iron as Fe203 3 total nickel as Ni203 4 calculated for H20 = 0.30

Crystal chemical formula:

(Cuo.oiBe2.99)(Mgo.oiAl1.74Cro.o3Feo.2iNio.o5)Si60i8(Lio.xNao.oiKo.oiH2Oo.3o) 148 J. Gemm., 1988,21,3

Table 2. Colour.causing trace elements in Russian hydrothermally-grown synthetic emeralds [ppm] Sample V Cr Fe Ni Cu e <100 2580 21700 3050 6760 d <100 4240 30100 2310 4240 c <100 2740 20300 4260 3470 b <100 4070 1%00 6100 1080 a <100 2400 21000 5100 800

assignment of absorption bands in the visible and (I1'in et al., 1980; Klyakhin et al., 198Ia,b; Shatsky ultraviolet area (compare section 111.3). According et al., 1981; Lebedev & Dokukin, 1984; Pugachev, to these data, copper was found in the divalent state 1984; Lebedev et al., 1986). replacing beryllium in tetrahedral sites. Chromium, The presence of distinct amounts of lithium in iron and nickel are found exclusively in the trivalent channel sites of the beryl lattice is derived indirectly state in octahedral aluminium sites. from infrared spectroscopical investigations in con The value for BeD was calculated according to nection with the low quantities of Na20, which crystal chemical principles as 1: Be + Cu = 3.00. were analytically determined by electron micro However, due [Q a possible presence of small probe analysis (cf. section IlIA). However, the amounts of lithium replacing beryllium in tetra quantitative amount of LilO in Russian synthetic hedral sites, the calculated BeD content is assumed emerald was unable to be determined by non to be an approximation only. destructive methods. The crystal chemical formula The presenceofwaterwas established by infrared of one specimen (sample a) reads (CUo.OJBel.W) spectroscopy (see section IlIA), and the total (M&J.oJ AIL74Cr003FCo.ll Nio.os)Si60Is(Lio.xN 30,0 I amount of water was calculated for a reasonable KO.OIH200'l0)' Samples of hydrothermally-grown value of 0.3 water ions in the formula unit, This synthetic beryl which are similar or almost identical value represents an average for hydrothermally. in chemical and physical properties were recently grown Russian beryl, which was found to contain described by Klyakhin et al. (198Ib) and Lebedev between 0.10 and 0.62 waterions in the formula unit et at. (1986). From the 13 faceted gemstones of Russian syn thetic emeralds investigated in the present study, 2 microscopic investigations revealed the presence of residues of colourless seed plates in six of the ~ e samples. Three of the synthetic emeralds were cut in a direction leaving the residue ofthe seed plate as 2 table facet ofthe stone (cf. Figure 6), and in three of the samples part of the seed plate was found to form ~ d 1 • 5,42 KeV the culet of the cut synthetic emerald (cf. Figure 7). CrK.. Thus, refractive indices of hydrothermally-grown 2, 6,41 KaV emeralds were obtainable from the table facets of 2 FeK iL ten samples using a standard Rayner refractometer, 3 _ Z03 K",V c • FeKn and the refractive indices of seed plates were ~ obtainable for three cut stones. Specific gravities of 4- 751 KeV - NiKj,. Russian synthetic hydrothermally-grown emeralds 2 were measured for those seven samples without 5- 804 KeV CuKiL residues ofseed plates. ~ b The results (Table 3) indicate a slight variability for optical data as well as for specific gravities ofthe 2 synthetic emerald material and constant values for the optical properties of seed plates. According to ~ a gemmological standard reference books, these values are within the range ofnatural emeralds from different localities. On the other hand, specific gravities and refractive indices of these Russian synthetic hydrothermal emeralds are found in the Fig. 2. Energy-dispersive X-ray l1uorescenGe spectra of colour causing trace elements (Cr, Fe, Ni, Cu) in samples (a) to upper part or even slightly above the range known (e) of Russian hydrurhermally-grown svrnhctic emer for synthetic emeralds with the exception of Lech ald, (d. Table Z), leitner synthetic emeralds (emerald-coated natural J. Gemm., 1988,21,3 149

Table 3. Range of refractive indices and specific gravities for Russian hydrothermally-grown synthetic emeralds

Synthetic emerald 3 nQ ne An d[g/cm ]* 1.580 1.573 0.006 2.68 to 1.586 to 1.579 to 0.007 to 2.70

*for samples without seed plate

Seed plate 3 nQ ne An d[g/cm ] 1.571 1.565 0.006 not available beryl cores). The values were also found to be The amounts of colour-causing trace elements in distinctively higher than Russian flux-grown synth Russian hydrothermally-grown synthetic emeralds etic emeralds (cf. Koivula & Keller, 1985). also exceed the range which is generally found in In general, in natural and synthetic beryl and natural emeralds from different localities. Accord emerald, increasing amounts of alkali metal oxides ing to these data alone, the refractive indices of the such as Li20, Na20, K20, Rb20, and Cs20 (with Russian material should also exceed the values of Li+ in tetrahedral Be sites as well as in channel sites, natural emeralds. On the other hand, most natural and all other alkalis located in channel sites of the emeralds reveal higher amounts of MgO and alkali beryl structure), as well as increasing amounts of metal oxides (especially Na20 contents) than the MgO and transition metal oxides such as V203, samples described in this paper. In general, an Cr203, MnO, FeO, Fe203, CoO, Co203, NiO, increase of alkali metal contents in natural and Ni203, CuO (located in octahedral and/or tetra synthetic emeralds is responsible for an increase of hedral sites of the beryl structure) cause increasing refractive indices. Thus, in Russian hydrotherm values of unit cell dimensions (especially of a0, ally-grown synthetic emeralds, the influence of high dependent on replacements of octahedral sites, and amounts of colour-causing transition metal oxides is of c0, dependent on replacements of tetrahedral partly compensated by the low contents of MgO sites), refractive indices and specific gravities (Pav and alkali metal oxides. Regarding these facts, lova, 1963; Bakakin et al, 1967, 1970; Filho et al, refractive indices and specific gravities in the range 1973; Cerny & Hawthorne, 1976; Solntsev et al, of natural emeralds become understandable. 1976; Rodionov & Pavlyuchenko, 1980; Bukin et The unit cell dimensions of Russian synthetic al, 1980; Klyakhin et al, 1981a,b; Shatsky et al, hydrothermally-grown emeralds (Table 1) are found 1981; Franz, 1982; Pugachev, 1984; Lebedev et al, to lie within the range of natural beryls as well as 1986; Deer et al, 1986). within the range of hydrothermally-grown samples Increasing amounts of transition metal elements described in Russian literature, which contain in general are responsible for increasing refractive transition metal oxides between 2.0 and 5.0 wt.% in indices and specific gravities in synthetic emerald. octahedral aluminium sites and lower lithium and/ The differences in physical properties of Russian or copper contents in tetrahedral beryllium sites synthetic hydrothermal emeralds compared with (Bakakin et al, 1967, 1970; Filho et al, 1973; other synthetic emeralds of various producers are Solntsev et al, 1976; Il'in et al, 1980; Bukin et al, due to the high amounts of colour-causing trace 1980; Klyakhin^a/., 1981a,b; Shatsky étal, 1981; elements such as Cr, Fe, Ni, and Cu in the Russian Franz, 1982; Pugachev, 1984; Lebedev étal, 1986). material (compare section III. 3), which exceed the Samples of this type of natural and synthetic beryl, amounts of transition metal elements found in other in which octahedral replacement of Al3+ is domi flux-grown or hydrothermally-grown synthetic nant over tetrahedral replacement of Be2+ are called emeralds. An exception is observed for Lechleitner o-beryls (Bakakin et al, 1967, 1970). synthetic emeralds (emerald-coated beryl seeds) All samples investigated were inert to long- and with extraordinarily high refractive indices. The short-wave ultraviolet radiation. This result is thin overgrowth of this synthetic emerald may understandable in view of the high concentrations contain up to 10.01 wt.% Cr203 causing refractive of iron in the synthetic material, which is responsi indices up to n0 1.610, ne 1.601 (Schmetzer et al, ble for the quenching of chromium fluorescence. 1981a,b). ISO J. Gemm., 1988,21,3 WAVELENGTH ( nm l 350 400 500 600 700

------?----- 3 9 11",8 6 J ~ ' ...., I , I I ... 20 I I " e " " " 5

11 ~8 6 - ... 2 " '"'\ ,,~ I ... .. ,, I " 17 I 20 18_ 16 I , 7, I /3 - " I I I "

., ,, 3 , ,

...... b ~ lJ.J /6 ~ 119 tJ 131.. -' '8 <: \

30 25 20 15 WAVENUMBER (1000 em -1) --. -- --._1/c ---lc

Fig. 3. Polarized absorption spectra of natural emeralds from different sources; sample (a) from Chivor, Colombia, representing a typical chromium-vanad iurn emera ld spectrum withou t dislin ct Fe absorption bands; sam ple (b) from Jos, Nigeria, repre senting a typical ch romiurn-vanad iurn emerald spec trum with an FeH absorp tion band in the near infrared (polarizarion d; c) and two Fe!" bands in the bluish-violet and ultraviolet; sample (c) from Ankadilalana, Madagascar, sample (d) from Sta, Terezinba de Goias, Brazil, and sample (e) from Miku, Zambia, representing the superimposed spectra of chromium-vanadium emerald and aquamarine in various intensity ratios (the aquamarine spectrum consisting of tWO FeH absorption bands in the near infrared [polarization II and ..L c], two Fe!" bands in tbe blueish-violet and ultra violet, and an FeH/FeH intervalence transi tion in the red area [polari zation II cll; the positions of absorprion minirna and pleochroism of the samples are given in Table 4, the positions and assignmems of absorption maxima are given in Table S. J. Gemm., 1988,21,3 151

III.2 Absorption spectroscopy and colour of natural ultraviolet range (maximum I at 23,500 cm1, || c > and synthetic emeralds _L c; and maximum II at 27,000 cm1, _l_c ^> || c) In gemmological nomenclature it is generally are assigned to Fe3+ replacing Al3+ in octahedral accepted that emerald is the green variety of beryl, coordination. A broad absorption band in the red the colour of which is caused by traces of chromium area (from 16,700 to 13,300 cm"l, || c) is assigned to a or by traces of vanadium and chromium. In natural Fe2+/Fe3+ charge-transfer process. This inter- and synthetic beryl, the two spin-allowed strong valence transfer absorption in the red is not absorption bands of Cr3+ in octahedral Al3+ sites observed in samples revealing distinct absorption are located in the red and blue range of the visible bands of Fe3+ in the bluish-violet (at 23,500 cm"1) region. The two spin-allowed strong absorption and ultraviolet (at 27,000 cm"1) range and the Fe2+ bands of V3+ in octahedral sites of the beryl absorption with polarization _L c (at 12,200 cm"1) structure reveal similar absorption maxima (Wood in the near infrared. However, in all samples which & Nassau, 1968; Beckwith & Troup, 1973) and, show an additional absorption of Fe2+ with polari thus, in samples bearing both transition metal zation || c (at 12,000 cm"1) in the near infrared, the elements, chromium and vanadium, the absorption Fe2+/Fe3+ charge-transfer absorption in the red is bands of Cr3+ and V3+ are superimposed and no also observable. This absorption band is respon separated absorption maxima are observable sible for the blue colour of aquamarine. (Schmetzer, 1982). In the most recent papers of Solntsev et al. (1984, Natural emeralds from most sources show dis 1985), the band with polarization _l_ c (at 12,200 tinct amounts of both colour-causing trace ele cm"1) is assigned to Fe2+ in tetrahedral Be2+ sites ments, chromium and vanadium, and in samples and the 12,000 cm"1 band with polarization from some localities, e.g. in some emeralds from || c is assigned to Fe2+ in octahedral Al3+ sites. Muzo, Colombia, the amount of V203 even exceeds Consequently, the charge-transfer absorption in the 1 the amount of Cr203 (e.g. Nassau & Jackson, 1970; red between 16,700 and 13,300 cm" with polariza Franz, 1982). But in general, the intensities of both tion || c is assigned to a Fe2+/Fe3+ in ter valence absorption bands of Cr3+ in the red and blue areas absorption within Fe2+ and Fe3+ ions, both located are increased due to the presence of V3+. Only one in adjacent octahedral sites of the beryl structure. commercially interesting source of vanadium- In natural emeralds from different sources, all bearing, chromium-free green beryl is known (Sali- types of iron absorption bands which are known in ninha, Bahia, Brazil), and some samples of a similar colourless to intense blue beryls are also observable. type were also described from other localities (e.g. In samples from some localities, e.g. in part of from Kenya; cf. Schmetzer, 1982; Ghera & Lucch- natural emeralds from Colombia or Pakistan, no esi, 1987). For samples of this type of green beryl, absorption bands of ferrous or ferric iron are their acceptance as emerald in gemmological observable by spectroscopic investigations (Figure nomenclature is still in discussion. 3a). The pleochroism of these samples is described In synthetic emeralds which are commercially as green or slightly bluish-green || c and yellowish- produced, in general the amount of chromium green J_ c, absorption maxima are given in Table 4. exceeds the amount of vanadium, but samples with Natural emeralds from other localities, e.g. some V203 > Cr203 were also described in literature (e.g. samples from Jos, Nigeria; Sandawana, Zimbabwe; Biron synthetic emeralds; Kane & Liddicoat, Lake Manyara, Tanzania; Itabira, Brazil or Ural 1985). Mountains, USSR, reveal the presence of a domi In natural and synthetic iron-bearing beryl, three nant absorption band of Fe2+ in the infrared at basic types of spectra are observed, which are 12,200 cm"1 with polarization _L c and two strong assigned to three types of iron in the beryl lattice. absorption bands of Fe3+ in the bluish-violet and Though different authors came to various models ultraviolet area at 23,500 and 27,000 cm"1 (Figure for the assignment of iron absorption bands in beryl 3b). Both types of iron do not influence the visible (e.g. Wood & Nassau, 1968; Samoilovich et al., part of the absorption spectrum and, thus, do not 1971; Schmetzer et al., 1974; Price et al., 1976; influence or change the chromium-vanadium col Parkin et ai, 1977; Goldman et al., 1978; Platonov our and pleochroism of the samples (cf. Table 4). In et al., 1978, 1979; Blak et al., 1982; Solntsev et al., these emeralds, an absorption of Fe2+ in the 1984,1985), the positions of absorption maxima are infrared with polarization || c is not observable or is not in discussion. found to be very weak in intensity, and no inter- 2+ 3+ In general, two absorption maxima in the near valence transfer absorption of Fe /Fe in the red infrared (maximum I at 12,000 cm"1 || c, and area with polarization || c is present. maximum II at 12,200 cm"1 _L c) are assigned to In a third type of natural emerald, variable bivalent iron in two different lattice sites. Two amounts of bivalent iron are present in two sites absorption bands in the bluish-violet and the (tetrahedral and octahedral) and trivalent iron is 152152 J.J. Gemm.,Gemm., 1988,1988,21, 21, 3

TableTable 4.4. ExamplesExamples forfor absorptionabsorption minimaminima inin ththee visiblevisible rangrangee andand pleochroismpleochroism ofof naturanaturall emeraldsemeralds asas weUwell asas RussiaRussiann hydrothermaUy-grownhydrothermally-grown syntheticsynthetic emeraldsemeralds

NNatura alUrall emeraldsemeralds LocalityLocality!/ PleochroismPleochroism PositioPositionn ofof absorptioabsorptionn minimaminima SpectrumSpectrum l l samplesample ic\\c _L_...L Cc ic[cm-I]\\c[cm~ ] [run][nm] ...LJ_c[c c[em-I]m ] [run][nm] Miku,Miku, ZambiaZambia (e)(e) blubluee yellowishyellowish-- 20,60020,600 484855 19,80019,800 505505 FigFig.3e. 3e greegreenn Sta.S ta. TerezinhaTerezinha dede blubluee yellowishyel1owish-- 20,40020,400 490490 19,70019,700 508508 FigFig.. 3d3d Goias,Goiâs, BrazilBrazil (d)(d) greegreenn Ankadilalana,Ankadilalana, blueblue yellowishyellowish-- 20,40020,400 490490 19,70019,700 508508 FigFig.3c. 3c MadagascarMadagascar (c)(c) greegreenn jos,Jos, NigeriNigeriaa (b)(b) bluishbluish-- yellowish-yellowish- 20,10020,100 494988 19,90019,900 503503 FigFig.3b. 3b greengreen greengreen Chivor,Chivor, ColombiaColombia (a)(a) bluish-bluish- yellowishyel1owish-- 20,00020,000 500500 19,80019,800 505505 FigFig.3a. 3a greengreen gree greenn

RussianRussian hydrothermally-growhydrothermally-grownn syntheticsynthetic emeraldsemeralds PleochroismPleochroism PositioPositionn ooff absorptioabsorptionn minimminimaa SpectrumSpectrum l _1 SampleSample lie\\c ...L_i_ cC Ilc[cm-||c[cm~']] [nm[run]] ...L_Lc[cm c[cm-I]] [nm][nm] _ (e) blubluee yellow-yellow- 20,4020,4000 494900 19,90019,900 503503 Fig.4eFig. 4e greengreen (d(d)) blubluee yellow-yellow- 20,30020,300 494933 19,90019,900 503503 Fig.4dFig. 4d greengreen (c(c)) blueblue yellow-yellow- 20,3020,3000 493493 19,80019,800 505505 Fig.4cFig. 4c greengreen (b(b)) greenish-greenish- yellow-yellow- 20,2020,2000 494955 19,80019,800 505505 Fig.4bFig. 4b blubluee greengreen (a(a)) greenish-greenish- yellow-yellow- 20,2020,2000 494955 19,80019,800 505505 Fig.4aFig. 4a blueblue greengreen presenpresentt inin octahedraoctahedrall sitessites (Figure(Figure 3c,d,e)3c,d,e).. TheseThese chromium-vanadiumchromium-vanadium (emerald)(emerald) component,component, werewere emeraldemeraldss reveareveall a completecomplete absorptionabsorption spectrumspectrum ofof foundfound byby thmee presenpresentt authorauthor inin additionaladditional samplessamples aquamarinaquamarinee consistingconsisting ofof twotwo Fe2+-Fe2+ bandsbands iinn thethe fromfrom differentdifferent sources,sources, e.g.e.g. inin emeraldsemeralds frofromm SantaSanta infrareinfraredd (at(at 12,00012,000 emcm -1I,, polarizatiopolarizationn n|| c,c, andand atat Terezinha,Terezinha, CarnaibaCarnaiba,, habiraItabira andand SocotD,Socotö, Brazil;Brazil; 12,20012,200 emcm -I,-1, polarizationpolarization ...L_l_ c),c), twotwo Fe3 + bandsbands inin Ankadilalana,Ankadilalana, MadagascarMadagascar;; LakLakee ManyaraManyara,, TanzaTanza ththee bluish-violetbluish-violet andand ultravioletultraviolet (at(at 23,50023,500 andand nia;nia; Gravelotte,Gravelotte, SouthSouth AfricaAfrica;; Habachtal,Habachtal, Austria;Austria; 27,00027,000 em-I)cm-1) aass wellwell asas a FeH/FeFe2+/FeH3+ intervalenceintervalence MariaMaria MineMine,, Mozambique;Mozambique; Machingwe,Machingwe, ZimZim transfetransferr absorptionabsorption bandband iinn ththee redred (between(between 16,70016,700 babwebabwe.. TheThe pleochroismpleochroism ooff thesthesee samplessamples variesvaries andand 13,30013,300 emcm --1I;; polarizationpolarization lie).|| c). LikLikee iinn naturalnatural accordingaccording ttoo ththee intensityintensity ratioratio ofof thethe aquamarineaquamarine aquamarinesaquamarines,, thmee amountsamounts ofof allall thesethese typetypess ofof andand emeraldemerald componentscomponents (Figure(Figure 4c,d,e)4c,d,e) fromfrom ferrouferrouss anandd ferricferric ironiron mamayy bebe variablevariable,, andand thusthus thethe bluishcgreenbluish-green ttoo greenish-blugreenish-bluee andand blueblue II|| cc,, withwith 22+ 3+ H2+ 3 + Fe +,, Fe + andand Fe /FeIFe + absorptionabsorption bandbandss areare yellowish-green...Lyellowish-green _L c (cf.(cf. TableTable 4)4).. founfoundd toto varyvary iinn intensity,intensity, too.too. IInn commerciallcommerciallyy availableavailable syntheticsynthetic emeraldsemeralds ThiThiss completecomplete aquamarinaquamarinee spectruspectrumm isis superimsuperim fromfrom differentdifferent producerproducerss withwith thethe exceptioexceptionn ofof poseposedd onon ththee ordinaryordinary chromium-vanadiumchromium-vanadium specspec LechleitneLechleitnerr syntheticsynthetic emeraldemeraldss (emerald-coated(emerald-coated trutrumm ofof emerald,emerald, causingcausing a distincdistinctt shiftshift ofof thethe colourlesscolourless naturalnatural iron-bearingiron-bearing beryberyll seeds),seeds), nono absorptioabsorptionn minimuminimumm inin ththee spectrumspectrum |II| cc fromfrom greengreen absorptionabsorption bandsbands ofof bivalenbivalentt iroironn inin thethe infraredinfrared ttoo bluish-greenbluish-green,, greenish-blugreenish-bluee oror blueblue,, ie.i.e. towardstowards withwith polarizationpolarization II|| or...Lor J_ c areare foundfound toto bbee superimsuperim highehigherr wavwavee numbernumberss (lower(lower wavelengths;wavelengths; cf.cf. TableTable posedposed ttoo thethe chromium-vanadiumchromium-vanadium emeralemeraldd specspec 4).4). ThisThis principleprinciple wawass firstfirst describeddescribed foforr emeraldsemeralds trum.trum. InIn RussianRussian anandd GilsonGilson flux-grownflux-grown syntheticsynthetic frofromm ZambiZambiaa withwith a strongstrong aquamarineaquamarine andand a weakweak emeralds,emeralds, absorptionabsorption bandsbands ofof FeH3 + araree founfoundd iinn thethe emeralemeraldd component,component, revealingrevealing a pleochroismpleochroism ofof bluish-violebluish-violett anandd ultravioletultraviolet range.range. AccordingAccording toto blubluee |II| c andand yellowish-greeyellowish-green...Ln _l_ c (Tabl(Tablee 4)4).. MeanMean NassaNassauu (1980)(1980),, thisthis typetype ooff iron-beariniron-bearingg syntheticsynthetic whilewhile,, similarsimilar typestypes ofof absorptionabsorption spectraspectra consistingconsisting emeraldemerald wawass producedproduced byby GilsonGilson forfor a shortshort periodperiod ofof anan aquamarineaquamarine componentcomponent asas wellwell aass ofof a ofof time.time. ConsequentlyConsequently,, ththee presencpresencee ofof ironiron bandsbands J.Gemm., 1988,21,3 153 WAVELENGTH l nm l 350 400 500 600 700

/1" I e I I I I 6' I 8/ ,."~'}i...... 11 9r d / " ...~ "

" I'~ I I ,'C ,I ,I 6, 98 ...... 1"_J 11

,<21/9 r ~ .... " I\ I /] , 8 lJ.J I \ (j I I ~ I \6 a "'C r l~ en I I a: I \ o \ V) --- CO "'C

30 25 20 15 WAVENUMBER floOD em -1) ------lIc ---lc

Fig, 4. Polarized absorption spectra of samples (a) 10 (e) of Russian hydrothermally-grown synthetic emeralds; the spectra reveal a superimposition of absorption bands of Cr ' +, Fe", and Ni" in octahedral site' and Cu" in tetrahedral sites, all four colour-causing trace elements being present in variable amounts in different samples (for analytical data d. Table 2); the positions of absorption minima and pleochroism of the sarnples are given in Table 4, the positions and assignments of absorption maxirna are given in Table 5. The orientation of the c-axis of sample (d) versus the facets of the cut stone was very unfavourable in order to obtain polarized spectra of good quality; only in this special Casespectrum ---- represents a condition with polarization II c > polarization.L c, and spectrum--represents a condition with polarization...L c > polarization II c. 154 J. Gemm., 1988,21,3

Table 5. Spectroscopic data of natural emeralds and Russian hydrothermally-grown synthetic emeralds

Position of absorption maxima Polarization Assignment Designation natural emeralds synthetic emeralds of absorption in Figs. [cm"1] [nm] [[cm1] [nm] bands 3 and 4 10,900* 917* He Cu2+tetr. 1 12,000 833 \\c Fe2+oct. 2 12,200 820 -L.C Fe2+tetr. 3 13,300 752 J_c Cu2+tetr. 4 13,300- 752-599 \\c Fe2+/Fe3+ 5 16,700 14,600 685 14,600 685 ||c Cr3+oct. 6 14,700 680 14,700 680 J_c Cr3 + oct. 7 15,100 662 15,100 662 \\c Cr3+oct. 8 15,500 645 15,500 645 ||c Cr3 + oct. 9 15,700 637 15,700 637 J_c Cr3 + oct. 10 15,900 629 15,900 629 \\c Cr3 + oct. 11 16,500 606 \\c Ni3+oct. 12 16,600 602 16,600 602 _Lc Cr3 + oct. 13 16,800 595 ||c Ni3+oct. 14 22,000 555 _i_c Ni3 + oct. 15 23,200 431 23,200 431 _Lc Cr3 + oct. 16 23,500 426 23,500 426 ||c>_Lc Fe3 + oct. 17 23,800 420 23,800 420 ||c Cr3 + oct. 18 24,200 413 _Lc Ni3+oct. 19 27,000 370 27,000 370 J_c^>||c Fe3+oct. 20

*after Solntsev (1981a,b), Lebedevera/. (1986) assigned to bivalent iron or to bivalent as well as with yellow-green or greenish-yellow J_ c (Table 4). trivalent iron in an emerald sample of questionable The absorption spectra of all samples consist of origin is sufficient to prove the stone as natural several absorption bands in the infrared, visible and emerald. ultraviolet range (Figure 4a-e) which are assigned to Though nickel was determined in natural emer Cr3+, Fe3+ and Ni3+ in octahedral sites and to Cu2+ alds from Cobra mine, Transvaal, South Africa, in in tetrahedral sites (Table 5). These assignments are concentrations up to 0.025 wt.% (Schrader, 1983), based on the known positions of Cr3+ and Fe3+ nickel absorption bands (for the position of absorp absorption bands (e.g. Wood & Nassau, 1968; tion maxima confer Table 5) were found neither in Solntsev, 1981a, Klyakhin et al., 1981b) and on the the spectra of samples from Cobra mine nor in positions of Ni3+ and Cu2+ absorption bands as spectra of emeralds from other localities. Thus, the published in the most recent Russian literature influence of nickel on the colour of natural emeralds (Solntsev, 1981a,b; Klyakhin etal, 1981b; Lebedev of known sources is negligible. et al, 1986).

