Volume 21 / No. 2 / 1988

Volume 21 No.2 April 1988 The Journal of Gemmology

GEMMOLOGICAL ASSOCIATION OF GREAT BRITAIN OFFICERS AND COUNCIL

President: *Sir Frank Claringbull, Ph.D., F.Inst.R, 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.Allnutt,M.Sc, J.A.W.Hodgkinson,FGA *J. B.Nelson, Ph.D., Ph.D.,FGA D. Inkersole, FGA FRMS, F.Inst.R, FGA *E.M.Bruton,FGA B. Jackson, FGA W. Nowak, C.Eng., *C.R.Cavey,FGA *E. A. Jobbins, B.Sc, C.Eng., F.R.Ae.S.,FGA P.J.E.Daly,B.Sc, FIMM,FGA M. J. O'Donoghue, FGA C. B. Jones, FGA MA, FGS, FGA *A.E. Farn, FGA *G. H.Jones, B.Sc, Ph.D., *RG. Read, C.Eng., A. J. French, FGA FGA MIEE, MIERE, FGA *R. R.Harding, B.Sc., D.G.Kent, FGA A. W.R. Round, FGA D.Phil, FGA D.M.Larcher,FGA *K. Scarratt,FGA J.W.Harris, B.Sc, A. D. Morgan, FIBF, FGA E. Stern, FGA M.Sc.,Ph.D. *C.H. Winter, FGA

^Members of the Executive Committee

Branch Chairmen: Midlands Branch: P. J. West, 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 TheJournal of Gemmology

VOLUME 21 NUMBER TWO APRIL 1988

Cover Picture Tanzanian enstatite rough (see 'Gemmological investigation of a large faceted east African enstatite', p.92). Photograph by Tino Hammid.

ISSN: 0022-1252 66 J. Gemm., 1988,21,2

GEMDATA A computer program for gem identification

Now available in an expanded version with colour-enhanced text, GEMDATA will run on any IBM PC-compatible computer. It is designed to help with both appraisal identifications and gemmological studies. A full report of the program was given in the Journal of Gemmology, 20,7/8,467-73. Optional yearly update of GEMDATA will be available. GEMDATA is supplied on a 5 Winch double-sided, double-density disk, and contains the following three sections :- 1. Gem Identification from a databank of over 220 gems 2. Gem Comparisons (side-by-side display of the constants of selected gems) 3. Gem Calculations (S.G., reflectivity, critical angle, Brewster angle) The GEMDATA package, complete with disk, operating notes and gem index, costs £75.00 (plus postage and VAT). To order your package please use the coupon given on p. 126.

Gemmological Association of Great Britain Saint Dunstan's House, Carey Lane, London EC2V 8AB Telephone: 01-726 4374 Fax: 01-726 4837 Cables: Geminst, London EC2 J.J. Gemm.,Gemm., 1988,21,21988, 21, 2 6767

AnAn importantimportant AustralianAustralian contributioncontribution toto gemmology gemmology

R. Keith Mitchell, FGAFGA

AlmostAlmost fortyforty yearsyears agoago thethe latelate LesterLester B.B. BensonBenson picture,picture, sincesince thethe latterlatter consistsconsists ofof anan infiniteinfinite Jnr,Jnr, a brilliantbrilliant innovatorinnovator withwith thethe GemologicalGemological numbernumber ofof imagesimages ofof thethe tinytiny hole,hole, andand thethe longlong InstituteInstitute ofof America,America, hithit onon thethe 'distant'distant vision'vision' oror exposureexposure neededneeded ifif a smallsmall enoughenough holehole isis used.used. TheThe 'spot''spot' methodmethod ofof obtainingobtaining approximateapproximate refractiverefractive samesame principleprinciple isis usedused inin moremore elaborateelaborate lensedlensed indexindex readingsreadings fromfrom cabochoncabochon oror otherother curvedcurved cameras,cameras, whewhenn stoppingstopping downdown toto a veryvery smallsmall polishedpolished surfaces.surfaces. EverEver sincesince thenthen successivesuccessive stustu apertureaperture increasesincreases thethe deptdepthh ofof focusfocus veryvery substansubstan dentsdents havehave struggledstruggled toto putput thisthis methodmethod toto use.use. tially.tially. ButBut inin thesethese thethe increasedincreased focalfocal depthdepth isis stillstill WithWith thethe instrumentinstrument scalescale viewedviewed fromfrom a distancedistance limitedlimited byby thethe presencepresence ofof a lenslens.. TheThe pinholepinhole ofof aboutabout 30cm30cm (1(1 foot)foot) thethe exercisexercisee involvesinvolves a goodgood cameracamera sufferssuffers nnoo suchsuch limitation.limitation. dealdeal ofof head-movement,head-movement, bothboth verticallyvertically andand fromfrom MrMr WalkerWalker hashas cleverlycleverly usedused thethe universaluniversal focusfocus sideside toto side,side, forfor thethe tinytiny imageimage ofof thethe spotspot ofof contactcontact principleprinciple toto improveimprove thethe LesterLester BensonBenson distantdistant fluidfluid slidesslides outout ofof sightsight withwith remarkableremarkable easeease andand itit vision RIRI method.method. isis oftenoften necessarynecessary toto re-positionre-position thethe stonestone onon thethe UsingUsing a pinholepinhole ratherrather lessless thanthan a millimetremillimetre inin instrumentinstrument,, andand ttoo jiggljigglee thethe headhead endlesslyendlessly beforebefore diameter,diameter, heldheld asas closeclose asas possiblpossiblee toto thethe eyeeye andand atat a thethe requiredrequired halhalff shadow,shadow, halfhalf light,light, positiopositionn isis distancdistancee ofof nono moremore thanthan 6cm6cm (2(2Vi1/2 inches)inches) fromfrom thethe obtained.obtained. Then,Then, withwith thethe elusiveelusive discdisc imageimage hoverhover refractometerrefractometer eyepiece,eyepiece, hhee seessees bothboth thethe scalescale andand inging precariouslyprecariously inin sightsight andand nicelynicely bisectedbisected,, oneone thethe contactcontact spotspot nicelynicely inin focusfocus atat oneone andand thethe samesame realisesrealises toto one'sone's totaltotal disgust,disgust, thatthat thethe instrumentinstrument time.time. ThisThis closercloser viewpoinviewpointt alsoalso meanmeanss thatthat farfar moremore scalescale iiss completelycompletely outout ofof focus!focus! ofof thethe scalescale isis nownow visiblevisible andand thethe spotspot nono longerlonger ForFor thethe presentpresent writer,writer, whowho hashas severesevere astigmaastigma playsplays itsits devilishdevilish hidehide andand seekseek gamegame withwith thethe tismtism andand wearswears bifocalbifocal glasses,glasses, thisthis lastlast problemproblem waswas viewer.viewer. AnAn approximateapproximate RIRI cancan bebe obtainedobtained withwith nono easilyeasily solved.solved. TheThe bisectedbisected spotspot imageimage waswas locatedlocated difficultydifficulty atat all.all. MrMr WalkerWalker eveneven suggestssuggests thatthat thisthis soso usingusing thethe distancedistance vision sectionsection ofof thethe spectaclespectacle simplifiessimplifies thethe procedureprocedure asas toto makemake accurateaccurate estiesti lens,lens, andand thethe heaheadd thenthen heldheld rigidlyrigidly steadysteady inin thatthat matesmates toto a thirdthird placeplace ofof decimalsdecimals possible.possible. positionposition whilewhile thethe rightright hanhandd raisedraised thethe specsspecs ttoo thethe I havehave nownow triedtried thisthis littlelittle devicedevice exhaustivelyexhaustively andand pointpoint wherewhere ththee scalescale couldcould bbee seen,seen, in focus,focus, cancan heartilyheartily recommendrecommend itit.. MyMy pinholepinhole was mademade inin throughthrough thethe 'reading''reading' sectionsection ofof thethe lens.lens. ButBut mostmost a developed,developed, unexposedunexposed (black)(black) photographicphotographic transtrans peoplepeople dodo notnot havehave thisthis simplesimple solutionsolution toto hand.hand. parencparencyy bbyy thethe simplesimple expedientexpedient ofof pushingpushing thethe However,However, thethe AugustAugust 19871987 issueissue ofof the Australian poinpointt ofof a ververyy finefine stringingstringing needleneedle a shortshort wayway Gemmologist prints prints anan excellentexcellent paperpaper byby GordonGordon S.S . throughthrough it.it. ThisThis gavegave meme a reasonablyreasonably cleanclean holehole ooff Walker,Walker, ASTC,ASTC, FlO,FIO, FGAA,FGAA, inin whichwhich hehe describesdescribes aboutabout O.5mm0.5mm inin diameter.diameter. (The(The blackblack surfacesurface isis a remarkablyremarkably simplesimple devicedevice whichwhich veryvery largelylargely advisableadvisable ttoo avoidavoid distractingdistracting reflectionsreflections fromfrom oneone overcomesovercomes thethe difficultiesdifficulties whichwhich havehave broughtbrought ofof a lighterlighter colour.)colour.) I placeplacedd a cabochoncabochon stonestone onon a miserymisery andand frustrationfrustration toto soso many.many. suitablysuitably smallsmall spotspot ofof contactcontact fluidfluid onon thethe prismprism ooff MMrr WalkerWalker isis anan opticianoptician asas wellwell aass a gemmogemmo thethe refractometer.refractometer. RemovingRemoving mmyy spectacles,spectacles, withwith logist,logist, andand isis obviouslyobviously familiarfamiliar withwith thethe pinholepinhole outout whichwhich I cancan focusfocus nothing,nothing, I broughtbrought thethe pinholepinhole diaphragmdiaphragm asas a primitiveprimitive devicedevice toto overcomeovercome focusfocus closeclose toto mymy rightright eyeeye atat a distancedistance ofof aboutabout 7.5cm7.5cm inging problemsproblems includingincluding eithereither longlong oror nearnear sight.sight. (three(three inches)inches) fromfrom thethe instrumentinstrument eyepiece.eyepiece. BothBoth SomeSome readersreaders maymay havehave experimentedexperimented withwith a scalescale andand spotspot werewere nicelynicely inin focusfocus andand a slightslight pinholepinhole cameracamera which,which, without a lens, cancan givegive a movementmovement ofof mymy headhead broughtbrought thethe spotspot imageimage toto thethe picturepicture inin whichwhich a scenescene isis alwaysalways inin focus,focus, regardregard positionposition wherewhere itit was bisectedbisected equallyequally intointo lightlight andand lessless ofof thethe distancedistance ofof thethe subjectsubject fromfrom thethe pinhole.pinhole. darkdark areas.areas. A readingreading ofof 1.541.54 forfor chalcedonychalcedony waswas InIn thisthis thethe onlyonly limitinglimiting factorsfactors areare thethe sizesize ofof thethe obtainedobtained immediatelyimmediately andand withwith thethe utmostutmost ease.ease. pinhole,pinhole, whichwhich regulatesregulates thethe sharpnesssharpness ofof thethe TheThe previousprevious needneed toto standstand upup andand movemove aroundaround

rather like an animated blancmange, while ogling Dialdex refractometer because the black screen the instrument from a distance, is obviated. The which moves down to mark the shadow-edge whole test can be carried out while sitting at the reading is always easily visible. But there is a bench or table. tendency among students to assume that they can This very simple procedure adds so much to still estimate readings to three places of decimals cabochon stone testing by making a difficult and when using the calibrated knob of this instrument rather elusive method absurdly easy, that one is left to read the RI. In point of fact the method is no wondering why no one has hit upon it before in the more accurate with the Dialdex than it is with the many years since Lester Benson published his standard scale refractometer, and readings should method in 1948.1 do, however, take leave to doubt still be regarded as rather approximate. The pinhole whether the reading facility is improved to the point device still helps here since it allows the shadow where a reliable third place of decimals could be edge to be seen from a closer viewpoint when the estimated. This has still to depend on the ability of head can be held much steadier without undue the individual observer to judge when the spot is strain, and a wider field of view allows one to judge exactly bisected. That judgement may be easier, but much more easily when the spot is accurately the spot image is still very mobile with the slightest bisected. movement of the head and such accuracy would still be difficult. But the fact remains that Mr Gordon Walker has found a way to make a rather tricky testing Reference procedure almost as simple as the test for a faceted Walker, G.S., 1987. A new 'spot reading' technique for the stone. All gemmologists should try it! refractometer. Australian Gemmologist, 16, 7, 253-6. It is only fair to mention that distant vision testing is usually less difficult with the Rayner [Manuscript received 8 January 1988] REFRACTOMETER SODIUM LIGHT SOURCE UNIT This very slim, compact unit, which houses a long-life pure sodium vapour bulb will, without doubt, assist in the detection of reliable and accurate refractive index readings. Illustrated with the Rayner Dialdex refractometer. Special introductory offer £125 plus postage and VAT Gemmological Instruments Ltd (UK only*). are pleased to announce the new Rayner Dialdex refractometer, Rayner refractometer sodium fluid and case, £182.00 plus light source unit. postage and VAT (UK only*) *Overseas customers will be sent a pro forma invoice. GEMMOLOGICAL INSTRUMENTS LTD A wholly owned subsidiary of the 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

Orientated lath-like inclusions of a new type in spinel

Dr Karl Schmetzer

Institute of Mineralogy and Petrography, University of Heidelberg, West Germany and Deutsche Stiftung Edelsteinforschung, Idar-Oberstein, West Germany

Abstract set of inclusions will produce a six-rayed star if the A bluish-violet spinel from Sri Lanka with orientated crystal is cut cabochon and viewed in directions inclusions was investigated by microscopy, X-ray single parallel to the four three-fold axes, i.e. at right crystal diffraction, and electron microprobe techniques. angles to the octahedral faces. The light bands of The sample reveals four sets of lath-like double refracting two different six-rayed stars intersect at 90° at each crystal inclusions which are orientated parallel to the of the poles of the three four-fold axes of the spinel three-fold axes of the host. The guest mineral is one of the forming four-rayed stars if the crystal is viewed at Al2SiO5 polymorphs, most probably sillimanite. A general survey of the literature dealing with orientated inclusions right angles to the cube faces (cf. Switzer, 1955). and asterism in spinel is given. Extremely rare are spinels which disclose only one single six-rayed star on the surface of the Orientated inclusions in spinel cabochon. In these spinels, only one triangular set In the present paper, orientated inclusions of a of intersecting needle-like inclusions is present new type in spinel are described. The sample lying in one single plane parallel to one octahedral investigated did not show asterism. This fact is due face of the spinel (Giibelin, 1968; Giibelin and to the dimensions of the lath-like guest crystals. Koivula, 1986). Nevertheless, a summary of the literature dealing The nature of the orientated needle-like inclusions with orientated inclusions and asterism in spinel is is described by different authors with some presented for comparison as well as in order to avoid controversy. This is due to the fact that both types confusion with other types of orientated needle- to of asterism in spinel mentioned above were not rod-like guest minerals in spinel. clearly separated in each publication. The needle The presence of orientated inclusions in natural like inclusions which are present in the common spinel was of certain interest to gemmologists type of asteriated spinels showing alternating six- because asterism in spinel results from diffraction and four-rayed stars, are most probably small rutile of light from these minerals. Asteriated spinels crystals. This opinion was already published by from Sri Lanka and Burma were described by Eppler (1958) and Strunz (1968) and was also different authors, e.g. Anderson and Payne (1954), confirmed by Giibelin and Koivula (1986). However, Switzer (1955), Giibelin (1957) and Eppler (1958). the only known experimental proof for the presence In general, alternating six- and four-rayed stars are of rutile in asteriated spinel was made by the present observed along the curved surface of the spinels author by X-ray powder diffraction (cf. Bank, which are cut in the cabochon form. The axes 1980, 1983). passing through the centre of each six-rayed star are The cause of a single six-rayed star in the second parallel to the four three-fold axes of the cubic rare type of asteriated spinel (cf. Giibelin 1957, spinel; the axes passing through the centre of each 1968; Eppler, 1958) is due to the presence of four-rayed star are parallel to the three four-fold orientated needle-like inclusions of sphene (Giibelin axes of the crystal. This common type of asterism in and Koivula, 1986). In that case, only one single spinel is caused by triangular sets of needle-like plane with three sets of parallel inclusions is inclusions (Figures 1, 2), which are orientated observable. parallel to the six edges of the octahedron faces <110>. According to the symmetry of the cubic Experimental procedures and results system in each plane parallel to the eight octahedron In the present paper, a faceted bluish-violet faces of the spinel with inclusions parallel to spinel from Ratnapura, Sri Lanka, was studied. <110>), three intersecting sets of needles at 120° This sample was submitted to the author by a gem intervals are observed (Figures 1,2). Each triangular collector in order to determine the nature of some

Fig. 1. Asteriated red spinel from Sri Lanka; view in a direction Fig. 2. Asteriated red spinel from Sri Lanka; various sets of parallel to one of the three-fold axes <111>; the axes of parallel orientated needle-like inclusions, most probably three sets of needle-like inclusions, most probably rutile, rutile. 75x. are orientated parallel to one octahedron face <111> at 120° intervals. 75x.

Fig. 3. Bluish-violet spinel from Sri Lanka containing four sets of Fig. 4. Bluish-violet spinel from Sri Lanka containing four sets of parallel orientated lath-like inclusions, most probably parallel orientated lath-like inclusions, most probably sillimanite. 50x. sillimanite. 70x.