1113 Absorption spectroscopy and colour of Russian Only in some older papers, the nickel doublet at hydrothermally-grown synthetic emeralds 16,500 and 16,800 cm'1 (polarization || c) is assigned According to chemical data (section III. 1 ; Tables to Ni2+ (Solntsev et al, 1978; Fin et al, 1980; 1, 2; Figure 2), samples of Russian hydrothermally- Bukin et al, 1981), but in the samples investigated grown synthetic emeralds investigated in this paper in the present paper no further spectroscopic contain variable but high amounts of four colour- criteria for the presence of Ni2+ were found. These causing transition elements: chromium, iron, nickel data support the assignment of this doublet to Ni3+ and copper. As described in section III.2 in detail, as published in the most recent Russian publica natural emeralds, in general, contain traces of tions. Obviously, under the oxygen partial pressures vanadium, chromium and, in most instances, iron. used for hydrothermal synthesis of emerald by The pleochroism of Russian hydrothermal syn Russian scientists, iron, nickel and chromium ions thetic emeralds varies from greenish-blue to blue || c, predominantly substitute Al3+ in octahedral sites as J. Gemm., 1988,21,3 155

Fe3+, Ni3+ and Cr3+ and copper is found to replace not influence the visible part of the absorption Be2+ in tetrahedral sites as Cu2+. Consequently, spectrum and the colour of the crystals (cf. Figure only subordinate amounts of Fe2+, Ni2+ and Cu+ 4a,b). With increasing copper contents, a distinct ions are assumed to be incorporated into the beryl influence on the visible part of the absorption structure during crystal growth (cf. Klyakhin et al., spectra becomes evident (Figure 4c,d,e), especially 1981b). in polarization _L_ c. The influence of copper, how Non-polarized absorption spectra of hydro- ever, does not distinctly shift absorption minima in thermally-grown Russian synthetic emeralds and the yellow to blue range (cf. Table 4) and thus, the the pleochroism of these beryls are similar with influence of copper on the colour of Russian spectra and pleochroism of natural emeralds reveal chromium- and nickel-bearing synthetic beryls is ing a chromium-vanadium (emerald) and aquamar subordinate. The absorption band of Fe3+ in the ine component. Due to these similarities overlook bluish-violet area at 23,500 cm-1 is superimposed ing the high amounts of nickel and copper in the on the maxima of Cr3+ and Ni3+ in this spectral samples as well as additional absorption maxima, range, and thus the influence of Fe3+ on the colour the absorption spectra of Russian synthetic hydro- of the samples is negligible. thermally-grown emeralds were assigned to Cr3+, Consequently, the colour and pleochroism of Fe3+, Fe2+ as well as to an inter valence transfer Russian hydrothermally-grown synthetic emeralds absorption of Fe2+ and Fe3+ (Lind et al., 1987). is due to the presence of high amounts of chromium However, spectra recorded in polarized light (cf. and nickel. In samples of this type, additional high Figure 4a-e) clearly indicate the presence of absorp amounts of trivalent iron and bivalent copper do not tion bands of both trace elements, Ni and Cu (Table remarkably contribute to the colour of these beryls. 5), which is confirmed by chemical data (Table 2; Figure 2). No evidence has been found up to now Ill A Infrared spectroscopy and types of water in either for the presence of bivalent iron in tetrahedral Russian hydrothermally-grown synthetic emeralds or octahedral coordination or for the presence of the Two types of water molecules were characterized Fe2+/Fe3+ charge-transfer absorption band in the in channel sites of natural and synthetic beryls and red region of visible light. emeralds using infrared spectroscopy. Type-I water In the absorption spectra of Russian hydro- molecules have their two-fold symmetry axis per thermal synthetic emeralds the absorption bands of pendicular to the crystallographic six-fold axis of chromium and nickel are found to be dominant in the beryl crystal and are not adjacent to alkali ions. the visible area, and the influence of iron and copper Type-II water molecules have their two-fold sym bands is subordinate. The colour of synthetic metry axis parallel to the crystallographic six-fold nickel-doped beryl is described as yellowish-green axis of the beryl crystal and are adjacent to alkali with a pleochroism of blue || c and yellow-green ions. In high alkali natural emeralds, predominant or yellow _l_ c (Emel'yanova et al., 1965; Solntsev, absorption bands of type-II water are observed and 1981a; Lebedev etaL, 1986). Due to the presence of only subordinate bands of type-I waterare found. In a strong nickel absorption doublet at 16,500 and low alkali natural emerald, e.g. in Colombian 16,800 cm-1 (polarization || c), the absorption emeralds, absorption bands of both types of water minimum of the ordinary chromium-vanadium are present. Up to 1980, in synthetic hydrotherm (emerald) spectrum is shifted from green or bluish- ally-grown emeralds, e.g. in Linde synthetic emer green to greenish-blue and blue (cf. Table 4). On the alds, only type-I water molecules were found. other hand, the presence of an absorption band Flux-grown synthetic emeralds do not contain any of Ni3+ at 22,000 cm-1 (polarization _L c) causes water molecules and thus do not reveal water an increase of yellow in the spectrum _L c. Thus, absorptions in the infrared (Wood & Nassau, 1967, due to the presence of high amounts of nickel, the 1968; Flanigen et al., 1967; Nassau, 1976, 1980; pleochroism of ordinary chromium-vanadium Nassau & Nassau, 1980). emerald (bluish-green || c, yellowish-green J_ c) is However, in the papers of Klyakhin et al. increased and changed to greenish-blue or blue || c (1981b), Shatsky etal. (1981), Kodaira^a/. (1982) and to yellow-green _L_ c (Table 4). This interpreta and Lebedev et al. (1986), hydrothermally-grown tion of colour and pleochroism in chromium- and synthetic beryl containing alkalies as well as type-I nickel-bearing emeralds is consistent with Russian and type-II water molecules were described. literature (Lokhova et al, 1980; Bukin et al, 1981; According to the most comprehensive work of Solntsev, 1981a,b; Lebedevétf al. 1986). Shatsky et al. (1981), high concentrations of type-II The influence of iron and copper on the colour of water were incorporated only in sodium- and Russian hydrothermally-grown synthetic emeralds lithium-bearing synthetic beryl, bot not in potas- is subordinate. In samples containing lower sian, rubidian and cesian beryls. Most recently, high amounts of copper, the absorption bands of Cu2+ do pressure hydrothermal treatment of flux-grown 151566 JJ.. Gemm.Gemm.,, 1988,21,1988,21,33

III.5Ill.S Microscopic featuresfeatures ofofRussian Russian hydrothermallyhydrothermally- grown syntheticsyntMtiC emeraldsemeralds IInn halhalff ooff ththee cucutt synthetisyntheticc emeraldemeraldss investigateinvestigatedd residueresiduess ooff ththee seeseedd platplatee consistinconsistingg ooff colourlescolourlesss berylberylss werweree founfoundd (Figure(Figuress 6-8)6-8).. IInn alalll samplessamples,, ththee anglanglee betweebetweenn ththee boundarboundaryy seeseedd plate/syntheticplate/synthetic emeralemeraldd anandd ththee opticaopticall axiaxiss ooff ththee syntheticsynthetic emeralemeraldd wawass determinedeterminedd bbyy meanmeanss ooff aann especiallyespecially 4* developedevelopedd samplsamplee holdeholderr (Schmetzer(Schmetzer,, 19851985,, 1986)1986).. FoForr alalll samplessamples,, thithiss anglanglee was measuremeasuredd betweebetweenn 3300 anandd 32°32°,, indicatinindicatingg thathatt foforr alalll samplesampless seeseedd plateplatess paralleparallell ttoo ((555 5 1100 66)) werweree useusedd whicwhichh forformm aann anglanglee ooff 31.0531.05°° witwithh ththee optiopticc axiaxiss ooff beryberyll (calculate(calculatedd forfor hexagonahexagonall beryberyll witwithh a:c = 11:0.9967):0.9967). . IInn alalll samplesampless witwithh seedseed,, familiefamiliess ooff paralleparallell growtgrowthh lineliness connecteconnectedd witwithh coloucolourr zoninzoningg werweree founfoundd paralleparallell ttoo ththee boundarboundaryy seeseedd plate/synthetiplate/syntheticc emeralemeraldd (Figure(Figuress 6-8)6-8).. IInn facetefacetedd samplesampless withouwithoutt residueresiduess ooff ththee seeseedd plateplate,, familiefamiliess ooff paralleparallell %T growthgrowth lineliness connectedconnected witwithh coloucolourr zoninzoningg werweree alsalsoo %T presenpresentt (Figures(Figures 9-10)9-10),, anandd ththee angleangle betweebetweenn thescthese facefacess anandd ththee c-axic-axiss ooff ththee synthetisyntheticc emeraldemerald wawass measuremeasuredd ttoo bbee equaequall ttoo 31°31".. ThusThus,, alalll 1313 samplessamples 3800 3500 3300 : examinedexamined werweree growgrownn fromfrom beryberyll seedsseeds paralleparallell ttoo WAVENUMBER (em-I) (cm-1) ((S5 5 1JO0 6)6).. ThiThiss detaidetaill ooff growtgrowthh conditionsconditions iiss mentionementionedd iinn somsomee RussiaRussiann publicationpublicationss (e.g(e.g.. KlyakhiKlyakhinn etal.,el aI., 1981b1981 b;; LebedeLebedevv & Askhabov,Askhabov, 1984;1984; LebedeLebedevv etel al., 19861986)) ttoo bbee ononee ooff ththee standardstandard Figf'ig_. 55.. InfrareInfraredd spectruspectrumm ofof RussiaRussiann hydrothermally-grownhydrothermally-grown techniquetechniquess suitablesuitable foforr hydrothermahydrothermall synthesisynthesiss ooff synthetis y mhet icc emeral• rneraldd indicatinindicati ngg ththee presencpresencee ooff type-type-lI andand type-Itype·I1I watewaterr mokcule,.molecules. beryberyll (cf.(cf. growtgrowthh conditionconditionss forfor LindLindee hydrotherhydrother mally-growmaJly-grownn synthetisyntheticc emeraldsemeralds;; Flanigen,Flanigen, 19711971;; beryberyll was describedescribedd andand thethe incorporatioincorporationn ofof type-Itype-I FlanigeFlanigenn & MumbachMumbach,, 1971).1971). SamplesSamples whichwhich areare andand type-Ilype-I1I watewaterr moleculemoleculess wawass observedobserved (Kodaira(Kodaira growgrownn fromfrom seeseedd plateplatess paralleparallell ttoo (1120)(1120) werweree alsoalso etetal, al., 1984)1984).. mentionementionedd inin ththee RussiaRussiann paperpaperss citedcited above,above, butbut InfraredInfrared spectrspectraa ooff ththee commerciallycommercially growgrownn typetype obviouslyobviously nono syntheticsynthetic emeralemeraldd ofof thithiss typtypee waswas ofof RussianRussian hydrothermahydrothermall syntheticsynthetic emeralemeraldd (Figure(Figure availableavailable forfor ththee presenpresentt investigationinvestigation.. SinceSince growthgrowth 5)5) clearlclearlyy reveareveall twtwoo strongstrong absorptionabsorption bandbandss atat zoninzoningg paralleparallell ttoo (5(5 S5 1010 66)) isis subordinatesubordinate iinn 1 natural emeralds, if present at all, the recognition of 3,5953,595 andand 3,6983,698 emcm t and,and, consequently,consequently, thethe incorincor natural emeralds, if present at all, the recognition of poratioporationn ooff watewaterr moleculemoleculess ofof typestypes I andand IIII isis thithiss structuralstructural featurefeature bbyy microscopimicroscopicc examinationexamination indicated.indicated. AccordingAccording ttoo ththee presencpresencee ofof sodiumsodium iiss sufficiensufficientt toto characterizcharacterizee a samplesample ofof unknownunknown onlyonly inin ververyy smallsmall amountsamounts (Table(Table 1)I),, type-IItype-II waterwater naturnaturee asas syntheticsynthetic emerald.emerald. moleculesmolecules obviouslobviouslyy areare adjacentadjacent ttoo lithiulithiumm ionsions inin ThThee applicationapplication ofof colourlescolourlesss berylberyl seedsseeds whichwhich channelchannel sitessites ooff thethe berylberyl structure.structure. araree cutcut paralleparallell toto (S(5 5 1010 6)6) causecausess ththee developmentdevelopment DuDuee toto thethe presencepresence ofof bothboth typestypes ofof waterwater ofof additionaladditional characteristiccharacteristic growthgrowth microstructuresmicrostructures molecules,molecules, thethe infraredinfrared spectraspectra ofof RussianRussian hydrohydro whichwhich areare nevernever foundfound inin naturalnatural emeraldsemeralds (Figures(Figures thermally-grownthermally-grown syntheticsynthetic emeraldsemeralds areare identicalidentical 6-11,6-11,13-16) 13-16).. TheseThese growthgrowth structures,structures, whicwhichh partlypartly witwithh thosethose ofof lowlow alkalialkali naturalnatural emeralds,emeralds, e.g.e.g. withwith resembleresemble growthgrowth structuresstructures inin LindeLinde hydrothermhydrotherm partpart ofof naturanaturall emeraldsemeralds fromfrom Colombia.Colombia. Therefore,Therefore, ally-grownally-grown syntheticsynthetic emeralds,emeralds, areare easilyeasily observableobservable infraredinfrared spectroscopyspectroscopy isis unableunable ttoo distinguishdistinguish bebe withwith thethe gemgem microscopemicroscope usingusing immersionimmersion liquids.liquids. tweentween thesethese particularparticular varietiesvarieties ofof naturalnatural andand SimilarSimilar oror almostalmost identicalidentical structuresstructures werewere alreadyalready syntheticsynthetic emeralds.emeralds. TheseThese resultsresults areare consistentconsistent mentionedmentioned byby RussianRussian authorsauthors (Klyakhin(Klyakhin elet aI.,al., withwith thethe paperpaper ofof StocktonStockton (1987),(1987), inin whichwhich simisimi 1981b;1981b; GranadchikovaGranadchikova et al., 1983;1983; LebedevLebedev & laritielaritiess betweenbetween infraredinfrared spectraspectra ofof RussianRussian synthesynthe Askhabov,Askhabov, 1984;1984; LebedevLebedev elet al., 1986).1986). InIn general,general, tictic hydrothermalhydrothermal emeraldsemeralds andand naturalnatural emeraldsemeralds areare thethe observationsobservations describeddescribed inin {hethe paperpaperss citedcited areare described.described. UnfortunatelyUnfortunately,, nono explanationexplanation forfor thesethese confirmedconfirmed byby thethe investigationsinvestigations ofof thethe presentpresent similaritiessimilarities oror identitiesidentities isis givengiven oror discusseddiscussed inin thethe author,author, andand a smallsmall partpart ofof thisthis informationinformation isis alsoalso paperpaper cited.cited. foundfound inin gemmologicalgemmological paperspapers publishedpublished soso far.far. J. Gemm., 1988,21,3 157

Microscopic investigations of the boundary seed tent with that general scheme are rare (Figure 17). plate/synthetic emerald as well as the_ examination Confined to the boundaries between seed plates of growth lines parallel to (5 5 10 6) at high and synthetic hydrothermally-grown emerald, magnifications reveals the presence of a distinct small opaque particles were observed (Figure 18), type of step-like microstructure. The boundary which were obviously trapped at the start of the between the seed plate and the synthetic emerald growth process. The synthetic emeralds themselves does not reveal a plane surface but shows a cobbled were found to be extremely pure, and in some appearance. This boundary consists of a cellular faceted samples, only growth structures but no pattern which is formed by several crystal faces with foreign inclusions were observable. slightly oblique orientation with respect to the seed In several gemmological papers, opaque hexa plate (Figure 11). From each of these cellular gonal-shaped platelets are mentioned as inclusions centres of nucleation, sub-individuals of synthetic in Russian hydrothermally-grown synthetic emer emerald are grown with a preferred subparallel alds (Gübelin, 1986; Lind et al., 1987) and some orientation oblique to the seed plate (Figure 12). inclusions of this type were also found in the 13 The size of these sub-individuals and the form of samples investigated by the present author (Figure the polycentrically growing step-like surface (Fig 19). The presumption of Gübelin (1986), that these ures 7-10) is continuously changed during the particles are platinum platelets seems unlikely growth process. according to growth conditions of commercially produced samples (cf. section IV). In the publica tion of Granadchikova et al. (1983) these platelets are also pictured, and a possible explanation is found in the paper of Klyakhin et al. (1981b), who c-axis mentioned hematite as an inclusion in hydrother A mally-grown synthetic emerald. This explanation / seed parallel seems more reasonable according to growth condi / to(5.5.10.6) tions of the samples using oxide buffers in the equilibrium field hematite-magnetite. In addition, Klyakhin and his co-workers also /jA^^ preferred mentioned two- and three-phase inclusions, which \A^^ orientation of were occasionally found in the samples examined for this paper. Typical are double refractive crystal subindividuals inclusions confined to growth tubes with liquid or two-phase fillings (Figures 20, 21) or similar multi phase-inclusions, which are not confined to a small crystal (Figure 22). Some of the synthetic emeralds also contained feathers consisting of liquid, two- phase and three-phase inclusions (Figures 23, 24), probably filled with two immiscible liquids and one gaseous phase.

Fig. 12. Schematic representation of the orientation of the seed plate parallel to (5 5 10 6) in Russian hydrothermally- grown synthetic emerald versus c-axis and preferred IV. Growth conditions and properties of Russian orientation of sub-individuals. hydrothermally-grown synthetic emeralds Two papers in Russian dealing with growth In a certain direction which is inclined about 34° conditions and properties of industrially-grown versus the seed plate, a characteristic block struc synthetic hydrothermal emeralds are available to ture of subparallel orientated sub-individuals with the present author. In the paper of Godovikov et dl. curved surfaces is observable (Figures 13, 14). In (1982), some details about industrial growth pro some synthetic emeralds a distinct colour zoning cesses of synthetic gem materials in USSR are was observable between different sub-individuals, described. In the publication of Granadchikova et and interference striations were found confined to al. (1983), properties of natural emeralds from Ural the subgrain boundaries. These boundaries be mountains, flux-grown and hydrothermally-grown tween sub-individuals of variable size are charac research material and synthetic emeralds of the terized by growth features, forming angular growth industrial hydrothermal production in USSR are patterns with the edges of the sub-individuals as compared. According to Godovikov et al. (1982), bisectors of the respective angles (Figures 15, 16). industrial growth of hydrothermal synthetic emer Irregular growth structures, which are not consis ald in USSR is performed at L'vov, Ukraine. The 158 J. Gemm., 1988,21,3

Fig. 6. Russian hydrothermally-grown synthetic emerald; fa Fig. 7. Russian hydrothermally-grown synthetic emerald; fa ceted sample with residue of the seed parallel to the ceted sample with residue of the seed at the culet, table, growth lines and colour zoning parallel to the step-like growth lines and colour zoning parallel to the boundary colourless seed/synthetic emerald. Crossed boundary colourless seed/synthetic emerald, irregular polarizers. 20x. ly changing subgrain boundaries almost perpendicular to seed plate and colour zoning. 38x.

Fig. 8. Russian hydrothermally-grown synthetic emerald; fa Fig. 9. Russian hydrothermally-grown synthetic emerald; fa ceted sample with residue of the seed parallel to the ceted sample without residue of the seed, step-like table, step-like growth lines and colour zoning parallel growth lines and colour zoning, irregularly changing to the boundary colourless seed/synthetic emerald, subgrain boundaries almost perpendicular to the colour irregularly changing subgrain boundaries almost per zoning. Crossed polarizers. 20x. pendicular to seed plate and colour zoning. Crossed polarizers. 40x.

Fig. 10. Russian hydrothermally-grown synthetic emerald; fa Fig. 11. Russian hydrothermally-grown synthetic emerald; fa ceted sample without residue of the seed, step-like ceted sample with residue of the seed at the culet, growth lines and colour zoning, irregularly changing cellular pattern of the boundary seed plate/synthetic subgrain boundaries almost perpendicular to the col emerald, subgrain boundaries between sub- our zoning. Crossed polarizers. 40x. individuals originating from each of this cellular nucleation centres with cobbled appearance. 90x. J. Gemm., 1988,21,3 159

Fig. 18. Russian hydrothermally-grown synthetic emerald; Fig. 19. Russian hydrothermally-grown synthetic emerald; in opaque particles confined to the boundary colourless clusions of opaque hexagonal platelets, most probably seed/synthetic emerald. View in a direction perpen hematite. lOOx. dicular to the boundary. 40x.

Fig. 20. Russian hydrothermally-grown synthetic emerald; in clusion of a double refractive crystal. Crossed polari zers. lOOx.

Figs. 23, 24. Russian hydrothermally-grown synthetic emerald; feather with three-phase inclusions, probably consisting of two immiscible liquids and one gaseous phase; dependent on the direction of view, all three phases show transparency (Figure. 23), or two liquid phases show transparency and the gaseous phase shows total internal reflection, or one liquid phase shows transparency and one liquid and one gaseous phase show total internal reflection (Figure 24). Figure 23, 70x; Figure 24, 95x. 160 J. Gemm., 1988,21,3

Fig. 13. Russian hydrothermally-grown synthetic emerald; Fig. 14. Russian hydrothermally-grown synthetic emerald; block structure of subparallel orientated sub- irregularly changing subgrain boundaries between individuals with curved surfaces. 30x. sub-individuals with preferred orientation. 35x.

Fig. 15. Russian hydrothermally-grown synthetic emerald; angular growth patterns with the edges of sub- individuals as bisectors of the angles. 45x.

Fig. 16. Russian hydrothermally-grown synthetic emerald; Fig. 17. Russian hydrothermally-grown synthetic emerald; angular growth pattern with the edge of a sub- irregular growth structure. 45x. individual as bisector of the angles. 50x. J. Gemm., 1988,21,3 161

Fig. 21. Ru..ian hydrothermally-grown synthetic emerald; the Fig. 21. Russian hydrothermally-grown symhctic emerald; identical inclusion of Figure 20, consisting of. double three-phase incl usion, pro bably consisting of two refractive crystal and a growth lube with liquid filling. immiscible liquids and one gaseous phase, 10Ox. 100". following growth conditions are mentioned: equilibrium field (cf. Klyakhin et al., 1981b). temperature range SSO-620°C, temperature gradient In the opinion of the present author, (he most method, pressure 1000 bars, stainless steel auto striking difference between part of the samples . claves200-800ml in volume without precious metal grown for research purposes and specimens of (he liners are used, growth rate of synthetic emerald industrial production is the lack of precious metal 0.2-0.3 mm per day, in 20-30 days from seed plates (platinum or gold) inserts in the industrial process of about 6 cm2 in size synthetic emerald crystals of (Godovikov et al., 1982; Granadchikova el al., 10-20 grams in weight are grown, the thickness of 1983), whieh are mentioned in some research synthetic emerald layers attains 5-7 mm, natural papers (e.g, Shatsky ec al., 1981; Klyakhin et al., beryl or oxides of Be,Aland Siare used as nutrients. 1981b; Lebedev el al., 1986).According to Granad No details about the exact composition of the chikova et al, (1983), this experimental detail of solutions used for the growth process and no growth conditions is responsible for the incorpora information about the temperature gradient applied tion of high amounts of iron and nickel in the are given. However, temperature and pressure are in synthetic emerald crystals, originating from the the range of growth conditions mentioned for walls of the steel autoclaves. In the opinion of the scientific research material, and growth features of present author, the lack of precious metal inserts the research material (Klyakhin et al., 1981b; could also be responsible for the copper contents of Lebedev & Askhabov, 1984; Lebedev et al., 1986) the samples. However, it is also possible that certain are identical with properties of industrially-grown amounts of iron, nickel and copper are added to the samples as described in this paper and by Granad nutrient material, too. chikova et al. (1983). Thus, the compositions of Due to the fact that the influence of chromium solutions and the temperature gradients mentioned and nickel is dominant for the colour of the samples in scientific research papers are assumed to be (which is certainly known to the producers), the similar or almost identical with the conditions used iron- and copper contents of these synthetic emer for the industrial process. alds are most presumably more or less accidental. The solutions are characterized as 'acidic solu However,since the influence of nickel on the colour tions' or as 'fluor-bearing solutions of complex of nickel- and chromium-bearing synthetic emer compositions' as wellas 'acidic solutions of complex alds as well as the interpretation of absorption compositions; temperature gradients mentioned are spectra of chromium- and nickel-bearing synthetic t:,T == 45°C, t:,T == 20-100°C,or;;'T == 70-13O"C, at emeralds was the subject of various Russian re growth temperatures between 590 and 620°C and search papers (e.g. Lokhova el ai., 1980; Bukin et pressures between 800 and 1500 bars (Solntsev et al., 1981; Klyakhin el al., 198Ib), the incorporation al., 1976, 1978; Il'in el al., 1980; Klyakhin , 1980; of nickel is assumed to be most presumably none Bukin et al., 1980; Solntsev, 1981a; Shatsky et al., accidental. As described in section 111.3 in detail, 1981 ; Lebedev & Askhabov, 1984; Pugachev, 1984; this nickel content is responsible for a colour and Lebedev et al., 1986). According to the valence pleochroism of the synthetic emeralds, which re states and lattice sites of iron, nickel, and copper as sembles that of natural emerald from particular they are indicated from absorption spectra (cf. occurrences, e.g. from Zambia, Brazil or Madagas section III. 3; Table 5), the samples were grown car (cf. Table4). under oxygen partial pressures in the Fe304-FeZ03 The high contents of transition metal oxides are 162162 J.J. Gemm.,Gemm., 1988,21,31988,21,3

alsalsoo responsibleresponsible forfor somesome physicalphysical propertiesproperties ofof thethe VI.VI. AcknowledgementsAcknowledgements syntheticsynthetic hydrothermally-grownhydro thermally-grown emeraldsemeralds,, e.ge.g.. forfor SamplesSamples ofof RussianRussian hydrothermally-grownhydrothermally-grown specificspecific gravitiesgravities andand refractiverefractive indices,indices, whichwhich areare syntheticsynthetic emeraldsemeralds useusedd inin thithiss studystudy werweree kindlykindly founfoundd toto bbee wi!:hinwithin !:hethe naturanaturall rangerange.. TheThe presencepresence loaneloanedd bbyy ProfProf.. DrDr E.E. GubelinGübelin ofof Meggen,Meggen, SwitzerSwitzer ofof bothboth type-Itype-I anandd type-IItype-II waterwater moleculemoleculess inin land,land, byby AA.. HodgkinsonHodgkinson ofof GlasgowGlasgow,, anandd byby DrDr R.R. RussiaRussiann industrially-grownindustrially-grown syntheticsynthetic emeralds,emeralds, DiehDiehll ofof FreiburgFreiburg,, WestWest GermanyGermany.. Mrs.Mrs. M.M. VysoVyso- whicwhichh isis typicatypicall forfor naturanaturall samples,samples, iiss alsalsoo duduee toto canskacanska ofof Heidelberg,Heidelberg, FRGFRG,, waswas helpfuhelpfull withwith thethe growtgrowthh conditionsconditions.. MosMostt probablyprobably,, lithiuli!:hiumm ionsions inin translatiotranslationn ooff originaloriginal literaturliteraturee inin RussiaRussiann lanlan thethe channelschannels ofof thethe beryberyll latticelattice causcausee thethe stabilizastabiliza guage,guage, parpartt ofof whicwhichh wawass madmadee availablavailablee byby DDrr AA.. SS.. tiontion ofof type-IItype-II waterwater molecules.molecules. LebedevLebedev ofof NovosibirskNovosibirsk,, USSRUSSR.. Dipl.-Geol.Dipl.-Geol. AA.. TheThe choicchoicee ofof seedseed plateplatess ofof colourlesscolourless beryl,beryl, RüttimanRuttirnannn ofof Terrachem,Terrachem, MannheimMannheim,, FRG,FRG, waswas whkhwhich werweree cucutt parallelparallel toto (S(5 S5 1010 6),6), obviouslyobviously helpfulhelpful withwith X-raX-rayy fluorescencefluorescence analysisanalysis,, andand typtyp dominatesdominates growthgrowth structuresstructures inin thethe syntheticsynthetic emeremer inging waswas dondonee byby Dipl.-MinDipl.-Min.. L.L. KieferKiefertt ofof HeidelHeidel aldald crystals,crystals, e.g.e.g. growtgrowthh zoninzoningg paralleparallell ttoo thethe seedseed bergberg,, FRG.FRG. platplatee asas wellwell aass ththee typicaltypical blockblock structurestructure ofof sub-individualssub-individuals forminformingg ththee hydrothermally-grownhydrothermally-grown beryberyll crystalcrystalss (cf.(cf. LebedeLcbedevv & AskhabovAskhabov,, 1984).1984). BotBothh featuresfeatures araree ofof highhigh diagnosticdiagnostic valuevalue;; theythey werewere ReferencesReferences neveneverr foundfound inin naturanaturall emeraldsemeralds beforebefore andand thetheyy areare Bakakin,Bakakin, V.V. V.V.,, Rylo\l,Rylov, G.G. M.M.,, Sdov,Belov, NN.. V.,V., 1967.1967. CorrelationCorrelation betweenbetween thethe chchemica emicall corncompositio posi tionn andand uniu ni tt cellcell parametersparameters easilyeasily recognizablrecognizablee iinn !:hethe immersioimmersionn microscope.microscope. ofof berylberyl.. Doklady Akad. Nauk SSSR, EarthEanh SC1.Sci. Secl.,Sect., 173173,, 129-32129·32.. Sakakin,Bakakin, VV.. V.V.,, RylovRylov,, G.G. M.M.,, BelovBelo\l,, NN.. V.V.,, 1970.1970. X-rayX-ray diffractiondiffraction datadata forfor identificationidentification ofof berylberyl isomorphs.isomorphs. V.V. ConclusionsConclusions Geodw,mslry,Geochemistry, 1970,/970,924-33. 924-33. TheThe industriaindustriall productioproductionn ofof RussianRussian hydrotherhydrother Beckwith,Beckwith, PI~. J.J.,, TroupTroup,, G.G. J.J.,, 1973.1973. TheThe opticaopticall andand infraredinfrared 3+ mally-growmally-grownn syntheticsynthetic emeraldemeraldss isis performeperformedd inin absorptioabsorptionn ofof VV'· inin beryberyll (Bc;AI,Si,O,.).(Be3Al2Si6O18). Phys.Phy,. sIal.stat. sol.,sol., steelsteel autoclaveautoclavess withoutwithout preciousprecious metalmetal insertsinserts (a)(a) 16,16, 181-618 I -6.. Blak,Blak, A.A. R.,R., Isotani,Isotani, S.,S., WatanabeWatanabe,, S.,S., 1982.1982. OpticaOpticall absorptionabsorption usinusingg seedseed plateplatess ofof colourlesscolourless beryl,beryl, whichwhich araree cutcut andand electronelectron spinspin resonancresonancee inin blubluee andand greegre<:nn naturanaturall beryl.beryl. paralleparallell toto (S(5 S5 1010 6).6). DueDue ttoo thesthesee growtgrowthh condicondi Phys. Ch.rn.Chem. Minerals,Mi""ra/s, 8,8, 161-6161-6.. tionstions,, distinctdistinct amountamountss ooff chromium,chromium, ironiron,, nickelnickel BukinBukin,, G.G. V.,V., Godovikov,Godovikov, AA.. A.,A., KlyakhinKlyakhin,, V.V. A.,A., Sobole\l,Sobolev, V.V. S.,S., anandd coppecopperr areare incorporatedincorporated inin ththee syntheticsynthetic cryscrys 1980.1980. SyntheticSynthetic emeraldemerald.. In:In: Gem minerals. Proceedings of tals and characteristic microstructures are formed. the XI general meeting of IMA, NovosibirsNovosibirskk 19781978,, publ.publ. tals and characteristic microstructures are formed. LeningradLen; n grad,, 1980,1980, pppp.. 36-4436-44 I[i inn Russian]Russian I.. BothBoth featuresfeatures areare ofof highighh diagnosticdiagnostic value,value, theythey areare BukinBukin,, G.V.,G.V., Lokhova,Lokhova, G.G. G.,G., Ripinen,Ripinen, O.O. I.,I., Veis,Veis, NN.. S.,S., 19811981.. easilyeasily recognizablrecognizablee bbyy non-destructivnon-destructivee techniquestechniques EffecEffectt ofof isomorphousisomorphous impuritieimpuritiess onon ~olurcolor characteri,ti"characteristics ofof suchsuch asas tractracee elementelement analysis,analysis, byby absorptionabsorption specspec berylshcryb.. In:In: Iss/ed.Issled. Fiz. Svoistv i SO'lOvaSostova SinULSintet. MineralovMi~eriliov i troscopytroscopy inin thethe visiblevisible anandd ultravioletultraviolet rangerange anandd byby Monokristallov,MonokTi,/oIlO'lJ, NovosibirskNovosibi~k,, 1981,1981, pp.pp. 20-ZO-81in8 [in Russian]Russianl.. Cerny,Cerny, P.P.,, Hawthorne,Hawthorne, F. C.c.,, 1976.1976. RefractiveRefractive indiceindicess \lersu.versus microscopicmicroscopic examinatioexaminationn usinusingg immersionimmersion liquids.liquids. alkalialkali content.contents iinn beryl:beryl: genera)general limitationlimitationss andand appli~ationsapplications ThThee chemicalchemical compositioncomposition ofof thethe samples,samples, i.e.i.e. thethe ttoo somesome pegma(iticpegmatitic types.types. Ganad.Canad. Mineral., 14,491-7_14, 491-7. highhigh amountamountss ooff transitiontransition metalmetal oxidesoxides present,present, areare Deer,Deer, W. A.,A., HowieHowie,, RR.. A.,A., Zussman,Zussman, J.,J., 1986.1986. Rock-formingRock-forming responsibleresponsible forfor ththee highighh valuesvalues ofof refractivrefractivee indicesindices m;'lera/,.minerals. Vol. lB,1B, Second Edition, DisilicatesDi,i/ieates and RingRing Silicates.Silicate>. LongmaLongm.ann ScientificScientific & Tecbnical,Technical, Harlow,Harlow, England.Eng andand specificspecific gravities,gravities, asas welwelll asas forfor thethe highhigh unitunit cellcell Emel'yanovaland. , E.N., Grum-Grzhimailo, S.V., Boksha, O. N., dimensions.dimensions. TheThe coloucolourr andand pleochroispleochroismm ofof thethe Emel'yanova, E.N., Grum-Grzhimailo, S.V., Boksha, O. N., samplessamples isis causecausedd bbyy tracestraces ooff bothboth dominantdominant VarinaVarina,, TT.. M.,M., 1965.1965. ArtificialArtificial beryberyll cont.iningcontaining VV,, Mn,Mn, CoCo transition metal elements, chromium and nickel, anandd NiNi.. Sov. I'hyS.-CrySl,Phys.-Cryst, 10,46-9.10, 46-9. transition metal elements, chromium and nickel, Filho,Filho, H.H. dede AA.. S.,S., Sigbinolfi,Sighinolfi, G.G. PP.. & Galli,Galli, E.,E., 1973.1973. andand !:hethe influenceinfluence ofof iroironn anandd coppecopperr iiss subordinate.subordinate. ContributionContribution toto ththee crystacrystall chemistrchemistryy ofof beryl.beryl. Contr.Con". TheThe presencpresencee ofof type-Itype-I andand type-Itype-III watewaterr molecules,molecules, MineralMineFa/.. and Petrol., 38,38, 279-90279·90.. whichwhich wawass regarderegardedd toto bbee diagnosticdiagnostic forfor naturalnatural Flanigen,Flanigen, EE.. M.,M., 1971.1971. HydrothermaHydro(bermall processprocess foforr growinggrowing emeraldemerald uupp ttoo now,now, iiss explainableexplainable bbyy growthgrowth crystalcry s tal ss havinha vi ngg thethe structurs t ruc lUree ofof berylberyl inin alalkalin kalinee halid e mediummedium.. UnitedUnited State,States Patent,Patent, 33,, 567567,642., 642. conditions,conditions, iinn whichwhich alkalialkali ionionss werweree incorporatedincorporated Flanigcn,Flanigen, E.E. M.,M., Breck,Breck, DD.. W.W,, MumbachMumhach,, NN.. R.,R., TaylorTaylor,, AA.. M.,M., intintoo ththee channelschannels ooff thethe berylberyl structure.structure. TheThe 1967.1967. CharacteristicsCharacteristics ooff synthetisyntheticc emeralds.emeralds. Amer. Mineral.,Mineral., syntheticsynthetic emeraldemerald crystalscrystals consistconsist ooff subsub- 52,744-72.52, 744-72. Flaoigcn,Flanigen, EE.. M.M.,, MumbachMumbacb,, NN.. R.,R., 1971.1971. HydrothermaHydro(hermall processprocess individuals,individuals, thethe formatioformationn ooff whicwhichh isis duedue toto thethe foforr growinggrowing crystalcrystalss havinhavingg ththee structurstructuree ofof berylberyl inin anan acidacid growthgrowth conditionsconditions applied,applied, especiallyespecially duedue toto thethe halidhalidee medium.medium. UniteUnitedd StatesStates Patent,Patent, 3,3, 567,567, 643643.. orientationorientation ofof ththee seedseed plateplate.. WitWithh a detaileddetailed Franz,Franz, G.,G., 1982I 982.. KristallchemiK ri s tal khcm iee \Ionvon Seryl!,Beryll, VarietVarietä att SmaSmaragd ragd.. knowledgknowledgee ooff alalll propertiesproperties ofof thisthis exceptionalexceptional typetype FOr/

GodovikovGodovikov,, A.A. A.,A., Sukin,Bukin, G.G. V.V.,, Vinokurov,Vinokurov, VV.. A.,A., Kalinin,Kalinin, D.D. NassauNassau,, K.,K., 1976.1976. SyntheticSynthetic emeraldemerald:: thethe coufusingconfusing historhistoryy andand V.V.,, Klyakhin,Klyakhin, VV.. A.,A., MatrosovMalrosov,, V.V. N.N.,, NenashevNenashev,, B.B. G.,G., tbethe currentcurrent technologieste~hnologies.. J.J. Crystal Grow/h,Growth, 35,35, 211·22.211-22. Serbulenko, M. M. G., G., 1982. 1982. Development Development of synthesisof synthesis techniques lechni. NassauNassau,, K.K.,, 1980.1980. Gem,Gems Made by Man. RadnorRadnor,, ChiltonChilton BookBook que, foforr mineralsminerals ofof economiceconomic importanceimportance iinn ththee USSR.USSR. Company,Company, Pennsylvania.Pennsylvania. G'ol.Geol. Geofiz.,Geofi~., 1982, 1982, 12, 12,42·54 42-54 [in [in Russian]. Russian[. NassauNassau,, K.,K., Jachon,Jackson, KK.. A.,A., 1970.1970. TrapicheTrapiche emeraldsemeralds fromfrom Goldman,Goldman, D.D. S.,S., RossmanRossman,, GG.. R.,R., ParkinParkin,, K.K. M.M.,, 1978.1978. ChannelChannel ChivorandChivor and Muzo,Muzo, Colombia.Colombia. Amer. Mineral., 55.55, 416-27.416-27. coustituentsconstituents inin berylberyl.. Phys. Chem. Minerais,Minerals, 3,3, 225-35225·35.. NassauNassau,, K.K.,, NassauNassau,, I.,J., 1980.1980. ThThee growlhgrowth ofof symheticsynthetic andand GTanadchikova,Granadchikova, B.B. G.,G., Andreenko,Andreenko, E.E. D.,D., Solodova,Solodova, Yu.Yu. P.P.,, imitatioimilalionn gemsgem,.. InIn:: FreyhartFreyharl,, H. C. (Ii(Ed. d.):): Cryslals.Crystals. Grow/h,Growth, BukinBukin,, G.G. V.V.,, KlyakhinKlyakhiu,, V.V. A.,A., 1983.1983. DiagnosticsDiagnostics ofof naturalnatural PropertiesPropmies and Applications.A ppl i cations. Vol. 2: Grow/handGrowth and Propmie<.Properties. andand synthetisyntheticc emeralds.emeralds. hv.Izv. Vyssh. Uchehn.Uchebn. Zll'l!ed.,Zaved., Geol.Geol. Springer,Springer, Beriin,Berlin, pp.pp. I-50.1-50. Razved., 26,26, 87-9387-93 [in[in Russian]RussianJ.. ParkinPar kin,, K.K. M.,M., Loeffler,Loeffler, B.B. M.,M., BurnsB u TnS,, RR.. G.,G., 1977.1977. MossbauerMössbauer Gubelin,Gübelin, E.E.,, 1986.1986. DiDiee diagnostischendiagnostischen EigenschafteEigeuschaftenn derder neuenneuen speclraspectra ofof kyanitekyanile,, aquamaTineaquamarine andand cordieritecordierite showingshowing Syutbeseu.Synthesen. Goldschmiede Zeitung, 84,84, 11,69-76.11, 69-76. intervalencintervalencee cbargecharge transfertransfer.. Phys. Che",.Chem. Minerals,Mineral" 1I,, Hänni,Hanni, H. H. A., A., 1981. 1981. Chemischer Chemischer Vergleich Vergleich zwischen 7.wischen natürlichen natUT 301·1!.301-11. lichen unundd synthetischesynthetischeun Smaragdeu.Smaragden. Z.Z. 01.Dt. Gemmol. GGes., ... , PavlovaPavlova,, I.I. G.,G., 1963.1963. DependencDependencee ofof ththee refractiverefractive indice,indices ooff 30,214-8.30, 214-8. beryberyll onon compositioncomposition andand modmodee ofof geuesis.genesis. Doklady Akad.Akad. HänniJla nni,, HH.. A.,A., 1982.1982. A contributiocont ri bnt ionn 10to thethe separaseparabilit bil ity y ofof naturalnatural NaukSSSR,Navk 5SSR, EarthEarlhSci. Sci. Seer.,Sect., 150,150, 109-12109-12.. andand syntheticsynthetic emeralds.emeralds. J. Gemm., 18,18, 138-44138-44.. PlatonovPlatonov,, AA.. N.N.,, PolshinPoishin,, ll.E. V.,V., Taran,Taran, M.M. N.,N., 1979.1979. OnOn thethe Hofmann,Hofmanu, C., C., Schrader, Schrader, H. H.-W., -W., Stender, Steuder, E., 1985.E., 1985. Rasterelektronenmikroskopie. Ra,terelek formforms s ofof occurr~nceoccurrence ofof FeFe inin berylsberyls.. Zap. Vse,.Vses. Mineral.Mineral. Einigetronenmikroskopie. Anwendungen in der Einige Edelsteinforschung. Anwendungen in der Edelstein Obsh., 108,725-30108, 725-30 [in[in RussianJ.Russian]. Goldschmiedeforsch ung. Zeitung, Gold,e 83hm, iede6, 76-7. Zeilung, 83, 6, 76-7. PlatonovPlatonov,, AA.. N.N.,, TaranTamn,, M.M. N.N.,, Minko,Minko, O.O. E.E.,, PolshynPoI,hyn,, EE.. V.,V., Il'iniJ'in,, AA.. G.,G., Klyakhin,Klyakhin, V.V. A.,A., PavlyuchenkoPavlyuchenko,, V.V. S.,S., Chepuruova,Chepurnova, 1978.1978. OptiOptica call absorptioa bsorplionn sspectr peelraa audand nanatur luree ofof colocolorr ofof G.G. A.A.,, 1980.1980. PhysicalPhysical propertiesproperties ofof singlesingle crystal,crystals ofof somesome iron-containiniron-containingg beryls.beryls. Phys. Chern.Chem. Mineral"Minerals, 33,, 87-887 -8.. varvarietie iel iess ofof berbery ylI growngrown undeunderr hydrothermalhydrothermal conditionconditions s.. IIn:n : Price,Price, D.D. C.,C., Vance,Vance, E.E. R.,R., Smilh,Smith, G.,G., EdgarEdgar,, A.,A., Dickson,Dickson, BB.. L.,L., Vyra,hchi"aVyrashchivanie nie Kri'lal/o"Kristallov BBerillievykh eril/ievyk h Mineralov i JIssled. ssled. ikhikh 1976.1976. MössbaueMossbauerr effecteffect studiesstudies ofof berylberyl.. J. de Physique,Physique, Svoi,ro,Svoistv, NovosibirskNovosibirsk 1980,1980, pp.pp. 3-13·111 [in[in Russian]Russianj.. CollfJljueColloque C6, supplement 12,/1 , 37,37, 81811-17 1-17.. Kane, R.R. E., E., Liddicoat, Liddicoat, R. T.,R. Jr.,T., 1985.Ir., 1985. The BironTbe Biron hydrothermal hydrother. Pugachev,Pugachev, AA.. I.,I., 1984.1984. EffectEffect ofof Po,Po2 onon structuralstructural impuritiesimpurities ofof syntheticmal synthetic emerald. Gemsemerald. & Gemology, Gem.& Gemology, 21, 156-70. 21, 156-70. irouiron inin hydrothermal hydrothermal beryl. beryl. In: Fiz.-Khim.lu: Fiz.-Khim. Issled. Issled. Sul'fidnykh Sul'fid KlyakhinKlyakhiu,, V.V. A.,A., 1980.1980. MelhodMethod foforr ththee studystudy ofof growlhgrowth rale,rates ofof Silik.nykhSilik. Sist., Novosibirsk 5,sl., Novosibirsk 1984, pp. 87-93 1984, [in pp.Russian]. 87-93 [in Russianj. berberyl yI. . InIn:: Vyra'htVyrashchivanie h i"anie KristallovK riswllov BerillievykBerillievykh h Mineralov i RodionovRod io nov,, A.A. Ya.Ya.,, PavlyuchenkoPa vi yuchenko,, VV.. S.,S., 1980.1980. CCrystallizatio rys taJliza tionn ofof JIssled.ssled. ikh SSvoistv, voi,ro, NovosibirsNovosibirskk 1980,1980, Ppp p.. 30-30-44 [in[in Russian]Ru ssian].. colouredcoloured varietievarieliess ofof berylberyl undeunderr gas-transportgas-transport conditious.conditions. Klyakhin,Klyakhin, V.V. A.,A., Shalskii,Shatskii, V.V. S.,S., LebedevLebedev,, A.A. S.,S., Pavlyuchenko,Pavlyuchenko, InIn:: Vy'a,/u:hivanieVyrashchivanie KKristallov Tis/al/w BBerillievykh erillievyk h MMineralov illeralov i ls,led.Issled. V.V. S.,S., Il'inI1'iu,, AA.. G.,G., 1981a.1981a. ExperimenlalExperimental ,tudystudy foforr thethe entryentry ikhSvoi,ro,ikh Svoistv, Novosibir:skNovosibirsk 1980,1980, pp.pp. 62-7062-70 [in[in Russian].Russian]. ofof isomorphousisomorphous impuritiesimpurities intointo synthelicsynthetic hydrolhermalhydrothermal Samoilovich,Samoilovich, M.M. L.L,, TsinoberTsinober,, L.L. L,I., Dunin-BarkovskiiDunin-Barkovskii,, RR.. L.,L., beryl.beryl. In:In: 10-E]O-E VVses. ..,. Soveshch. po Eksperim. i Tekhn. 1971.1971. NaturNaluree ooff thIhee coloringcoloring iinn iron·iron-containin containingg beTYI.beryl. 5w.Sov. Mineral. i Petrogr., KieK i"vv 1981,1981, pp.pp. 188-97188-97 [in[in RussianRussian] J.. Phys.-Cryst.,Phys.-Cry"., 16,16, 147-50147-50.. Klyakhin,Klyakhin, V.V. A.A.,, LebedevLebede~,, AA.. S.,S., Il'inI1'in,, A.A. G.,G., Solntsev,Solntsev, VV.. P.P:,, Scarrall,Scarratt, K.,K., 1987.1987. NoteNotess frofromm tbethe Laboratory -- 1111.. J. Gemm.,Gemm., 1981b.1981 b. GrowingGrowing of of hydrothermal hydrothermal beryl. beryl. In: SintezIn: Sinuz i Vyrashchivanie i Vyra,h 20,406·22.20, 406-22. Optich.chi"an;e Kristallov Optic i h.Yuvelir. K riSlallov Kamnei, ; Yu"e]ir. Novosibirsk K amnei, Novo,i birsk Schmetzer,Schmetzer, K.K.,, 1982.1982. AbsorptionsspektroskopieAbsorptionsspektroskopie unundd FarbeFarbe vonvon 3+ 1981,1981, pppp.. 45-6645-66 [in[in Russian]Russianj.. VV; + --haltigehaltigenn nanatürliche IU rlicbenn OxideOxid~nn undund SSilikateilika tenn - eei inn Kodaira,Kodaira, K.K.,, IwaseIwase,, Y,Y., Tsunashina,Tsunashina, A.A.,, Matsushita,Matsushita, T.,T., 1982.1982. BeilragBeitrag zurzur KristallchemiKri"allchemiee desdes Vanadiums.Vanadiums. N. Jb. Mine,.Miner. HigHighh ppressur ressu ree hydhydrotherma rotbermall syOlsynthesi hesi,s ofof berbery ylI crcrystals ystal ,.. J.J. Abh., 144,73-106.144, 73-106. CryslalCrystal Growlh,Growth, 60.60, 172·4.172-4. Schmet~er,Schmetzer, K.,K., 1985.1985. EiEinn verbesserteverbesserterr "robenhallerProbenhalter unundd seineseine Kodaira,Kodaira, K.,K., Tsujino,Tsujino, F.E,, Shimada,Shimada, S.,S., MalSu,hila,Matsushita, TT.. 1984.1984. AnwendungAnwendung auauff ProblemeProbleme derder UnterscheidunUnlerschcidungg naliirlichernatürlicher HigHighh pressurpressuree hydrOlhermaltreatmenthydrothermal treatment ofof water-freewater-free berylberyl und synthetischersynthelischer Rubine Rubinc sowie sowie natürlicher natiirlicher und synthetischer und symheti crystals.J.crystals. J. Cry'lalCrystal Growlh,Growth, 67,654-5.67, 654-5. Amethyste.scher Amethysle. Z. Dt. Gemmol. Z. 01. Ges., Gemmol. 34, 30-47. Ge,., 34,30-47. Koivula,Koivula, JI.. I.L,, 1984.1984. RussianRussian hydrothermahydrolhermall symheti~synthetic emerald,.emeralds. Schmetzer,Schmetzer, K.,K., 1986.1986. AnAn improveimprovedd samplesample holderholder andand itilss Uscuse inin Gems & GemQIQ!tj,Gemology, 2020,, 245245.. ththee distinctiodistinctionn ofof nanatura t urall an d syntheti s ymhelic c rubyruby aa,s wellwell asas Koivula,Koivula, JJ.. I.I.,, 1985.1985. MoreMore onon RussiaRussiann hydrothermahydrothermall syntheticsynthetic naturan al urall andand ssyntheti ynthelic c arneamethyst t h yst.. J. Gemm., 2020,, 20-20-3333.. emeralds.emeralds. Gems&Gems & Gemology, 21,21, 59-6059-60.. Schmetzer,Schmetzer, K.K.,, BankBauk,, H.,H., 1980.1980. SmaragdeSmaragde ausaus SambiaSambia mitmit KoivulaKoivula,, J.J. I.,I., KellerKeller,, P.P. C.,C., 1985.1985. RussiaRussiann flux-growflux-grownn synlhelksynthetic ungewohnlichemungewöhnlichem Pleochroi,mus.Pleochroismus. Z.Z. 0/.Dt. Gemmol. GtGes.,•. , 292',, emeralds.emeralds. Gems&Gems & Gemology, 21,21, 79-8579-85.. 149-51.149-51. LebedevLe bedev,, AA.. S.S. 1987.1987. PPrivat ri vatee commcommunications uuicalions.. Schmetzer,Schmetzer, K.,K., BankBank,, H.,H., 1981.1981. AAun unusuaunusuall pleochroispleochroismm iinn Lebedev,Lebedev, AA.. S.,S., AskhabovAskhabov,, AA.. M.M.,, 1984.1984. Reg~neralionRegeneration ooff berylberyl ZambianZambian emeraldsemeralds.. J. Gemm., 17,17, 443-6.443-6. crystals.crystals. Zap. Vses. Mineral. Obsh., Il3,113, 618-28618-28 [in[in Russian].Rus Schmeller,Schmetzer, K.,K., Bank,Bank, H.,H., Stahle,Stähle, V.,V., 1981a.1981a. ZuZumm ChromgehaltChromgehalt sian]. iin,n synthetischey n theli sch enSn Smaragdüberzüge maragd ii be .. ligenn vonvon Beryl!Beryllkerne kernenn Lebedev,Lebedev, A.A. S.,S., DokukinDokukin,, A.A. A.A.,, 1984.1984. EffeclEffect ofof pressurepressure onon ('('Synthetisch S ynthetischee SSmaragde maragde'' derder HerstellunHers te l! ungg LochleiLechleitner) toer).. Z.Z. eOlryentry ofwal~rof water intimoo beryberyll duringduring hydrothermahydrolhermall synthesis.synthesis. In:In: 01.Dt. Gemmol. GeGes., .. , 30,30, 210-3.210-3. Fiz.-Khim.Fi~.-Kh,m. Issled.1ssled. SuVfidnykhSul'fidnykh Silik. Sist.,S'SI., NovosibirskNovosibirsk Schmclzer,Schmetzer, K.K.,, BankBank,, H.H.,, Stahle,Stähle, V.,V., 1981b.1981b. ThThee chromiumchromium 1984,1984, pp.pp. 79·8679-86 [in[in RussianJ.Russian]. contentcontent ofof I.echleimerLechleitner synthetisynthelicc emeraldemerald overgrowth.overgrowth. Gem