Fig. 5. Bluish-violet spinel from Sri Lanka; view in a direction Fig. 6. Bluish-violet spinel from Sri Lanka; view in a direction parallel to one of the three-fold axes <111>; cross- parallel to one of the four-fold axes <100>; four different sections of one set of lath-like crystals the axes of which are sets of parallel lath-like inclusions are orientated parallel orientated parallel to the direction of view; three sets of to the four three-fold axes <111>; the crystals are parallel inclusions are observable parallel to the remaining orientated against each other according to the body three-fold axes <111>. 75x. diagonals of a cube. 35x. JJ.. Gemm.,Gemm., 1988,21,21988,21,2 7711

needle-likneedle-likee inclusions.inclusions. TheThe stonestone wawass boughtbought andand somsomee smalsmalll correctionscorrections witwithh ththee twtwoo arcsarcs ofof thethe duringduring a tritripp ttoo SrSrii LankLankaa iinn 19801980.. goniometergoniometer headhead,, oneone planplanee ofof ththee reciprocareciprocall latticelattice ThThee microscopimicroscopicc investigationinvestigation ofof thethe samplesample ofof ththee hoshostt crystacrystall wawass adjustedadjusted perpendiculaperpendicularr ttoo ththee revealerevealedd fourfour setsetss ooff paralleparallell lath-likelath-like inclusioninclusionss ttoo primarprimaryy X-raX-rayy beambeam.. A direcdirectt X-raX-rayy photograpphotographh ofof bbee presenpresentt (Figures(Figures 3,3, 4)4).. TheThe orientationorientation ooff ththee thithiss reciprocareciprocall latticlatticee planplanee revealerevealedd ththee orientationorientation axesaxes ofof ththee doubldoublee refractinrefractingg crystalscrystals wawass determineddetermined ofof ththee planplanee ttoo bbee paralleparallell ttoo ononee ofof ththee octahedronoctahedron ttoo bbee paralleparallell toto ththee fourfour bodbodyy diagonaldiagonalss ooff a cubecube facesfaces {Ill}{111} ooff ththee hoshostt crystal.crystal. ThiThiss investigationinvestigation (Figure(Figuress 5,6)5, 6).. AccordinAccordingg ttoo ththee symmetrsymmetryy ooff thethe discloseddisclosed thathatt ononee setset ooff inclusioninclusionss wawass paralleparallell toto hosthost,, ththee orientatioorientationn ooff ththee axeaxess ooff ththee lath-likelath-like ononee ofof ththee three-folthree-foldd axesaxes <111> ooff ththee spinel.spinel. guesguestt mineralmineralss wawass assumeassumedd ttoo bbee paralleparallell ttoo ththee Thus,Thus, ththee axesaxes ooff alalll fourfour differendifferentt setssets ofof lath-likelath-like fourfour three-folthree-foldd axesaxes ooff ththee cubicubicc spinelspinel.. ThiThiss wawass inclusionsinclusions,, whicwhichh areare relaterelatedd ttoo eaceachh otheotherr aass ththee confirmedconfirmed bbyy a combinationcombination ooff microscopmicroscopyy anandd xX- bodbodyy diagonalsdiagonals ooff a cubecube,, areare confirmedconfirmed ttoo bbee rarayy singlesingle crystacrystall diffraction.diffraction. orientateorientatedd paralleparallell ttoo ththee foufourr three-folthree-foldd axeaxess FirstlyFirstly,, ththee hoshostt spinelspinel wawass affixeaffixedd witwithh rubberubberr toto <111<111>> ooff ththee cubiccubic spinelspinel (cf.(cf. FigureFiguress 5,5, 6)6).. a goniometergoniometer head.head. Then,Then, thethe directiondirection ofof oneone setset ofof ParallelParallel ttoo eacheach ooff ththee fourfour three-folthree-foldd axesaxes ooff a lath-likelath-like guesguestt crystalscrystals waswas orientatedorientated microscopicallymicroscopically spinelspinel,, threethree symmetrsymmetryy equivalenequivalentt orientationsorientations ofof almosalmostt paralleparallell ttoo thethe primarprimaryy X-raX-rayy beabeamm ofof a ththee cross-sectionscross-sections of.lath-likeof .lath-like crystalcrystalss araree possiblepossible.. precessioprecessionn cameracamera.. TheThe deviationdeviation betweebetweenn ththee However,However, paralleparallell ttoo eacheach ooff ththee three-folthree-foldd axeaxess ofof crystalcrystal axeaxess anandd ththee X-raX-rayy beabeamm wawass assumeassumedd ttoo bbee ththee spinelspinel investigated,investigated, onlyonly ononee singlesingle directiondirection ofof lessless thathann 5°.5°. AfteAfterr threthreee orientatioorientationn photographsphotographs ththee cross-sectioncross-sectionss ofof ththee guestguest crystalcrystalss wawass observedobserved

AIK",

/'v1gKc<. SiK,x. l ... AIKt/.

/'v1gKc<.

FigFig.. 77.. EnergyEnergy dispersivdispersivee X-raX-rayy spectruspectrumm ooff bluish-violebluish-violett spinespinell frofromm SrSrii LankaLanka (below(below)) anandd superimposesuperimposedd X-raX-rayy spectrumspectrum ooff ththee hoshostt spinelspinel andand ththee guestguest phasephase,, mosmostt probablprobablyy sillimanitesillimanite (above).(above). 72 J. Gemm., 1988,21,2

(Figures 3-5). At present, the reasons for this Conclusions restriction is not understood by the author. In summary, the bluish-violet host spinel from A chemical investigation of the inclusions was Ratnapura, Sri Lanka, contains four sets of lath undertaken by electron microprobe techniques. like inclusions. The axes of these doubly refracting Due to the fact that the widths of the cross-sections minerals are orientated parallel to the four three of the lath-like inclusions (Figure 5) which were fold axes <111> of the cubic spinel. The main exposed to the surface on different facets were components of the crystals are Al and Si. Morpho smaller than the diameter of the electron beam, logical and petrological arguments support the quantitative analyses of the inclusions were not determination of the inclusions as the Al2Si05 performable. However, semiquantitative investiga polymorph sillimanite. This new type of inclusion tions using the energy dispersive analysis system of is different from orientated rutile and sphene the microprobe disclosed the composition of the crystals in asteriated spinels from Sri Lanka. lath-like mineral. In Figure 7 the energy dispersive X-ray spectrum of the host spinel is compared with Acknowledgements the superimposed X-ray spectra of the host spinel The author is grateful to Mr HJ. Müllenmeister and the guest mineral. In both diagrams, the of Markt Schwaben, West Germany, who submitted intensities of the Mg signals were made comparable the bluish-violet spinel for investigation. Asteriated using appropriate counting times. The super spinels from Sri Lanka were kindly supplied by imposed X-ray spectrum of both host and guest Prof. Dr H. Bank of Idar-Oberstein, West Germany. mineral, shows an additional line of Si as well as an Financial support was given by grants of the increased intensity of the Al signal, compared with Wirtschaftsministerium des Landes Rheinland- the intensity of Al in the pure host spectrum. Thus, Pfalz, West Germany. the presence of Al and Si as main components in the guest mineral are disclosed. This interpretation is References based on the assumption that Mg is not present in Anderson, B.W., and Payne, C.J., 1954. Three gemstones from the guest compound, which was proved by the X- Burma. Journal of Gemmology, IV, 335. ray scanning technique (X-ray images for MgK«, Bank, H., 1980. Sternspinelle aus Sri Lanka. Zeitschrift der Deutschen Gemmologischen Gesellschaft, 29, 96-7. AlKoc and Silw) for several cross-sections of the Bank, H., 1983. Über Gahnospinelle und Gahnite. Zeitschrift der guest phase exposed to the surface of one facet. Deutschen Gemmologischen Gesellschaft, 32, 141-2. From these chemical data, the orientated inclu Dahanayake, K., Liyanage, A.N. and Ranasinghe, A.P., 1980. Genesis of sedimentary gem deposits in Sri Lanka. Sedimentary sions in spinel are determined as one of the Al2SiOs Geology, 25, 105-15. polymorphs andalusite, sillimanite, and kyanite. Dahanayake, K., and Ranasinghe, A.P., 1981. Source rocks of According to the morphology of the lath-like guest gem minerals. A case study from Sri Lanka. Mineralium minerals in spinel, only sillimanite and andalusite Deposita, 16, 103-11. Eppler, W.F., 1958. Notes on asterism in spinel and chatoyancy in form needle- to lath-like crystals, while kyanite in chrysoberyl, quartz, tourmaline, zircon and scapolite. Journal general is found in tabular plates. Two arguments of Gemmology, VI, 251-63. favour the determination of the inclusions as Gübelin, E.J., 1957. A contribution to the genealogy of inclusions. sillimanite: orientated needle-like inclusions of Journal of Gemmology, VI, 1-47. sillimanite were recently determined in asteriated Gübelin, E., 1968. Die Edelsteine der Insel Ceylon. Gübelin, Lucerne. quartz from Sri Lanka as well as in chrysoberyl Gübelin, E.J., and Koivula, J.I., 1986. Bildatlas der Einschlüsse in cat's-eyes from India (Woensdregt et ai, 1980; Edelsteine. ABC Verlag, Zürich. Soman and Nair, 1985). According to recent Munasinghe, T., and Dissanayake, C.B., 1981. The origin of petrological studies of PT conditions of spinel- gemstones of Sri Lanka. Economic Geology, 76, 1216-25. Soman, K., and Nair, N.G.K., 1985. Chatoyancy in chrysoberyl bearing mother rocks from Ratnapura area, Sri cat's-eye from pegmatites of Trivandrum District, Southern Lanka, sillimanite is the only common Al2Si05 India. Journal of Gemmology, XIX, 412-15. polymorph in these Precambrian metamorphic Strunz, H., 1968. Atomare Struktur, Eigenschaften und Klassifikation rocks (Dahanayake et a/., 1980; Munasinghe and der Edelsteine, in: Mackowsky, M-T. (Herausgeber): Edelsteine. Aufschluss, 18. Sonderheft, 68-102. Dissanayake, 1981; Dahanayake and Ranasinghe, Switzer, G., 1955. Star spinel showing four six-rayed stars. Gems 1981). & Gemology, 8, 163-4. Woensdregt, C.F., Weibel, M., and Wessicken, R., 1980. Star quartz asterism caused by sillimanite. Schweizerische mineralogische und petrographische mitteilungen, 60, 129-32. [Manuscript received 25 September 1986 ] J.J. Gemm.,Gemm., 1988,21,21988, 21, 2 7373

SyntheticSynthetic opaopall

Alan Hodgkinson, FGA, Dia.Dip.Dia.Dip.

Clarkston,Clarkston, GlasgowGlasgow G76G76 7JD7JD

EarlEarlyy iinn ththee 1980s1980s therethere arrivearrivedd iinn LondonLondon a rangrangee ooff attractiveattractive opalopalss withwith a veryvery naturanaturall lookinglooking prismaticprismatic playplay ooff colourcolour withiwithinn ththee stones.stones. TheThe yellowsyellows,, greens,greens, orangeorangess andand redredss werweree seeseenn againstagainst a generalgeneral palepale bluishbluish semi-transparency,semi-transparency, andand whenwhen illuminatedilluminated fromfrom behinbehindd bbyy a fibrfibree optiopticc lighlightt thethe stonesstones showedshowed a palpalee orangorangyy colourcolour.. ThiThiss wholewhole appearancappearancee isis compatiblcompatiblee witwithh certaicertainn naturanaturall opalsopals anandd thertheree waswas nnoo 'chicken'chicken wirewire'' aass witwithh ththee GilsonGilson syntheticsynthetic opalopal.. ThThee materiamateriall gainegainedd somesome groundground untiuntill identifieidentifiedd latelaterr asas synthetic.synthetic. ThThee materiamateriall iiss apparentlyapparently synthesizedsynthesized iinn Japan,Japan, anandd iitt iiss helpfuhelpfull ttoo notnotee thathatt whewhenn examineexaminedd bbyy immersioimmersionn microscopmicroscopee betweebetweenn partlpartlyy oorr totalltotallyy crossecrossedd polarspolars,, a distinctivdistinctivee stratificatiostratificationn iiss seeseenn aass iinn FigurFiguree 1.1. ThThee effeceffectt iiss ververyy similasimilarr ttoo thathatt notednoted aass Venetia'venetiann blindsblinds'' iinn synthetisyntheticc hydrothermalhydrothermal FigFig.. 1I.. SynthetiSyntheticc opaopall examineexaminedd bbyy immersioimmersionn microscope.microscope. emeraldsemeralds,, anandd a similasimilarr occurrencoccurrencee iinn ColombianColombian CrosseCrossedd polarizerspolarizers.. 25x25x.. hydrothermahydrothermall emeraldsemeralds.. ThThee larglargee dardarkk areareaa iinn thethe fluorescenfluorescentt anandd nnoo phosphorescenphosphorescentt responsresponsee witwithh microphotograpmicrophotographh iiss ththee drildrilll holholee ooff a partpart-drille -drilledd ththee synthetisyntheticc opaopall describeddescribed,, whereawhereass similasimilarr natunatu 4 mmmm beabeadd - ththee materialmaterialss ranginrangingg frofromm 3 mmmm rarall opaopall invariablinvariablyy fluorescefluorescess anandd phosphorescesphosphoresces beadbeadss ttoo 1166 x 1414 mmmm ovaovall cabochons.cabochons. stronglystrongly.. A supporsupportt testestt foforr ththee opaopall materiamateriall iiss thatthat ultravioleultraviolett long-wavlong-wavee radiatioradiationn produceproducess littllittlee [Manuscript receivedreceived 26 26 October October 1987 1987 ) ]

ObservationsObservations onon turquoise,turquoise, lapis-lazulilapis-lazuli andand coral,coral, andand somesome ofof theitheirr simulantssimulants

Prof.Prof DrS. Dr S. TakiandDrM. Taki and Dr M. Hosaka,FGA* Hosaka, FGA*

InstituteInstitute ofInorganicof Inorganic SynthesisSynthesis,, FacultyFaculty ofof Engineering,Engineering, YamanashiYamanashi University,University, Kofu,Kofu, Japan.Japan.

*Present*Present addressaddress:: InstituteInstitute ofof GemmologyGemmology andand JewelleryJewellery ArtsArts ofYamanashi, of Yamanashi, TokojichoTokojicho 1955-1,1955-1 ,Kofu, Kofu, Japan. Japan .

AbstractAbstract ResultResultss Various aspectsaspects of of the the chemical, chemical, physical physical and and gemmo gemmologicalThThe e X-raX-rayy powdepowderr diffractiodiffractionn patternpatternss ooff thethe logical propertiepropertiess ofof naturalnatural,, GilsoGilsonn stimulantsstimulants anandd GilsoGilsonn simulantssimulants ooff turquoiseturquoise,, lapis-lazullapis-lazulii andand imitationimitationss ooff turquoiseturquoise,, lapis-lazullapis-lazulii anandd coracorall havhavee beebeenn coralcoral matchedmatched thosthosee ooff ththee naturanaturall materials.materials. describeddescribed bbyy CrowninghshielCrowninghshieldd (1974),(1974), WilliamsWilliams anandd HoweverHowever,, inin ththee cascasee ofof thethe GilsonGilson lapis-lazulilapis-lazuli NassaNassauu (1976),(1976), SchiffmannSchiffmann (1976)(1976),, NassaNassauu (1977,(1977, 19791979)) significantsignificant amountamountss ooff zinczinc werweree detectedetectedd bbyy X-rayX-ray and Schmetzer (1985). In this paper the results of X-ray and Schmetzer (1985). In this paper the results of X-ray fluorescence analysianalysiss (compar(comparee Schmetzer,Schmetzer, 1985)1985).. diffractiondiffraction (XRD(XRD)) anandd X-rayX-ray fluorescencefluorescence (XRF(XRF)) analysianalysiss onon GilsoGilsonn simulantsimulantss andand otherother imitationsimitations (which(which werweree ThThee imitatioimitationn turquoiseturquoise,, lapilapiss lazullazulii anandd coralcoral rectangularectangularr blockblockss importedimported fromfrom WestWest Germany)Germany) araree consisteconsistedd essentiallyessentially ooff calcitcalcitee andand polystyrene.polystyrene. comparedcompared withwith thosthosee frofromm naturanaturall materialsmaterials.. IInn additionaddition TheirTheir specificspecific gravitiegravitiess (hydrostati(hydrostaticc method)method) werewere ththee brokebrokenn surfacesurfacess ooff thesthesee materialmaterialss araree vieweviewedd bbyy iinn ththee 1.65-1.701.65-1.70 range.range. XRFXRF analysisanalysis showedshowed thethe scanninscanningg electronelectron microscopemicroscope (SEM)(SEM) anandd thethe patternspatterns presencepresence ofof coppercopper,, cobalcobaltt andand antimonyantimony inin thethe obtaineobtainedd comparedcompared witwithh thosthosee resultinresultingg fromfrom ththee naturanaturall turquoiseturquoise,, lapis-lazullapis-lazulii anandd coracorall imitationsimitations respecrespec materialsmaterials.. TheThe effecteffectss ooff aciacidd treatmentreatmentt oonn thethe surfacessurfaces areare tivelytively.. ThesThesee elementelementss maymay acactt aass colourincolouringg agentsagents also photographed.photographed. inin thethe respectivrespectivee imitationimitation gems.gems. ~~-.-.---..

20fJm

FigFig.. I.1. GilsoGilsonn turquoiseturquoise afteafterr HHFF aciacidd treatment;treatment; thethe obviousobvious grainsgrains ofof abouaboutt 2200 /xmJLm inin sizesize anandd thethe matrix,matrix, whicwhichh maymay bbee differentdifferent frofromm thethe compositiocompositionn ooff ththee grainsgrains,, appear.appear.

5ym Fig. 2. Natural turquoise before acid treatment; the pillar-shaped crystal of about 0.4 x 2 ^tm in size.

5ym Fig. 3. Natural turquoise after HF treatment; the visible pillar-shaped crystals which are randomly distributed. 76 J. Gemm., 1988,21,2

5ym Fig. 4. Gilson lapis lazuli before acid treatment; the particles of various sizes.

5ym Fig. 5. Gilson lapis lazuli after HF acid treatment; the porous texture formed by partial dissolution. J. Gemm., 1988,21,2 77

« 20|Jm Fig. 6. Natural lapis lazuli befuic acid treatment; the plate-like crystals of about 10-30 /mi in length.

20|Jm

Fig. 7. Gilson coral before acid treatment; the angular particles of about 2-20 /urn in size and the rounded particles rather larger than the angular particles. 78 J. Gemm., 1988,21,2

20|Jm

Fig. 8. Natural coral before acid treatment; the wave-like pattern showing the marks of growth.

20|Jm

Fig. 9. Natural coral after HCl treatment; the further visible wave-like pattern J. Gemm., 1988,21,2 79

, , 5J.1rn

Fig. 10. Imitation turquoise, lapis lazuli, and coral before acid treatment; the complex broken-surface with plastic and calcite particles.

5J.1rn

Fig. II. Imitation turquoise, lapis lazuli, and coral after HCl acid treatment; many holes are formed by the dissolution of CaC03 as one component. 8080 J].. Gemm.Gemm.,, 1988,21,21988,21,2

UndeUnderr ththee SEMSEM GilsoGilsonn turquoiseturquoise showsshows a similarsimilar ReferenceReferencess patterpatternn (slightl(slightlyy deformeddeformed spheres)spheres) ttoo thathatt describeddescribed Williams,Williams, J.D.,J.D., andand NassauNassau,, K.K.,, 1976-7.1976-7. A criticacriticall examinationexamination ooff bbyy EpplerEppler (1974).(1974). However,However, the the greater greater magnification magnification synthetisyntheticc turquoiseturquoise.. Gems & Gemology, 15IS,, 226-32.226-32. (X500(XSOO)) givesgives aa better better three three dimensional dimensional picture picture than than NassauNassau,, K.K.,, 1977.1977. ThThee non-single-crystanon-single-crystall syntheticssynthetics:: turquoise,turquoise, opal,opal, etcetc.. Lapidary Journal,JOUTnill, 3131,, 1,1, 18-31.18-31. thethe thin-sectionthin-section (X246(X246)) ooff EppleEpplerr taketakenn witwithh a NassauNassau,, K.K.,, 1979.1979. AAnn examinatioexaminationn ooff thethe newnew GilsoGilsonn 'coral'.'coral'. Gems conventionaconventionall microscopemicroscope.. & Gemology, 16,16, 179-85.179-85. Schiffmann,Schiffmann, C.A.C.A.,, 1976.1976. ComparativeComparative gemmologicagemmologicall studystudy ooff [Manuscript received received 22 22January January 1987, 1987, revised revised 25 25 lapis-lazullapis-lazulii anandd ititss newnew substitutesubstitute.. Journal o/Gemmology,of Gemmology, XV,XV, June 1987] 172-9.172-9. Crowningshield, R., R., 1974. 1974. Imitation Imitation lapis-lazuli. lapis-lazuli. Gems Gems & Gemology, & Gem 14, 327-36.ology, 14, 327-36. EpplerEppler,, W.E.,W.E., 1973-4.1973-4. NaturaNaturall andand syntheticsynthetic turquoiseturquoise.. Gems&Gems & Gemology, 14,226-9.14, 226-9. Schmetzer,Schmetzer, K.K.,, 1985.1985. ThThee compositiocompositionn ofof ththee lapis-lazullapis-lazulii imitationimitation ofof GilsonGilson.. Journal of Gemmology, XIXXIX,, 571-8571-8..

PORTABLEPORTABLE POLARISCOPEPOLARISCOPE

NeNeww fromfrom thethe GemmologicalGemmological InstrumentInstrumentss LtdLtd rangrangee ooff equipment.equipment. ThThee RayneRaynerr battery-operatedbattery-operated portablportablee polariscopepolariscope;; basedbased onon thethe principlprinciplee ofof a Scopelight.Scopelight. SimplySimply inserinsertt a gemstongemstonee intointo ththee polariscoppolariscopee 'well','well', rotatrotatee thethe filter, andand viewview witwithh easeease whethewhetherr ththee gemstonegemstone isis singlysingly oror doublydoubly refractive.refractive. QuickQuick andand effortlesseffortless distinctiondistinction betweebetweenn manymany gemgem species.species.

IdeallyIdeally suitedsuited ttoo thethe gemmologisgemmologistt andand jewellejewellerr alikealike andand attractivelyattractively pricepricedd atat £34.5£34.500 plupluss postagpostagee anandd VAVATT (UK(UK onlyonly - overseasoverseas customerscustomers wilwilll bbee sentsent a prproo formaforma invoice).invoice). GEMMOLOGICALGEMMOLOGICAL INSTRUMENTINSTRUMENTSS LTLTDD A whollywholly ownedowned subsidiarysubsidiary ofof thethe GemmologicalGemmological AssociationAssociation ofof GreatGreat BritaiBritainn SaintSaint Dunstan'Dunstan'ss House,House, CareyCarey Lane,Lane, LondoLondonn EC2VEC2V 8AB8AB TelephoneTelephone:: 01-72601-726 43744374 Fax:Fax: 01-72601-726 48374837 Cables:Cables: Geminst,Geminst, LondonLondon EC2EC2 J. Gemm., 1988, 21, 2 81

A fishy 'gem'?

R. Keith Mitchell, FGA

In 1985 I wrote a short paper about a small of separate thin inorganic sections cemented with a man-made oval plaque, or plate, with thin pearl-like resin to a slate backing. sections of what were eventually identified as Dr Schreuders has given me details of the new ooliths, pisoliths or 'cave pearls'. This was published specimen and tells me that it is actually a polished l in Journal of Gemmology . fragment of the bony palate of a large fish known

Fig. 1. A section through a large 'cave pearl'. Fig. 2. A polished fragment of 'musselcracker, palate.

A letter in a subsequent issue2 mentioned that Dr Jaques Deferne, of the Museum at Grotte de colloquially as a 'musselcracker'. This is the com Bramabian, Garde, France, had cut a fine section mon name for two species, Sparadon durbanensis from a much larger cave pearl, which Mr Andre and Cymatoceps nasutus, both members of the family Hettena, of Geneva, sent on to me. This 'pearl' Sparidae. They feed mostly on hard black mussels section, which I now illustrate in Figure 1, was or on Crustacea, sea urchins and other hard-shelled 39mm in diameter, and fluoresced very white in its sea animals. They need powerful jaws and a strong lighter areas and a sandy yellow in the outer darker bone structure to crush such prey and the palate rings under long UV light. apparently develops protuberant knobs which, A year later I received a letter from Dr H. when polished flat, give rise to the well-marked, Schreuders, of Cape Town, enclosing another tessellated pattern of my illustration, a pattern strange ornamental 'stone' which he thought looked which carries through to the underside of the like my original illustration. specimen. There is a suggestion of a silky radial I have to agree that there is a strong resemblance, growth pattern on some of the surfaces sectioned by but this new specimen, Figure 2, is a homogeneous polishing, but there is no sign of the concentric organic solid and is natural, whereas my plaque is a 'onion ring' structure seen in pearls and in 'cave composite object assembled by man from a number pearls'.

II thinthinkk thathatt thithiss iiss ononee ooff thosthosee materialmaterialss whicwhichh ReferenceReferencess araree simplsimplee enougenoughh ttoo recognizrecognizee bbyy sighsightt onconcee ononee iiss 1.I. Mitchell,Mitchell, R.K., R.K., 1985. 1985. Something Something strange. strange. Journal Journal of Gemmology, ofGemmo awarawaree ooff theitheirr existenceexistence.. TestTestss foforr bonbonee oorr toottoothh XIXlogy,, 6, 498.XIX, 6, 498. substancessubstances,, includinincludingg slighslightt reactioreactionn ttoo aciacidd mamayy 22.. MitchellMitchell,, R.K.R.K.,, 19851985.. LetteLetterr ttoo ththee EditorEditor.. JournalJournal ofof Gemmology, XIXXIX,, 88,, 737737.. helphelp,, bubutt ththee materiamateriall reallreallyy doedoess nonott resemblresemblee mammaliamammaliann bonebone.. ThThee polispolishh anandd slighslightt translucentranslucen- ccyy iiss mormoree liklikee thathatt ooff finefine porcelainporcelain,, quitquitee differentdifferent frofromm ththee duldulll surfacsurfacee anandd opacitopacityy ooff ththee plaquplaquee iinn mmyy originaoriginall paperpaper.. [Manuscript received 22 JanuaryJanuary 1988]

MorMoree onon Nelson'sNelson's 'FMIR'FMIR BodyBody Colour'Colour'

KurtKurtNassau, Nassau, Ph.DPh.D

LebanonLebanon,, NNJJ 0883308833,, USAUSA

1 WitWithh ththee Editor'Editor'ss permissionpermission,, letlet meme adaddd toto thethe originaoriginall article 1 continuouslcontinuouslyy givegivess ththee impressionimpression 1,2 33 exchangexc\langee betweebetweenn DDrr JameJamess B.B. Nelson 1,2 andmeand me .. 1I thathatt ththee twtwoo araree aatt leasleastt veryvery closelyclosely related.related. promisepromise ttoo bbee briefbrief andand,, soso aass ttoo sharpensharpen ththee focus,focus, ConsideConsiderr ononee simplesimple exampleexample.. A diamonddiamond colcol willwill covecoverr onlyonly essentialessentialss (which(which,, iinn mymy opinion,opinion, oureouredd bbyy greengreen 'naturals''naturals~, oorr a colourlesscolourless diamonddiamond 2 werweree nonott answereansweredd bbyy NelsonN elson )).. turnedturned greegreenn bbyy cyclotrocyclotronn irradiatioirradiationn atat ththee girdle,girdle, YesYes - colourcolour measurementmeasurementss havhavee triumphetriumphedd inin botbothh appearappear greengreen ttoo ththee eyeeye becausbecausee internalinternal 1 thethe manmanyy fields NelsoNelsonn listed 1, bubutt alalll havehave thisthis inin reflectionreflectionss spreadspread ththee colourcolour throughoutthroughout thethe stone.stone. common:common: theitheirr measurementsmeasurements correspondcorrespond veryvery ThThee FMIFMIRR bodbodyy coloucolourr wouldwould,, howeverhowever,, nonott showshow closelyclosely toto thethe colourcolour thatthat isis visuallyvisually perceived.perceived. anyany tracestraces ofof greengreen accordingaccording toto Nelson'sNelson's ownown 1 2 NelsonNelson clearlyclearly states2 thatthat thethe FMIRFMIR bodybody descriptions 1,2.' . colour*colour* ofof a gemstonegemstone isis notnot thethe samesame asas thethe colourcolour I conclude,conclude, asas previously3,previously3, thatthat Nelson'sNelson's model*t perceivedperceived byby thethe eye,eye, althoughalthough I dodo feelfeel thatthat hishis jusjustt isis notnot appropriateappropriate toto thethe realreal worldworld ofof gemgem- stones.stones. Footnote:Footnote: *For*For thethe sakesake ofof clarity,clarity, oneone shouldshould alwaysalways distinguishdistinguish betweenbetween 'FMIR'FMIR bodybody colour'colour' andand 'body'body colour;colour', sincesince gemmogemmo- ReferencesReferences logistslogists oftenoften useuse 'body'body colour'colour' toto designatedesignate thethe visuallyvisually- perceivedperceived colourcolour nearnear .the.the centrecentre ofof a stonestone - asas forfor oneone example,example, I.1. Nelson,Nelson, J.B.,J.B., 1986.1986. TheThe colourcolour barbar inin thethe gemstonegemstone industry.industry. Journal of Gemmology, 20,4,217-37. inin thethe GIAGIA courses.courses. ItIt is,is, I think,think, imperativeimperative toto adhereadhere fullyfully toto Journal of Gemmology, 20, 4, 217-37. thethe terminologyterminology ofof thethe gemstonegemstone discipline.discipline. 2.2. Nelson,Nelson, J.B.,J.B., 1987.1987. TheThe bodybody colourcolour ofof gemstones.gemstones. JournalJournal of f 2 Gemmology, 20,20, 7/8,7/8, 460-6.460-6. tII realizerealize thatthat NelsonNelson states'states "I"I havehave nono needneed forfor anyany kindkind ofof 3.3. Nassau,Nassau, K.,K., 1987.1987. OnOn thethe colourcolour ofof gemstonesgemstones andand Nelson'sNelson's 'model'''.'model' ". I am,am, ofof course,course, usingusing thisthis wordword asas sciencescience epistemoloepistemolo- 'body'body colour'.colour'. Journal of GemmologyGemmology, , 20,20, 6,6, 350-1.350-1. gistsgists dodo (see(see anyany ofof KarlKarl Popper'sPopper's writings,writings, forfor example),example), whowho recognizedrecognized thatthat everyevery measurement,measurement, nono mattermatter howhow simple,simple, isis notnot anan absolute,absolute, butbut merelymerely 'models''models' somesome aspectaspect ofof reality.reality. [Manuscript received 8 January 1988]1988]

NotesNotes onon thethe inclusionsinclusions inin aa greyish greyish kyanite kyanite

A. Ghera*, G. Graziani* and EE.. GubelinfGübelin†

*Dipartimento*Dipartimento didi ScienzeScienze delladella TerrTerraa,, UUniversitniversitaà deglidegli StudiStudi 'La'La Sapienza', PiaPiazzalzzalee AA.. MoroMoro 55,, 00185 00185 R Romeome, ,Ital Italyy. . †BenzeholzstrasstBenzeholzstrassee 11 ,6, 6040466 Meggen,Meggen, LuLu..,, SwitSwitzerlandzerland..

AbstracAbstractt A greyisgreyishh kyanitkyanitee andand ititss numerounumerouss inclusioninclusionss werweree ststudiedudied.. OpticalOptical observationsobservations were made andand X-raX-rayy diffrdiffractionaction andand electronelectron microprobemicroprobe analyses analyses were were per performed. formed. TheThe recognizerecognizedd inclusioninclusionss are:are: andalusiteandalusite,, apatite,apatite, calcitcalcitee anandd zirconzircon.. ThThee tubulatubularr inclusioni~c1usionss oorr channelschannels aarere sometimes sometimes made made eVident evident by byfilhngs fillings consist consisting ing ooff andalusitandalusitee andand kyanitkyanitee aass welwelll aass iroiron oxideoxidess anandd hydroxides.hydroxides. . . ApproximatApproximatee P-T conditionss foforr ththee formatioformatIOnn ooff thisS kyanitkyanitee ssamplamplee araree estimated.. KeKeywordsy words . . Kyanite,Kyanite, mineral incluinclusions,sions, andaluandalusite,.slte, apatite, apatite, calcalcite, cithematite,e hematite, lepidocrocite, lepidocrocite, maghemite, maghemlte zircon,, Zircon channels,, chan nel;, electron microprobe data, X-ray diffraction. electron microprobe data, X-ray diffraction. FigFig.!.. 1. NumerouNumerouss transparentransparentt crystacrystall inclusionss anandd bunches off narronarroww channelschannels,, causcausee aann evanescenevanescentt cat's-eycat's-eyee efeffectfect.. IntroductioIntroductionn lOxlOx.. A greyish-blue,greyish-blue, gemgem qualityquality kyanitekyanite sasamplmplee (12(12 x 9 x 3mm) was examined (Figure 1). The colour of 9 x 3mm) was examined (Figure 1). The colour of OpticaOpticall propertiepropertiess werweree determinedeterminedd bbyy meanss ooff the sample is not homogeneous, as a greyish hue is the sample is not homogeneous, as a greyish hue is a universauniversall stage.stage. PleochroisPleochroismm iiss barelybarely noticeable, distributedistributedd unevenlunevenlyy iinn ththee crystacrystall (Whit(Whitee andand witwithh aa:: colourlesscolourless,, ßB:: violet-greviolet-greyy anandd yy:: cobaltcobalt White, 1967; Faye and Nickel, 1969), resulting in White, 1967; Faye and Nickel, 1969), resu!ting in blue-grey.. ThThee refractivrefractivee indiceindicess werweree determineddetermined numerous intensively coloured areas which are numerous intensively coloured areas which are bbyy meanss ooff ththee immersioimmersionn methodmethod,, yieldingyielding:: n", = larglargee anandd undefined.undefined. a 1.711.7122 ± 0.0040.004;; nutßl = 1.721.7200 ± 0.0030.003;; nYy = 1.721.7288 ± FurthermoreFurthermore,, numerounumerouss mineraminerall inclusioninclusionss werweree 0.0030.003;; nAt> = 0.0150.015; 2V",a = 83°83°.. noted inside the crystal. These are euhedral, often noted inside the crystal. These are euhedral, often ThThee densitdensityy wass measuremeasuredd bbyy a MettleMettlerr H 0 scalscalee aggregated, forming bunches of prismatic, some 2 aggregated, forming bunches of prism.atic, some witwithh distilledistilledd watewaterr aass displacemendisplacementt liquid,, anandd iitt timetimess elongatedelongated,, transparentransparentt crystalcrystalss (Figur(Figuree 2)2).. 33 wawass founfoundd ttoo bbee equaequall ttoo 3.673.6700 ± 0.000.0044 gg/cm/cm .• BesideBesidess sporadisporadicc transparentransparentt fibroufibrouss inclusionsinclusions,, IItt wawass possiblpossiblee ttoo calculatcalculatee ththee uniunitt celcelll parapara rarraree minutminutee opaquopaquee mineralmineralss were observeobservedd alsoalso.. metermeterss bbyy meanss ooff X-raX-rayy powdepowderr diffractomdiffractometryetry,, ThThee formeformerr araree colourlesscolourless,, biréfringenbirefringentt slislimm rodsrods,, usinusingg NNii filtered,, CuCUke

€ID) CopyrighCopyrightt ththee GemmologicaGemmologicall AssociatioAssociationn ISSNISSN:: 0022-1250022-12522 84 J. Gemm., 1988,21,2

Fig. 2. Various large andalusite and anhedral transparent cal- Fig. 3. Groups of channels, rigorously orientated parallel to the cite crystals. 20x. c axis of the host kyanite, are mainly responsible for the chatoyancy effect. 200x.

In order to investigate the chemical composition A noticeable amount of inclusions made it possi of this sample, some inclusion-free areas were ble to determine the ignition loss. The iron and analysed by means of a Jeol-50A electron micro- titanium contents corresponded with the expected probe, using natural and synthetic standards. Mat values, while the MnO content is a little higher and rix corrections were performed using the EMPADR the alkali content is quite low (Pearson and Shaw, VII program (Rucklidge and Gasperrini, 1969). 1960; Albee and Chodos, 1969).

Table 1. Microprobe analysis, optical properties and X-ray data of greyish kyanite.

Number of ions on the basis of 20 (0)

Si02 37.58 wt.% Si 4.049 4.05 A1203 62.19 Al 7.898 Ti02 0.07 Ti 0.006 FeO* 0.21 Fe 0.019 MnO 0.20 Mn 0.018 MgO - Mg _ Cr203 - Cr _ BaO tr. Ba 7.95 SrO _ Sr _ CaO - Ca K20 0.05 K 0.007 Na20 - Na _ H 0+\ ** 2 - H - H20-/ TOTAL 100.30 na = 1.712 ± 0.004 a = 7.059 ± 0.002 A nß = 1.720 ± 0.003 b = 7.907 ± 0.007 Â ny = 1.728 ± 0.003 c = 5.571 ±0.003 À birefringence: ± ±0.016 2Va = 83° = 89.1° ±0.3° 3 g (g/cm ) = 3.670 ± 0.004 ß = 101.6°± 0.3° g °\ = 3.783 ± 0.004 Y = 105.6° ± 0.6°

* All iron as FeO. ** Not determined. J. Gemm., 1988,21,2 85

Table 2. Microprobe analyses of the inclusions of greyish kyanite.

Andalusite Apatite Calcite Zircon

Si02 37.64 Si02 _ CaO 55.34 Si02 33.34 A1203 61.52 AI2O3 0.05 MgO 0.17 Zr02 63.18 Ti02 0.05 FeO* 0.16 FeO* 0.03 Ti02 0.08 FeO* 0.28 MnO 0.01 MnO 0.08 A1203 1.07 MnO 0.04 MgO 0.26 43.91 FeO* 0.60 co2t MgO - CaO 53.25 R.E. tr. Cr203 - BaO - MnO tr. CaO - SrO - MgO 0.22 BaO tr. Na20 0.24 CaO 0.65 SrO - P2O5 41.36 P2O5 - Na 0 C0 — H 0+\** 2 — 2 2 - K20 F H2O-/ + H20 \ ** Cl 0.19 H 0+\ ** H20-/ 2 - H20-J

TOTAL 99.53 wt.% 95.52 99.53 99.14

* All iron as FeO ** Not determined t Calculated

Inclusions Long, prismatic crystals (up to 0.03 x 0.05mm) The numerous inclusions were analysed by the are also present, with refractive indices lower than electron microprobe (Table 2). those of kyanite. The microprobe analyses indi Conspicuous euhedral, prismatic crystals (up to cated that they are apatite. The absence of fluorine 0.70 x 0.40mm), characterized by high relief and and the presence of small amounts of chlorine low birefringence, were observed (Figure 2). suggest that they may be carbonate or hydroxy- These inclusions are roughly aligned with the c apatite (Figure 5). axis of the host kyanite. The microanalyses show Sporadic thin non-pleochroic long prismatic the presence of Si and Al in the same ratio as is crystals (up to 0.017 x 0.003mm) were also noted, found in kyanite, and of other minor elements. with very high relief, and refractive indices higher Therefore these crystals were identified as poly than the host kyanite. Electron microprobe scans morphs of Al2Si05, probably andalusite, based on revealed that the crystals are euhedral and pris their morphology (Figure 4). Moreover, a Rigaku matic. Their composition was found to be essen X-ray microdiffractometer MDG2193V was used. tially Zr02 and Si02 with small amounts of A1203, The microdiffractograms revealed the reflections of CaO and FeO. This indicates therefore that they are andalusite and concurred well with the crystallog- zircon, characterized by the lack of Rare Earths and raphic data reported by JCPDS, card No. 13-122. phosphorus (Figure 6). Thus the guest mineral was confirmed as andalusite, Iso-orientated to the elongated crystals just de the low-temperature, low pressure polymorph of scribed, are thin needle-like euhedral channels (up Al2Si05 (Brown and Fyfe, 1971). to 3 x 0.005mm). These channels are parallel to the c Other transparent and colourless inclusions were axis of the host kyanite and their presence is made then examined. Some anhedral greyish crystals (up evident by fillings consisting of minute andalusite to 0.20 x 0.15mm) show a composition very close to crystals (Figure 7), and yellow or brownish-red pure CaC03, with small amounts of MgO, FeO and minute crystalline material (Figure 8). Moreover MnO. The C02 content was calculated by differ various little transparent crystals are visible (up to ence, bearing in mind the crystallochemical for 0.002 x 0.001mm). These channels are sometimes mula. caused by the traction of some inclusions, mainly 86 J. Gemm., 1988,21,2

Fig. 4. Euhedral andalusite crystal with an outstandingly well- Fig. 5. Elongated prismatic apatite crystals are distributed developed association of the {110} and the {011} among the thin channels. 200x. prisms. 30x.