Shatsky,Shatsky, VV.. S.,S., Lcbedev,Lebedev, AA.. S.,S., P-dvlyuchenko,Pavlyuchenko, V.V. S.,S., Kovekv.,Koveleva, Solntsev,Solntsev, V.V. 1'.,P., KharchenkoKharchenko,, E.E. I.I.,, Hukin,Bukin, G.G. V.,V., KlyakhinKlyakhin,, V.V. L.L. T.,T., Kozmenko,Kozmenko, O.O. A.A_,, YudinYudin,, A.A. N.N.,, Belov,Belov, NN.. V.,V., 19811981.. A.A.,, Lebedev,Lebedev, AA.. S.,S., LokhovaLokhova,, G.G. G.,G., RipinenRipinen,, O.O. I.I.,, 1978.1978. Study y ooff condicondition t ionss ofof ententerin eringg ofof alkalinealkaline cacation t ionss inin thethe StudyStudy ooff microisomorphimicroisomorphicc substitutionssubstitutions inin naturanaturall andand beryberyll ststructure ruCturc.. GGeokhimiya, eokh imiya, 1981, 33,, 35351-6 1-600 [in[in Russian]Russian I.. synthesized beryl. beryl. In: In; Issled. Iss/ed. po po Eksperim. Ek,per;m. Mineral., M;neral., Novosibirsk Novosi Solnt,ev,Solntsev, V.V. P,P., 19811981 a.a. NatureNature ofof colorcolor oentrescentres andand EPREPR inin berylberyl 1978,birsk pp. 39-531978, [inpp. Russian]. 39-53 [in Ru.sianl. andand chrysoberylchrysoberyl.. Tr. I Inst.nsl. Geol.Geol. Geofiz., Geofiz.,Akad. Akad, NaukNauk SSSR,SSSR, Solntsev,Solntsev, V.V. 1'.,P., LebedevLebedev,, AA.. S.,S., PavlyuchenkoPavlyuchenko,, V.V. S.,S., Klyakhin,Klyakhin, Sih,Sib. Old., 499,92·140499, 92-140 [in[in Russian]Rus,iani-. V.V. A.A.,, 1976.1976. CoppeCopperr centrescentres iinn syntheti~synthetic berylberyl.. SO'l).Sov. Phys.Phys. Solntsev,Solntsev, V.V. P.1'.,, 19811981b b.. AbsorptionAbsorption spectraspectra anandd EPEPRR spectrspectraa ofof Solid Slole,State, 18,805·6.18, 805-6. tracetrace impuritiesimpurities iinn beryllium-containinberyllium·containingg mineralmineralss andand theirtheir Stockton,Stockton, C.C. M.M.,, 1984.1984. TheThe chemicalchemical distinctiondistinction ooff naturalnatural fromfrom relatiorelationn ttoo specimenspecimen ~olor.color. In:In: Issled.Iss/cd. Fiz. SvoistvS"";SltJ i So.ul~aSostava ,yntheticsynthetic emeralds.emeralds. Gems& Gemology, 2020,, 141-5141·5.. Sintet.Simel. MineralovMin.ralov i Monokristallov,Monokri'lal/av, NovosibirsNovosibirskk 1981,1981, pp.pp. SlOckton,Stockton, C.C. M.,M., 1987.1987. ThThee separatioseparationn ofof naturanaturall fromfrom syntheticsynthetic 37-437-477 [in[in Russian].Russian]. emeraldemerald.s byby infrareinfraredd spectroscopy.spectroscopy. Gems & Gemology, 2323,, Solnt.ev,Solntsev, VV.. 1'.,P., Bukin,Bukin, G.,G., V.V.,, Klyakhin,Klyakhin, V.V. A.,A., LokhovaLokhova,, G.G. G.,G., %-9.96-9. PugachevPugachev,, A.A. I.,I., 1984.1984. NaturNaturee ofof colorcolor centrescentres andand liPREPR ofof Wood,Wood, D.D. L.L.,, NassauNassau,, KK.. 1967.1967. InfrareInfraredd spectraspectra ofof foreignforeign iron-containiniron-containingg berylsberyls.. InIn:: Fiz.-Khim.Fiz,-Kh;m. Issled.In/ed. Sul'fidnykhSul'fidnykh moleculesmolecules iinn beryl}.beryl. J. Chern.Chem. Phys., 4741,, 2220-82220-8.. Sihk.Silik. S;$I.,Sist., NovosibirsNovosibirskk 19841984,, ppPI'.. 109-19109-19 [in[in Russian]Russiani-. Wood,Wood, D.D. L.,L., NassauNassau,, K.K. 1968.1968. ThThee chara.L(cri~alioncharacterization ofof herylberyl Solnt,ev,Solntsev, V.V. 1~,P., BukinBukin,, G.G. V.,V., Lokhova,Lokhova, G.G. G.,G., VeisVeis,, NN.. S.,S., 1985.1985. and emeraldemerald by by visible visible and andinfrared infrared absorption absorption spectroscopy. spectro. EPEPRR andand opticaopt ica lI aabsorptio bsorp ti onn .pe~traspectra ofof ironiron-containin -contai ningg Amer.scopy. Mineral., A mer. 53 Mineral.,, 777-800. 53, 77 7-800. berylsbcryb.. ]T.lnsl.Tr. Inst. G'of.Geol. Geof,,,., Geofiz.,Akad. Akad. NaukSSSR,Nauk SSSR, Sih.Sib. Old.,Otd., 610,610, 128-34128-34 [in[in Russian]Russian].. [[ManuscriptManuscript receivedreceived 25 25 January January 1988]1988]

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GemmologicaGemmologicall Associatio Associationn ooff Grea Greatt BritaiBritainn SainSaimt Dunstan'Dunstan'ss HouseHouse,, CareCareyy LaneLane,, LondoLondonn EC2EC2VV 8A8ABB TelTel:: 01-7201-72643746 4374 FaFaxx No0.01. 01-72-72664837 4837 J. Gemm., 1988,21,3 165

Radiation induced structural damage in beryl

John I. Koivula

Gemological Institute of America, 1660 Stewart Street, Santa Monica, California 90404, USA

Abstract Further, the surfaces of the topaz crystals are Stress-induced structural defects in beryl, similar to those first reported in irradiated topazes, are described cooled with running water during irradiation which and illustrated. As with topaz, the build-up of excess sets up extreme temperature gradient, from the electrical charge and heat in the beryl, during irradiation, outer surface to the core, in the crystals (Nassau, is thought to be the cause of these defects. 1985, Schmetzer, 1987). This causes even more internal strain which, in the most severe cases, Introduction relieves itself through cleavage along the basal For several years now, colourless topaz has been pinacoid and through the formation of needle-like imported into the United States from Nigeria. structural defects parallel to the a- and c-axes Large quantities are brought in annually for the sole (Schmetzer, 1987). In some crystals these defects

Fig. 1. Electron-induced structural damage showing the Fig. 2. Electron-induced structural damage showing the hex orthorhombic symmetry of the irradiated blue topaz agonal symmetry of the irradiated yellow beryl host. host. Viewed perpendicular to the c-axis, at an angle Viewed parallel to the c-axis direction. 35x. inclined to the a-axis. 20x.

purpose of treatment, by a combination of irradia may take on a bold 'fish skeleton' or 'fern-like' form tion and heating, to turn the topaz blue. (Figure 1). But in all cases involving topaz these During linear accelerator (linac) treatment, when defects mirror the orthorhombic symmetry of their high-energy electrons in the 10 to 20 mega- host. electronvolt range are used, a great deal of heat is When shipments of topaz are received from generated together with an excessive negative Nigeria it is common to have a few crystal sections charge within the topaz. Due to the limited depth of and fragments of colourless 'goshenite' beryl mixed penetration of the electrons both the heat and the in with the colourless topaz (Peter and Bobbi electric charge are unevenly distributed within the Flusser, Personal Communication). But, because of topaz structure (Nassau, 1985; Schmetzer, 1987). the quantities of rough involved, and the commer This results in strain. cial nature of this mass-treatment process, the few

piecespieces ofof berylberyl araree neveneverr separatedseparated fromfrom thethe bulkbulk ooff ConclusionConclusion topatopazz beforebefore irradiationirradiation...... butbut onlyonly afterafter thethe operaopera OOff threethree linac-treatedlinac-treated NigeriaNigeriann berylsberyls examined,examined, tiontion.. twotwo ofof themthem showedshowed ththee prominenprominentt hexagonalhexagonal defectdefect structure.structure. IfIf thesethese berylsberyls werweree toto bebe treatedtreated onon a commercialcommercial basis,basis, usingusing a strongstrong beabeamm ofof DescriptionDescription ofof ththee berylberyl electronselectrons generategeneratedd byby a linealinearr accelerator,accelerator, thenthen WhenWhen thethe treatedtreated topaztopaz isis removedremoved fromfrom thethe linaclinac perhapperhapss asas manymany asas two-thirdtwo-thirdss ooff themthem wouldwould itit isis thenthen relativelyrelatively easyeasy toto spotspot anyany beryberyll 'ringers''ringers' developdevelop thithiss internaJinternal hexagonahexagonall pattern.pattern. thatthat maymay havhavee beebeenn presentpresent.. SinceSince allall thethe colourlesscolourless TheThe fineness ooff thesthesee defectdefect 'needles''needles;, togethertogether beryberyll hashas turnedturned toto a goldengolden yellow,yellow, iitt nownow standsstands withwith theitheirr dense,dense, close-packeclose-packedd naturenature (Figure(Figure 2),2), isis outout iinn starkstark contrastcontrast witwithh thethe brownish-to-bluebrownish-to-blue reminiscentreminiscent ofof thethe rutilrutilee needlesneedles foundfound iinn SriSri topaztopaz.. LankanLankan starstar corundums.corundums. ThisThis suggestssuggests thatthat ThreeThree linac-treatelinac-treatedd yellow,yellow, anhedralanhedral crystalcrystal fragfrag perhapperhapss six-rayedsix-rayed starstar berylsberyls couldcould bbee cutcut fromfrom thethe mentsments ofof NigerianNigerian beryl,beryl, weighingweighing bebetwent wen 8.928.92 andand besbestt ofof thesethese treatedtreated stones.stones. 21.021.055 carats,carats, werweree recoveredrecovered fromfrom a recenrecentt treatmenttreatment rurunn ofof topaztopaz andand examinedexamined usinusingg a standardstandard gemgem- AcknowledgementsAcknowledgements mologicamologicaJl microscope.microscope. JusJustt likelike somesome ooff thethe elecelec TheThe authorauthor woulwouldd likelike ttoo thanthankk PeterPeter andand BobbiBobbi tron-treatedtron-treated topazestopazes previouslpreviouslyy describedescribedd byby FlusserFlusser ooff OverlandOverland Gems,Gems, LosLos Angeles,Angeles, California,California, SchmetzerSchmetzer (1987),(1987), whichwhich showedshowed radiation-inducedradiation-induced foforr supplyingsupplying ththee irradiateirradiatedd beryl.beryl. MichaelMichael GrayGray ooff defectdefectss thatthat delineateddelineated theitheirr orthorhombiorthorhombicc symmetsymmet GraystoneGraystone EnterprisesEnterprises,, Venice,Venice, California,California, 'win'win rryy (Figure(Figure 1),1), twtwoo ofof thesethese berylsberyls exhibitedexhibited similarsimilar dowed'dowed' ththee beryberyll foforr photomicrography.photomicrography. structuraJstructural defectdefectss thatthat mirroredmirrored thethe hexagonaJhexagonal symmetrysymmetry ofof theitheirr hosthost (Figure(Figure 2).2). DefectsDefects suchsuch asas ReferencesReferences thesethese havehave neveneverr beforbeforee beenbeen reportedreported asas inclusionsinclusions NassauNassan,, K.,K., 1985.1985. AlteringAltering thethe colorcolor ooff topaztopaz.. Gem,Gems and inin beryberyll frofromm anyany locality.locality. Gemology, 21,21, 1I,, 26-34.26-34. InIn a follow-upfollow-up examinationexamination ofof severalseveral hundredhundred Schmelzer,Schmetzer, K.,K., 1987.1987. ColouColonrr andand irradiation-induceirradiation-inducedd defectsdefects inin topaz treatedtreated with with high-energy high-energy electrons. electrons. Journal JO"'IIO./ of Gemmology, of Gem caratscarats ooff un-irradiateun-irradiatedd NigeriaNigeriann beryberyll nnoo suchsuch mology,20, 6, 362-8. 20, 6,362-8. defectsdefects werewere observedobserved.. ThisThis suggestssuggests thatthat Hnaclinac generatedgenerated electron-irradiatioelectron-irradiationn iiss responsible.responsible. [Manuscript[Manuscript receivedreceived 8January 8 January 1988J1988]

AANN EXCITINEXCITINGG NENEWW OPPORTUNITOPPORTUNITYY ININ GEIVIM:OLOGICALGEMMOLOGICAL EDUCATIONEDUCATION

TheThe GemmologicalGemmological AssociationAssociation hashas collaboratedcollaborated withwith thethe GemGem TestingTesting LaboratoryLaboratory ofof GreatGreat BritainBritain toto anangearrange a programmeprogramme ofof one-dayone-day courses.courses.

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The emeralds of Fazenda Boa Esperança, Tauá, Ceará, Brazil: occurrence and properties

D. Schwarz*, Dr H. A. Hänni**, F. L. Martin Jr† and M. Fischer**

*Deutscher Akad. Austauschdienst, Gemmological Centre, Federal University of Ouro Preto, Minas Gerais, Brazil **Mineralogical Institute, University of Basel, Switzerland †Belo Horizonte, Minas Gerais, Brazil

Abstract The emerald-producing Fazenda Boa Esperança serious mining operations on a larger scale, but soon (Tauá, Ceará) in Brazil, the regional and local geology, gave up due to the high development costs involved. and the properties of the emeralds are discussed. In 1983, the company Mineraçâo Brasileira Ltda. The emerald occurrence is situated in biotite schists undertook detailed geological mapping of the area and tremolite-bearing schists containing phlogopite and (Andrade, 1983; Korpershoek, 1983). chlorite. Its formation is closely related to anatectic pegmatites which have intruded into the rock series. 2. Geology The emeralds are associated with very large apatite Figure 2 presents the regional geology in which crystals and locally, with corundum. the emerald deposit at Fazenda Boa Esperança is Chemical analyses show low contents of Cr2O3 and situated. V2O3 (<0.25 wt.%) and rather high contents of FeO The following presentation of the regional and (0.91-1.17 wt.%), MgO (2.42-2.69 wt.%) and Na2O (1.69-1.96 wt.%). local geological conditions of the emerald deposit is The following substitutions explain the low Al- based on the work of Gomes et al. (1981), Mello et contents:- al. (1978) and Korpershoek (1984). Al3+,VI = (Mg,Fe)2+ + Na+ Al3+,VI = (Fe,Cr,V)3+,VI 2.1 Regional Geology The Tauá emeralds contain many mineral inclusions. Over 80% of the surface of Cearâ State is mainly So far, phlogopite, tremolite, molybdenite, allanite and composed of Precambrian crystalline rocks. Apart apatite have been identified. In addition, accumulations from this, granitic and dioritic-gabbroidal intrusive of very small fluid droplets and/or mineral dust and rocks and pegmatites also occur. plane cavities occur, mostly exhibiting a one-phase filling. The concentrations of these inclusions lower the At the end of the Brazilian orogenesis (ca. gemmological quality of the emeralds. 650-600 million years), the main geological struc tures including the characteristic faults, had been 1. Introduction formed. Tectonic movements along some of the The Fazenda (farm) Boa Esperença lies 40 km faults during the Palaeozoic-Mesozoic eras led to a NNE of Tauâ, a small town in the south-east of the partitioning of the crystalline basement into numer federal state of Cearâ (Figure 1). The region is one of ous fault blocks. Thus, Fazenda Boa Esperança lies the driest in Brazil, and the caatinga vegetation on the southern border of the Bloco Santa Quiteria, typical of this arid area known as the Sertao, which is described in Figures 2 and 3 as Unit II. In consists essentially of low thorny bushes, stunted the north, the Bloco Santa Quiteria overlies leptites trees and numerous species of cacti. and, to a lesser degree, biotite gneisses of Unit III. The emerald deposit of Fazenda Boa Esperança, On the other hand, in the more southern area the which lies less than 1 km east of National Highway Bloco Santa Quiteria underlies a polymetamorphic BR 020 (linking Fortaleza with the capital Brasilia), volcano-sedimentary unit, the Complexo de Pedra has been known for a long time. Since the early Branca (Unit I in Figures 2 and 3). 1950s, emeralds (and/or green beryls) have been The latter is lithologically very varied and is extracted by garimpeiros (Brazilian freelance min composed of quartzites, leptites, mica schists, para- ers). At the beginning of the 1970s, the mining and ortho-gneisses, migmatites, amphibolites, ser- company Mineraçâo Sao Pedro Limitada began pentinites etc. The Complexo de Pedra Branca is

-0 <0.,. o"" o .,.o ""'" 5°30' ...... I 1 ... I I \I \I QTroia \I \ , r '...... ~_ .... \ ) "J "'~I Esperanca ~tf'---- , ) LaPi I 9 /' "... ,,/ ... t ...... _----_ ..------" ...... I .// ~ I""'".. ,-, , ...... , I ...... / ,., ~ '" r .... , V. BOI ..., I'~--'" lnharnu s , ... I,,, ...... ~ "'biTric; -, ....'-.;>{ --11"-~_./ ..,.~' <, " : ,...-- l_~ .... \ v...... , ...... 1-' .\ " ,,:>.:,. CL- Marrua )..\\ ,,' --- ... .",.--_ ..... ,;' ~'1 Y ~ - TAUA "..r-:...... :.... 0 I \ )-'5ao '", ..... "\" , " "...... , •./ Vicente '....., .....-...... - ..... , ...... l>:' 'f\ \ , " 1 , " I - \ Catarina V )--- \ _-~---- I - ..... , " ",.JiI' I ...... I, ..... "I r ... "\ ,..."" I I ...... 1 ,... I .... \ ,... 6°16'

5km

Fig. I. Geographical situation of the emerald deposit at Boa Esperanca, Taua, Ceara.

regarded as a 'Nucleo Antigo'" at least 2000 million near Taua, The age of these late-tectonic dykes is years old, and overprinted by the Brazilian given as about 600 million years. orogenesis. In the Bloco Santa Quiteria, several diorite 2.2 Localgeowgy andgenetic aspects massifs occur whose age and stratigraphical correla Tectonically speaking, the Fazenda Boa Esperan tion are still unknown. Furthermore, several gabbro ca lies on the southern border of the Bloco Santa bodies occur with a minimum age of 1900 million Quiteria (Unit II in Figures 2 and 3). This area is years, and two granite intrusions occur within the mainly composed of biotite gneisses and -schists largest diorite massif (Diorite de Taua), The intru and leptites, as well as ultramafic rocks, amphibo sions are considered to be syntectonic with the lites and a large number of pegmatitcs (Figure 3). Brazilian orogenesis. Emerald is found in the biotite schists near the A system of rhyolitic to dacitic dykes appear in pegmatite veins. This unit lithologically presents a the south-western portion of the Bloco Santa very varied development and comprises ultramafic Quiteria, which cut both the Complexo de Pedra rocks (metamorphosed to talc-schists, tremolites Branca and the Taua diorite. These dykes can be up etc.), metabasites, amphibolites (often undergoing to 300 metres wide and several kilometres long. transformation to hornblende-gneiss), leptites, as Otherdykes belonging to the same lithological type, well as biotite gneisses and emerald-bearing biotite fill concentric fractures in the syntectonic granites schists. The latterare, at least partially, described as *.8lu(;k:swhich split a fuMed region into different zones. -rhey may have 'trernolite schists with phlogopite and chlorite' been formed du ri ng an earl icr peri cd\ or or ig inat cd from the same (Cassedanne and Mello, 1979). Additionally, deforrna t ion phase w hj to;h 10Jdcd the region bu t, howe ve r~ had al r~.al.l y consolidated (Khain & Sbcvnaann, in G(lmC-S et .u.. 198 I l. numerous dykes and pegmatite veins occur. 170 J.Gernm., 1988,21,3

-r :;; ~ ;! s~

t= I I , 0 500 1000 1500 m

Lept.i t es E§J D~ c ite dykes D...... Ultramafic rocks ... . Lp. pti tes and biot ite D gnei sses (Unit III )

Amphihol i t es Leptites . ~mp h i bo l i tes . u l t ra m ~fi c - 0 rocks ~nd p p.gm ~ ti t e s (U ni t II) Mesocr at ic biot i te and £li (lti t.1' onl'i ss!'s and - hornbl ende gneisses ~ EZ?2 amphibol i t t>s (llni t I ) Leucocr at ic hiot.i te ts=S1 gne isses ~nd lept i t es

Fig. 2. Regional geologyof the emerald deposit. JJ.. Gemm.Gemm.,, 1988,211988,21,,3 3 171711

III

\ .. "

50 250 m

LeptitesLeptites andand (to(to a llesseesserr degree)degree) biotitp.biotite gneissegneissess OIl]DID Uni t IIillI

PegmatPegmatiteitess ... . ~.* .. * * .• I

UUltramafiI tramaficc rocksrocks .. UniUni t IIII AmphiboAmphibolitel itess ~ BiotiteBiotite gnegneisseissess aanndd --schistschistss c::J

BiotiteBiotite gneissesgneisses andand (to(to aa llesseesserr degree)degree) ~ UniUni t II amphiboamphiboliteli tess

BB = beryberyll., emeraemeralldd CC = corucorundumndum , sasapphirpphi ree

FigFig.. 3.3 . LocalLocal ggeologeologyy ofof Ihethe eemeralmeraldd depodepositsiI .. 172 J. Gemm., 1988,21,3

The complete volcano-sedimentary sequence as formed where an adequate supply of colour- well as the layers directly overlying it were inten providing elements from the basic or ultrabasic sively folded; the volcano-sedimentary unit under rocks is available. Chromium is possibly supplied went at least three deformation phases. by some of the chromian magnetite in the ultra The ultramafic rocks occur as oval, lenticular or mafic rocks. irregular bodies. These, as did the other rocks of the The emeralds are generally small and seldom unit, experienced a regional metamorphism and longer than 2 cm. Occasionally, fragments of larger were transformed to talc-schists, talc-tremolite crystals have been found. The prismatic crystals schists, and tremolitites. Some of the ultramafic (combination of six-sided prisms and basal pina- rocks contain grains of magnetite and are consider coid) exhibit different shades of green, whereby an ably magnetic. apple-green seems to be the most abundant colour. The numerous pegmatites form long and irregu According to Cassedanne and Mello (1979), this lar bodies, and also concordant intrusions. They green colour in the Tauâ emeralds stems from the usually have a simple composition mainly of quartz addition of vanadium. The authors'chemical analy and albite. They are coarse- to fine-grained, with the ses could not confirm this, and their work suggests latter appearing to be the predominant type. rather that Cr and Fe are responsible for the colour Cassedanne and Mello (1979) suggest that this (see section 3). fine-grained facie s originates from the cataclasis during the tectonic deformation. The pegmatites as In a preliminary classification of emerald de well as the leptites contain minute red grains of posits (Schwarz, 1987), the Tauâ occurrence was garnet. assigned to the 'classical' type of genesis, charac- The pegmatites are mainly quite homogeneous. tized by the association of mafic-ultramafic rocks Where differentiated, muscovite-rich portions and pegmatites (Be-supplier). As the Tauâ pegma occur, or, in some, finely-layered biotite can be tites cannot be considered to be 'true' pegmatites present. Sometimes, concentrations of quartz are containing light elements, but rather as mobilisa developed. Apart from these, the following miner tions, i.e. anatectic pegmatites, the question as to als are present: beryl, columbite-tantalite, tourma the origin of the Be has still to be answered. The line, apatite, molybdenite and native bismuth or question of whether this deposit and other similar bismutite (Cassedanne and Mello, 1979). ly-formed emerald mineralizations should be consi The pegmatites do not seem to be directly dered to be a sub-type of the classical emerald derived from late magmatic processes, which usual genesis, or rather as a specifically separate class of ly are accompanied by significant hydrothermal genesis, will only be resolved after further detailed activity. Such an origin would seem to be improb studies are carried out. able, because their unusual composition can only The emerald is occasionally associated with un with difficulty be linked to a simple granitic origin. usually large (up to 15 cm), beautifully formed They were probably locally mobilised during the apatite prisms. These are dark green to bluish in regional metamorphism, when pressure and colour and often so clear and free of inclusions as to temperature rose notably. This led to a partial make them of great interest to the gem cutter. anatexis and to the formation of Na-rich pegma Apart from emerald, corundum has been tites, determined by the nature of the host-rock. observed in Unit III in three habits (Figure 3) Their composition differs from the K-rich pegma (Korpershoek, 1984). Firstly, the mineral occurs as tites in the hanging wall, reflecting the composition minute (<0.1 mm) xenomorphic grains of the blue of the neighbouring leptites (Korpershoek, 1983). variety of corundum - sapphire, which occurs as an The emerald-bearing biotite schists (or tremolitic accessory mineral in the tremolite-talc schist. Also, schists with phlogopite and chlorite) neighbouring colourless to blue corundum crystals have been the 'anatectic' pegmatites are products of chemical found in a contact metamorphic rock mainly com reactions (metasomatism) between the pegmatites posed of oligoclase (20-22% An). These corundums and the basic or ultrabasic rocks. By exometamor- are characterized by a nearly right-angled parting of phic processes, i.e. through the change of the the rhombohedron (1011). The third habit of the original rock by the addition of components of corundum is as colourless, prismatic crystals, origi another surrounding chemical medium, the neces nally up to 3 mm long, which have largely been sary elements for the formation of beryl can reach replaced by sericite, and which occur together with the biotite schist and crystallize in the form of black tourmaline in muscovite schists. exometamorphic beryl (or emerald). Most of the beryls so-formed correspond to those which are 3. Optical and chemical data of the Tauâ found in the pegmatites themselves, i.e. they are Emeralds mostly pale green; the beryl variety emerald is only Optical data stemming from a number of authors J.J. Gemm.,Gemm., 1988,21,31988,21, 3 173173