«* .-ï%-i-4>

BS3**£r*"*r _?•****, '•ßtifPK: ,

r^>: i

: *toÈfr JK f

Fig. 6. Long euhedral prismatic crystal of zircon. SEM photo- Fig. 7. Rare presence of minute euhedral andalusite crystals graph. 3000x. inside the channels. 250x.

Fig. 8. A channel filled with yellow lepidocrocite plates, un- Fig. 9. The channels are sometimes caused by the traction of usually mixed with iron oxide slabs displaying a bright minute andalusite crystals. 250x. red colour. 250x. J.J. Gemm.,Gemm., 1988,21,21988,21,2 8787

thethe minuteminute andalusiteandalusite crystalscrystals (Figure(Figure 9)9).. extendedextended overover a largelarge P-TP-T rangerange (Richardson(Richardson et al.,al., AmongAmong thethe aboveabove mentionedmentioned mineralmineral inclusionsinclusions 1969).1969). areare yellowyellow slabsslabs formedformed byby thinthin lamellae.lamellae. SomeSome InIn anyany case,case, thethe absenceabsence ofof pyrophyllitepyrophyllite inin thethe timestimes thesethese areare intergrownintergrown withwith brownish-rebrownish-redd mimi samplesample woulwouldd suggestsuggest lowerlower temperaturetemperature andand presspress nutenute lenticularlenticular plateletsplatelets (up(up toto 0.0030.003 x O.OOlmm).0.001mm). ureure valuesvalues inin thisthis kyanite-andalusitekyanite-andalusite assemblage,assemblage, TheThe electronelectron microprobemicroprobe analysesanalyses discloseddisclosed thethe i.e.i.e. 3S0°-400°C350°-400°C andand 2.5-3.02.5-3.0 KbarKbar respectively.respectively. exclusiveexclusive presencepresence ofof ironiron inin bothboth thesethese kindskinds ofof TheThe presencepresence inin somesome channelschannels ofof kyanitekyanite togethertogether inclusions,inclusions, indicatingindicating thatthat theythey areare iron oxides andand withwith ironiron oxidesoxides andand hydroxides,hydroxides, indicatesindicates thathatt thethe hydroxides respectively.respectively . latterlatter ironiron mineralsminerals crystallizedcrystallized afterafter a subsequentsubsequent TheThe yellowishyellowish lamellaelamellae appearappear toto bebe similarsimilar toto fillingfilling upup ofof thethe channelschannels withwith anan iron-richiron-rich fluid.fluid. lepidocrocite laminae lamina econtaining containing hematite, hematite, maghemite maghemite LepidocrociteLepidocrocite dehydrationdehydration isis proveprovedd bbyy thethe prepre andand Fe hydroxides describeddescribed byby GrazianiGraziani andand GiibeGübe- sencesence ofof reddishreddish ironiron oxides,oxides, probablprobablyy hematitehematite oror linlin(1981) (1981).. maghemite,maghemite, whichwhich couldcould havehave formedformed atat temperatempera TheThe opticaloptical characteristicscharacteristics ofof thethe smallsmall transtrans turestures aroundaround oror aboveabove 300°C,300°C, dependingdepending onon presspress parentparent colourlesscolourless crystalscrystals areare veryvery similarsimilar toto thosethose ofof ureure conditionsconditions (Kulp(Kulp andand Treites,Treites, 1951).1951). thethe hosthost kyanite.kyanite. ThisThis suggestssuggests thatthat kyanitekyanite alsoalso isis AcknowledgementsAcknowledgements presentpresent asas a fillingfilling materialmaterial ofof thethe channels.channels. TheThe authorsauthors wishwish toto thankthank DrDr S.S. Lucchesi,Lucchesi, TheThe electronelectron microprobemicroprobe analysesanalyses showshow thethe prepre DipartimentoDipartimento didi ScienzeScienze delladella Terra,Terra, UniversityUniversity ooff sencesence ofof SiSi andand AAll andand otherother elementselements inin identicalidentical Rome,Rome, forfor usefuluseful suggestions.suggestions. WeWe areare gratefulgrateful toto MrMr proportionsproportions toto thosethose ofof thethe kyanitekyanite crystals.crystals. TheThe G.G. DiDi Egidio,Egidio, DepartmentDepartment ofof Chemistry,Chemistry, UniversityUniversity concurrence of the optical observations and the concurrence of the optical observations and the ofof Rome,Rome, forfor hishis assistanceassistance inin carryingcarrying outout scanningscanning chemicalchemical analysesanalyses revealsreveals thatthat thethe describeddescribed crystalcrystal electronelectron microprobemicroprobe analyses.analyses. lineline materialmaterial isis alwaysalways kyanite. VeryVery minute,minute, elongated,elongated, slightlyslightly reddishreddish needlesneedles (up(up toto 0.0140.014 x 0.002mm)0.002mm) werewere observed;observed; thesethese areare ReferencesReferences intergrownintergrown withwith thethe apatiteapatite prismaticprismatic crystals.crystals. Albee,Albee, A.L.,A.L., Chods,Chods, A.A.A.A.,, 1969.1969. MinorMinor elementelement contentcontent ofof These needles are randomly aligned and often coexistent Al AI,SiO2SiO5 polymorphs.s polymorphs. American AmericanJournal Journal of Science, of Scien These needles are randomly aligned and often 267,ce, 310-16. 267, 310-16. angular.angular. TheyThey maymay bbee oneone ofof thethe threethree polymorphspolymorphs Appleman,Appleman, D.E.,D.E., Evans,Evans, H.T.,H.T., 1973.1973. JobJob 9214:9214: Indexing and ofof titaniumtitanium oxide.oxide. least-squares refinement refinement of ofpowder powder diffractiondiffraction data.data. USUS Dep.Dep. ofof Commerce,Commerce, NationaNationall Tchn.Tchn. InformationInformation Service,Service, DocumentDocument NoNo PB-216PB-216 188188.. DiscussionDiscussion Brown, G.C.,G.C., Fyfe, Fyfe, W.S., W.S., 1971. 1971. Kyanite-andalusite Kyanit~-andalusite equilibrium. equilib TheThe characteristiccharacteristic featurefeaturess ofof thisthis greyishgreyish kyanitekyanite Contributionsrium. Contributions to Mineralogy to Mineralogy and Petrology, and 33Petrology,, 227-31. 33, 227-31. andand thethe presencepresence ofof numerousnumerous inclusionsinclusions ofof diffediffe Faye,Faye, G.H.,G.H., NickelNickel,, E.H.,E.H., 1969.1969. OnOn thethe originorigin ofof colourcolour andand rentrent kindskinds leadlead toto thethe followingfollowing considerations:considerations: pleocroismpleocroism ofkyanite.of kyanite. Canadian Mineralogist, 10,10, 35-46.35-46. Graziani, G., G., Gübelin, Giibelin, E., E., 1981. 1981. Observations Observations on some on scapolitessome scapo TheThe samplesample isis remarkableremarkable forfor itsits unusualunusual greyishgreyish- lites ooff CentralCentral Tanzania.Tanzania. Journal of Gemmology, 17,17, 6,6, blueblue colourcolour andand byby noticeablenoticeable amountsamounts ofof oneone ofof thethe 395-405. minorminor elementselements (i.e.(i.e. manganese).manganese). Holdaway, M.J.,M.J., 1971. 1971. Stability Stability of andalusite of andalusite and the and aluminium the alumi Particular mention is made concerning the differ nium silicatesilicate phasephase diagram.diagram. American Journal of Science,Science, Particular mention is made concerning the differ 271271,97-131., 97-131. enceence betweenbetween thethe measuredmeasured andand calculatedcalculated densitydensity Kulp,Kulp, J.L.,J.L., Treites,Treites, A.F.,A.F., 1951.1951. DifferentialDifferential thermalthermal analysisanalysis ofof values.values. SuchSuch a differencedifference shouldshould bebe attributedattributed toto thethe naturalnatural hydroushydrous ferricferric oxides.oxides. American Mineralogist, 36,36, largelarge amountamount ofof inclusionsinclusions ofof lowerlower densitydensity suchsuch asas 23-44.23-44. andalusite,andalusite, calcitecalcite andand apatiteapatite inin thethe kyanite.kyanite. ConseConse Pearson,Pearson, G.R.,G.R., Shaw,Shaw, D.M.,D.M., 1960.1960. TraceTrace elementselements inin kyanite,kyanite, 3 sillimanitesillimanite andand andalusite.andalusite. American Mineralogist, 45,45, 808-808- quently,quently, valuesvalues asas highhigh asas 3.783.78 g/g/cmcm3 couldcould bebe 17.17. expectedexpected inin anan inclusion-freeinclusion-free greyishgreyish kyanitekyanite ofof thethe Richardson, S.W., S.w., Gilbert, Gilbert, M.C., Bell,M.e., P.M., Bell, 1969. P.M., Experimental 1969. Ex kindkind analysedanalysed inin thisthis study.study. perimental determinationdetermination ofkyanite-andalusiteof kyanite-andalusite andand andaluandalu- TheThe numerousnumerous parallelparallel channelschannels andand finefine fibrousfibrous site-sillimanitesite-sillimanite equilibria;equilibria; thethe aluminiumaluminium silicatesilicate tripletriple point. AmericanAmericanJournal Journal of of Science, Science, 267 267,, 259-72. 259-72. inclusionsinclusions areare responsibleresponsible forfor thethe weakweak chatoyantchatoyant Rucklidge,Rucklidge, J.,J., Gasperrini,Gasperrini, E.L.,E.L., 1969.1969. Electron microprobe data effect.effect. TheThe presencepresence ofof syngeneticsyngenetic andalusiteandalusite inin thethe reduction. EMPADR VII. ManualManual reissue.reissue. DepartmentDepartment ofof kyanitekyanite allowsallows thethe individualindividual plottinplottingg ofof thethe Geology.Geology. UniversitUniversityy ofof Toronto,Toronto, Toronto,Toronto, Canada.Canada. kyanite-andalusitekyanite-andalusite equilibriuequilibriumm curvecurve inin thethe White,White, E.W.,E.W., White,White, W.B.,W.B., 1967.1967. ElectronElectron microprobemicroprobe andand opticaloptical absorptionabsorption studystudy ofof colouredcoloured kyanites.kyanites. Science, 158,158, AlzSiOAl2Si05s systemsystem asas a firstfirst clueclue toto definedefine thethe P-TP-T 915-17.915-17. conditionsconditions underunder whichwhich thisthis samplesample forme.dformed (Hold(Hold- away,away, 1971).1971). OnOn thethe otherother hand,hand, thethe impossibilityimpossibility ofof definingdefining thethe exactexact reactionreaction boundaryboundary curvecurve onon thethe diagramdiagram allowsallows onlyonly thethe emphasisemphasis ofof 4 KbarKbar andand temperaturetemperature ofof 500°C500°C asas a maximum.maximum. InIn fact,fact, thethe fieldfield inin whichwhich thesethese twotwo polymorphspolymorphs coexistcoexist cancan bebe [Manuscript received 1111 November 1987]1987] 8888 J.J. GemmGemm.., 1988,, 21,221, 2

InvestigationInvestigation ofof cat's-eyecat's-eye zirconszircons fromfrom SriSri LankaLanka

Mahinda Gunawardene, F.G.A., D.Gem.G. and Marion Gunawardene, D.Gem.G.D.Gem.G.

GemGem TestingTesting Laboratory, 1mIm SierlingSierling 2,, 65816581 Hettenrodt,Hettenrodt, WestWest Germany.

IntroductionIntroduction thatthat country.country. TheThe chatoyancychatoyancy cancan occuroccur eithereither Zircon,Zircon, ththee mostmost commoncommon radio-activeradio-active gemstone,gemstone, naturallynaturally oror afterafter heatheat treatmenttreatment toto thethe gem.gem. isis foundfound abundantlyabundantly inin thethe sedimentarysedimentary gemgem bedsbeds ofof However,However, thethe formerformer isis rarerare (Figure(Figure 1).1). TheThe SriSri Lanka.Lanka. TheThe chemicalchemical andand structuralstructural aspectsaspects ooff majoritymajority ofof stonesstones nownow availableavailable areare subjectedsubjected toto a zirconzircon werewere detaileddetailed bbyy GottfriedGottfried et al. (1956);(1956); processprocess ofof heatingheating (Figure(Figure 2).2). ThisThis articlearticle aimsaims VitanegeVitanege (1957);(1957); VanceVance andand AndersonAnderson (1972)(1972);; thereforetherefore atat describingdescribing thethe gemmologicalgemmological andand SahamaSahama (1981)(1981) andand recentlyrecently byby RupasingheRupasinghe (1984).(1984). chemicalchemical propertiepropertiess ofof 'natural''natural' andand 'treated' cat'scat's- ThereThere havehave beenbeen manymany reportreportss iinn gemmologicalgemmological eyeeye zircon.zircon. ParticularParticular detailsdetails onon thethe causecause ofof thethe literatureliterature onon zirconzircon witwithh chatoyancychatoyancy effecteffect iinn thethe chatoyancychatoyancy inin botbothh typestypes areare discussed.discussed. paspastt as wellwell asas inin recenrecentt yearsyears ((seseee Eppler,Eppler, 19581958;; FryerFryer et aI.al, , 1983,1983, 19841984 andand 1985).1985). DurinDuringg ththee lastiast GemmologicalGemmological propertiesproperties fefeww monthmonthss ththee authorauthorss werweree informeinformedd ofof anan SeveraSeverall gemmologicagemmologicall testtestss werweree conducteconductedd ttoo occurrencoccurrencee ooff zircozirconn cat's-eycat's-eyee iinn BibiléBibile, SriSri Lanka.Lanka. determindeterminee ththee propertiepropertiess ooff twtwoo typetypess ooff cat's-eyecat's-eye InvestigatinInvestigatingg thithiss informatioinformationn durinduringg a recenrecentt visitvisit zirconszircons,, especiallespeciallyy ttoo distinguisdistinguishh betweebetweenn treatedtreated ooff ononee ooff ththee authorauthorss ttoo ththee 'Ge'Gemm Island'Island',, iitt becamebecame anandd untreated.untreated. apparenapparentt thathatt a larglargee numbenumberr ooff zircozirconn cat's-eyescat's-eyes werweree availablavailablee iinn ththee localocall gegemm marketmarket.. ThThee suddensudden ColouColourr occurrencoccurrencee ooff phenomenaphenomenall zirconzirconss frofromm SrSrii LankaLanka ThThee zircozirconn cat's-eyecat's~eyess showshownn iinn FigureFiguress 1 anandd 2 arousearousedd ththee authorsauthors'' interesinterestt ttoo researcresearchh iinn detaildetail exhibiexhibitt overaloveralll lighlightt browbrownn anandd whitish-grewhitish-greyy colourscolours whethewhetherr thertheree iiss aann actuaactuall naturanaturall occurrencoccurrencee oror respectivelyrespectively.. ThThee cat's-eycat's-eyee effeceffectt iinn 'natural'natural'' zirconzircon whethewhetherr somesome typtypee ooff enhancemenenhancementt iiss carriecarriedd ououtt ttoo wawass ratheratherr weaweakk iinn appearancappearancee comparecomparedd witwithh ththee producproducee a chatoyancchatoyancyy effect.effect. remarkablremarkablee chatoyancchatoyancyy iinn heat-treateheat-treatedd samplessamples.. ThThee author'author'ss visivisitt ttoo SriSri LankLankaa yieldeyieldedd ththee ThThee treatetreatedd stones exhibiteexhibitedd a slighslightt bluishbluish-shee-sheenn answeanswerr ttoo ththee probleproblemm ooff zircozirconn cat's-eycat's-eyee effeceffectt iinn undeunderr reflectereflectedd light.light.

FigFig.. 11.. ZircoZirconn exhibitinexhibitingg a 'natural'natural'' cat's-ey cat's·eyee effeceffectt founfoundd iinn FigFig.. 22.. Heat-treateHeat-treatedd zircozirconn exhibitinexhibitingg a chatoyancchatoyancyy effecteffect,, MosMostt BibiléBibile,, SrSrii LankaLanka.. WeighWeightt 3.43.433 ctct.. ooff ththee stonestoness investigateinvestigatedd iinn thithiss studstudyy araree off thithiss typetype.. WeighWeightt 5.55.522 ctct..

Fig. 3. Growth tubes which are arranged parallel to one direction Fig. 4. The growth tubes seen in 'natural' zircon cat's-eye from in the 'natural' zircon cat's-eye from Sri Lanka. Sri Lanka are often filled with minute mineral matter. Photographed by using colour filter to enhance the tube Dark-field illumination. 55 x. like inclusions. Transmitted and reflected light illumin ation. 50 x.

Refractive index and specific gravity None of the samples exhibited any noteworthy Because of the high refractive index of zircon it luminescence when illuminated under either ultra was necessary to use the Riplus type refractometer violet radiations. and this provided, with great difficulty, the usual shadow-edges for high and intermediate type Gem microscope observations zircons. The 'natural' cat's-eye zircon provided the Under high magnifications a clear-cut answer to intermediate type values, whereas the treated ones the origin of the zircon cat's-eye can be obtained. gave the values for high type (Table 1). The specific The 'natural' chatoyant zircon contained numerous gravities of the samples were determined hydro- growth tubes arranged parallel to one direction in statically on a Sartorius balance at room temperature. the gem (Figure 3). These tubes seem to be quite The cat's-eye zircons revealed specific gravities large in diameter (Figure 4) and are often filled with ranging from 4.00 to 4.69. mineral matter. Although the mineral plates have not contributed to the effect of chatoyancy they Spectroscopic and ultraviolet radiation analysis were identified as biotite mica (Figure 5). The absorption spectra of these zircons were The inclusions in heat-treated cat's-eye zircons determined by the use of hand-held prism-type were in no way similar to those described above,. In spectroscope. The most diagnostic 653.5 nm appearance they were comparatively free from absorption line accompanied the other lines at inclusions. However, with magnification fine disc 660.5, 662.5, 621.0, 615, 589.6, 562.0, and 516.2 shaped fissures were visible (Figure 6). These ultra- nm. thin tension fissures were arranged in a parallel

Table 1. The gemmological properties of'natural' and heat-treated zircon cat's-eyes from Sri Lanka.

Refractive Specific Absorption Inclusions index gravity spectrum in nm 'Natural' zircon 1.83 4.04 660.5, 653.5, Hollow tubes parallel in one cat's-eye (1 sample) 621, 589.5 direction and often filled with biotite mica inclusions.

Heat-treated 1.92-1.97 4.60-4.69 660.5, 691.0, Fine disc-shape tension zircon cat's-eyes 662.5, 653.5, fissures arrange in one (10 samples) 621, 615, 589.6 orientation. Cracks on the 562, 537.6, unpolished surfaces. 516.2. 9090 JJ.. Gemm.,Gemm., 1988,21,21988,21,2

Fig. 5. TheThe enclosedenclosed mineralsminerals withinwithin thethe tubestubes werewere identifiedidentified asas Fig. 6.6. FineFine disc-likedisc-like tensiontension fissures arrangedarranged inin paralleparallell orien-orien biotitbiotitee micamica inin zirconzircon cat's-eyecat's-eye ofof untreateduntreated origin.origin. Dark-Dark- tationtation inin heat-treatedheat-treated zirconzircon cat's-eyescat's-eyes areare nownow availableavailable field illumination.illumination. 8080 x.x. inin thethe trade.trade. Dark-fielDark-fieldd illumination.illumination. 6060 x.x. suchsuch asas Hf,Hf, Th,Th, andand U.U. TheThe resultsresults obtainedobtained inin thisthis analysisanalysis areare givengiven inin TableTable 2.2.

TheThe causecause ofof chatoyancychatoyancy ThThee chatoyancychatoyancy inin zirconszircons fromfrom SriSri LankaLanka describeddescribed inin thisthis paperpaper isis causedcaused bbyy thethe parallelparallel arrangementarrangement ofof hollowhollow oror growthgrowth tubestubes oror ultra-thinultra-thin disc-likedisc-like fissures.fissures. IInn naturalnatural zirconzircon cat's-eyescat's-eyes thethe arrangementarrangement ofof growthgrowth tubestubes takestakes placplacee inin oneone direction.direction. IfIf thethe needle-likeneedle-like inclusionsinclusions orientorient compactlycompactly withinwithin thethe gemgem ththee effecteffect isis pronounced.pronounced. However,However, iinn manymany instances,instances, asas oneone shownshown inin FigureFigure 1,1, thethe includedincluded tubestubes areare ratheratherr farfar apartapart fromfrom eacheach otherother andand thisthis causescauses somewhatsomewhat indistinctindistinct Fig,Fig. 7, VisibleVisible fire crackscracks ofteoftenn seenseen oonn unpolisheunpolishedd surfact!ssurfaces ofof heat-treatedheat-treated zirconszircons fromfrom SriSri Lanka.Lanka. TransmittedTransmitted lightlight chatoyancy.chatoyancy. illumination.illumination. 5353 x,x. ThThee finefine disc-shapedisc-shape fissurefissuress cancan alsoalso produceproduce a cat's-eyecat's-eye effecteffect ifif thethe arrangementarrangement takestakes placplacee inin a orientationorientation inin ththee stonestone andand whenwhen suchsuch zirconszircons areare regularregular manner.manner. Heat-treatmentHeat-treatment influencesinfluences suchsuch cutcut en-cabochonen-cabochon thetheyy providprovidee a chatoyancychatoyancy withwith a arrangementsarrangements withinwithin zirconszircons andand thisthis leadleadss toto bluish-sheenbluish-sheen underunder reflectereflectedd light.light. ManyMany heatheat- chatoyancy.chatoyancy. treatedtreated zirconzircon cat's-eyescat's-eyes observedobserved exhibitedexhibited firefire crackscracks (Figure(Figure 7)7) onon unpolishedunpolished surfacesurface areas.areas. HeatHeat treatmenttreatment ofof zirconzircon cat's-eyecat's-eye Heat-treatinHeat-treatingg zirconzircon isis well-knownwell-known andand isis reportedreported ChemicalChemical analysisanalysis inin detaidetaill bbyy WebsterWebster (1975)(1975).. TheThe majoritmajorityy ofof zirconszircons MicroprobeMicroprobe analysisanalysis werweree conductedconducted onon twotwo founfoundd inin SriSri LankaLanka areare oftenoften subjectedsubjected toto heat.heat. cat's-eycat's-eyee zirconszircons ofof naturalnatural andand heat-treatedheat-treated origins.origins. However,However, itit waswas onlonlyy quitequite recentlyrecently thatthat treaterstreaters TheThe treatedtreated zirconszircons containedcontained nnoo ironiron andand showedshowed beganbegan toto produceproduce a cat's-eyecat's-eye inin zircon.zircon. TheThe processprocess lessless percentagpercentagss ofof thethe commoncommon radio-activeradio-active elementselements iiss similarsimilar inin practicepractice toto thatthat ofof heat-treatingheat-treating

TableTable 2.2. ChemicalChemical datadata (in(in wt%)wt%) forfor 'natural''natural' andand heat-treatedheat-treated zirconzircon cat's-eyescat's-eyes fromfrom SriSri Lanka.Lanka.

aa Si02 FeO Zr02Zr02 Hf02 Th02 V0U02 'Natural''Natural' zirconzircon 34.2834.28 0.040.04 63.7063.70 1.401.40 0.250.25 0.670.67 cat's-eyecat's-eye

b Heat-treatedHeat-treated 33.9633.96 nd 65.1065.10 1.191.19 0.220.22 0.340.34 zirconzircon cat's-eyecat's-eye b a TotalTotal ironiron calculatedcalculated asas FeFeOO bndnd = notnot detecteddetected J.J. Gemm.,Gemm., 1988,21,21988,21,2 9191

amethystamethyst toto setset inin a schillerization.schillerization. AtAt thethe requestrequest ofof ReferencesReferences thethe operatorsoperators thethe authorsauthors havehave keptkept thethe exactexact detailsdetails Eppler,Eppler, W.W. F.F. 1958.1958. NoteNotess onon asterisminasterism in spinelspinel andand chatoyancychatoyancy inin ofof thethe processprocess secret.secret. ItIt waswas apparentapparent however,however, thatthat chrysoberyl,chrysoberyl, quartz,quartz, tourmaline,tourmaline, zirconzircon andand scapolite.scapolite. J.J. thethe temperaturetemperature usedused inin thisthis instanceinstance was lowerlower Gemm., VI,VI, 6,6, 251-63251--moonstone-likemoonstone-like quartzesquartzes oftenoften resultsresults inin treatedtreated E.E. 1984.1984. Cat's-eyeCat's-eye zircon.zircon. InIn GemGem TradeTrade LaLabb Notes.Notes. Gems. Gemol., XX,XX, 2,2, 112.112. zircons.zircons. However,However, asas hahass beenbeen observedobserved bbyy oneone ofof Fryer,Fryer, C.C. W.,W., Crowningshield,Crowningshield, R.,R., Hurwit,Hurwit, K.K. N.N.,, andand Kane,Kane, R.R. thethe authorsauthors itit isis notnot atat allall anan easyeasy tastaskk toto treattreat zirconszircons E.E. 1985.1985. Zircon,Zircon, cat's-eye.cat's-eye. InIn GemGem TradeTrade LabLab Notes,Notes, Gem. toto showshow chatoyancy.chatoyancy. Gemol., XXI,XXI, 2,2, 114.114. Gottfried,Gottfried, D.,D., Senftle,Senftle, F.F. E.E. andand Waring,Waring, C L.L. 1956.1956. AgeAge determinationdetermination ofof zirconzircon crystalscrystals fromfrom Ceylon.Ceylon. American Mineralogist, 41,41, 157--

.." NENEWW GEMMOLOGGEMMOLOGYY COURSECOURSE TheThe GemmologicalGemmological AssociationAssociation ofof GreatGreat BritainBritain isis proudproud toto announceannounce thatthat itit hashas introducedintroduced a newnew homehome studystudy coursecourse inin gemmology.gemmology. ThiThiss preparepreparess studentsstudents forfor ththee examinationsexaminations leadingleading toto thethe awardaward ofof thethe Association'sAssociation's FellowshipFellowship Diploma.Diploma. TheThe newcoursenew course isis radicallyradically differentdifferent fromfrom otherother gemmologicalgemmological courses,courses, andand presentspresents a new,new, friendly,friendly, stepstep- by-steby-stepp approachapproach toto learninglearning thatthat shouldshould bbee welcomedwelcomed byby studentsstudents allall overover thethe world.world.

FFor or further details, contactcontact thethe EducationEducation Department,Department, GemmologicalGemmological AssociationAssociation ofof GreatGreat Britain,Britain, SaintSaint Dunstan'sDunstan's House,House, CareyCarey Lane,Lane, LondonLondon EC2VEC2V 8AB8AB.. Tel:Tel: 01-7264374.01-7264374. Cables:Cables: GEMINST.GEMINST. 9292 J.J. Gemm.,Gemm., 1988,21,21988, 21, 2

GemmologicalGemmological investigationinvestigation ofof a largelarge facetedfaceted easteast AfricanAfrican enstatiteenstatite

John I. Koivula*, C.W. FryerFryer†t and James E. Shigley, Ph.D.*Ph.D.*

'Gemological*Gemological InstituteInstitute ofof America,America, SantaSanta Monica,Monica, California.California. tGIA†GIA GemGem TradeTrade Laboratories,Laboratories, Inc.,Inc., SantaSanta MonicaMonica andand NewNew York.York.

AbstractAbstract asas hypersthene,hypersthene, waswas superficiallysuperficially coveredcovered withwith ThisThis articlearticle describesdescribes thethe identificationidentification andand scientificscientific numerousnumerous extremelyextremely fine parallelparallel striationsstriations (Figure(Figure documentationdocumentation ofof a large,large, gem-quality,gem-quality, facetedfaceted TanzanianTanzanian 2)2) thatthat resultedresulted fromfrom thethe surfacesurface exposureexposure ofof enstatiteenstatite thatthat waswas presentedpresented toto thethe GemologicalGemological InstituteInstitute abundant,abundant, minute,minute, acicularacicular growthgrowth tubes.tubes. TheThe ofof America.America. TheThe resultsresults ofof chemicalchemical analysis,analysis, X-rayX-ray growthgrowth tubestubes werewere soso fine andand evenlyevenly disseminateddisseminated powder diffraction, and various gemmological tests, powder diffraction, and various gemmological tests, thatthat theythey gavegave thethe roughrough crystalcrystal a directionallydirectionally- carriedcarried outout onon thisthis gemstone,gemstone, areare reported.reported. dependentdependent translucencytranslucency thathatt complementedcomplemented itsits IntroductionIntroduction ratherrather strongstrong pleochroism.pleochroism. TheThe pleochroismpleochroism andand GIAGIA waswas recentlyrecently givengiven a large,large, gem-qqality,gem-quality, thethe generalgeneral appearanceappearance werweree whatwhat oneone mightmight expectexpect orangish-brown,orangish-brown, roughrough crystallinecrystalline mass,mass, minedmined inin ofof a pyroxene.pyroxene. Tanzania,Tanzania, thatthat weighedweighed approximatelyapproximately 7575 carats.carats. TheThe rougroughh crystallinecrystalline masmasss was subsequentlysubsequently cutcut ShownShown iinn FigureFigure 1,1, thethe roughrough,, presentepresentedd toto thethe GIAGIA byby MrMr MichaelMichael GrayGray ofof LosLos Angeles,Angeles, California,California, intointo a large,large, antiqueantique cushioncushion modifiemodifiedd stepstep cut,cut, shownshown inin FigurFiguree 33,, weighinweighingg 46.5646.56 caratscarats.. WeWe believebelievedd thithiss ttoo bbee perhapperhapss ththee largeslargestt knownknown facetefacetedd pyroxenepyroxene.. OncOncee facetedfaceted,, ththee gegemm anandd a remaininremainingg fragmenfragmentt ooff ththee rougroughh crystacrystall werewere subjectesubjectedd ttoo a varietvarietyy ooff testintestingg techniquetechniquess ttoo determindeterminee ititss propertiepropertiess anandd correccorrectt identityidentity,, whichwhich proveprovedd ttoo bbee enstatite.enstatite.

GemmologicaGemmologicall propertiepropertiess Microscopy ExaminatioExaminationn ooff ththee facetefacetedd stonstonee witwithh a gemgem mologicamologicall microscopmicroscopee revealerevealedd a multitudmultitudee ooff extremelextremelyy finefine aciculaacicularr inclusioninclusionss aass welwelll aass a fewfew coarscoarsee oneoness (Figur(Figuree 4)4).. ThThee inclusionsinclusions,, alalll lyinlyingg paralleparallell ttoo ononee anotheanotherr iinn a singlsinglee directiondirection,, werweree thicklthicklyy disseminatedisseminatedd throughouthroughoutt ththee stonestone.. HaHadd a decisiodecisionn beebeenn madmadee ttoo fashiofashionn ththee rougroughh crystacrystall iinn aa properlproperlyy orienteorientedd cabochocabochonn formform,, iitt woulwouldd probablprobablyy havhavee resulteresultedd iinn a finefine cat's-eycat's-eyee stonstonee displayindisplayingg excellenexcellentt chatoyancy.. DistincDistinctt coloucolourr anandd growtgrowthh zoneszones,, ooff aa lighlightt yellowish-browyellowish-brownn huehue,, runninrunningg iinn aa directiodirectionn perpendiculaperpendicularr ttoo thathatt ooff ththee aciculaacicularr inclusionsinclusions,, werweree alsalsoo visiblvisiblee througthroughh ththee microscopemicroscope.. OnOnee ooff thesthesee iiss showshownn bisectinbisectingg ththee aciculaacicularr inclusioninclusionss iinn FigurFiguree 5..

RefractiveRefractive indexindex UsinUsingg aa sodiusodiumm vapouvapourr lighlightt sourcsourcee anandd aa DupleDuplexx FigFig.. 1I.. TanzaniaTanzaniann enstatitenstatitee rougroughh beforbeforee facetingfaceting.. PhotoPhoto byby TinoTino IIII refractometerefractometerr ththee refractivrefractivee indeindexx ooff ththee facetefacetedd Hammid.Hammid. stonstonee wawass observeobservedd ttoo bbee a0: == 1.662,1.662,"y7 == 1.6731.673,, anandd

©© CopyrighCopyrightt ththee GemmologicaGemmologicall AssociatioAssociationn ISSNISSN:: 0022-1250022-12522 J. Gemm., 1988,21,2 93

Fig. 2. Fine parallel striations on surface of rough enstatite Fig. 3. Faceted antique cushion step cut enstatite weighing 46.S6 crystal. Magnified 8Sx. carats (possibly the world's largest), size 21.52 x 20.34 x 13.73 mID. Photo by Tina Hammid. the intermediate reading f3 = 1.667. Because f3 was Spectroscopy determined to be slightly closer to a , the stone A GIA-GEM spectroscope unit with a Beck exhibited a biaxial positive optic character. The prism spectroscope was used to check the visible birefringence is 0.011. This was the first indication light absorption characteristics of this faceted gem. that the gemstone might be enstatite since hypers The spectroscopic examination, carried out at room thene is biaxial negative with a higher birefringence temperature, showed a textbook spectrum for (0.012-0.021). brown enstatite (Liddicoat, 1981). A strong sharp line at 506.0 nm, flanked closely by two weak lines Specific Gravity at 503.0 and 507.5 nm are readily visible. The stone The specific gravity of the faceted stone and the also shows a single band located between 547.5 and rough crystal were determined in two ways. Using 550.0 nm as well as a series of weak bands in the pure methylene iodide with a known specific blue. gravity of 3.32 as a heavy liquid, it was found that both the faceted stone and rough crystal section Pleochroism sank slowly. On the basis of this observation the The presence of strong pleochroism in this stone specific gravity was estimated to be approximately was first noted during microscopic examination. 3.35. Next, utilizing a Voland double pan diamond Strong pleochroism is a characteristic feature of balance the specific gravity was determined by the many coloured pyroxenes. Since the material was hydrostatic method. The values so obtained on the determined to be biaxial it was thought that perhaps two pieces ranged from 3.33 to 3.41. three distinct pleochroic colours might be observed

Fig. 4. Some of the coarse and fine acicular inclusions observed in Fig. S. Colour-growth zone, bisecting the acicular inclu sions at a the faceted enstatite. Magnified SOx. right angle, as seen in the faceted enstatite. Magnified SOx. 94 J. Gemm., 1988,21,2

through a calcite dichroscope. A strong fibre-optic Cr203 0.08, MnO 0.18, sum: 99.62 wt%. Pyroxenes light source was used during testing. As suspected, such as enstatite and hypersthene belong to a solid through the dichroscope, three distinct pleochroic solution series in which magnesium and iron colours were observed: (1) greenish-brown, (2) substitute for one another in varying amounts. The yellowish-brown, and (3) reddish-brown. series extends from pure end member enstatite (Mg2(Si03)2) to pure end member orthoferrosilite Luminescence (Fe2(Si03)2). The series is arbitrarily divided into The reaction of this gem material to both long six regions, each with a mineral name and range of wave (366.9 nm) and short-wave (253.7 nm) ultra composition. The names and ranges (numbers refer violet radiation is negative. to percentage of Fe2(Si03)2 in formula) are as follows: enstatite (0-12), bronzite (12-30), hypers Hardness thene (30-50), ferrohypersthene (50-70), eulite Using a set of hardness points, a microscope, and (70-88), and orthoferrosilite (88-100). The chemical oblique incident illumination, the hardness of both analysis and measured properties of this gemstone the rough crystal section and the faceted stone was indicate that it is enstatite with approximately 11% determined. The tests, carefully performed on Fe2(Si03)2 in its composition. inconspicuous areas, showed a hardness of approxi mately 5V2 to 6 on the Mohs' scale. Conclusion X-ray diffraction Properties obtained from the battery of standard Using a sharp-edged diamond scribe, a tiny gemmological tests, such as refractometry, spectro amount of powder was carefully scraped from the scopy, and specific gravity, together with the results girdle edge of the faceted stone. The powder was obtained by X-ray powder diffraction and electron used to prepare a spindle for X-ray powder microprobe analysis, prove this gemstone to be the diffraction. The sample was mounted in a Debye- orthopyroxene enstatite. It is close to the borderline Scherrer powder camera and exposed for eight between enstatite and bronzite. At 45.56 carats it is hours to X-rays generated at 46 kV and 26 mA much larger than any faceted enstatite previously from a copper target tube. The diffraction pattern reported (Arem, 1977) and may be the largest obtained matched that of orthopyroxene in the area faceted enstatite yet reported. of the enstatite-hypersthene portion of a complex six-member solid solution series between enstatite Acknowledgements and orthoferrosilite based on the magnesium/iron The authors thank Mr and Mrs Hyman Savinar ratio (Deer et al, 1978). of Los Angeles for donating this gem to the GIA for its research and display collection (GIA # 14512 Chemical analysis A,B). In order to establish where the faceted stone and rough crystal section fit into this solid solution References series, it is necessary to determine, through Arem, J.E, 1977. Color Encyclopedia of Gemstones, Van Nostrand chemical analysis, the percentages of both iron and Reinhold Company, New York. magnesium that are present. Deer, W.A., Howie, R.A., and Zussman, J., 1978. Rock- Using the electron probe microanalyser at the Forming Minerals, Volume 2A Single-Chain Silicates, John California Institute of Technology, Carol Stockton, Wiley and Sons, Inc., New York. Liddicoat, R.T., Jr, 1981. Handbook of Gem Identification, GIAs senior research gemmologist, found average Gemological Institute of America, Santa Monica, California. weight per cent values as follows: Si02 56.99, MgO 33.78, FeO 7.45, A1203 0.74, CaO 0.36, Ti02 0.04, [Manuscript received 30 October 1986 ] J.J. Gemm.,Gemm., 1988,21,21988, 21, 2 9595