TablTablee 1.1. RefractivRefractivee indiceindicess andand birefringencesbirefringences ooff thethe ThuaTauâ emeraldsemeralds

l1e no 6nAn ReferenceReference 1.5801.580 ± 0.0010.001 1.5861.586 ± 0.0010.001 0.000.0066 CassedanneCassedanne & MellMelloo (1979)(1979) 1.5791.579 1.5871.587 0.0080.008 Branco eret al.al. (1984)(1984) 1.579 -- 1.5821.582 1.5851.585 - 1.5891.589 0.000.0066 - 0.0080.008 SchwarzSchwarz (1987)*(1987)* 1.570 -- 1.5741.574 1.577 -- 1.5811.581 0.000.0077 - 0.0080.008 SchwarzSchwarz (1987)**(1987)**

*Rang*Rangee ofof opticaloptical datadata inin darkdark emeraldsemeralds **Range**Range ofof opticaopticall datdataa inin lighlightt emeraldsemeralds concerningconcerning thmee emeraldsemeralds frofromm FazendaFazenda BoaBoa EsperEsper- CrCr,, V andand FcFe (Figure(Figure 4)4) likewiselikewise compensate:compensate: an"aança areare presentedpresented inin TablTablee 11.. (b(b)) 2A133+-t .VI'VI = Fe33++,vl'VI + (Cr,V)3+,Vl(Cr,V)3+'VI TheThe electronelectron microprobemicroprobe analysesanalyses (Table(Table 2)2) werewere (see(see FranzFranz elet ai.,al., 1986).1986). carriedcarried outout witwithh anan ARL-SEMARL-SEMQQ instrument,instrument, inin TheThe calculationscalculations aatt ththee bottombottom ofof TableTable 2 showshow whichwhich ththee WDSWDS spectrometerspectrometer waswas useusedd iinn combinacombina thathatt principallyprincipally substitution-typesubstitution-type (a)(a) occursoccurs iinn thethe tiontion withwith anan energyenergy dispersivedispersive systemsystem (EDS,(EDS, TNTN cascasee ofof thesethese emeralds,emeralds, andand differencedifferencess inin chargecharge 2000)2000) (Schwander(Schwander andand GloorGloor,, 1980).1980). TheThe inin betweenbetween Mg2Mg2 + andand Fe2+ versusversus AI'Al3 + areare compencompen strumentalstrumental workingworking conditionsconditions werewere 15kV15kV satedsated byby Na+.Na+. FigurFiguree 4,4, exhibitingexhibiting a gradiengradientt <1<1 acceleratingaccelerating voltagevoltage,, 30mA30mA beabeamm currentcurrent witwithh a showsshows a slightslight excessexcess ooff (Mg+(Mg+Fe Fe)) overover NaNa.. ThisThis cancan 33 + beabeamm diametediameterr ofof abouaboutt 2 micrometresmicrometres.. TheThe stanstan bbee explainedexplained byby a smallsmall amountamount ofFeof Fe I whicwhichh needneed + dardsdards useusedd foforr thethe analyseanalysess comprisedcomprised syntheticsynthetic nonott bebe compensatedcompensated chargewisecharge wise byby Na I.. ProbeProbe oxidesoxides andand simplesimple silicatesilicate minerals.minerals. analyseanalysess cannocannott indicatindicatee oxidatiooxidationn statestate nornor positionposition TheThe analysesanalyses werewere cationicallycationically normalizednormalized toto SiSi = ooff thethe ionsions withinwithin thethe latticlatticee andand asas ththee FFee cancan occuroccur 2+ 3 + 6 atoms.atoms. LowLow Cr20!Cr203 andand V20rvalues 203-values ((<0.2 <0.255 WI.wt.% %)) eitheeitherr asas FeFeZ t oror Fe t iinn ththee octahedraloctahedral oror tetratetra- contrastcontrast withwith highighh valuevaluess forfor FeFeOO (0.91(0.91 - 1.171.17 hedrahedrall positionspositions,, a certaincertain degredegreee ooff uncertaintyuncertainty inin wt.%),wt.%), MgOMgO (2.42(2.42 - 2.62.699 wt.%)wt.%) andand NaNazO20 (1.69(1.69 -- thethe crystacrystall chemicalchemical treatmentreatmentt ofof thisthis elementelement cancan 1.961.96 wt.%)wt.%).. ThThee loloww AlAl contentcontentss araree compensatedcompensated occuroccur.. FigurFiguree 4 comparecomparess chemicalchemical plotplotss betweenbetween bbyy MgMg andand FeFeZ'2+ througthroughh thethe reactions:reactions: ththee TamiTauâ andand ItabirItabiraa emeraldsemeralds (Hanni,(Hänni, et at.,al., 1987)1987).. 3+ VI 2+ + (aj(a) A1Al3 t,vl' = (Mg,Fe)2+(Mg,Fe) + Na"Na TheThe TamiTauâ samplessamples araree characterizedcharacterized byby a largerlarger

TablTablee 2.2. MicroprobeMicroprobe analyseanalysess ofof TauaTauâ emeraldsemeralds

Si02 66.9266.92 67.1367.13 65.9965.99 63.1663.16 63.7663.76 63.763.755 A1Ah2003 15.8315.83 15.5715.57 14.8414.84 14.6614.66 14.9314.93 14.8414.84 CrZCr2003 .10.10 .19.19 .06.06 .23.23 .10.10 .23.23 V 0 .00.00 .00.00 .06.06 .00.00 .00 .00 v2Zo33 .00 .00 FeFeOO .91.91 1.171.17 1.051.05 1.031.03 1.001.00 l.ll1.11 MgOMgO 2.462.46 2.692.69 2.422.42 2.462.46 2.472.47 2.552.55 NazONa20 1.691.69 --1.731.73 1.1.9 911 1.851.85 1.961.96 1.871.87 TotalTotal 87.9187.91 88.4888.48 86.3386.33 83.3983.39 84.2284.22 84.3584.35

FormulaFormula OnOn thethe basibasiss ofof 6 SSii atomsatoms

SiSi 6.0006.000 6.0006.000 6.0006.000 6.0006.000 6.0006.000 6.0006.000 AAll 1.6731.673 1.6401.640 1.5911.591 1.6541.654 1.6561.656 1.6461.646 CrCr 0.0070.007 0.0130.013 0.0040.004 0.0170.017 0.000.0077 0.01 0.0177 2+ FeFel t 0.060.0688 0.08 0.0877 0.08 0.0800 0.0810.081 0.0790.079 0.0880.088 MgMg 0.320.3299 0.35 0.3588 0.3280.328 0.3480.348 0.3460.346 0.350.3588 NNaa 0.2930.293 0.3000.300 0.3360.336 0.3410.341 0.3580.358 0.3420.342 ~ 8.3708.370 8.3988.398 8.3398.339 8.4418.441 8.4468.446 8.4518.451

TotaTotall FFee calculatedcalculated asas FeOFeO 174 J. Gemm., 1988,21,3

0.5 I I ' 1 i 1 i A i

0.4 k +u +• Tauâ 0.3 + + • Itabira eu • Z 0.2 •

0.1 • il.t .

0 0 I 1 1 i i 1 i 1

0.0 0.1 0.2 0.3 0.4 0.5 0.6

Mg + Fe

Fig. 4. Comparison between the relationship Na vs. (Mg+Fe) in emeralds from Tauâ and Itabira. amount of Na, Mg and Fe, substituting for Al, than form of thin pseudohexagonal platelets lying either in the Itabira material. parallel to the basal plane of the emerald or parallel to the prism planes of the emerald, intersecting each 4. Inclusions other at angles of 60 and 120° (Figure 11). Their The most conspicuous property exhibited by the colour is usually a light brown. Tauâ emeralds is the presence of numerous mineral inclusions, which strikingly reflect the mineralogy Tremolite and geology of the area at the time of the formation The habit of the tremolite crystals varies from of the emerald. So far, the following mineral prismatic needles to thick stalks or 'bamboo-like' inclusions have been identified: forms (Figures 5, 6). The crystals are colourless through weakly green to dark green, are randomly Biotitelphlogopite oriented throughout the emerald crystal, and some The probe analyses in Table 3 show that the mica times form dense aggregates. These are typical inclusions in the Tauâ emeralds are phlogopite protogenetic inclusions, and are often broken at one (Mg/Fe>2). Their distribution pattern in the host or both ends, or 'sharpened' to a pencil-like form crystal as well as variations in habit and colour (Figure 7). Table 3 gives two typical analyses. The indicate the occurrence of two distinctively diffe chemical analyses of the amphiboles correspond to rent genetic types; firstly, of protogenetic inclusions tremolite or tremolitic hornblende respectively. mainly of a dark brown colour with irregular or rounded shapes and which are irregularly distri Molybdenite buted within the emerald (Figures 10, 11). In Although molybdenite (Figure 8) occurs in part contrast to these, mica crystals of syngenetic origin as perfect although often warped (pseudo-) hex are crystallographically oriented. These are in the agonal platelets with a metallic lustre, partially J. Gemm., 1988,21,3 i75

Table 3. Microprobe analyses of mineral inclusions in Tauâ emeralds

Phlogopite Tremolite* Allanite**

Si02 42.58 41.68 52.41-56.04 31.28 Ti02 .32 .31 .00- .12 .00 A1203 12.44 12.35 2.42- 4.48 14.43 Cr203 .11 .17 .22- .47 .00 V203 .00 .00 .00- .03 .00 FeO 6.70 7.68 6.45- 7.00 10.60 MnO .04 .00 .12- .40 .00 MgO 22.90 21.90 19.06-20.33 1.27 CaO .04 .06 11.40-12.17 9.71 Na20 .63 .56 .63- 1.17 .21 K20 8.74 8.68 .00- .05 .13 F -2.4 -2.7 .90- 1.20 n.d. Total 96.90 96.10 67.63

* Range encountered in 8 inclusions of tremolite; fluorine not quantitatively determined in all crystals.

** Partial analysis. Cerium was qualitatively determined; usually about 30 wt.% in allanites.

corroded crystals are more common and these then are more or less evenly distributed throughout the take on irregular 'ink stain' or skeletal forms (Figure emerald (Figure 12). 5). Shallow cavities (mainly containing a single phase) and numerous cracks add to the general Allanite (orthite) opacity (Figure 13). Allanite appears both as zoned prismatic and thick 'stems' (stalks), and as fibrous columnar crystals with a dark brown colour, mainly arranged in sheaf-like aggregates (Figure 8). Table 3 presents Acknowledgements a partial chemical analysis of an allanite crystal. We wish to acknowledge the generous co operation of the Mineraçâo Brasileira Limitada Apatite (MBL) and Mr Peter Bartholomew, during the Apatite forms colourless and transparent crys investigation at the Fazenda Boa Esperança, as well tals, occurring mainly as short prisms. as for the use of maps and unpublished material. Mr Raimundo Mariano G. Castelo Branco kindly sup Other mineral inclusions plied material for the chemical analyses and the One of the mineral inclusions could not be mineral inclusion studies. One of the authors (D.S.) identified. This is a strongly orangeish-red coloured is grateful to the following institutions for financial irregular crystal (Figures 5, 14). support and the provision of materials: Deutscher The Tauâ emeralds can contain numerous tremo Akademischer Austauschdienst (DAAD), Deuts lite crystals (with very little or no mica), but can also che Gesellschaft für Technische Zusammenarbeit be totally free of tremolite. This depends on the (GTZ), Deutsche Forschungsgemeinschaft (DFG) composition of the respective host rock of the and the Fritz Thyssen Foundation. We also wish to emerald, i.e. whether the latter is mainly a biotite/ thank Professor H. Schwander for his support phlogopite schist or a tremolite-bearing schist with during the microprobe studies. phlogopite and chlorite. In general, the Tauâ emeralds produced nowa days are not of a high quality, mainly due to the large References number of inclusions in them. Apart from the Andrade, H. L. de, (1983). Mapeamento geológico da área de Boa mineral inclusions described above, many minute Esperança. Relatório interno MBL, Mineraçao Brasileira particles exist which, in part, form dense clouds Ltda., Fortaleza/CE (unpublished). Branco, R. M. G. C., Schwarz, D., Svisero, D. P., Mendes, J. C., resulting in reduced transparency. These collec 1984. Dados mineralógicos da esmeralda da Fazenda Boa tions of minute liquid droplets and/or mineral dust Esperança, Município de Tauá/CE. XXXIII Congresso Bra- 176 J.Gemm., 1988,21,3

Fig.7a Fig.7bFig.7a

Fig.7a

Fig. 12 Fig. 13 rig. S, Tau'; emeralds with numerous protogenetic mineral protogeneuc origin of these crystals is supplied by the inclusions. Apart from columnar-prismatic or ham totally random orientation 10 that of the host cry stal. boo-like tremolite crystals with a light- to dark-green SOx. colour, brownish, mainIy rounded, micas and opaq ue rnolvbden ite can be seen, The latter mineral is usuallv Fig .7b. Pencil-shaped prorogenetic tremolite crystals, ran strongly corroded when il then forms ink- spot or domly oriented within the emerald . SOx. skeletal textures. On the left of the figure , 3 strongly orange -red unidentified crystal can b. seen. 35x. Fig . 8. Perfectl y formed , {pseudo-) hexagonal platelet of molybdenite (black, opaque) with dark brown colurn Fig. 6. Prism atic crystal of tremolire with a dar k green colour, nar cr ystals of allanite, which usually occurs in sheaf alone end intergrown with mol ybdenite, SOx. like aggregates. 70x.

Fig. 7a. Protngene tic crystal of tremolite. These are broken at Fig. 9. Association of mineral inclusions in a Taua emerald one or both ends, ind icating the effects of mechanical shown in polarized light (crossed nicols): column ar influences (transport, tectonic movements) prior 10 prismatic trcrnolite crystal. next to mica platelets and inclusion in the emerald. A further indicat ion of the opaque mclybdeniic. 35x. }. Gcmm., 1988,21,3 177

Fig. ~ Fig. ~ ....--;:;; :---- ~---~

Fig.Fig.~ 8 Fig.Fig.9~

Fig.Fig. 14~ Fig. ~ Fig. 10. Protogeneric dark brown mica inclusion (phlogopite), Fig. 12. Numerous minute particles (liquid droplets andlor The crystals are irregularly bordered and randomly mineral dUSI), the large number of which lead to a oriented in the emerald. SOX. distinct reduction in the transparency and therefore the gemmological quality of the Taua emeralds. SOX. Fig. II. This Taw emerald contains numerous mica crystals which can be classified into two genetic types: Fig. 13. The reduction of transparency in the emeralds can be a) mica crystals with a protogenetic origin, and which caused by the numerous shallow cavities, which often are characterized by lheir usually dark colour and contain a single-phase filling (liquid or gas). lOx. irregular forms. They are randomly oriented in the emerald host crystal; Fig. 14. Strongly orange-red unidentified crystals on the left! b) syngenetic mica crystals are transparent, light right border of the photograph. 7Ox. brown platelets usually with a definite pseudo hexagonal outline. They lie either parallel to the basal plane of the emerald, or parallel to the prism face of the emerald (the crystals appear as dark streaks in the Figure, which intersect at angles of 6Q and 120'). Note; All photographs were taken using immersion liquids. J.J. GemmGemm..,, 1988,21,31988,21, 3 178178

si/eisileiro ro dede GM/OgiO,Geologia, Rio dede Janeiro, Janei ro Resumos,, Resumos, Breves Breves Comunicaçoes Com internointerno MBL,MBL, MiQera~aoMineraçao BrasileiraBrasileira Ltda., FortalezaiCEFortaleza/CE unica~oes etc.,etc., 262·3.262-3. ((unpublished) unpublished).. Cassedanne, J. J. J., 1., Mello, Mello, F. de,F. de1979,, 1979, As esmeraldas As esmeraldas de Tauá de Taui Korpershoek,Korpershoek, H.H. R.,R., 19841984.. SafIraSafira nana ocorrenciaocorrência dede esmeraldaesmeralda dede PilaoPilão Arcado.Arcado. MineraMineraçãofaoMetalurgia. Metalurgia. XLIII,XLIII, 410410,, 5050-8·8.. Tana.Tauá. MineraMineraçãofiioM'lalllrgia Metalurgia,, 453,453, 35-4235-42.. Franz,Franz, GG..,, Grundmann,Grundmann, GG..,, I\ckermand,Ackermand, DD..,, 1986,1986, RockRock Mello,Mello, 1\A.. 1\A.. de,de, Souza,Souza, EE.. M.M. dede,, Mendonca, JJ.. C.. de,de, 19781978.. A formformin ingg bcryberyI l fromfrom aa regionalregional metamorphicmetamorphic terraterraiin ((TauerTaucrnn tectonicatectonica linearlinear nono EstadoEstado dodo Ceara.Ceará. AlUlisAnais XXX Congr. Window,Window, Austria:)Austria:) ParagenesesParageneses andand crystalcrystal chemistry.chemistry. Bras. Goal.,Geol., Recife,Recife, 393·407.393-407. TIcker",Tscherm.. Mineral.Mineral. PelrographPetrograph.. Mill.Mitt. 35,35 , 167·92.167-92 . Schwander,Schwander, H.,H., Gloor, Gloor, F., F. 1980., 1980. Zur Znr quantitativen quamitativen Mikrosonden-Analyse Mikroson. Gomes,Gomes, 1J.. R. dede CC.., Gatto,Gatto, C.C. M. P.P . P.,P., Souza,Souza, G.G. M.. C.. de,, Lnl,Luz, von den·Analysegeologischen Probenvon geologischen mittels kombiniertem Proben mittels kombinier D.D. S.S. de,de, Pires,Pires, J.J. dede L.,L., TexTexeiraeira, W.,W., 1981.1981. Geologi

POR.TABLEPORTABLE POLARISCOPEPOLARISCOPE

NeNeww fromfrom thethe GemmologicalGemmological InstrumentsInstruments LtdLtd rangrangee ooff equipment.equipment. ThThee RayneRaynerr battery-operatedbattery-operated portablportablee polariscopepolariscope;; basedbased oonn thethe principlprinciplee ooff a Scopelight.Scopelight. SimplSimplyy inserinsertt a gemstongemstonee intintoo ththee polariscoppolariscopee 'well', , rotatrotatee ththee filter, anandd vievieww witwithh easeease whethewhetherr ththee gemstongemstonee iiss singlysingly oorr doubldoublyy refractive.refractive. QuicQuickk anandd effortleseffortlesss distinctiondistinction betweebetweenn manmanyy gegemm speciesspecies..

IdeallIdeallyy suitesuitedd ttoo ththee gemmologisgemmologistt anandd jewellejewellerr alikalikee andand attractivelattractivelyy pricepricedd aatt £34.5£34.500 plupluss postagpostagee anandd VAVATT (UK(UK onlyonly - overseaoverseass customercustomerss wilwilll bbee sensentt a prproo formformaa invoice)invoice).. ,.>. :J!I) ." GEMMOLOGICAGEMMOLOGICALL INSTRUMENTINSTRUMENTSS LTLTDD _:k ~ .:i1"_ AA wholl whollyy owneownodd subsidiar$"hstdiaryofth.y of the GemmologicaGtlmmological&!I

~;' ... ., .. <'. SainSaintt Dunstan'Dunstan'ss HouseHouse,, CareCareyy LaneLane,, LondoLondonn EC2EC2VV 8ABABB TelephoneTelephone;: 01-7201-72643746 4374 FaxFax;: 01-7201-7266 48348377 CablesCables;: GeminstGeminst,, LondoLondonn EC EC22 J.J . Gemm.,Gemm., 1988,21,31988,21,3 179179

HallmarkedHallmarked syntheticsynthetic emeraldemerald

Alan Hodgkinson,Hodgkinson, FGAFGA

Clarkston,Clarkston, GlasgowGlasgow G76G76 7JD7JD

The flux-grownflux-grown Lennix Lennix emeralds emeralds probably probably provide pro vide thethe mostmost interestinginteresting rangerange ofof syn,heticsynthetic emeraldemerald inclusionsinclusions toto datedate - soso muchmuch soso matthat thcirtheir appearanceappearance toto thethe inexperiencedinexperienced eyeeye givesgives a convincingconvincing imim pressionpression ofof Nature'sNature's ownown handiwork.handiwork. TheyThey werewere firstfirst reportedreported inin thisthis Journal byby FarnFarn (1980)(1980) andand describeddescribed inin mormoree detaildetail laterlater byby GrazianiGraziani et al.al. (1987).(1987). TheThe firstfirst specimenspecimen seenseen byby thethe authorauthor waswas loanedloaned inin 19831983 bbyy DennisDennis Price,Price, thethe MidlandsMidlands lapidarylapidary andand gemmologist.gemmologist. TheThe latestlatest werweree receivedreceived frofromm MonsieurMonsieur LensLens himselfhimself inin 1987.1987. ThThee authorauthor iiss grateful toto both.both. TheThe refractivrefractivee indicesindices foforr stonesstones ofof botbothh periodsperiods coincidecoincide:: rarayy o(,0)o 1.5641.564 anandd £8 rarayy 1.560,1.560, DRDR 0.004.. Fig.. I.l. ThThee specifispecificc gravitgravityy iiss 2.6552.655.. UndeUnderr ultra-violetultra-violet lighlightt thetheyy shoshoww a googoodd reredd responsresponsee iinn long-wavelong-wave radiatioradiationn anandd a slightlslightlyy reducereducedd responsresponsee iinn shortshort wave. ThrougThroughh ththee ChelseChelseaa filtemterr thetheyy shoshoww a brightbright raspberrraspberryy redred.. ThesThesee fluorescenfluorescentt effectseffects,, duduee ttoo chromiumchromium,, araree mormoree obviouobviouss iinn ththee latelaterr specimensspecimens.. ThThee absorptioabsorptionn spectruspectrumm showshowss a stronstrongg chrochro miumiumm patterpatternn iinn ththee redred,, bubutt ththee 477n477nmm linlinee iinn ththee blubluee wawass mormoree fugitivfugitivee anandd showeshowedd bettebetterr whewhenn ththee yellowish-greeyellowish-greenn owo rayray waswas isolatedisolated byby thethe polarizerpolarizer drawindrawingg bacbackk ththee chromiuchromiumm cut-ofcut-offf a att ththee violeviolett enendd ooff ththee spectrumspectrum.. ThThee crystalcrystalss seeseenn showeshowedd well-developewell-developedd pinapina- coidcoidss frofromm 5-16mm5-16mm,, whilswhilstt ththee prisprismm facefacess werweree frofromm 2.5-5m2.5-Smmm iinn length.. FigFig.. 22..

FigureFigure 1I.. AA vievieww througthroughh aa pinacoipinacoidd facfacee revealrevealss generagenerall apparitionapparitionss iinn naturanaturall aass welwelll aass synthetisyntheticc parpartt ooff ththee hexagonahexagonall crystacrystall plaplann emphasizeemphasizedd bbyy stonesstones.. AA horizontahorizontall immersioimmersionn microscopmicroscopee usinusingg chromchromee variationva:-iationss neanearr ththee edgedgee witwithh aa serieseriess ooff benzybenzyll benzoatbenzoatee RRII 1.57l.57,, gavgavee aa closecloserr loolookk aatt ththee growtgrowthh lineliness nonott alwayalwayss paralleparallell ttoo thmee outsidolltsidee prisprismm intriguinintriguingg inclusioinclusionn repertoirerepertoire.. wallswalls.. ThThee growtgrowlhh lineliness repearepeatt perhapperhapss sevesevenn oorr eigheightt time timess bu butt ar aree onlonlyy peripheral peripheral,, whil whilee ththee centracentrall FigureFigure 2.2. (25x(25x)) StockingStockingss oonn aa washinwashingg linlinee araree areareaa hahass evereveryy appearancappearancee ooff bein beingg naturanaturall bbyy lenlenss cavitiecavitiess whicwhichh hanhangg frofromm ththee pinacoipinacoidd washinwashingg (n(noo pupunn intended!)intended!).. CertainlCertainlyy thertheree ararce variouvariouss lineslines,, anandd ththee contentcontentss beckobeckonn yoyouu closecloserr witwithh veil-likveil-likee inclusioninclusionss floatinfloatingg aboutabout,, bubutt wwee seseee sucsuchh highehigherr magnificationmagnification..

©© Copyrigh Copyrightt ththee GemmologicaGemmologicall AssociatioAssociationn ISSNISSN:: 0022-1250022·12522 181800 JJ.. Gemm.Gerom.,, 1988,21,1988,21,33

Fig. 3. Fig. 4.

Fig. 5. Fig.Fig. 6.6.

Figure 5.5. A generalgeneral aspectaspect ofof ththee LennixLennix emeraldemerald isis a seriesseries ofof smallsmall diffusediffusedd spotspotss sucsuchh asas wwee seesee inin naturalnatural stonestoness wherwheree micmicaa pagepagess havehave beebeenn unableunable toto precipitatprecipitatee outout completecomplete crystalscrystals oror havhavee beenbeen largellargelyy deVOUreddevoured byby rhethe hostilhostilee resorbingresorbing growthgrowth environment.environment. CloserCloser examinatioexaminationn ofof thesthesee diffusediffuse spotsspots inin thethe eaclierearlier specimenspecimen revealerevealedd a curiouscurious phenomenonphenomenon..