LechleitnerLechleitner syntheticsynthetic rubiesrubies witwithh naturalnatural seedseed anandd syntheticsynthetic overgrowthovergrowth

Dr K. SchmelzerSchmetzer and Prof. Dr H. BankBank

InstitutInstitutee ofof MineralogyMineralogy anandd Petrography,Petrography, UniversitUniversityy ooff HeidelbergHeidelberg,, WestWest GermanGermanyy anandd DeutscheDeutsche StiftungStiftung EdelsteinforschungEdelsteinforschung,, Idar-ObersteinIdar-Oberstein,, WesWestt GermanyGermany

AbstractAbstract patterpatternn andand thinthin flux-grownflux-grown coatincoatingg werewere formerlyformerly A newnew type type of of Lechleitner Lechleitner synthetic synthetic ruby ruby was was investi investigatedproduceproduced d anandd marketedmarketed byby ChathamChatham anandd KnischkaKnischka gated witwithh respectrespect toto determinativdeterminativee propertiesproperties usefuusefull forfor andand recentlyrecently bbyy anan unknowunknownn produceproducerr (cf(cf.. SchmetSchmet distinctiondistinction fromfrom naturanaturall samples.samples. ThThee neneww synthesissynthesis zer,zer, 1986a,b).1986a,b). consists of natural seeds of corundum from Sri Lanka, consists of natural seeds of corundum from Sri Lanka, WithWith ththee basibasicc knowledgeknowledge ofof Lechtleitner'sLechtleitner's propro whichwhich areare coatedcoated bbyy a thinthin layerlayer ooff flux-grownflux-grown syntheticsynthetic ruby. Spectroscopic,Spectroscopic, chemical and microscopic propertiesprop cess,cess , somesome ofof ththee observationobservationss ooff KanKanee anandd GunaGuna ertiesare aregiven. given. wardenewardene becomebecome moremore easilyeasily understandableunderstandable.. MostMost probably,probably, thethe twotwo cucutt camplescamples revealinrevealingg curvedcurved IntroductionIntroduction growtgrowthh striations,striations, whichwhich werewere availablavailablee toto KaneKane LechleitneLechleitnerr syntheticsynthetic rubierubiess anandd sapphiressapphires werewere (1985),(1985), consistedconsisted onlyonly ofVerneuil-grownof Verneuil-grown seeds,seeds, thethe firsfirstt announcedannounced bbyy BanBankk (1983(1983)) andand latelaterr describeddescribed overgrowthsovergrowths ooff whichwhich werewere completelycompletely removedremoved bbyy KaneKane (1985(1985)) andand GunawardeneGunawardene (1985).(1985). AccordAccord duringduring thethe cuttingcutting processprocess.. ThThee visuavisuall appearanceappearance inging toto ththee publicationspublications mentionedmentioned,, facetefacetedd samplessamples ofof variouvariouss formformss ofof flufluxx residueresiduess picturepicturedd iinn thethe ofof LechleitneLechleitnerr syntheticsynthetic rubierubiess anandd sapphiressapphires revealreveal paperpaper ofof GunawardenGunawardenee (1985(1985)) araree iinn parpartt typicaltypical forfor curvecurvedd growthgrowth striationsstriations andand flufluxx materiamateriall inin thethe flufluxx inclusioninclusionss inin thethe overgrowtovergrowthh (e.g(e.g.. FiguresFigures forformm ofof wispwispyy veilsveils andand fingerprintsfingerprints (Kane,(Kane, 1985)1985) asas 14-17)14-17) asas wellwell aass forfor inducedinduced fingerprinfingerprintt patternpatternss inin welwelll asas variousvarious formsforms ooff fluxflux residuesresidues (Gunawar(Gunawar ththee Verneuil-growVerneuil-grownn seedsseeds ooff LechleitneLechleitnerr syntheticsynthetic denedene,, 1985).1985). DuDuee ttoo ththee investigationinvestigation ofof rougroughh andand corundumcorundumss (e.g.(e.g. FiguresFigures 18-24).18-24). However,However, withoutwithout facetefacetedd samplessamples ooff LechleitnerLechleitner syntheticsynthetic corundumcorundum a detaileddetailed investigationinvestigation ofof thethe Verneuil-grownVerneuil-grown byby oneone oofthef the presentpresent authorsauthors (Schmetzer,(Schmetzer, 1986a,1986a, b)b),, corunducorundumm versuversuss flux-growflux-grownn corundumcorundum contactcontact itit isis evidentevident thathatt facetefacetedd anandd pre-shapepre-shapedd formformss aass zonezone aass welwelll asas withoutwithout anan investigatioinvestigationn ooff ththee areasareas welwelll asas irregularirregular fragmentsfragments ofof Verneuil-grownVerneuil-grown withwith andand withouwithoutt curvedcurved growthgrowth striationsstriations inin eacheach syntheticsynthetic corundumcorundumss werweree usedused byby thethe produceproducerr aass sample,sample, whicwhichh iiss mosmostt convenientlyconveniently performableperformable seedsseeds foforr hishis synthesis.synthesis. TheThe syntheticsynthetic VerneuilVerneuil seedsseeds withwith ththee immersioimmersionn microscopmicroscopee usinusingg methylenemethylene- werweree overgrownovergrown withwith a thithinn layelayerr ooff syntheticsynthetic iodideiodide asas immersioimmersionn liquid,liquid, thethe assignmenassignmentt ooff corundumcorundum inin a flufluxx processprocess.. ThisThis methomethodd ooff inclusionsinclusions ttoo thethe seedseed oorr thethe overgrowtovergrowthh iiss concon synthesissynthesis isis generallygenerally describedescribedd bbyy KoivulKoivulaa (1983)(1983).. nectednected witwithh somesome uncertainty.uncertainty. Unfortunately,Unfortunately, MostMost probablyprobably,, ththee fluxflux usedused bbyy LechleitneLechleitnerr forfor curvecurvedd growthgrowth striationsstriations werweree nonott mentionementionedd iinn thethe paper of Gunawardene and therefore, a more de crystalcrystal growtgrowthh isis inin ththee systemsystem Liz2O-Mo00-Mo03-PbF3-PbF2z paper of Gunawardene and therefore, a more de and/orand/or PbOPbO.. DuDuee ttoo ththee smallsmall thicknesthicknesss ofof thethe tailetailedd interpretationinterpretation ooff hishis figurefiguress iiss extremelyextremely syntheticsynthetic flux-growflux-grownn layelayerr ofof LechleitneLechleitnerr syntheticsynthetic difficult.difficult. rubierubiess anandd sapphires,sapphires, thethe completecomplete overgrowthovergrowth oorr atat NoNott lonlongg agoago,, ththee firsfirstt samplessamples ooff a neneww typtypee ooff leasleastt parpartt ofof itit was removedremoved durinduringg ththee facetingfaceting LechleitneLechleitnerr syntheticsynthetic rubrubyy werweree madmadee availablavailablee forfor processprocess.. TheThe remainingremaining samplessamples consisteconsistedd ooff thethe investigationinvestigation.. IInn contrascontrastt toto thethe stonesstones mentionedmentioned VerneuiVerneuill seedseed withwith inducedinduced fingerprintfingerprint patternspatterns ooff above,above, thithiss neneww synthesissynthesis consistconsistss ooff naturanaturall coruncorun residuaresiduall fluxflux materiamateriall andand,, inin somesome casescases,, witwithh a thinthin dumdum crystalscrystals fromfrom SriSri LankaLanka whicwhichh werweree useusedd aass flux-growflux-grownn coatingcoating.. SimilarSimilar samplesampless ooff VerneuilVerneuil seeds,seeds, witwithh thithinn layerlayerss ofof syntheticsynthetic flux-grownflux-grown growgrownn syntheticsynthetic rubrubyy witwithh inducedinduced fingerprintfingerprint corundumcorundum asas overgrowthovergrowth.. DueDue ttoo thethe presencepresence ooff

natural inclusions in the seed crystals as well as due is normally observed in pink to violet rubies from to the visual appearance of the irregular boundary Sri Lanka and confirms the similarity in colour of between natural seed and synthetic overgrowth, Lechleitner synthetic rubies of the new type with samples of this synthesis are more difficult to the common type of rubies from Sri Lanka as recognize compared to the old type of stone with already mentioned above. Verneuil-grown seeds. Thus, a description of this The absorption spectra of Lechleitner synthetic new type of synthetic ruby appears necessary and rubies in the ultraviolet area are less uniform than helpful in order to avoid misinterpretations in the spectra in the visible region (Figure 3). This determinative procedures. result is understandable by various percentages of seed versus overgrowth in different samples; the Colour and spectroscopic properties influences of both are added to the ultraviolet For the present investigation six faceted samples spectra of the samples. Furthermore, different of the new type of Lechleitner synthetic ruby were types of corundum from Sri Lanka may have been available. The colour of the stones (Figure 1) is red used as seed crystals. Samples from this country with a light violet hue, which is equal to the reveal extremely variable transparencies in their coloration of the well known pink to violet series of ultraviolet spectra (cf. Schmetzer, 1985). For both natural rubies from Sri Lanka. In some samples, the reasons mentioned, the contribution of the natural coloration of the zone confined to the girdle of the seed of corundum from Sri Lanka to the spectrosco-

Fig. 1. Lechleitner synthetic rubies with natural seed and Fig. 2. Colour zoning in Lechleitner synthetic rubies with synthetic overgrowth. Size of the samples approx. 6 natural seed and synthetic overgrowth; in one sample mm. (Photo by O. Medenbach, Bochum, West Germany.) the 'silk' of the natural seed is visible. - Size of the samples 8x9 and 7x7 mm. (Photo by O. Medenbach, Bochum, West Germany.) cut stones is more intense compared to the colora pic properties of the entire overgrown sample is tion of the zone confined to the table of the synthetic variable and cannot be separated from the contribu ruby (Figure 2). This visual appearance resembles tion of the synthetic overgrowth. the colour zoning known from sapphires which are diffusion treated in order to improve the intensity of the blue coloration (Hänni, 1982). In Lechleitner synthetic rubies the strengthened colour intensity Chemical properties of some samples in the girdle area is due to an Investigations of residues of the flux material in increased thickness of the flux overgrowth in the Lechleitner synthetic rubies with natural seeds rim area compared to the lighter zone confined to using X-ray fluorescence and electron microprobe the table of the sample. This visual appearance of techniques yielded the presence of traces of Mo. the faceted samples indicates the use of very light This result is consistent with chemical investiga reddish or even colourless samples as seed crystals. tions of Lechleitner synthetic rubies with Verneuil Absorption spectra of Lechleitner synthetic seeds (Schmetzer, 1986a,b) and indicates crystal rubies with natural seeds reveal the typical absorp growth by the flux method with fluxes in the system 3+ tion bands of Cr in corundum which are superim Li20-Mo03-PbF2 and/or PbO. posed by a weak Fe2+/Ti4+ absorption in the red area of the visible region (Figure 3). This type of Microscopic properties absorption spectrum with a strong ruby component All six samples available at present to the authors and a weak blue sapphire absorption superimposed consist of natural seeds with an all-around thin J. Gemm., 1988,21,2 97

WAVELENGTH (rim)

300 350 I,()() SCXJ 6CXJ 700

~ <: g§ ! "

] as

30 25 20 15 WAVENUMBER ( 1000 crrrl}

Fig. 3. Absorption spectra of Lechleitner synthetic rubies with natural seeds and synthetic overgrowth; the Cr3+ absorption bands have weak Fe2+ITi4 + intervalence absorption bands in the red area superimposed. overgrowth of synthetic ruby (Figure 4). Obviously, in twin position (Figure 10), families of straight pre-shaped or cut samples as well as roundish or parallel growth planes that form an angle (Figure irregularly shaped seeds were used by Lechleitner II), irregularly shaped and rounded cavities as well (Figures 4-9). In some cases it is evident that very as negative crystals (Figure 12), rounded mineral light or even colourless corundum seeds were inclusions (Figure 13), rutile needles or 'silk' selected by the producer (Figures 6-8). Ifirregular (Figure 2), tabular mineral inclusions surrounded ly formed seeds are used for the process, the contact by liquid feathers (Figure 14), as well as partly zone between natural seed and synthetic over healed fissures with liquid and two-phase inclu growth (Figure 8) resembles swirl-like irregular sions (Figure IS). In unhealed cracks within the growth structures in natural rubies from Burma or seed, residues of the flux material are incidentally Sri Lanka, which are known to gemmologists as observed (Figure 16), which are induced during the 'treacle: Similar growth structures with irregularly period of crystal growth by the flux method. shaped seeds are also known to the authors from the In the synthetic overgrowth of Lechleitner synth first generation of Knischka synthetic rubies. etic rubies, various forms of flux residues are The natural seeds used by Lechleitner display included (Figures 6-9, 17, 18). Doubly refracting various forms of structural properties and inclu crystals are occasionally observed at the boundary sions, which are common for rubies and sapphires between natural seed and synthetic overgrowth from Sri Lanka: intercalated lamellae of corundum (Figures 13, 19). According to investigations of 98 J. Gemm., 1988,21,2

Fig. 4. Lechleitner synthetic ruby; rounded natural seed and Fig. 5. Lechleitner synthetic ruby; contact zone between all-around synthetic overgrowth. 26x. natural irregularly shaped seed and synthetic over growth. Crossed polars, 35x.

Fig. 6. Lechleitner synthetic ruby; contact zone between Fig. 7. Lechleitner synthetic ruby; contact zone between irregularly shaped natural seed and synthetic over pre-shaped or faceted natural seed and synthetic growth resembling swirl-like irregular growth struc overgrowth. 25x. tures ('treacle') in natural ruby; flux residues are trapped in the overgrowth. Crossed polars, 45x.

Fig. 8. ' Lechleitner synthetic ruby; contact zone between Fig. 9. Lechleitner synthetic ruby; contact zone between pre-shaped or faceted natural seed and synthetic pre-shaped or faceted natural seed and synthetic overgrowth; flux residues are trapped in the synthetic overgrowth; flux residues are trapped in the synthetic overgrowth. Crossed polars, 45x. overgrowth. 65x. J. Gemm., 1988,21,2 99

Fig. 10. Lechleitner synthetic ruby; natural seed with interca Fig. 11. Lechleitner synthetic ruby; natural seed with families lated lamellae of corundum in twin position on r of straight parallel growth planes parallel to ZU {1121} (10Ï1). Crossed polars, 50x. that form an angle of 124°; flux residues in the synthetic overgrowth. 40x.

Fig. 12. Lechleitner synthetic ruby; natural seed with negative Fig. 13. Lechleitner synthetic ruby; natural seed with rounded crystals. 60x. doubly refracting mineral inclusion (centre); doubly refracting crystals (most probably corundum) con fined to the contact zone between natural seed and synthetic overgrowth (left). Crossed polars, 35x.

Fig. 14. Lechleitner synthetic ruby; natural seed with platy Fig. 15. Lechleitner synthetic ruby; natural seed containing mineral inclusions (most probably mica) surrounded healed fissures with liquid and two-phase inclusions by liquid feathers. 85x. (centre); synthetic overgrowth with residues of the flux (right). 40x. 100 J. Gemm., 1988,21,2

Fig. 16. Lechleitner synthetic ruby; natural seed with induced Fig. 17. Lechleitner synthetic ruby; synthetic overgrowth with flux material. 55x. residues of the flux. 45x.

Fig. 18. Lechleitner synthetic ruby; synthetic overgrowth with Fig. 19. Lechleitner synthetic ruby; doubly refracting crystal residues of the flux. 60x. (most probably corundum) confined to the boundary between natural seed and synthetic overgrowth. Cros sed polars, 75x.

Fig. 20. Lechleitner synthetic ruby; synthetic overgrowth with Fig. 21. Lechleitner synthetic ruby; synthetic overgrowth with needle-like inclusions. lOOx. needle-like inclusions. 95x. JJ.. Gemm.Gemm.,, 1988,21,21988,21,2 101011

ChathaChathamm synthetisyntheticc rubierubiess aass welwelll aass KnischkaKnischka ReferenceReferencess synthetisyntheticc rubierubiess (Schmetzer(Schmetzer,, 1986a)1986a),, similasimilarr incluinclu BankBank,, H.H.,, 19831983.. NeuNeuee synthetischsynthetischee RubinRubinee nacnachh LechleitneLechleitnerr alalss sionsionss whicwhichh araree alsalsoo confineconfinedd ttoo ththee boundariesboundaries ÜberzuUberzugg auauff natürlichenatiirlichenn unundd synthetischesynthetischenn RubineRubinenn sowisowiee betweebetweenn subsequensubsequentt growtgrowthh zonezoness werweree identifiedidentified farblosefarblosenn KorundeKorundenn dederr VerneuilsyntheseVerneuilsynthese.. ZeitschriftZeilschrifl derder DeutschenDeUlschen Gemmologischen Gesellschaft,Gesellschafl, 3232,, 207207.. aass corunducorundumm formeformedd bbyy spontaneouspontaneouss nucleationnucleation.. GunawardeneGunawardene,, M.M.,, 19851985.. GemmologicaGemmologicall propertiepropertiess ooff synthetisyntheticc ThiThiss explanatioexplanationn iiss alsalsoo applieappliedd ttoo ththee identicaidenticall typtypee corundumcorundumss coatecoatedd bbyy LechleitnerLechleitner.. JournalJournal of Gemmology, ooff inclusioinclusionn iinn LechleitneLechleitnerr synthetisyntheticc rubiesrubies.. A neneww 1919,557-70., 557-70. forformm ooff needle-likneedle-likee inclusioninclusion,, whicwhichh was nonott HänniHanni,, H.A.H.A.,, 19821982.. ZuZurr ErkennunErkennungg diffusionsbehandelterdiffusionsbehandelter Korunde. Zeitschrift Zeilschrifl der der Deutschen Deulschen Gemmologischen Gemmologischen Gesellschaft, Gesell observeobservedd beforbeforee iinn LechleitneLechleitnerr synthetisyntheticc rubiesrubies 31, 49-57.schafl, 31, 49-57. containincontainingg VerneuiVerneuill seedsseeds,, iiss picturepicturedd iinn FigureFiguress 2200 KaneKane,, R.E.R.E.,, 19851985.. A preliminarpreliminaryy reporreportt oonn ththee neneww LechleitnerLechleitner anandd 2121.. AAtt presentpresent,, ththee compositiocompositionn ooff thesthesee needleneedless synthetic ruby ruby and and synthetic synthetic blue blue sapphire. sapphire. Gems Gems & Gemology, & Gemol iiss unknown.unknown. 21, 35-9.ogy, 21, 35-9. KoivulaKoivula,, J.I.j.1.,, 19831983.. InduceInducedd fingerprintsfingerprints.. GemsGems& & Gemology, 1919,, ConclusionConclusionss 220-7220-7.. SchmetzerSchmetzer,, K.K.,, 19851985.. DistinctioDistinctionn ooff naturanaturall anandd syntheticsynthetic ThThee neneww typtypee ooff LechleitneLechleitnerr synthetisyntheticc rubyruby rubierubiess bbyy ultravioleultraviolett absorptioabsorptionn spectroscopspectroscopyy - possibilitiespossibilities consistconsistss ooff naturanaturall seedseedss ooff lighlightt colourecolouredd oorr colourcolour anandd limitationlimitationss ooff ththee methodmethod.. ZeitschriftZeilschrifl der DeutschenDeulschen leslesss corundumcorundum,, whicwhichh araree coatecoatedd bbyy a thithinn layelayerr ooff Gemmologischen Gesellschaft,Gesellschafl, 3434,, 101-29101-29.. synthetisyntheticc flux-growflux-grownn rubyruby.. DuDuee ttoo ththee facfactt thathatt SchmetzerSchmetzer,, K.K.,, 1986a1986a.. NatürlicheNaliirliche und synthetischesynchelische Rubine - EigenschaftenEigenschafcen und Bestimmung.Beslimmung. SchweizerbartSchweizerbart,, Stuttgart.Stuttgart. naturanaturall inclusioninclusionss araree presenpresentt iinn ththee seedseedss ooff thethe SchmetzerSchmetzer,, K.K.,, 1986b1986b.. ProductioProductionn techniquetechniquess ooff commerciallycommercially stonesstones,, a carefucarefull investigatioinvestigationn ooff ththee syntheticsynthetic availablavailablee gegemm rubiesrubies.. AustralianAuslralian Gemmologisl,Gemmologist, 16,95-100.16, 95-100. overgrowtovergrowthh anandd ththee contaccontactt zonzonee betweebetweenn naturalnatural anandd synthetisyntheticc corunducorundumm hahass ttoo bbee performeperformedd inin [Manuscript receivedreceived 16 16 December December 1986 1986 ] ] ordeorderr ttoo determindeterminee ththee samplesampless unequivocallyunequivocally.. TheThe investigatioinvestigationn ooff tractracee elementselements,, i.ei.e.. ththee chemicalchemical determinatiodeterminationn ooff residueresiduess ooff ththee flufluxx bbyy electronelectron microprobmicroprobee oorr X-raX-rayy fluorescencefluorescence analysianalysiss aass welwelll aass spectroscopispectroscopicc investigationinvestigationss araree helpfuhelpfull iinn identiidenti ficationfication procedures.procedures.

AcknowledgemenAcknowledgementt FinanciaFinanciall supportsupport wawass receivereceivedd bbyy grantgrantss ooff thethe WirtschaftsministeriuWirtschaftsministeriumm dedess LandeLandess RheinlandRheinland- Pfalz,Pfalz, WestWest Germany,Germany, asas partpart ofof a projectproject forfor appliedapplied research.research. 102 J. Gemm., 1988, 21, 2

Colour-changing chromiferous tourmalines from East Africa

Prof. Dr Hermann Bank and Dr Ulrich Henn

Deutsche Stiftung Edelsteinforschung, Idar-Oberstein, West Germany

East Africa is well known as a producer of various This special optical effect, found in gemstones coloured tourmalines of gem quality. Occurrences like alexandrite, garnet, corundum, spinel, zircon, of elbaite (Voi, Kenya), dravite (Osarara, Kenya) fluorite, kyanite and diaspore, has, to the authors' and uvite (Magadi, Kenya; Moshi and Gere vi Hills, knowledge, never before been described in tourma Tanzania) are mentioned by Dietrich (1985). Furth lines. ermore red (Bank, 1974), light-brown, yellow, green The colour-changing tourmalines from East (Bank, 1975) and golden-yellow (Hännitf al., 1981) Africa show the following gemmological pro as well as red dravite (Dunn, et al., 1975) from perties: Kenya are described in gemmological literature. n0= 1.644-1.645 Occurrences of green tourmalines in East Africa ne= 1.622-1.623 are commercially important. Three groups can be An = -0.022 distinguished by their type of coloration: D = 3.04-3.06 g/cm3 1. vanadiferous green tourmalines from Gerevi pleochroism: brownish-green or yellowish-green to Hills, Tanzania (Bassett, 1953; McKie, 1955; emerald-green Webster, 1961); For chemical analyses with an electron microprobe 2. chromiferous green tourmalines (Bank and Ber- (Cameca microbeam) two samples of 5.41 and 1.73 desinski, 1967; Crowningshield, 1967/1968); ct were selected: and sample 1 sample 2 3. vanadium-chromium-tourmalines from Umba 5.41 ct 1.73 ct 35.29 34.87 Valley, Tanzania (Zwaan, 1974). Si02 Most of the green tourmalines from East Africa 33.57 31.73 A120 3 were described as vanadium-coloured members of MgO 11.13 11.40 solid-solution-series between dravite and uvite CaO 1.95 2.63 (Schmetzer and Bank, 1977) Na20 1.53 1.39 dravite Na Mg3 Al6 [(OH,F)(OH)3(B03)3 Si6018] Cr203 0.36 0.64 0.04 0.06 uvite CaMg3(Al5Mg) [(OH,F)(OH)3(B03)3Si6018] V203 formed by replacement of sodium and aluminium Ti0 0.18 0.48 by calcium and magnesium. total 84.07 83.20 Schmetzer (1978) mentioned green vanadiferous Datainwt.-% and chromiferrous dravites from Tanzania (Gerevi The results of chemical investigations proved the Hills, Umba Valley) and Kenya (Kwale District, samples to be chromiferous dravite-uvite mixed Tsavo Park, Lualenyi) as well as uvite from Land- crystals with slight excess of uvite. The uvite anai, Tanzania. Bluish-green dravites from East portions amount to 55 and 65% respectively. The Africa are described by Dunn (1978). vanadium contents are low but in the range of In a large number of green tourmalines from East detection limit of the microprobe. Africa (probably from Lelatema, Tanzania) one of Spectroscopical studies yielded typical absorp the authors (H.B.) has found some stones showing a tion spectra of chromiferous minerals. Absorption distinct change of colour from green in daylight to bands caused by Cr3+ possess maxima at 606 and brownish-red or red in artificial light. 450 nm.

AcknowledgementsAcknowledgements Dietrich,Dietrich, R.V.,R.V., 1985.1985. The'tourmalineThe tourmaline group. VanVan NostrandNostrand FinancialFinancial supportsupport waswas givengiven byby grantsgrants ofof thethe ReinholdReinhold Company,Company, NewNew York.York. Dunn,Dunn, P.}.,P.J., Arem,Arem, J.E.,J.E., Saul,Saul, J.,J., 1975.1975. RedRed dravitedravite fromfrom Kenya.Kenya. WirtschaftsministeriumWirtschaftsministerium desdes LandesLandes RheinlandRheinland- JournalJouTnal oJof Gemmology, XIV,XIV, 386-7.386-7. Pfalz,Pfalz, FRG,FRG, withinwithin a projectproject forfor appliedapplied research.research. Dunn, P.J., P.J., 1978. 1978. Blue-green Blue-green gem gem dravite. dravite.Journal Journal of Gemmology, oJGemmolo MicroprobeMicroprobe analysesanalyses andand spectroscopicalspectroscopical investigainvestiga XVI,gy, 92-3. XVI, 92-3. tionstions werewere carriedcarried outout atat thethe InstitutInstitut fUrfür GeowisGeowis- Hanni,Hänni, H.A.,H.A., Frank,Frank, E.,E., Bosshart,Bosshart, G.,G., 1981.1981. GoldenGolden yellowyellow tourmaline of of gem gem quality quality from from Kenya. Kenya. Journal Journal of Gemmology, oj Gemmo senschaften,senschaften, UniversityUniversity ofof Mainz,Mainz, WestWest Germany.Germany. XVII,logy, 437-42. XVII, 437-42. McKieMcKie,, D.,D., 1955.1955. NoteNotess onon somesome mineralsminerals fromfrom Tanganyika.Tanganyika. ReferencesReferences Records ojof the Geological SurveySurvey ojof Tanganyika,Tanganyika, 5,5, 81-94.81-94. Bank,Bank, H.,H., Berdesinski,Berdesinski, W.,W., 1967.1967. ChromhaltigerChromhaltiger Turmalin.Turmalin. Schmetzer, K., K., Bank, Bank, H., H., 1977. 1977. Zur ZurNomenklatur Nomenklatur ostafrikanischer ostafrikani ZeitschTiJtZeitschrift deTder Deutschen GesellschaJtGesellschaft Edelsteinkunde, HeftHeft scher Turmaline.Turmaline. ZeitschriJtZeitschrift deTder Deutschen Gemmologischen 61,30-32.61, 30-32. GesellschaJt,Gesellschaft, 2626,, 208-9. 208-9. Schmetzer, K., 1978. Vanadium III als F arbtriigeT bei natiirlichen Bank, H.,H., 1974. 1974. Rote Rote Turmaline Turmaline mit mit hoher hoher Licht Licht- - und undDoppelbrechung Doppel Schmetzer, K., 1978. Vanadium III als Farbträger bei natürlichen Silikaten und Oxiden - ein Beitrag ZUT Kristallchemie des aus Kenya.brechung Zeitschrift aus Kenya. der Deutschen ZeitschriJt Gemmologischen deT Deutschen Gemmologi Silikaten und Oxiden ein Beitrag zur Kristallchemie des Vanadiums. Dissertation, Heidelberg. Gesellschaft,schen GesellschaJt, 23, 89-92. 23, 89-92. Vanadiums. Dissertation, Heidelberg. Webster, R., 1961. Tanganyika tourmaline. Gemmologist, 30, Bank, H.,H., 1975. 1975. Hellbraune Hellbraune und und gelbe gel sowie be sowie grüne griine schleifwürdige schleifwiir Webster, R., 1961. Tanganyika tourmaline. Gemmologist, 30, 41-5.41-5. Turmalinedige Turmaline niedriger Licht- niedriger und mittlerer Licht- Doppelbrechungund mittlerer Doppel Zwaan,Zwaan, P.C.,P.C., 1974.1974. Garnet,Garnet, corundumcorundum andand otherother gemgem mineralsminerals aus Kenia.brechung Zeitschrift aus Kenia. der Deutschen ZeitschTiJt Gemmologischen der Deutschen Gemmologi fromfrom Umba,Umba, Tanzania.Tanzania. Scripta Geologica, 20,1-41.20, 1-41. Gesellschaft,schen Gesellschaft, 24, 166. 24, 166. Bassett,Bassett, H.,H., 1953.1953. A vanadiferousvanadiferous varietyvariety ofof tourmalinetourmaline fromfrom Tanganyika.Tanganyika. Records ojof the Geological SurveySurvey oJof Tanganyika,Tanganyika, 3,93-6.3, 93-6. Crowningshield,Crowningshield, R.,R., 1967/68.1967/68. DevelopmentsDevelopments andand highlightshighlights atat thethe GemGem TradeTrade LabLab inin NewNew York.York. Gems & Gemology, 12,12, [Manuscript received 14 January 1988]1988] 242-3.242-3.

A notenote onon the the Barkhausen Barkhausen effect effect

Kurt Nassau, Ph.DPh.D

LebanonLebanon,, NJNJ 08833,08833, USAUSA

Minster'sMinster's techniquetechnique ofof usingusing thethe BarkhausenBarkhausen ReferencesReferences 1 effecteffect toto identifyidentify syntheticsynthetic diamonds l isis a veryvery 1.1. Minster,Minster, D.,D., 1987.1987. TheThe separationseparation ofof naturalnatural fromfrom syntheticsynthetic ingeniousingenious approach.approach. ThThee ferromagneticferromagnetic nickelnickel inin diamonddiamond usingusing thethe BarkhausenBarkhausen effect.effect. Journal ojof Gemmology, clusionsclusions causingcausing thisthis effecteffect are,are, ofof course,course, derivedderived 20,20, 7/8,7/8, 458-9458-9.. 2 2.2. Nassau,Nassau, K.,K., 1980.1980. Gems Made by Man. Chilton,Chilton, Radnor,Radnor, fromfrom thethe solventsolvent useusedd inin diamonddiamond synthesis .• ItIt Pennsylvania,Pennsylvania, 177. shouldshould bbee noted,noted, however,however, thathatt thethe literatureliterature showsshows 3.3. Meyer,Meyer, H.O.A.,H.O.A., in Gubelin,Gubelin, E.J.,E.J., andand Koivula,Koivula, J.I.,J.I., 1986.1986. thatthat itit isis possiblepossible toto synthesizesynthesize diamonddiamond byby usingusing Photoatlas ojof Inclusions in Gemstones, ABCABC Editions,Editions, Zurich;Zurich; non-ferromagneticnon-ferromagnetic solventssolvents suchsuch asas platinum2 93.93. whichwhich wouldwould thenthen givegive a falsefalse negativenegative result.result. InIn [Manuscript received 8 January 1988]1988] addition,addition, oneone mightmight obtainobtain a falsefalse positivpositivee resultresult fromfrom thethe reactionreaction ofof a naturanaturall diamonddiamond containingcontaining 3 ferromagnetiferromagneticc inclusionsinclusions suchsuch asas magnetite .• Accordingly,Accordingly, greagreatt cautioncaution mustmust bebe usedused inin interinter pretingpreting thethe resultsresults ofof a Barkhausen-effectBarkhausen-effect test.test.

r[J© CopyrightCopyright thethe GemmologicalGemmological AssociationAssociation ISSN:ISSN: 0022-12520022-1252 104 J. Gemm., 1988, 21, 2

Crystalline and organic

A.E. Farn, FGA

Seaford, East Sussex, BN25 3HP

Talking to a mixed audience of retail jewellers and pearl's arrival is the part played by the epithelial gemmologists recently on the history of pearls, I cells of the thin-skinned mantle which covers the found myself explaining that, for the major part of soft viscera of the oyster. These cells produce a my laboratory career, I had concentrated upon waterproof organic covering of conchiolin, which coloured stones in jewellery. I considered myself has an SG of 1.34. They then secrete the secondary fortunate to have what I then considered the most layer of bio-mineralized calcite as a prismatic layer interesting aspect of practical gem testing in a trade with an SG of 2.71. The inner lining of nacreous laboratory. Despite my concentration upon col mother-of-pearl (aragonite) has an SG of 2.93. oured stones, it was inevitable that some pearl lore This feat of producing both crystalline and penetrated. Our purpose-built X-ray generating set organic materials of quite different specific gravities was constantly in use for pearls, YAGs, diamonds, by the skin tissues of this lowly creature with no green grossulars, Vernueil synthetics and so on. head, no brain, no eyes and very elementary During the holiday periods I did a certain nervous system, is truly a wonder of nature. amount of X-ray pearl testing so that, despite my If by chance the oyster is invaded by a parasitical emphasis that I was a coloured stone man, I did in worm (cestode/trematode) it entombs in it a sac or fact know something about pearls. cyst. It covers the skeletal remains with conchiolin Following the retirement and death of colleagues, which hardens to become the nucleus of a pearl. it was inevitable that the important section of The subsequent overlapping layers which envelope laboratory work, pearl testing, should continue, and the nucleus are platelets of rhombic aragonite in I became the 'pearl man' at the laboratory. Having groups of three. These have a pseudo-hexagonal now embraced the pearl testing side of the labora structure which, when penetrated by a beam of tory's activities I found that I was achieving a name X-rays, yield the well-known six spot pattern seen and some expertise in this particular discipline. I in lauegrams of natural pearls. enjoyed watching the details appear in the develop As gemmologists we tend to think in terms of ing dish as the negatives yielded their exposure crystals and gemstones. I like to think that from secrets. These were mostly shadowgraphs or radio 1925 when Basil Anderson was invited to investi graphs. The lauegrams could be even more exciting. gate the problem of the new Japanese cultured pearl When a large suspect pearl weighing close to a that here began the real assault and study of both hundred grains was sent for testing accompanied by crystalline and organic materials. a request for urgent treatment, tension mounted as B.W Anderson was brought up with a back the negatives showed a worrying 'halo' pattern. ground of mineral and geological knowledge and a Negative, yet an indication that I was dealing family link with the nitrate deposits of Chile. with a blending of two distinct components, just as Nevertheless he was a man who appreciated organic surely as if they were as different as crystals and products. Like other keen gardener/gemmologists organics. he preferred food from soil unadulterated by che At the talk to the mixed audience I hoped to micals, not even powdered apatite as a fertilizer! stimulate an interest in the history of pearls and an Having inherited B.W Anderson's role in the appreciation of the marvel of nature which the lowly laboratory I turned from crystalline gemstones to pearl-bearing oyster achieves. The origin of pearls the first gems in gemmology, pearls. They are has been to a very considerable extent well defined. unique in requiring no aid from man, being ready The 'grain of sand' theory is fast disappearing, in furnished with beauty, rarity and 'orient'. They company with other die-hard phrases such as remain unique examples of a crystalline/organic semi-precious. homogenous gem. What has always impressed me in the history of a [Manuscript received 30 October 1987 ]

Another low cost accessory

The late J.R.H. Chisholm, MA, FGA

At the end of the recent article by Hugh Craw from the photographs (Figures 1 and 2) the ultra ford, FC A (Some low cost accessories, J. Gemm., violet light box is simply constructed of plywood 1986,20,4,240-1), the Editor expressed his willing (glued together). The object it is desired to illumin ness to receive descriptions of other inexpensive ate is placed in the lower (open) half of the box, gem-testing accessories made by readers. Thirty- which is loosely lined with black velvet: the UV three years ago I described one such in a paper light bulb is in the upper half of the box underneath (Simple photomicrography, J.Gemm., 1954, IV, 5, a bent sheet-aluminium reflector and the light 217-23) illustrated by my then thirteen year old passes from the upper to the lower half through a eldest son (now FRPS, but still an amateur), and 2V2 x IVs inch opening: under this is fixed a holder

two years before that I had described another into which a piece of Wood's glass can be slid. I fear inexpensive accessory (Live-box techniques, that the UV light bulb and Wood's glass may not J.Gemm., 1952, III, 7,279-81), but it was not made now be obtainable so cheaply as they were thirty by me and second-hand "live-boxes" are probably years ago, but to make the rest of the apparatus not obtainable so cheaply now as they were then. should not even now cost many pennies. The present article describes a piece of apparatus also made more than thirty years ago. As can be seen [Manuscript received 12 November 1987]