Figure 6.6. (240x)(240x) 'Primitive'Primitive lifelife ceIls;cells'. TheThe incluinclu sionssions looklook forfor allall thethe worldworld likelike somesome livingliving cellscells inin Fig. 7.7. thethe processprocess ofof dividingdividing andand multiplyingmultiplying intointo moremore complexcomplex livingliving material.material. InIn factfact rhethe ball-likeball-like aggreaggre Figure 3. (S6x)(56x) SeemsSeems toto presentpresent threethree andand eveneven gategate aceare a multiplemultiple generationgeneration ofof daughterdaughter phenakitephenakite multi-phasemulti-phase inclusionsinclusions crammingcramming allall availableavailable spacespace crystals.crystals. InIn thethe moremore recentrecent emeraldsemeralds thesthesee seemseem toto inin thethe stocking-likestocking-like shapes.shapes. bebe moremore likelike a badlbadlyy brokenbroken pavementpavement area.area.

Figure 4. (120x)(120x) ShowsShows thethe contentscontents inin greatergreater Figure 7.7. (120x)(120x) 'Indian'Indian emerald'!emerald'! SurelySurely thisthis detaildetail andand nownow itit cancan bebe appreciatedappreciated thatthat lhethe gasgas mustmust bebe anan IndianIndian emeraldemerald withwith thethe typicaltypical featurefeature phasephase isis notnot freefree livingliving inin a liquidliquid ftlledfilled cavitycavity asas inin ofof parallelparallel negativenegative prismprism cavitiescavities toppedtopped oror botbot nature,nature, butbut maroonedmarooned byby thethe entrappedentrapped flux andand tomedtomed wirhwith a flatflat pinacoidpinacoid faceface andand oppositelyoppositely haloedhaloed byby whatwhat isis possiblypossibly a glassglass surroundsurround wallwall terminatedterminated byby a steppingstepping downdown ofof rhethe cavity,cavity, whilewhile whichwhich isis inin turnturn enclosedenclosed byby a mosaicmosaic ofof phenakitephenakite thethe gasgas phasephase onlyonly addsadds fidelity. AgainAgain wewe havehave toto crystalscrystals allall enclosedenclosed withinwithin thethe oneone stocking.stocking. NoteNote gaspgasp atat thethe achievementachievement ofof MonsieurMonsieur Lens,Lens, rhatthat hishis thethe washingwashing lineline ofof chromechrome variationsvariations fromfrom whichwhich itit emeraldemerald shouldshould soso closelyclosely mimicmimic thethe inclusionsinclusions ofof isis suspended.suspended. thethe AjmerAjmer provinceprovince emerald.emerald. j.J. GemmGemm..), 1988,21,31988,21,3 181181

Figure 8.8. CrossedCrossed polarizedpolarized lightlight revealedrevealed aa shoalshoal ofof colourfulcolourful alienalien crystalscrystals swimmingswimming parallelparallel andand closeclose toto thethe prismprism walls.walls. TheThe brightbright interferenceinterference colourscolours indicateindicate theirtheir birefringentbiréfringent crysta1linecrystalline nana ture.ture. ItIt occurredoccurred toto meme thatthat theythey tootoo werewere phenakitephenakite crystals.crystals. However,However, thethe Photoatlas of inclusionsinclusions inin gemstr.mesgemstones (Giibelin (Giibelin and and Koivula, Koivula , 1986)1986 )shows show swhat wha t appearsappears toto bebe anan identicalidentical featurefeature inin a LennixLennix emeraldemerald whichwhich thethe authorsauthors identifiedidentified asas berylberyl crystals.crystals.

Figure 9.9. (SOx)(50x) 'Duty'Duty mark;mark'. IslandsIslands ofof fluxflux trappedtrapped inin thisthis LennixLennix emeraldemerald showshow a characterischaracteris tictic rippleripple growthgrowth circularcircular andand ovaloval frames.frames. TheThe chancechance likenesslikeness toto thethe headhead ofof GeorgeGeorge IIIIII andand thethe Fig. 8. ovaloval frameframe areare similarsimilar toto thethe dutyduty marksmarks onon sterlingsterling silversilver mademade inin thethe UKUK betweenbetween 17861786 andand 18201820 whichwhich signifiedsignified thatthat thethe preciousprecious metalmetal dutyduty hadhad beenbeen paid.paid. NoteNote eveneven thethe TeutonTeuton nosenose andand periwig.periwig. SomeSome woulwouldd welcomewelcome a systemsystem ofof 'hallmarking''hallmarking' whichwhich woulwouldd separateseparate thethe naturalnatural fromfrom thethe syntheticsynthetic gemstone,gemstone, butbut thisthis wouldwould spoilspoil allall thethe pleasurepleasure ofof ourour gemmologicalgemmological sportsport andand itit shouldshould bbee mentionedmentioned thathatt therethere araree unfortunatelyunfortunately thosthosee whowho havhavee transtrans poseposedd hallmarkshallmarks inin thethe paspastt andand doubtlessdoubtless ththee samesame fraternitfraternityy woulwouldd playplay gemmologicalgemmological trickstricks alsoalso.. ItIt isis perhapperhapss fortunatefortunate thathatt thethe LenniLennixx isis a fluxflux growngrown producproductt andand asas sucsuchh produceproducess ththee normallnonnaUyy lowlow RIRI readingreadingss belobeloww thosthosee recorderecordedd iinn naturenature.. FigFig.. 9.. I feelfeel loweI owe muchmuch ofof mymy fascinationfascination witwithh gemmogemmo- logy to Dr Gübelin's exploration of these largely logy to Dr Giibelin's exploration of these largely ReferenceReferencess unplumbeunplumbedd crystacrystall depthsdepths.. InIn ththee samsamee wawayy thathatt wwee FarnFaro., AA.. E.E.,, (1980)(1980).. NoteNoless frofromm ththee LaboratoryLaboratory.. JournalJdurnaJ of owowee ssoo greagreatt a debdebtt ttoo ththee latlatee B.WB. W.. AndersoAndersonn forfor Gemmology, XVIIXVII,, 2,2, 73-8073·80.. chartincbartingg ththee arenarenaa ooff spectroscopy,spectroscopy, ssoo musmustt DrDr GrazianiGraziani,, G.G.,, GübelinGiibelin,, E.E.,, MartiniMarlini,, M.M.,, 1987. ThThee Lenni"Lennix GübeliGiibelinn bbee creditecreditedd witwithh beinbeingg somewhasomewhatt ooff a synthetisyntheticc emeraldcmenlld.. Gems & Gemology, 2323,, 33,, 140-71Ml-7.. JacqueJacquess CousteaCousteauu iinn venturinventuringg intintoo ththee subterrasubterra GübelinGiibelin,, E..E.,, KoivulaKojvula,, JJ.. I.I.,, 19861986,, PhotoatlasPhotoazla. of inclusionsinc/unon, in gemstones. ABABCC EditionEdition,, ZurichZurich.. neaneann worlworldd ooff gemstonegemstoness anandd mappinmappingg ththee wawayy withwith hihiss masterfullmasterfullyy educativeducativee photographyphotography.. [[ManuscriptManuscript received 1818 MarchMarch J1988 988]] 182 J. Gemm., 1988,21, 3

Quantitative cathodoluminescence - a modern approach to gemstone recognition

Dr. Johann Ponahlo

Austrian Gemmological Research Institute, Vienna, Austria

Introduction ten or discredited method. Its renaissance in gem- The use of cathodorays is well known among mology started when Gaal(1) published his work in physicists, dating back more than one century. But the seventies. Besides books by Marfunin(4) and the use of cathodoluminescence (CL) as a means for Lumb(3), information on CL of minerals is still gemstone recognition is not so well established sparse and papers are widely scattered among among gemmologists of today. numerous periodicals. Practically nothing is pub It was an Italian mineralogist, A. Pochettino(6), lished on CL of gemstones. who, apparently, was the first to investigate the CL-effects in minerals, observing and measuring Luminescence apparatus them as early as 1910. At about the same time the There are two different ways used to generate (5) Austrian mineralogist, H. Michel , then keeper of electrons the mineralogical department of the Austrian a) by using a 'hot cathode' or, Museum for Natural History, also one of the first b) by using a 'cold cathode' device. gemmologists of central Europe, began, by visual The 'hot cathode' apparatus requires a high inspection of CL-colours, to differentiate between vacuum and precise alignment of the filaments. genuine and synthetic gemstones. Later on CL of Samples need a conductive coating as a pre- gemstones, unfortunately, became a nearly forgot treatment to prevent surface charges. But the

Fig. 1. Luminoscope® mounted on a Zeiss-Standard WL microscope with Zeiss-photomultiplier SF and amplifier On the right a box for the generation and regulation of accelerating high voltage and current, with coil-current regulator for the electron-beam and vacuum meter.

apparatus can be operated at voltages above 60 kV. electrons are available for quantum jumps. With The 'cold cathode' technique demands less emeralds equation (1) was simplified to become sophisticated equipment which can operate in a low equation (2) vacuum at voltages up to 20 kV. During its I = a + b.W (2) operation enough positive ions are produced to This is the equation of a straight line. Such straight neutralise any electrostatic charging. lines are shown in Figure 4 having different gra The CL-investigations described later were car dients (or angles of inclination). ried out by means of a 'cold cathode' equipment, When measuring the CL-intensities of rubies an called a Luminoscope®, supplied by the Nuclide exponential equation (3) was found to give the best Corp., Acton, USA. The research was undertaken fit with experimental data: by the Austrian Gemmological Research Institute I = a.Wb (3) of the Erste Österreichische Gemmologische which for ease of statistical treatment and presenta Gesellschaft e.V., Vienna, Austria. Details of the tion of results (in Figure 8) was used in its apparatus were already published by Ponahlo & logarithmic form (4): Koroschetz(7'8). Figure 1 shows the Luminoscope® logI = loga + b.logW (4) mounted on a microscope Zeiss-Standard WL. Results of CL-measurements on emeralds A few words on CL-theory From Figure 4, it is evident that with emeralds We know that CL-effects in solids depend on the there exist two different areas of CL-intensities that existence of so-called 'centres' which are capable of can be clearly separated from each other, if the absorbing energy from photons or electrons that are values of I (measured in arbitrary units, propor impinging on their surfaces. The centres can be tional to the amplifier photocurrent) are plotted as divided into 'intrinsic' and 'extrinsic' ones. Primarily ordinate figures against the values of the power of the former are lattice imperfections. The latter are excitation W (measured in watts) on the abscissa. caused by certain impurity elements present in the Within certain predetermined conditions of power host-crystals. When considering CL-effects of of excitation, the values of I decrease linearly with emeralds or rubies attention should be paid to decreasing W The results are straight lines for each extrinsic centres only. emerald tested, with 'steep gradients' representative The impurity elements can roughly be grouped of synthetic stones, and with 'low gradients' exclu into sively characteristic of each genuine emerald tested a) 'activators' which give rise to spontaneous CL, so far, regardless of origin. even when present in trace amounts. With most For ease of comparison of data for a larger gemstones these are the transition metal ions: number of both genuine and synthetic emeralds - V+3, Cr+3, Mn+3 and/or Mn+2. including each time the measurement of the same b) 'quenchers' which impede any spontaneous reference stone - the entire data were saved on luminescence process to take place, even in the magnetic tape of a Hewlett Packard HP-41CV presence of some activator material in the same pocket calculator with HP-Digital Cassette Drive crystal. Of the 3d-elements, the transition metal and HP-Thermal Printer plus HP-Interface mod ions Fe+2, Co+2 and Ni+2 are considered to act in ule. These data were then subjected to statistical such a way. treatment. By means of a coordinate transformation When measuring CL-intensities of emeralds and program any slight change of the gradient of the rubies the following relationship (1) was found to straight line of the reference stone could easily be exist between I = intensity of the emitted CL- corrected to standard conditions previously fixed. colour (red with emeralds and rubies) and W = i.V The same procedure was applied, with equally good = power of excitation of electrons; i = exciting results, to the logarithms of the CL-intensities current and V = exciting voltage. versus power-of-excitation data obtained with I = a + b.W + c.W2 + d.W3 (1) rubies as will be shown later. This cubic equation results from statistical poly Growth lines were easily observed in many Gilson nomial regression of the experimental data. With synthetic emeralds. The new Lennix synthetic d>0 equation (1) is characterized by a curve emeralds exhibited a blueish tinge of CL-colour showing a convex form with respect to the abscissae with a rather brilliant brick red showing through. at low values and a maximum at high values of Figure 3 gives an example for both features. In power of excitation. The former is known as dark previous studies on such synthetic emeralds an even voltage effect which results when electrons of an more intense blueish overcast could be observed. activator element are lacking enough energy for a Lower gradients than for all other synthetic quantum jump. The latter arises as an effect of emeralds resulted from measurements of hyd- saturation at high power of excitation when no more rothermally man-made Lechleitner emeralds. But 184 J. Gemm., 1988,21,3

Fig. 2. CL of emeralds: upper left (dark) a genuine Colombian Fig. 3. Crimson-red CL-colour of a Lechleitner synthetic emerald (reference stone 0.85 ct), lower left a synthetic emerald with bluish and white blots; 8.5 kV at 0.9 m A. Gilson emerald showing growth-lines (0.86 ct), upper and lower right two synthetic Lennix emeralds with bluish overcast on scarlet-red basic CL-colour (0.96 and 1.67 ct); 7.5 kV at 0.8 mA.

Fig. 5. Seven rubies placed in vacuum-chamber of the Luminoscope® (flashlight); for details see text.

Fig. 6. The same rubies as in Figure 5 during bombardment Fig. 7. A Knischka synthetic ruby (above) and a less intensely with electrons exhibiting CL-intensities of marked luminescing Ramaura synthetic ruby during the impact differences; for details see text. of electrons; for details see text. Jj.. Gemm.Gemm.,, 1988,21,31988,21,3 181855

1< -!!I >\l, 16 ~~ LU~~< QUANTITATIVE CATHODOLUMINESCENCE ofa~~ QUANTITATIVE CATHODOLUMINESCENCE 1.5 0:> OOFF SYNTHETISYNTHETICC EMERALDEMERALDSS 5~~> VALUES OF I FITTED TO REGRESSION LINE QCCioQ VALUES OF I FinED TO REGRESSION LINE ~§ 9§ 1.3 Qa ---CHAT=CHATHACHAT =CHATHAMM SYNTHETISY THETICC EMERALDSEMERALDS, .U.S.A USA. —- GILGILSS =GILSO= GILSONN SYNTHETISYNTHETICC EMERALDSEMERALDS,, FRANCFRANCEE 1.2 —- '-LINLINDD =LIND=LlNDEE SYNTHETI SYNTHETICC EMERALDSEMERALDS, ,U.S.A USA. LX =LENNIX SYNTHETIC EMERALDS, LX =LENNIX SYNTHETIC EMERALDS. FRANCFRANCEE 11 IGIG =SYNTHETI=SYNTHETICC EMERALDEMERALDSS BBYY PROPROFF NACKENNACKEN, ,FORME FORMERR IG-FARBENAGIG FARBENAG. 1.0 —- CSCSEE =GENUIN=GENUINEE COLOMBIACOLOMBIANN STANDARSTANDARDD EMERALEMERALDD 09

0.8

0.4

02 .... .' . 01 ...... , ..... 0 CS('SIE

EXCITATIOt)(CltAT N POWEPOW(RtR (WATTS=WWATIS w)) ~r 1 22 33 4 5 6 7

Fig,Fig. 4.. QuamitativeQuantitative cathodolumcathodoluminescencinescencee ofof syntheticsynthetic emeraldsemeralds. thesethese stonesstones showedshowed differentdifferent CL-coloursCL-colours thanthan ofof thethe oldold oror newnew ChathamChatham man-mademan-made emeraldsemeralds thosethose observedobserved onon anyany ofof thethe naturalnatural emeraldsemeralds tested.tested. tested. Furthermore,Furthermore, theirtheir CL-intensitiesCL-intensities werewere nonott Thus,Thus, eacheach 'I-versus-W'I-versus-W-plot-plot'' ofof darndata obtainedobtained unifonnlyuniformly distributeddistributed overover thethe entireentire irradiatedirradiated fromfrom quantitativequantitative CL-testsCL-tests wouldwould revealreveal quicklyquickly surface,surface, asas cancan bebe seenseen fromfrom FigureFigure 3.. eithereither thethe genuinegenuine oror thethe syntheticsynthetic originorigin ofof ththee RecentRecent measurementsmeasurements onon a newernewer syntheticsynthetic stone,stone, stonestone dependingdepending onon thethe 'gradient''gradient'o off thethe straightstraight lineline thethe RegencyRegency-create-createdd emerald,emerald, indicatedindicated strongstrong CL·CL- relativerelative toto thethe gradientgradient ofof thethe genuinegenuine ColombianColombian intensity,intensity, nearlynearly asas intenseintense asas thatthat obtainedobtained withwith anyany emeraldemerald referencereference stonestone (compare(compare FigureFigure 4).4). 186 J. Gemm., 1988,21,3

Results of CL-measurements on rubies right), two oval stones, one a Chatham synthetic (in Similar results were obtained with quantitative the middle of the uppermost row), the other a CL-intensity measurements on rubies. Pronounced Lechleitner synthetic ruby (second left in the differences could be found between all genuine middle row), and a round disc of a Verneuil ruby. rubies from Thailand tested so far and their synthe Figure 6 shows these stones in identical arrange tic counterparts regardless of their producers. Man- ment luminescing during a bombardment with made stones by Kashan, Chatham, Ramaura, electrons. Note the subdued CL-intensity of the Knischka, Lechleitner and old and new Verneuil two genuine Thai stones. A distinctly higher CL- synthetics were investigated. intensity is displayed by both the Ramaura and the To present the entire data a plot based on formula Knischka synthetics. A more intense glow is dis (4) was used. Three different logarithmic ordinate played by the Lechleitner synthetic ruby. A marked scales, each differing by one order of magnitude increase in CL-intensity becomes obvious when (10) from the other, and one logarithmic scale on the observing the CL-intensities of the two oval stones, abscissa had to be chosen as can be seen from Figure one a Chatham synthetic and the other a Verneuil 8. Outer left is the logarithmic ordinate scale with ruby. the lowest figures. It was used to plot the (log Other genuine rubies from Burma, India, Kenya, I)-values of CL-intensities of genuine Thai rubies Sri Lanka and Tanzania, which were included in with their (log W)-values on the abscissa. The 95% these measurements, gave inconsistent results of confidence band results from regression analyses of CL-intensities. Therefore, at present, genuine data measured on more than forty Thai rubies. Note rubies from these localities cannot be differentiated the narrow confidence band of these data in the from their synthetic counterparts by means of this diagram (hyperbolae drawn as solid lines from method. uppermost left to lowest right in Figure 8). The inner left-hand logarithmic scale of (log I) CL-spectra of jadeites and some jade-like has ten times greater values than the left-hand outer minerals scale. Such higher values were consistenly found 'Jade' in its proper sense comprises two minerals when measuring CL-intensities of synthetic only: Jadeite, a clinopyroxene, and nephrite, an Kashan rubies. The two broken lines enclose a amphibole. But there exists numerous other green broad band valid for all Kashan synthetic rubies ornamental stones frequently mixed up with both of that could be investigated. So far no exception has these minerals. Among them green grossulars been found. (erroneously called 'Transvaal jade') and amazo- In order to plot the data for Knischka synthetic nites are often met with in gemmologial laborator rubies another tenfold increase of the logarithmic ies. Each of these ornamental stones can be sepa ordinate scale was necessary. This scale is projected rated from the other by making use of their on the outer right-hand ordinate of Figure 8. CL-colours and/or CL-spectra, as will be described Because of the few Knischka synthetic stones below. available one dotted straight line is reproduced in Figure 9 is a photomacrograph of a broken Figure 8. It is located in the middle of a broad band cabochon-jadeite, (centre), flanked by a round (dash-dotted lines) results of measurements on green translucent African grossular (above) and a synthetic Chatham rubies. From Figure 8 it is dyed green agate (below). Figure 10 demonstrates evident that both Knischka and Chatham rubies the vivid CL-colours of two of these minerals. The show up to hundred times stronger CL-intensities jadeite luminescing canary-green and the grossular than genuine rubies from Thailand. intensely orange-yellow with a brownish tint. Fi Ramaura synthetic rubies exhibited distinctly gure 11 shows a polished translucent mottled-green weaker CL-intensities than the Chatham man-made jadeite ring in its natural colour. This ring was products, somewhat between those of Knischka mistaken for grossular because of its rather strong and Kashan rubies. Figure 7 gives a visual impres yellowish-green CL-colour (compare Figure 12). sion of the CL-intensities of a Ramaura and a However, when more specimens had been tested, it Knischka synthetic ruby. was realized that the lack of a brownish tint in the Recent tests made with new synthetic Lechleit CL-colour shown could be considered an indicator ner rubies furnished nearly the same results as for jadeite. With grossular, the orange-yellow CL- found with Kashan synthetic rubies. colour and its brownish tint were always already The photomacrograph of Figure 5 showing seven noticeable at exciting energies as low as 5 kV. rubies was taken in incandescent light: two genuine Nevertheless, such subtle differences in CL-colours rubies from Thailand (centre and lower left), one called for an improvement of the method; the more drop-shaped Knischka synthetic ruby (upper left), so since cut and polished true jadeites are costly one brilliant-cut Ramaura synthetic ruby (lower objects. Finally, when it became obvious that J. Gemm., 1988,21, 3 187

CL-spectra of gemstones are practically unknown no longer visible, whereas the weak band in the to gemmologists and in the literature, preliminary yellowish-green range has more than doubled its tests were started. intensity. No obvious change of peak-wavelengths Basic requirements for recording and analysing has occurred. The medium strong band in the CL-spectra of gemstones were the installation of (NIR) at 766 nm is found again, as in the spectrum additional and more complicated apparatus. The S F of the white jadeite whose blue CL-colour turned photomultiplier mounted on the body tube of the into pink (see Figure 16). This band in the NIR may Zeiss-Standard WL microscope had to be replaced exert some influence on the CL-colour of jadeites. by a newly developed fibre-optic system (Zeiss- The sharp lines visible in many CL-spectra are Schott) to guide the light emitted from the irradia emission lines of the helium gas used to generate a ted specimen through the microscope to a VIS- plasma with a steady leak of gas in the cold cathode NIR-monochromator. Then the photomultiplier tube during experiments. Besides a carrier gas of had to be flanged to the exit slit of the monochroma- electric charges helium exerts a cooling effect of the tor. The CL-light could thus be diffracted into its samples under test. spectral components which, in turn, were converted Quite different CL-spectra were recorded from into electric signals by means of the photomulti the green grossulars tested so far. In Figure 19 three plier. Finally, the electric signals of the entire CL-spectra typical of grossulars are presented. CL-spectrum were amplified (at low noise level) by They differ from each other in their peak intensities means of a Zeiss-amplifier MPC 64. By this means, only. All specimens were luminescing with an then, the CL-colours emitted from the surface of orange colour and brownish tint. A grossular CL- the irradiated specimen could be recorded as spec spectrum, thus, consists of two distinct bands with tral components in a wavelength range between 380 peak-wavelengths at 590 and 719 nm. Considering and 1000 nm. The whole assemblage was automated EPR-studies made on African grossulars (cf. Hage, and operated by a Hewlett-Packard 2000 S compu Zabinski & Amthauer(2)) the band at 719 nm could ter. Spectra could be stored in a double-floppy disk be due to Cr+3, a trace element which has always and reproduced using both a printer and a plotter. been found in these green grossulars. Figure 15 shows two jadeite CL-spectra: the one Another type of CL-spectrum occurred when with higher peaks originating from the canary- amazonites from both South Africa and Brazil were green luminescence of the broken cabochon of tested. This is demonstrated in Figure 20. Such Figure 10 (centre). The other spectrum was taken spectra consist of three peaks occurring at 506, 690 from a jadeite exhibiting a pinkish CL-colour. The and in the range 830 to 840 nm; one in the blue and natural colours of the latter were a vivid green and one in the orange part of the visible spectrum and white. The peaks of both spectra are centred at 407, another one in the NIR. According to the high 557 and 692 nm. Such CL-spectra seem to be typical intensity of the 506 peak the corresponding CL- of many natural green or white translucent or colour of all the amazonites tested was a brilliant opaque jadeites. sky-blue. But there seems to be a subtle difference However, some green jadeites displayed royal between the amazonites from South Africa and blue CL-colours, visible only under bombardment from Brazil which might become obvious in further with highly energized electrons above 12 kV. investigations. The spectrum contained in Figure Sometimes, after prolonged irradiation, the blue 20 belongs to that Brazilian amazonite whose CL-colour would change into a pinkish-red. Then, photomacrograph of blue CL-colour is shown in the peaks originally found at 407, 557 and 692 nm, Figure 14. The spectrum of the amazonite from gave way to a new strong and broad band with a South Africa is reproduced in Figure 21. In this peak maximum at 766 nm (NIR). This follows from CL-spectrum the 690-band is missing. Yet, it is Figure 16 which contains one spectrum of Figure 15 noted that this amazonite exhibits nearly the same for comparison. blue CL-colour, if one compares Figure 14 with One green jadeite luminesced in a rather intense Figure 13. With regard to the sparse information published on activator elements in amazonites and blueish-violet CL-colour; Figure 17 shows its CL- (4) spectrum. If the peak wavelengths of this spectrum the contradictory results found (Marfunin ) more are compared with those of the spectra of Figures 15 detailed studies on this peculiar feldspar seem to be and 16, they are found to occur at the same necessary and are under way. wavelengths. This would indicate that the different CL-colours of the specimens tested so far are caused Conclusion and summary by different peak-intensities relative to each other. In view of the striking results obtained by The CL-spectrum of the jadeite-ring of Figure 12 quantitative CL of emeralds and rubies, i.e. with its canary-green CL-colour is reproduced in measurements of the variation in the integral in Figure 18. The peaks in the bluish-violet range are tensity of the red CL-colour of these gemstones 188 J.J. Gemm. Gemm.,, 1988,21, 1988,21,33

fIer -~.LU >-LL>- y= 4.10410 " ' I I I I I V5~ 410 Z~z^ QUANTITATIVE CL OF THAI w« 5 QUANTITATIVE CL OF THAI I-LULL< GENUINE RUBIES AND SYN 5 ~O ..JU) GENUINE RUBIES AND SYN 7 6 THETIC KASHAN, CHAT Ow THETIC KASHAN. CHAT- 6 0::>OLLI w-.JQ 7 HAM, RAMAURA AND HAM. RAMAURA AND 7 ~~3 8 0:0 KNISCHKA RUBIES 8 9 KNISCHKA RUBIES VALUES FITTED TO "WW~CCQ 9 1-0: 11.IQ 0 -·' VALUES FITTED TO =aWt, R 0.995 I 0 • ~CO l= aW, R 0.995 ~:J LOG-LOG-PAPER -.J«-CÛ LOG-LOG-PAPER ~~ 1985 ~2p5 1985

2 2

3 3

4 4

5 6 6 7 7 8 8 9 9 110 ' 1 (J THAI RUBIES. MASTERSTON[S 1 0 •

BORDER·UN S KASHAN SYNTH RUBIES -0--0-- KASHAN SYNTI I OF LOWEST 2 UV·FLUORESC[NC FOUND - " - 0-.. - 2 BOBORDER-LINESRDER· LINES CHATHA: CHATHAM M SY SYNTH' I R.UB RUBIEIES S ··0—···Q ····0 ···a ··· UPPER BaRD R LINE KNISCIIKA 3 UPPER BORDER LINE: KNISCHKA j- SYNTHSYNTH RUBIES. RUBIE S 3

RAMAURRAMAURA SYNTHA SYNTH RUBIES. RUBIE I SBETWEE I BETWEEN N KNKNISCHKISCHKA AAN AND KASD KASHAHAN SYN NSYNTHTI I RUBIES. RUBIE S

510 . 5.10" 1 I I I I I 3 o· 3.10- 5 6 7 8 9' 7 1.10°

"XCITATiONEXCITATIO POWN POWE R IWAITSR [WATTS---W WI ]

Fig. 8.8 . QuamitalivcQuantitative c31hodoluminescence cathodoluminescence of of natural natura land and sy synthetinlheticc rubies rubies. . J. Gemm.,1988,21, 3 189

Fig. 9. Translucent green grossular (top), broken drop-shaped Fig. 10. The upper two cabochons of Figure 9 under the impact green jadeite (middle) and dark green translucent dyed of electrons (10.5 kV at 1.0 mA); note orange-yellow agate ready for CL-test in vacuum-chamber of the CL-colour of the grossular against canary-green CL- Luminoscope® (flashlight). colour of jadeite; dyed agate is non-luminescing.

Fig. 11. True jadeite-ring, erroneously identified as green Fig. 12. The same ring showing yellow CL-colours with green grossular by visual inspection in daylight. ish tint, rather similar to the orange-yellow of the grossular; but note the conditions of test 14.0 kV at 1mA.

Fig. 13. Plate of green non-translucent African grossular ex Fig. 14. Brazilian amazonite displaying a vivid blue CL-colour hibiting numerous small luminescing dots of yellow with white twisted bands similar to its natural appear ish-brown CL-colour (left piece) against bright violet- ance. The emitted blue CL is strongly polarized. 7.0 blue CL-colour of a South African amazonite (faceted) kV at 1.0 mA. with 12.5 kV at 0.7 mA. 190190 J.J. Gemm.,Gemm., 1988,21,31988,21, 3

280,0280,0

230,0230/0

.. 180,0180/0 "::I -;;,. "U l30,0130/0 .~.. ~ 80,080,0

30.030,0

-20,0-20/0 nm 0 0 0 0 0 0 ~ 0o 0o o0 0o 0o o0 o0 II>to II>in II>in II>in II>in II>in II>in Mo --.#j II>in IDID I"'-t^ cD00 eno>

FigFig.. 15.15. TwoTwo CCL-spectr L·spect raa ofof jadeitesjadei les,, (a)(a) witwithh SIstron rongg bandbandss typicaltypical ooff canary·greencanary-green CL-colourCL-colour,, (b)(b) withwith weakerweaker bandbandss resresultin ultingg frofromm a whitewhite jadeitjadeitee showinshowingg pinkishpinkish CL.colour.CL-colour.

280.0280,0 , M

230,0230,0 h

1S0.0180,0 h '" "::I -;;,. Z 130.0130.0 h 'Ei" '" "..: 80,080,0

30,030, 0

'I ~r ~ j; -•20.20. 0a nm 0 0 0 0 0 0 0 nm 0o o0 0o 0o 0o 0o 0o II>in II>in II>in II>in II>in II>in II>in Mr> >-.I» II>m 00UD Cl"'-v oeo cno>

Fig.Fig. 16.16. CL-spectrumCL-spectrum ofof a jadeitjadeitee showiogshowing pinkish·redpinkish-red CL-colourCL-colour afteafterr prolongeprolongedd irradiatioirradiationn (broken(broken line);line); CL·spectrumCL-spectrum ofof thtbee canary·greencanary-green luminescingluminescing jadeitjadeitee ofof FigurFiguree 1155 (ful(fulll Jine);line); spectruspectrumm wawass taketakenn bbyy stepstepss ofof 2 nm.nm. }.J. Gemm.Gemm.,, 1988,21,31988,21,3 191191

69.0069.00

59.0059.00

49,0lo9,000

"' 1"::l 39,0039.00 ~ " "=•"S 29,0029.00 ~

19,0019,00

9,009,00

-1,00•1 .00 0 0 eo 0 0 0 nm oeo 0o 0o 0o eoo o0 0o Inin I/')m Inin Inin Inm Inm LI'tm PICO ... II'>in ID(O t^ GQ«o 01 >$ "" en Fig.Fig. 1717.. CL-spectruCL-spectrumm ofof a bluish-violetbluish-violet luminescinluminescingg greengreen jadeitejadeite;; 'ipe<;trumspectrum waswas taketakenn byby stepstepss ofof 3 nm.nm.

490.490.00

mk. v\ 390,0390.0

., !:l§ 290.0290.0 0; > ,~ ~2 190,0190.0

90.090.0 V. A/ % '•.n,L,'v' N 'VVV.,1 '.•"iV^'V W'i nmn m -10,0- 10.0 0 >w^

Fig.Fig. 1818.. CL-spe.,trumCL-spectrum ofof thethe greenish-yellogreenish-yelloww luminescingluminescing moniedmottled greengreen jadeite-rinjadeite-ringg ooff FiguresFigures 1111 andand 12.12. SpectrumSpectrum wawass taketakenn bbyy stepstepss ooff 4 nmnm.. 192192 1-J. Gemm.Gemm.,, 1988,21,31988,21,3

11001100

909000 h

700700 h

"'" " 505000 ..'" .~ ;;; ~ 303000

100100 h

-,-10 000 nm 0 0 0 0 0 0 nm 0o 0o 0o o0 0o 0o 0o 0o o0 o0 o0 0o ~ II>in .0to c-. ID CI'Ia»

Fig.Fig. 1919.. ThreeThree CL-specuaCL-spectra ofof greengreen AfricanAfrican grossularsgrossulars.. NoteNote ththee differentdifferent CL-intettsities.CL-intensities. TheThe twotwo strongstrong bandbandss areare characteristiccharacteristicss ofof thithiss mineraminerall witwithh itsits brownish-tintebrownish-tintedd orangeorange CL-colour.CL-colour. SpectraSpectra werweree takentaken bbyy stepstepss ooff I1 nm.nm.

185,0185,0 h

135. 0a

IL,"lA* , "'" -;"g 85.85, a0 -~'" ;;; 'II, ~ l'A 35,035,0 rf X>"'"'Vv,c vv'.^H h., UA-^T ' '* '.''V.'-V-, J • »•--.V, • ii i v rl • 11 -15.0 nnmm o o o o o o o in in m in in in in o ^* in KD i^ 00 CT>

FigFig.. 20.20. CL-spectrumCL-spectrum ooff a3 sky-blusky. bluee luminescinluminescingg BrazilianBrazilian amazonite,amazonite, takentaken bbyy stepssteps ofof 2 om.nm. JJ.. GcrnDL,Gemm., 1988,21,31988,21,3 193193

96.096,0

76.076.0

"il. ~§ 56.056,0 % ;; :> .~.. §~ 36.036,0

16.016.0

Ly-A*"' •«.-_ ../--ii. *>».»,. -4.0 -* nm o o o It)o o o o o in in m m II>m in 11'1in en ^» It)in %D "'"i^ 00 eno> Fig.Fig. 21.21. CL-spectruCL-spectrumm ofof a sky-bluesky-blue luminescinluminescingg SouthSouth AfricanAfrican amazonitearnazonite,, takentaken byby stepssteps ofof 2 nm.nm.

witwithh diminishindiminishingg exCltmgexciting power,power, thisthis methodmethod thithiss paperpaper willwill alsoalso bebe testetestedd forfor applicatioapplicationn toto seemsseems toto havhavee thethe potentiapotentiall toto develodevelopp intointo a routineroutine genuinegenuine andand syntheticsynthetic sapphiressapphires - somesome resultresultss havehave procedureprocedure inin largerlarger gemmologicagemmologicall laboratorieslaboratories alreadyalready beenbeen obtainedobtained witwithh treatedtreated anandd untreateduntreated wherwheree newnew securesecure diagnosticdiagnostic methodsmethods araree requiredrequired corundumscorundums - andand toto manmanyy otheotherr syntheticsynthetic gemgem toto differentiatedifferentiate betweenbetween genuinegenuine anandd syntheticsynthetic stonesstones thatthat havehave nono naturalnatural equivalent.equivalent. FutureFuture workwork emeraldemeraldss and,and, especiallyespecially,, betweebetweenn genuinegenuine ThaiThai maymay bbee carriedcarried ououtt onon thethe applicationapplication ofof CLCL- rubierubiess andand theitheirr difficult-to-analysedifficult-to-analyse syntheticsynthetic councoun microspectrophotometrymicrospectrophotometry toto thethe locationlocation ofof thethe terparts.terparts. ConsideringConsidering thethe highhigh pricesprices ofof thesethese originorigin ofof certaincertain gemstones.gemstones. gemstonegemstoness whicwhichh cancan nownow safelysafely bbee separatedseparated fromfrom ananyy syntheticsynthetic material,material, ththee costcostss ofof thethe wholewhole equipmentequipment:: microscopemicroscope,, photomultiplierphotomultiplier andand ReferenceReferencess amplifieramplifier,, Luminoscope®,Luminoscope®, vacuumvacuum pumppump andand a fewfew I.1. Gaal,Gaal, RR.. A.A. 1':,P., 1976-1977I ?76-1 ?77.. CathodoluminescencCathodoluminescencee ofof getngem accessoriesaccessories,, wilwilll certainlycertainly bbee ofof minorminor importance.importance. materials.materials. Gems alllland G~mok>llY,Gemology, 15,237-44.15, 237-44. RecordingRecording CL-spectraCL-spectra maymay seemseem toto bebe a moremore 22.. HagerHager,, H.H.,, Zahinski,Zabinski, W.w.,, Amthauer,Amthauer, G.G.,, 1?84.1984. EPREPR studstudyy ooff costlcostlyy aass welwelll asas a mormoree sophisticatedsophisticated method.method. ButBut SouthSouth AfricanAfrican gros.ularsgrossulars (South(South AfricaAfriean n jades)jades).. N. JJb. b. Miner. Mh. H. 10,433-43.10, 433-43. takintakingg intointo accountaccount thethe enormouenormouss amountamount ofof rere 3.3. LumbLumb,, M.M. D.,D., \978.1978. LumjlUSCrnceLuminescence rp~cttasciJPy.spectroscopy. AcadcriticAcademic searchsearch work,work, technicaltechnical experiencexperiencee andand monetarymonetary PresPresss (ed.)(00.),, London.London. invesrrnentinvestment involveinvolvedd inin thethe crystacrystall growinggrowing industryindustry 4. Marfunin,Marfunin, A. A.S., S.,1979. 1?7? Spectroscopy, SpeclroSC"l!Y, luminescence luminerc""co and alld radiation radia a computerizedcomputerized modemmodern instrumentinstrument forfor microspecmicrospec- lion centers in minerals. Springer-verlag,Springer-Verlag, Berlin,Berlin, especiallyespecially pp.pp.215-6. 215-6. trophotometrtrophotometryy ofof CLCL mightmight becomebecome a necessitynecessity inin a 5.5. MichelMichel,, HH.. 1926.1926. Die künstlichenkiinSllich"n Edelsteine.Elklrtnne. WilhelmWilhelm gemmologicagemmologicall researchresearch laboratorylaboratory withiwithinn thethe nextnext DiebeneDiebenerG.m.b.H.,r G.m.b.H., Leipzig.Leipzig. fewfew yearsyears.. AdmittedlyAdmittedly,, therethere isis a longlong wayway toto gogo inin 6.6. Pochellino,Pochettino, A.,A., 1913.1913. ÜbeUbetr diedie LLuminescenzerscheinunge uminescenzerscheinungenn takintakingg CL-spectraCL-spectra ofof gemstones.gemstones. TheThe presentpresent workwork inin KrystallenKrysrallen.. Z. Kryst.,Kry>t., 5151,, 113-31.113-31. 7. Ponahlo, J., Koroschelz, Th., 1985. Quantitative Kathodo shouldshould bebe consideredconsidered a fustfirst stepstep towardstowards benerbetter 7. Ponahlo, J., Koroschetz, Th., 1985. Quantitative Kathodo-lumineszenz - ein lumineszenz - ein neuesneues verfahrenVerfahren zurutr UnterscheidungUnterscheidung gemstonegemstone recognition.recognition. echterechter vonvon synthetischensynthetischen SSmaragde maragdenn unundd RRubinen u binen.. Z. DI.Dt. ThereThere areare a numbernumber ofof otherother gemstonesgemstones containcontain Gemmol. Ges.,Ges., 34 34,, 132-42. 132-42. iningg chromiuchromiumm asas anan activatoractivator elementelement besidebesidess thethe 8. Ponahlo,Ponahlo, J., J., Koroschetz, Koroschelz, Th., Th., 1986. \986. Quantitative Quantitative cathodoluminescence cathodolu minescence of gemstone•. A urtral. Gemmol., 16, 64-11. oneone describedescribedd iinn thisthis paperpaper.. Spinel,Spinel, alexandrite,alexandrite, of gemstones. Austral. Gemmol., 16, 64-71. chrome-diopsidechrome-diopside,, hiddenitehiddenite - ttoo mentiomentionn a fewfew - areare (Manuscript[Manuscript receivedreceived I11 J October 1987, revised 20 JanuaryJanuary beinbeingg testetestedd atat present.present. ThThee methodsmethods describeddescribed inin 1988]1988] 194 J. Gemm., 1988,21,3

Gemmological Abstracts

ABDALLAGH, A., 1988. L'amétrine. (The ame- trophotometer for the purpose of making optical trine.) Revue de Gemmologie, 94, 8, 2 figs in absorption measurements at different concentra colour. tions of irradiation, the maximum dose being In the opinion of the author, the amethyst-citrine 20MGy. Optical absorption bands observed were combination known as ametrine has not so far been 8500 and 14,800cm"1 assigned to d-d transitions of found naturally. M.O'D. Fe2+ in b and c sites respectively; 19,500 and 1 5 5 5 5 25,500cm assigned to E^ Ai and B2^ A! d-d BANCROFT, P., 1988. Mineral museums of eastern transitions of Mn3+ respectively. M.O'D. Europe. Mineralogical Record, 19,1,1-52, illus. in black-and-white and in colour. CASSEDANNE, J., 1988. L'améthyste au Brésil. Describes the collections, locations, history and (Brazilian amethyst.) Revue de Gemmologie, 94, access details of fifteen museums in eastern Europe 15-18, 8 figs (lin colour). and the USSR. Many collections include fine First part of a survey of Brazilian amethyst gemstones. M.O'D. deposits classified according to type. M. O'D.

BROWN, G., 1988. Argyle diamonds in the Stuart COZAR, J.S., 1987. La falsa cacoxenita. (False Devlin Champagne Diamond Exhibition. Austra cacoxenite.) Boletin del Instituto Gemologico lian Gemmologist, 16,9, 319-22, 9 figs in colour. Espanol, 29, 30-43, 30 figs (18 in colour). A description of the Argyle mine in Western Inclusions in Moroccan hyaline quartz and in Australia which claims to be the world's largest amethyst from Uruguay, though originally believed producer of diamonds, and of a remarkable collec to be cacoxenite, were found by the electron tion of its fancy coloured diamonds ranging from microprobe to be rutile or goethite. M.O'D. yellow to blue, with various pinks, champagnes and cognac browns, mounted in exotic jewellery by Stuart Devlin for the Champagne Diamond Exhibi DEELMAN, J.C., 1986. Opal-CT in bamboo. Neues tion. [Where is it held?] R.K.M. Jahrbuch für Mineralogie, Monatshefte, 9, 407-15, 3 figs. BROWN, G., 1988. Crystalline quartz. Wahroongai Direct X-ray diffraction study has shown that the Newsy 22, 3,26-9, many sketched figures. opal in the culm of the bamboo Bambusa blumeana An exhaustive account of this abundant mineral, is opal-CT. Precious opal is designated opal-A in a which takes the subject rather beyond normal system of terminology that postulates opal-A as gemmological requirements, compiled from a num highly disordered, nearly amorphous opaline silica, ber of well-known authorities. The 'figuroscope' opal-CT as disordered a-cristobalite, a-tridymite (conoscope) patterns for colourless quartz and and opal-C as well-ordered a-cristobalite. M.O'D. amethyst have been transposed. R.K.M. FRITSCH, E., ROSSMAN, G.R., 1988. An update on BROWN, G., 1988. Using the quartz wedge in color in gems. Part 2: Colors involving multiple gemmology. Wahroongai News, 22, 3, 26-9, many atoms and color centres. Gems and Gemology, 24, sketched figures. 1, 3-15,11 figs in colour. An explanation of this accessory to the polarizing Discusses in detail colour caused by electron mineralogical microscope, advocating its use. interchange between adjacent atoms, e.g. R.K.M. oxygen-^metal charge transfer, as in yellow and blue beryl. Some interchanges skip an oxygen atom BUENO DE CAMARAGO, M., ISOTANI, S., 1988. and occur between metal atoms of different valency, Optical absorption spectroscopy of natural and e.g. Fe2+^>Ti4+ in blue sapphire. Fe3+^>Fe3+ gives irradiated pink tourmaline. American Mineralog yellow in corundum and deep red in tourmaline. ist, 13,17'2-80, 16 figs. Derealization of electrons cause intense colour in Natural pink Brazilian tourmaline irradiated by amber and lazurite. Colour centres caused by atoms gamma rays from 60Co was studied with a spec wholly or partially removed by natural or artificial J. Gemm., 1988,21, 3 195

radiation also cause colour, e.g. green diamond. A GAUTHIER, J.-P, FUMEY, P, 1988. Une gemme most informative paper. R. K. M. metamicte: l'ékamite. (Ekanite, a metamict FRYER, C.W, ED., CROWNINGSHIELD, R., HUR- gem.) Revue de Gemmologie, 94, 3-7, 7 figs (1 in WIT, K.N., KANE, R.E., 1988. Gem Trade Lab colour). notes. Gems and Gemology, 24,1,47-52,18 figs in A survey of ekanite, including a review of the colour. literature and assessments of the mineral's radioac Czochralski pulled synthetic alexandrites were tivity. M.O'D. free from inclusions and fluoresced more strongly than the natural stones under UV. Chalcedony with GRAY, M., 1988. Faceting large gemstones. Gems dendrite stain painted on; clinohumite; diamond and Gemology, 24, 1, 33-42,9 figs in colour. with green luminescence also had cyclotron With new and improved machines and techni 'umbrella' effect; diamond was seriously scratched ques, larger and larger size gems are cuttable and a by hardness test with a diamond point; and an topaz of 22,898 ct and a citrine of 19,548 ct are unusual banded structure in lapis lazuli, are all currently the world's heaviest and largest faceted illustrated and described. stones respectively. Such sizes are cut for prestige Examples of early cultured blister pearl found, rather than as wearable gems. Describes giant possibly dating from 1890, backing of saltwater equipment, saws, grinders, laps and dops needed. shell did not fluoresce. A fine tiara (comb) had Cold dopping is best. Table cut and polished first, pearls proved natural by their non-fluorescent then pavilion facets, then crown. An interesting reaction and by X-radiography. Heat treated sap paper on problems which few commercial lapidar phire had spalled and had an unusual dark hexagon ies need to face. R. K. M. as an inclusion. Another sapphire had intact, well- formed silk undamaged and was therefore con GÜBELIN, E., 1988. The diagnostic properties of the sidered not to have been heat treated. Pink, yellow latest synthetic stones. Australian Gemmologist, and purplish-red tourmalines from Nepal were 16, 9, 329-34 and 344-5,46 figs in colour. examined, RI 1.619-1.637 for the pink, and 1.620- This paper deals with Lennix, Biron, Sovient and 1.648 for the yellowish-green; birefringence varies Seiko synthetic emeralds and with Seiko, Lechleit- with colour. Turquoise necklace looked good quali ner and Knischka (rubies) synthetic corundums in ty, but found to be gibbsite bonded with plastic. considerable detail and with great efficiency. Detec R.K.M. tion is almost always dependant on recognition of characteristic inclusions. Dr Gübelin is the prime GARCIA GUINEA, J., LUQUE DE VILLAR, EJ., 1987. expert in these. R. K. M. Anâlisis de las posibilidades de existencia de diamantes en Espana. (Analysis of the possibili HARDER, H., 1986. Natürliche kobaltblaue ties of the existence of diamonds in Spain.) Spinelle von Ratnapura, Sri Lanka. (Natural Boletin del Instituto Gemolôgico Espanol, 28, 37- cobalt-blue spinels from Sri Lanka.) Neues Jahr 44, 6 figs in colour. buch für Mineralogie, Monatshefte, 3, 97-100. No kimberlite occurrences are yet recorded for Dark blue spinel containing cobalt is described Spain and most reports of diamond have proved to from the Ratnapura area of Sri Lanka. In addition to be quartz. A useful bibliography is appended. Co, traces of Fe, Ni, V and Ga are found in the M.O'D. specimens. No Ga has yet been reported from the synthetic product. In the analysed sample the high GARZÖN, J., 1987. Inclusiones de corindones sin- Co content is 0.09 and this gives too dark a blue for a teticos. (Inclusions in synthetic corundum.) good quality gemstone. M.O'D. Boletin del Instituto Gemolôgico Espanol, 29,6-28, 110 figs in colour. HARDER, H., SCHNEIDER, A., 1986. Isomorpher A very well-illustrated up-to-date account of the Einbau von Eisen und Titan zur Erklärung der inclusions found in synthetic corundum of all types. blauen Farbe von Rutil-und Spinell-haltigen M.O'D. seidig weissen Korunden nach einer Wär mebehandlung. (Solid solution of iron and tita GARZÖN, J., 1987. Pruebas diferenciales del di nium as an explanation of the blue colour of rutile amante y de sus imitaciones. (Proofs distin and spinel containing silky corundum after heat guishing diamond from its imitations.) Boletin del treatment.) Neues Jahrbuch für Mineralogie, Instituto Gemolôgico Espanol, 28, 6-14, 20 figs in Monatshefte, 5, 209-18, 5 figs. colour. Sample of rutile-bearing corundum annealed to A useful account of the present position of 1600°C for 30 minutes were changed to a fine diamond identification. M.O'D. sapphire blue from milky-white. The change is 196 J. Gemm., 1988,21,3

ascribed to electron transitions between Fe2+ and density of water increasing as temperature goes Ti4+ now possible in the corundum lattice. M.O'D. below 4°C, and for ice floating. (Author's abstract) R.K.M. HARDER, H., SCHNEIDER, A., 1987. Die Abkühlungsgeschwindigkeit als Ursache für die NASSAU, K., 1988. The 13 colors of gems and Bildung entweder von Sternkorunden oder von minerals. Lapidary Journal, 41, 11, 32-73,13 figs kornblumenblauen Saphiren. (The influence of (6 in colour). cooling history on the formation of star corun An abbreviated account of the causes of colour in dum or cornflower-blue sapphire.) Neues Jahr gemstones taken from the author's Physics and buch für Mineralogie, Monatshefte, 8, 344-6. chemistry of color, 1983.* M.O'D. Describes the cause of colour and star formation NIEDERMAYR, G., 1988. Mineralien und Smaragd in blue corundum. M.O'D. bergbau Habachtal. (The minerals and the emer HUDSON, S., 1988. North Georgia's fairy crosses. ald-bearing rocks of the Habachtal.) Emser Hefte, Lapidary Journal, 41,11,55-9,2 figs (1 in colour). 9, 1,2-48, 39 figs (23 in colour). Staurolite crystals are found at the Hackney The minerals and the emerald deposit of the Farm near the town of Blue Ridge, Georgia, USA. Austrian Habachtal are described. M.O'D. M.O'D. POUGH, EH., 1988. Gem treatment: andalusite. KARANTH, R.V., 1988. Silica bead industry in Lapidary Journal, 41, 11,14-17. Cambay, Gujarat State, India. Journal of the General overview of the varieties of andalusite. M.O'D. Geological Society of!ndiay 31,4,426-31. The manufacture of silica beads in Cambay has a tradition going back more than 2000 years. Today it POUGH, EH., 1988. Apatite. Lapidary Journal, 41, forms an important cottage industry in Gujarat. 12,14-18. Mechanised grinding and tumbling processes have A general survey of the apatite group of minerals been adopted recently but details are given of more with particular reference to those of gem quality. primitive methods of shaping, grinding and drilling M.O'D. using a bow drill. Colour enhancement of chalce dony is procured by heating nodules in a covered POUGH, EH., 1988. More or less altering the color of earthern pot buried in paddy husk which produces diamonds. Lapidary Journal, 41, 12, 28-32,4 figs a reducing atmosphere. Black onyx is produced by in colour. boiling the chalcedony in sugar solution followed by An account of the history and present state of the treatment with H2S04. R. A.H. art of diamond enhancement by one of the original practitioners. M.O'D. KOIVULA, J.I., KAMMERLING, R.C., 1988. Gem news. Gems and Gemology, 24, 1, 56-9, 8 figs in PROCTOR, K., 1988. Chrysoberyl and alexandrite colour. from the pegmatite districts of Minas Gérais, A report on Tucson '88 Gem and Mineral Show; Brazil. Gems and Gemology, 24,1,16-32,16 figs in theme mineral beryl; carved gems, charoite, alexan- colour. drites from Hematita, Brazil; 'hot pink' sapphires A further paper by an author importing gems from several places, some heat-treated; star sap from these sources. Alexandrites found recently in phire, one a fine purple, 23.97 ct, with an excellent the Hematita area rival or surpass the original star; tsavorite garnets, possibly from new locality; Uralian material in colour and quality and include spessartines from Ramona, California; various some fine alexandrite cat's-eyes. Describes locali other garnets; scapolite cat's-eye; Sri Lankan ties with maps and excellent photographs. Over faceted sillimanite 12.23 ct claimed to be the world's crowding of the worked areas has resulted in largest [Geological Museum in London has one of disputes and gun-fights. Minas Gérais chrysoberyl 19.8 5 ct] ; various synthetics are described. R. K. M. mines are probably the world's most productive. R.K.M. LINDSTEN, D.C., 1988. But will it last? Lapidary Journal, 41, 12, 57-60. ROBERT, D., 1988. L'émeraldolite, une nouvelle A description of the role played by hardness and matière. (Emeraldolite, a new material.) Revue de durability in gemstones. M. O'D. Gemmologie, 94,9-10, 8 figs (2 in colour). Emeraldolite is an undesirable name given to an MITCHELL, R.K., 1988. El and high ice. Wahroongai overgrowth of emerald on beryl. Eye examination is News, 22, 2,2-3. A guest editorial which explains the reason for ^Reviewed in Journal of Gemmology, 1985, XIX, 6, 547. J.Gemm.,1988,21,3 197

sufficient to detect the deception. M. O'D. THEMELIS, T, 1988. Appraising colored stones. Lapidary Journal, 41,11,43-8,1 fig. in colour. ROBERTSON, R.S., SCOTT, D.C., 1988. Precious The writer gives an account of his work as a opal and the weathered profile at Coober Pedy. gemstone appraiser and illustrates the docu Australian Gemmologist, 16, 9, 323-7, 2 maps, 10 mentation he uses. M. O'D. figs (8 in colour). A detailed account of the locality, geology and THEMELIS, T., 1988. Photomicrography. Lapidary geological history of this important opal area. Journal, 41,11, 53-4,2 figs in colour. R.K.M. An introductory discussion of the use of photo SAPALSKI ROSELLO, C, 1987. La esfalerita de los micrography in gem testing. M. O'D. Picos de Europa, Santander (Espana). (Sphalerite from Picos de Europa, Santander, Spain.) Boletin THEMELIS, T, 1988. Flashes in black opal. Lapidary del Instituto Gemologico Espanol, 28, 6-14, 20 figs Journal, 41,12,19,2 figs in colour. in colour. Brief account of the cause of the play of colour in Gem quality sphalerite from Picos de Europa, opal. M.O'D. Santander, Spain, is described and analyses given. M.O'D. VARGAS, G., VARGAS, M., 1988. Orienting color in quartz gems. Lapidary Journal, 41, 11, 49-52, 4 SCHMETZER, K., 1987. Zur Deutung der Farbur figs (3 in colour). sache blauer Saphire-eine Diskussion. (The cause The authors illustrate the best methods of obtain of colour in blue sapphire - a discussion.) Neues ing optimum colour from a given piece of quartz Jahrbuch für Mineralogie, Monatshefte, 8, 337-43, rough. M.O'D. 5 figs. In blue sapphires from different localities a WESTMAN, B. J., 1988. The enigmatic Hope. Lapid distinct Fe2+/Ti4+ charge transfer absorption is ary Journal, 41,12,42-105, 3 figs in colour. always observed with the spectroscope. Natural A brief history of the blue Hope diamond now in untreated or heat-treated sapphires without the the National Museum of Natural History, Smith Fe2/Ti4 bands are green. M. O'D. sonian Institution, Washington DC. M.O'D. WIGMORE, G., 1988. An uncommon material. Aus SCHUHBAUER, E., 1988. Mineraliensuche in Neva tralian Gemmologist, 16,9, 351,2 figs in colour. da und Utah. (Mineral seeking in Nevada and Describes manganoan sugilite, a massive purple Utah.) Lapis, 13, 5,11-27, 31 figs (19 in colour). mineral from Kalahari, South Africa, which is being Red beryl and topaz from a number of locations sold as Royal Lavulite, or Royal Azel. [A suggestion in the south-western United States are described that this is the world's rarest gem is surely an with excellent colour reproductions and occurrence exaggeration?] R.K.M. details. M.O'D. WILSON, WE., 1988. The Iron Cap mine, Graham SNOW, J., BROWN, G., 1988. Sri Lankan eka- County, Arizona. Mineralogical Record, 19, 2, nite. Australian Gemmologist, 16,9,346-8,7 figs 81-7,16 figs (7 in colour). (6 in colour). Fine gem-quality sphalerite is found at the Iron An investigation of an 0.512 ct specimen of this Cap mine, Graham County, Arizona, USA. Crystals extremely rare metamict gem, which was discovered are yellow to yellowish-green and may measure up by the late F.L.D. Ekanayake of Colombo in 1953. to 2.5cm across. The colour darkens to black with The constants and absorption spectrum of this increasing iron content. M. O'D. stone are slightly at variance with those published for the species, but such variation is to be expected ZEITNER, J.C., 1988. US diamond prospects. in a metamict substance. R. K. M. Lapidary Journal, 41,12,21-7, 3 figs in colour. The history of diamond occurrence in the Unites STOCKTON, CM., KANE, R.E., 1988. The distinc States is summarized. Diamonds have recently been tion of natural from synthetic alexandrite by discovered in Wyoming, Colorado and Michigan, infrared spectroscopy. Gems and Gemology, 24,1, and the use of remote sensing techniques may help 44-6,2 figs (1 in colour). future prospectors. M.O'D. Characteristic inclusions separate most natural alexandrites from their synthetic simulants, but in 1988. Abalone pearls. Lapidary Journal, 41, 11, the absence of such features infrared spectroscopy 40-1,4 figs in colour. gives markedly different absorption between the Good quality pictures of abalone from the Lowell natural and synthetic stones. R. K. M. Jones collection. M.O'D. 198 J. Gemm., 1988,21,3

Book Reviews

DRITS, V.A., 1987. Electron diffraction and high- MILLER, A.M., 1988. Gems and jewellery appraising, resolution electron microscopy of mineral structures. techniques of professional practise. Van Nostrand Springer, Berlin, pp. xii, 304. Illus. in black-and- Reinhold, Wokingham. Illus. in black-and-white white. DM248. and in colour. £9.50. Though somewhat advanced for most gemmo- To the best of my knowledge this is the first of its logists, this translation from a Russian original gives kind, and of course it has to be American. They say a useful insight into practices of mineral surface what happens first in the USA follows on to this examination with the most sophisticated techni country, sometimes for the good of us all. This book ques and equipment. After an introduction to will benefit all those FGAs involved in valuation/ crystal structures and the basic mechanism of appraisal work. Of particular merit are the chapters electron scattering by crystals the book goes on to on setting up as an appraiser which show how discuss the geometrical analysis of point electron- important even your stationery can be, including diffraction patterns. Several chapters deal with letters, etc., to prospective clients. It even deals with various aspects of electron diffraction with electron your general appearance; not only should you be microscope techniques. Minerals are introduced good at your work, you must look as if you can do it with the micas in the eighth chapter and layer too! minerals are examined after this point. The last To me Chapter 7 dealing with court appearances chapter deals with chain silicates and there is an and the whole area of expert witnesses is worth the extensive bibliography. M.O'D. price of the book. To others it may be something else. What it will not be are the chapters dealing with gemstones and antique jewellery. These are a little basic and have probably been done this way to GRAMACCIOLI, CM., 1986. 77 meraviglioso mondo give the book a broader sales area. dei cristalli. (The wonderful world of crystals.) However much of the book, although mainly Calderini, Bologna, pp. X, 291. Illus. in colour. about the American appraiser and his work, is very L50,000. professional. It will prove to you that we are some Despite the title this is a serious study of the way behind and although the National Association forms and habits of a wide range of minerals. The of Goldsmiths' Valuers Scheme is up and running crystals are shown in three-colour diagrams with we will have to sprint to catch up. P. S. axes and named faces. Photographs of mineral VARGAS, G0 VARGAS, M., 1987. Diagrams for facet specimens show examples mostly from Alpine ing. Vol. 3. Vargas, Thermal, California, pp. xxiv, regions. M.O'D. 149. Illus. in black-and- white. Price on applica tion. This third volume of faceting styles sent to the LEEDER, O., THOMAS, R., KLEMM, W, 1987. compilers from correspondents consists of sugges Einschlüsse in Mineralien. (Inclusions in miner tions from Australia. Words and numbers are used als.) Enke Verlag, Stuttgart, pp.180. Illus. in to describe the cuts. M.O'D. black-and-white. DM48. Chapters describe the nature of inclusions, the 1987. Diamonds 1988. The Economist, London, pp. H20, C02 and various binary and ternary systems, iii, 38. Price on application. continuing with notes on the use of thermo- The report while confident that the diamond barometry and other diagnostic techniques. The market has recovered from the slump of the 1970s remainder of the book is devoted to different types and early 1980s states that diamond investment of inclusion with notes on the minerals concerned. activity is still subdued. World production is not There is an extensive bibliography and several pages expected to increase very much and there will be a of good quality black-and-white photographs at the continuing swing to low cost centres of manufactur back. M.O'D. ing. M.O'D. J. Gemm., 1988,21,3 199

Proceedings of the Gemmological Association of Great Britain and Association Notices

OBITUARY their determination, for mineralogists, lapidaries, Mr Alistair D. Cairncross, JP, FGA (D.1948), jewellers, etc., with an appendix on pearls and coral, Perth, died suddenly on 7 March 1988. He will be by Dr Max Bauer; Edelsteinkunde Dritte Auflage, missed by many people and particularly by those vollkommen new bearbeitat von, by Dr Max Bauer whom he knew in the trade he loved. A man of many and Dr Schlossmacher; Der Diamant, by Fersmann loveable traits, so generous and happy in nature that and Goldschmidt. it has been a privilege for me and our staff at Mr R. Holt of R. Holt & Co. Ltd., London, for Cairncross Limited to work with him. His talents as the book Precious stones and gems by Edwin W. an artist and designer, in addition to his exceptional Streeter, Chapman and Hall, London, 1877. expertise in the Scottish fresh water pearls, made Dr Margherita Superchi, Milan, Italy, for Analisi him almost unique. He leaves his wife, Mary, and Gemmologica del Tesoro del Duomo di Milano (Gem two children. J.K.C. mological analysis of the Milan Cathedral treasure), by Centro Informazione e Servizi Gemmologici, Mrs Christina J. Sanders (née Hollander), FGA Camera di Commercio, Industria, Artigianato e (D. 1950), died in March 1988. She was a partner in Agricoltura di Milano. the Hollander family gemmology business for very many years and was still actively interested at the NEWS OF FELLOWS time of her death. On 4 June 1988 Mr Peter Read gave a talk on the development of his experimental Brewster-angle Mr John Sopp, FGA (D.1937 with Distinction), refractometer to the German Gemmological Asso Pinner, died suddenly on 20 February 1988. Mr ciation at their headquarters in Idar- Oberstein. Sopp spent his whole career with J.H.Lucas Ltd, After the illustrated talk he demonstrated the ability manufacturing jewellers, late of Kirby Street, Lon of the refractometer to measure the refractive index don EC1, apart from serving in the Royal Artillery of stones over a range of 1.40 to 3.3. When during the Second World War. He joined the questioned on the future development of the instru company as an apprentice designer, studying design ment, he told the audience that the Raynor Optical at the Central School of Art and gemmology at Company had nearly completed their work on a Chelsea Polytechnic. He then moved to the sales pre-production version and that it was hoped that and administration side and finally became Manag the refractometer, complete with a polarized laser ing Director, largely responsible for the export light source, would be available commercially trade. through Gemmological Instruments Limited by the end of the year. It is with great regret that we announce the death of Mr Douglas Wheeler, FGA, former Assistant MEMBERS' MEETING Secretary of the Gemmological Association of Great London Britain, on 7 May 1988. A full obituary is given on On 15 June 1988 at the Flett Theatre, Geological p. 130 above. Museum, Exhibition Road, South Kensington, London SW7, following the Annual General Meet GIFTS TO THE ASSOCIATION ing (see p. 201) a gemmological forum was held, The Council of the Association is indebted to the organized by Mr Christopher Cavey, FGA, and following for their gifts: chaired by Mr David Callaghan, FGA, Chairman of Sir Frank Claringbull for three books: Precious the Council. The panel consisted of Dr Roger stones - a popular account of their characteristics, Harding, B.Sc, D.Phil., FGA, Mr Alan Hodgkin- occurrences and applications, with an introduction to son, FGA, and Dr Jamie Nelson, Ph.D., FRMS, 200 J. Gemm., 1988,21,3

F Inst. E, FGS, FGA. The subjects covered, illus The meeting comprised the following lectures: trated by slides, models and practical demonstra Rare metals in pegmatites (Dr E Moller, Hah- tions, were as follows: the reasons for maintaining Meitner Institut, Berlin, East Germany); Fluid and up-dating collections in museums, visual optics processes during lithium mineralization in pegma and the body colour of gemstones. tites from SE Ireland (Mr M. Whitworth, Imperial College, London); Exotic minerals in Gondwana Midlands Branch pegmatites (Dr J. Kinnaird, St Andrews University, On 15 April 1988 at Dr Johnson House, Bull Scotland); The classification of pegmatitic rocks in Street, Birmingham, the Annual General Meeting SW England and aspects of the pneumatolytic was held at which Mrs Janet S. Leek, FGA, and Mr transition (Mr Lin Yucheng and Dr C. Halls, John R. Bugg, LL B, FGA, were elected Chairman Imperial College, London); Gemstone-bearing and Secretary respectively. This was followed by a pegmatites from Central and Southern Africa (Dr J. talk by Mr Doug Morgan, FGA, and Mr Dennis Kanis, Cascais, Portugal); Gem-bearing pegmatites Price, FGA, entitled 'Gem cutting and polishing for of the Pala district, San Diego County, California the amateur lapidary'. (Mr M. O'Donoghue, British Library, London); Inclusions in gemstones from pegmatites (Dr E.J. North West Branch Gübelin, Meggen, Switzerland). During the tea On 18 May 1988 at Church House, Hanover break there was a poster display on pegmatites and Street, Liverpool, Mr Nigel Grist, FGA, gave a talk their relationship to the chemical evolution of the about his work as a designer jeweller. Members were Galway granite, Western Ireland (Mr M. Whit able to view samples of his work, in particular worth, Imperial College, London, and Dr M. Feely, specimens of his 'Faberge type' flowers. University College, Galway, Ireland). The meeting On 2 June 1988 members of the Branch visited was opened by Dr D.J. Vaughan, President of the De Beers Consolidated Mines Limited in Charter Mineralogical Society and concluding remarks were house Street, London EC1. given by Mr D.J. Callaghan, Chairman of the Gemmological Association. JOINT ACTIVITIES WITH OTHER ORGANIZATIONS MEETINGS OF THE EXECUTIVE Society of Jewellery Historians COMMITTEE On 23 March 1988 at the Geological Museum, At a meeting of the Executive Committee held on Exhibition Road, South Kensington, London SW7, 6 April 1988 at Saint Dunstan's House, Carey Lane, an introduction to practical gemmology was held London EC2, the business transacted included the for members of the Association and the Society of election to membership of the following: Jewellery Historians. On 16 April 1988 a symposium entitled 'Glass in Fellowship jewellery'was held at the Society of Antiquaries, Aziz, Khalid, Karachi, Pakistan. 1987 Burlington House, London, by the Association and Bowers, Norman, Manchester. 1967 the Society of Jewellery Historians. Markov, Mark, London. 1987 The symposium comprised seven lectures, many Ordinary Membership given by experts in their field, and looked initially at B0e, Olav A., Alhus, Norway. the composition and structure of glass (Dr Ian De Winter, Rene, Amsterdam, Netherlands. Freestone), its identification with respect to gem- Donaldson, Geralyn A., Brussels, Belgium. stones (Ken Scarratt), and its use in ancient jewel Foxwejl, Russell N., London. lery (Jack Ogden). This was followed by a compre Harada, Kenji, Tokyo, Japan. hensive talk on glass intaglios and cameos (Gertrud Ishii, Tomoyuki, Tokyo, Japan. Seidmann), a look at the 17th and 18th century Jinnai, Kouji, Kanagawa Pref, Japan. pastes at the Museum of London (Amanda Her Karunanayake, Sarath P, Dehiwala, Sri Lanka. nes), a fascinating study made on 19th century glass Kelley, Kellie J., Clinton, Wash., USA. mosaic jewellery (Judy Rudoe), and a lecture on Lee, Bea W, Seoul, Korea. 20th century costume jewellery (Jane Stancliffe). Lee, Hung K., Taipei, Taiwan. Longden, Sharon D., Eckington. The Mineralogical Society McKay, Kenneth D., Swanage. On 22 April 1988 a half-day meeting entitled Mogi, Masako, Tokyo, Japan. The economic mineralogy and petrology of pegma Nakamura, Chiyo, Hokkaido, Japan. tites' was held at the Geological Society, Burlington Neomoto, Naoki, Tokyo, Japan. House, Piccadilly, London W1V 4BR, by the Ohmura, Keiko, Tokyo, Japan. Association and the Mineralogical Society. Ohshima, Takako, Osaka, Japan. J. Gemm., 1988,21,3 201

Oshima, Hirotomo, Tokyo, Japan. name of the Gemmological Association throughout Otsuka, Masae, Chiba Pref, Japan. the world, and Douglas's death marks the passing of Oudenes, Hendrik, Papendrecht, Netherlands. the trio. Petrides, Eugene, London. As a result of the poor financial position the Sekiguchi, Kazuyoshi, Tokyo, Japan. previous year, stringent economies had been im Shah, Anurag D., Nairobi, Kenya. posed by the Executive Committee and the Council. Shimizu, Terukazu, Tokyo, Japan. Mr Callaghan was pleased to report that there had Sugihara, Kaori, Tokyo, Japan. been a considerable improvement, and this drama Urata, Nami, Osaka, Japan. tic change was due to the Secretary, Mr Jonathan Washi, Shoichi, Chiba Pref, Japan. Brown, and his team. He thanked Jonathan and the Yim, Tae Y, Tokyo, Japan. staff for all they had achieved during the year, and Yokoyama, Haruaki, Fukuoka Pref, Japan. particularly Sandra Page for her work on the Yoshimoto, Misako, Fukuoka Pref, Japan. Diploma course. Mr Callaghan then thanked the Officers and At a meeting of the Executive Committee held on Council for their help and support during the year. 11 May 1988 at Saint Dunstan's House, the business He announced that there will be a change of transacted included the election to membership of venue for the Presentation of Awards this year, due the following: to the closure of Goldsmiths' Hall for alterations. The Presentation is to be held on 25 November 1988 Ordinary Membership at the original Guildhall in the City of London. Colucci, Thomas R., Chatham, NJ, USA. Mr Nigel Israel, Treasurer of the Association, Gainer, Pamela, Wokingham. presented the audited accounts for the year ended Hampton, John S., Lancaster. 31 December 1987. The adoption of the Report and Moulder, Robert P., Sandbach. Accounts was duly proposed, seconded by Mr Thompson, Neil C, Maidenhead. Kenneth Scarratt, and carried. Tirat, Pierre, Poitiers, France. Sir Frank Claringbull, Mr David J. Callaghan, COUNCIL MEETING Mr Noel W. Deeks and Mr Nigel B. Israel were At a meeting of the Council held on 3 May 1988 at re-elected President, Chairman, Vice-Chairman the Royal Automobile Club, Pall Mall, London and Honorary Treasurer, respectively. Messrs. C.R. SW1, the business transacted included the election Cavey, PJ.E. Daly, J.A.W. Hodgkinson, D. Inker- to membership of the following: sole, B. Jackson and M.J. O'Donoghue were re elected and Mrs Gwyneth Green elected to the Council. Messrs C.B. Jones and A.W Round retired Fellowship from the Council and Mr Callaghan thanked them Aloy, Richard N., San Jose, Calif., USA. 1976 for the help and support they had given. Gemayel, Farid, Jounieh, Lebanon. 1982 Messrs. Ernst and Whinney were reappointed Hellqvist, Ing-Britt E., Tumba, Sweden. 1987 Auditors, and the proceedings then terminated. Leung, Wai Hung, Kowloon, Hong Kong. 1987 Verjee, Nasim K., Nairobi, Kenya. 1982 GEM TESTING LABORATORY OF GREAT Ordinary Membership BRITAIN Archard, Trevor J., Hove. On 13 June 1988 the Gem Testing Laboratory Baldridge, Stephanie A., San Jose, Calif., USA. opened an office at 10 Vyse Street, Birmingham. A Kanis, Jan, Cascais, Portugal. qualified gemmologist is in attendance on Monday Langridge, John P., Sompting. and Tuesday of each week to provide a 'While you Mulkern, Michael P., Brewster, NY, USA. wait' testing service with a verbal report for most Tracy, Joseph M., Kansas City, Mo, USA. types of gemstone. The service is available to ANNUAL GENERAL MEETING 1988 members of the Association and further details may The 57th Annual General Meeting of the Associa be obtained from Alan Clark, FGA, at the London tion was held on 15 June 1988 at the Flett Theatre, laboratory on 01- 405 3351. Geological Museum, Exhibition Road, South Kens ington, London SW7. CORRIGENDA The Chairman, Mr David Callaghan, FGA, On p. 83 above, second column, 7th line, for opened the meeting by welcoming members. He '0.015', read'0.016' referred to the sad news of the death of Mr Douglas On p. 84 above, second column, first line, for Wheeler, FGA (obituary p. 130 above). The late 'possible', read 'impossible' Gordon Andrews and Harry and Douglas Wheeler On p. 84 above, in Table 1, the ± signs should formed a team that did so much for building the have been omitted after 'birefringence' 202 J. Gemm., 1988,21,3

Letter to the Editor

From Gordon S. Walker, ASTC, FIO, FGAA

Dear Sir, peripheral vision technique is horizontal in applica In reference to a paper in the April 1988 issue of tion instead of vertical in reference to the absorption the Journal, by R. Keith Mitchell, FGA, entitled lines and scale. 'An important Australian contribution to gemmol- I know a gemmologist who has a layman's way of ogy', I would like to make the following observa putting it. He says, 'I look around the corner of the tions, if I may. edge of the spectrum and then I see the absorption I quite understand Mr Mitchell's doubts concern lines' ing the third decimal place accuracy, particularly in It should be noted that the matter of the third reference to the mobility of the spot. decimal place is quite useless unless we address two So very often, in my field of study and practice, I other considerations which are of paramount im find that the actual problems which occur have portance: for unless we do this, the whole exercise is within themselves their own solutions - and such is useless and the results will be at the best very the case here. approximate indeed! When in deep water, I can either drown or The first is to achieve an accurate second decimal become a diver! reading by using the control of several singly With the refractometers I use, the spot takes on a refractive cabochons with flat ground and polished rugby ball shape which is made as small as possible. bases which are used as a check on the second (and third) decimal place read. The technique is as follows: The result is that 0.01 to 0.02 must be added to Using the point of the 'rugby ball' direct your the spot reading to give the same result as is gaze away from this and towards the scale side and achieved on the flat surface. The amount added even beyond this to utilize more of the peripheral appears to be standard for each operator. vision of the eye's retina. The central vision of the The second matter that needs to be mentioned is eye has a high proportion of cones which produce the need of a check on all commercially sold high visual acuity whereas the periphery has more refractometers, for some leave much to be desired. rods which have a higher sensitivity for movement. It is wise to check all instruments from time to time By using the mobility of the image, it is easy after with a material with a known RI, such as a flat some practice to judge equal swings with slightly ground and polished piece of optical crown glass, peripheral vision and record the higher and lower having an RI of 1.523 (or whatever the manufactur shadow edges of these swings, and taking the er's specifications are). middle position of such swings as the third decimal In conclusion please thank Mr R. Keith Mitchell place - such swings should be as small as practical. for his comments and opinions regarding the origin This method is not so easy with the Dialdex, but al paper. still possible. It is important to stress that not everyone will be Yours etc., able to get an accurate third decimal place in a short space of time and such should never be expected Gordon S. Walker from a student sitting for an examination is gem- June 1988 mology! PO Box 37, Belmont, NSW 2280, Australia. The mobility principle combined with the peripheral vision technique is not new; for this is the References very method used by gemmologists who get better Mitchell, R.K., 1988. An important Australian contribution to gemmology. Journal of Gemmology, 21, 2, 67-8. than average results with a spectroscope. Walker, G.S., 1987. A new 'spot reading' technique for the The main difference here is that the mobility and refractometer. Australian Gemmologist, 16, 7, 253-6. J. Gemm., 1988,21,3 203

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Historical Note The Gemmological Association of Great Canadian Gemmological Association, the Gem Britain was originally founded in 1908 as the and Mineral Society of Zimbabwe, the Education Committee of the National Gemmological Association of Hong Kong, the Association of Goldsmiths and reconstituted Gemmological Association of South Africa in 1931 as the Gemmological Association. Its and the Singapore Gemologist Society. name was extended to Gemmological TheJournal o/Gemmology was first Association of Great Britain in 1938, and published by the Association in 1947. It is a finally in 1944 it was incorporated in that name quarterly, published in January, April, July, under the Companies Acts as a company and October each year, and is issued free to limited by guarantee (registered in England, Fellows and Members of the Association. no. 433063). Opinions expressed by authors are not Affiliated Associations are the necessarily endorsed by the Association. Gemmological Association of Australia, the

Notes for Contributors The Editors are glad to consider original is consistent with 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 lO iOOO 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, whe!"eas 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 five copies 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 Volume 21 No.3 July 1988

1 hcJournal of Gemmology

Contents

Douglas Wheeler 130

Notes from the Laboratory — 12 K. Scarrâtt 131

The 10x lens A. E. Farn 140

Beryl papers ,

Etch figures on beryl J. I. Koivula 142

Characterization of Russian hydrothermally-grown synthetic emeralds K. Schmelzer 145

Radiation induced structural damage in beryl J. I. Koivula 165

The emeralds of Fazenda Boa Esperança, Tauä, Cearâ, Brazil: occurrence and properties D. Schwarz, H. A. Hänni, F. h. Martin and M. Fischer 168

Hallmarked synthetic emerald A. Hodgkinson 179

Quantitative cathodoluminescence — a modem approach to 182 gemstone recognition J. Ponahlo 194 Gemmological abstracts 198 Book reviews Proceedings of the Gemmological Association of Great Britain and Association Notices 199

Letter to the Editor 202

ISSN: 022-1252

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