Gemmological Abstracts

BALITSKI, V.S., BuBLIKOVA, T.M., SOROKINA, BROWN, G., 1987. Spodumene. Wahroongai News, S.L., BALITSKAYA, L.V., SHTEINBERG, A.S., 21, 4,25-7,3 figs. 1987. Man-made jewelry malachite. Gems & A compilation from authoritative sources of facts Gemology, 23, 3, 152-7, 9 figs (3 in colour). on this interesting gem species, including the new Silky, banded and bud-like [botryoidal] deep violet-blue variety from Afghanistan. [RIs are malachite is being made in the USSR by crystalliza incorrectly summarized as 1.66-1.75, gamma read tion from aqueous solutions in sizes ranging up ing should be 1.675.] R.K.M. wards from 0.5kg. Vases up to 8kg, produced in Sverdlovsk, were exhibited in 1984. This material is BROWN, G., 1987. Jade and opal news from South an exact counterpart of natural malachite and can be Australia. Wahroongai News, 21, 4,28,1 map. detected, so far, only by thermal analysis — a Estimated 60,000 tonnes of nephrite, including a destructive test. [Abstracter is puzzled that a miner rare black variety, considered recoverable at al which is mined in great quantity to be smelted as Cowell, SA. an ore of copper should be worth synthesizing. The New opal finds at Zorba and Halley's Comet mineral is surely plentiful?] R.K.M. mines in Coober Pedy area are shown roughly, and none too readably, on a sketch map. Brief news of BANK, H., HENN, U., BANK, F.H., 1987. A new productive areas at Mintabie and Andamooka from alexandrite deposit in Brazil. Gold- Mineral Industry Quarterly (S.Australia) No. 43. schmiedezeitung, 9, 91-2. R.K.M. A find of alexandrite has been made at Era Nova, near Belo Horizonte, Minas Gerais, Brazil. Some BROWN, G., 1987. Iolite. Wahroongai News, 21, 5, stones show a colour change from green, blueish- 20-3.6 figs. green, blue or brownish-green to violet or red. RI is Facts on iolite or cordierite, a gem blessed with given as 1.741-1.745 and 1.751-1.755 with a DR of more names than most, from several authorities. 0.007-0.010. The SG is 3.71-3.78. The deposit is R.K.M. reported to be secondary, the specimens being recovered from river gravel. M. O'D BROWN, G., 1987. Taaffeite - an update. Wahroon gai News, 21, 5,25-7. BERNER, R.A., LANDIS, G.R, 1987. Chemical Facts of this rare gem, discovered in 1945 by analysis of gaseous bubble inclusions in amber: Count Taaffe of Dublin, and the confusion between the composition of ancient air. American Journal the original rather erroneous micro-chemical of Science, 757-62. analysis and the more accurate electron-probe Gaseous inclusions in two separate samples of assessment by Karl Schmetzer in 1983, thanks to amber from the Dominican Republic were analyzed which the 'new' gem, taprobanite, is now identified by quadrupole mass spectrometry. It is concluded as a red form of taaffeite. R.K.M. that the inclusions represent ancient air modified by the partial reaction of 02 with amber to produce BROWN, G., 1987. Rhodochrosite. Wahroongai C02, by the addition of small amounts of hydrogen Afeo«, 21, 5,16-19,5 figs. gas and hydrocarbons from amber decomposition Facts on another ornamental gem species culled and, in the case of the Dominican amber, the from half a dozen reputable sources. Usually addition of excess argon during burial in sediments. massive, it cuts handsomely as pink and white This effect was not shown in control samples of cabochons, but scalenohedra and rhombohhedra Baltic amber. It is suggested from the data that are found which will facet, allowing for softness (4) Eocene and Oligocène atmospheres were not and three directions of perfect cleavage. [The appreciably different from those of today as far as ordinary ray (1.812) is above the range of the N2,02 and Ar are concerned. M. O'D. refractometer and the extraordinary ray (here

quoted as 1.60) can appear disconcertingly as a thermal diamond probe, the Diamond Beam (bat single reading at any point between 1.60 and the teries or mains), which identified diamond effi top of the scale, depending on the direction ciently (beep and red light) while simulants give no tested.] R.K.M. response, but are not identified. R.K.M.

BROWN, G., 1987. Fluorite. Wahroongai News, 21, BROWN G., SNOW, J., 1987. Gemmological study 12, 22-5, 5 sketched figures. club reports. Australian Gemmologist, 16, 8, 287- A good account of this common but beautiful 92, 18 figs in colour. mineral which is the no. 4 standard for Mohs' Describes a white opal triplet; a bog oak cameo; hardness and too soft for convenient use in jewel unusually translucent turquoise; a plastic imitation lery. It is best known in the form of massive ivory brooch; coated plastic imitation pearls and a purple/white Blue John, which comes from Derby Biwa cultured pearl necklace. R. K. M. shire. Rare gem qualities in other colours are cut for collectors. [Green massive material is often used for BROWN, G., SNOW, J., LAMB, J., 1987. A new carved figures in China. A drawing of inter treatment for turquoise. Australian Gemmologist, penetrant cubes has shading suggesting diagonal 16, 8, 307-9, 6 figs in colour. striation which does not occur in this mineral. Paraffin wax treatment for porous turquoise has Vicinal striation does occur, but approximates to been known for a long time although not much' cube edge directions. ] R. K. M. seems to have been written about it. This paper describes further deception by painting on black BROWN, G., 1987. Gem enstatites. Wahroongai 'matrix veins' with a mixture of wax and Indian ink, News, 21, 7, 23-5. which can be scraped off. R. K. M. A rather complex compilation of facts from two authoritative sources. R. K.M. CAMPBELL, LLC, 1987. Four stones of interest. South African Gemmologist, 2, 4, 3-5, 4 figs in BROWN, G., 1987. A new opalized fossil find. colour. Wahroongai News, 21, 12, 5. Four stones recently examined and illustrated The editor of WN quotes from Mineral Indust are two simulations of emerald, a Zambian emerald rial Quarterly that an opalized part of a skeleton of a with interesting inclusions and a tanzanite with 3 metre long plesiosaur has been found near Coober unusual surface features. M.O'D. Pedy. He speculates whether this invaluable scien tific find will succumb to commercial considera CASSEDANNE, J.P., SAUER, D.A., 1987. La topaze tions and end as calibrated opal cabochons? [A pity impériale. (Imperial topaz.) Revue de Gemmolo- if it does!] R.K.M. gie, 91,2-9,16 figs in colour. Occurrences of fine quality topaz in the Brazil BROWN, G., KELLY, S.M.B., 1987. An interesting ian state of Minas Gérais are described. M.O'D. copal resin necklace. Australian Gemmologist, 16, 7, 263-6, 7 figs in colour. CLUNAS, C., 1987. Jade carvers and their customers Various inclusions and other features seemed in Ming China. Transactions of the Oriental Cera natural and suggested copal, but distant vision RI mic Society, 50, 69- 85,7 figs. was approximately 1.60, instead of 1.54, and reac A study of textual material not long known in the tions to LUV and SUV light were not as expected. West has provided new light on the work of the jade Possible explanations are offered, but doubt must carver in the Ming period, 1368-1644 and on the remain. R.K.M. people who commissioned work from him. No references have been found to the tactile import BROWN, G., SNOW, J., 1987. Gemmological jot ance so often ascribed to jade - that seems to have tings. Australian Gemmologist, 16, 7, 267-70, 12 been a later fashion - but visual effects are clearly figs in colour. of great importance. M.O'D. Deals with natural turquoise beads colour- enhanced by dyeing and waxing; a plastic imitation FALLICK, A.E., JOCELYN, J., DONNELLY,T., GUY, walrus tusk scrimshaw, proved by blebs of plastic M., BEHAN, C, 1985. Origin of agates in volcanic left in recesses; a Japanese synthetic opal which did rocks from Scotland. Nature, 313, 6004,672-4,2 not readily show 'lizard skin' or 'chicken wire' figs. colour patches, or the columnar structure seen in Isotope ratios, 180160 of silica and D/H of bound Gilson type stones; imitation gold coral found to be water are presented for agates from Lower Devo a plastic-coated mixture of golden, 'thorny' coral nian lavas. These ratios are distinct from those and colourless plastic, with included bubbles; a obtained from agates from Tertiary lavas but the 108 J. Gemm., 1988,21,2

two ratios are linearly correlated and plot along a FRYER, C.W, ED., CROWNINGSHIELD, R., HUR- single line approximately parallel to the line de WIT, K.N., KANE, R.E., 1987. Gem Trade Lab fined by present-day meteoric waters. The data notes. Gems& Gemology, 23, 3, 164-8, 12 figs in suggest that bound waters associated with the colour. agates have preserved their hydrogen isotope ratios Alexandrite from a new find in Minas Gérais, since agate deposition: this supports arguments colour change similar to fine Russian stones, pro that the water content is of genetic significance. perties consistent with published figures, some M.O'D. cat's-eyes seen, illustrated in Gems& Gemology, 23, 2. A 2.67ct green marquise diamond had small FENNER, C, 1987. Blackfellow's buttons. Wahroon- darker green areas and was highly radioactive, gai News, 21,6,6-7. suggesting recent exposure to radium and that the Abstracted from Mostly Australian, a book pub stone could be a health hazard. An intense yellow, lished in 1945, this deals with the black glass treated diamond showed strong Cape absorption; tektites found in southern and western Australia, fluorescence in chalky greenish-yellow; chilled in and makes a case for their origin having been a liquid N, the stone showed 594nm line strongly single meteoric shower. R.K.M. proving radiation treatment; probably a natural Cape treated to increase the colour. FRITSCH, E., MISIOROWSKI, E.B., 1987. The his tory and gemology of Queen conch 'pearls! Gems Spectacular triple link 'Imperial' jadeite earrings & Gemology, 23, 4, 208-21,15 figs in colour. proved natural in colour; unusual quality to use in An excellent and well illustrated paper on this such a wasteful design. X-rays proved silver nitrate infrequently encountered rare 'pearl'. Although used to colour black cultured pearl necklace; natu usually below 10 carats in weight, they have occa ral blacks fluoresce under LUV, these were inert. A sionally been found up to 45 carats. Apart from large button-shaped pearl had a diamond watch colour the most valuable feature is the so-called inset into its back; question whether this was a 'flame' structure seen beneath the surface of the blister pearl or a whole pearl not resolved. best 'pearls' which are found in the Queen conch, A scenic quartz from Massachusetts, with a three Strombus gigas, which is now a protected species so dimensional 'picture' caused by jasper-like inclu supplies are diminishing. 'Conch' is correctly pro sions is illustrated. A deep orangeish-yellow, heat- nounced 'konk' [despite the fact that most people treated sapphire is described and illustrated. seem to use the soft 'ch' ending]. They are non- An extremely rare cat's-eye sillimanite (fibrolite) nacreous and should not be regarded as true pearls, was almost black in colour, with RI 1.66-1.68; these hence the quotes used for 'pearl'. Colour ranges can be nearly colourless, violet, grey or this dark from deep to pale pink, through brown and yellow form. An unusual brownish-grey taaffeite of 0.6let to white, with a regrettable tendency for the pinks to was examined by the Los Angeles laboratory, RI fade on prolonged exposure to strong sunlight. A 1.720-1.726 [high birefringence?]. A green cat's-eye broad absorption around 500nm indicates an orga chrome tourmaline from Umba River, Tanzania, nic colour, so fading should be no great surprise. SG gave a strong red through the Chelsea filter. Most averages at 2.85, higher than for coral (2.65) which items illustrated. R. K. M. can be confused with conch 'pearl'. This paper deals only with the S. gigas 'pearls', although there are FRYER, C, ED., CROWNINGSHIELD, R., HURWIT, other univalves known as conchs which, with other K.N., KANE, R.E., 1987. Gem Trade Lab notes. pink shells, may produce pink or other coloured Gems& Gemology, 23,4, 232-7,13 figs in colour. 'pearls'. R.K.M. A modified brilliant faceted amber is described as unusual; another amber was shown to be composite, FRITSCH, E., ROSSMAN, G.R., 1987. An update on pieces of broken (amber?) beads held in a plastic color in gems. Part 1: introduction and colors matrix. 'Riverstone' beads, neither coral nor mar caused by dispersed metal ions. Gems & Gemo ble, were shown to be calcium carbonate. Corun logy, 23, 3,126-39. 15 figs in colour. dum doublets were found in two important, bezel- This first of three parts explains a difficult set cluster rings, synthetic ruby and sapphire subject in reasonably simple terms. Quantum pavilions with natural sapphire crowns. Red mechanics are mentioned but not explained. Colour fluorescence of synthetic emeralds to LUV is is different according to the nature of the colorant discussed and a specimen in which flux inclusions ion, its valency, and the composition of the host fluoresced yellow is illustrated; yellow fluorescing mineral. The co-ordination with 4, 6, or 8 neigh oil suggests an oiled natural emerald, but some bouring atoms also affects it. Differences in these synthetic emeralds are known to have been oiled. factors in various crystal directions are among the Dyed quartzite beads simulated mottled jadeite; causes of pleochroism. R.K.M. another dyed quartzite necklace resembled fine JJ.. Gemm.Gemm.,, 1988,21,21988,21,2 109109

greegreenn jadeitejadeite.. A naturanaturall blackblack TahitianTahitian culturedcultured EmeraldEmeraldss ofof artifIcialartificial origioriginn araree discussed.discussed. ThoseThose pearpearll (20(20 x 18mm)18mm) wawass thethe largeslargestt seenseen bbyy thatthat Lab.Lab. illustrateillustratedd areare ththee BiroBironn anandd twtwoo SovietSoviet products,products, AnotheAnotherr calcareous,calcareous, non-nacreous,non-nacreous, concretionconcretion waswas oneone flux-grown,flux-grown, ththee otheotherr hydrothermalhydrothermal.. M.O'D.M.O'D. frofromm a 'thorn'thornyy oysteroyster'' andand hadhad 'flame'flame'' structurestructure asas seenseen iinn claclamm andand concconchh shells.shells. A ververyy largelarge dropdrop GÜBELINGUBELIN,, E.].,E.J., 1987.1987. ThThee genesigenesiss ooff mineraminerall incluinclu cultureculturedd pearpearll witwithh a 12mm12mm pre-drillepre-drilledd centrecentre wawass sionssions iinn gemstones.gemstones. Gem Bulletinen, Stockholms provedproved toto bbee offreshwateroriginof freshwater origin bbyy ititss strongstrong X-rayX-ray Gemmologiska Forening,Forening, 2, 2,1-28,3 1-28,311 fIgs. figs . fluorescence.fluorescence. HeaHeatt treatetreatedd naturalnatural rubiesrubies showedshowed A chapterchapter frofromm thethe author'sauthor's bookbook Photoatlas of shallowshallow spallspall cavitiescavities wherwheree materiamateriall hahadd 'blistered''blistered' inclusions ingemstones* in gemstones* is ireproduced.s reproduced . M.O'D.M.O'D . offoff iinn treatmenttreatment,, somesome fIlledfilled witwithh a glass-likeglass-like substance,substance, oneone hahadd acquireacquiredd a spotspot ooff golgoldd probablyprobably GÜBELINGUBELIN,, E.E.,, 1988.1988. LightningLightning RidgeRidge.. Lapis, 13,2,13, 2, duringduring setting.setting. SyntheticSynthetic rubiesrubies areare nonott oftenoften 15-30.15-30. 3377 figfIgss (34(34 iinn colour.colour. heat-treatedheat-treated butbut somesome maymay bbee quencquenchh crackecrackedd toto A beautifullbeautifullyy illustratedillustrated andand exhaustiveexhaustive accountaccount imitateimitate fracturesfractures iinn naturanaturall stones,stones, unusuallunusuallyy thesethese ooff thethe classicclassic AustraliaAustraliann opalopal fielfIeldd aatt LightningLightning mamayy spallspall andand showshow otherother signssigns ofof ththee treatmenttreatment RidgRidgee iinn NeNeww SouthSouth Wales.Wales. M.O'D.M.O'D. apartapart fromfrom crackincrackingg [which[which doedoess notnot requirerequire veryvery highhigh temperatures].temperatures]. HANNI,HÄNNI, H.A.,H.A., SCHWARZ,SCHWARZ, D.,D., FISCHER,FISCHER, M.M.,, 1987.1987. A newnew featurefeature isis addeaddedd toto thisthis editionedition ofof LabLab DiDiee SmaragdeSmaragde derder Belmont-MinBelmont-Minee bebeii habira,Itabira, notes,notes, quotingquoting abstractabstractss fromfrom itemitemss 2525,, 1515 andand 5 MinaMinass Gerais,Gerais, BrasilienBrasilien:: VorkommenVorkommen undund CharChar year~~Q~s ago. RK~R.K.M. akteristika.akteristika. (The(The emeraldemeraldss ooff thethe BelmontBelmont MineMine nearnear Itabirahabira,, MinaMinass Gerais,Gérais, Brazil:Brazil: theitheirr occurroccurr GRAZIANIGRAZIANI,, G.,G., GUBELIN,GÜBELIN, E.,E., MARTINI,MARTINI, M.,M., 1987.1987. enceence andand characteristics.)characteristics.) Zeitschrift der Deut TheThe LennixLennix syntheticsynthetic emeraldemerald.. Gems & Gemo-Gemo schen GemmologischenGemmologischen Gesellschaft, Gesellschaft, 36, 36,1/2,33-49 112,33-49, , logy, 23,3,140-7,23, 3, 140-7, 1010 fIgsfigs inin colour.colour. 2222 fIgsfigs (3(3 inin colour)colour),, 4 tables,tables, bibl.bibl. GrowGrownn byby flux-fusionflux-fusion aatt atmosphericatmospheric pressure,pressure, AAnn EnglisEnglishh versioversionn ooff thisthis articlarticlee wawass publishedpublished ththee crystalcrystalss areare describedescribedd aass shortshort hexagonahexagonall prismsprisms iinn theJournalofGemmology,the Journal ofGemmology, 1987,20,7/8,446--56.1987,20,7/8,446-56. withwith predominanpredominantt basalbasal pinacoidspinacoids.. [The[The ononee illusillus E.SE.S.. tratedtrated,, andand allall thosthosee seenseen earlierearlier bbyy abstracterabstracter,, werewere octagonaloctagonal anandd provideprovidedd excellentexcellent preformpreformss forfor HOCHLEITNER,HOCHLEITNER, R.R,, WEISEWEISE,, c.,C., 1987.1987. DieDie HimalayaHimalaya emerald-cuemerald-cutt stones.stones. SoSo fafarr nnoo oneone seemsseems ttoo havehave MineMine dedeii MesMesaa GrandeGrande iinn Kalifornien.Kalifornien. (The(The queriedqueried thisthis unnaturalunnatural shapeshape forfor a hexagonahexagonall cryscrys HimalayaHimalaya MineMine neanearr MesaMesa GrandGrandee inin California.)California.) tal,tal, oorr offereofferedd anyany explanationexplanation ofof hohoww itit waswas Lapis, 12,12, 10,10, 11-32,2011-32,20 fIgsfigs (12(12 inin colour).colour). achieved.]achieved.] RIsRIs varyvary slightlslightlyy aroundaround 1.5591.559 forfor e andand ThThee HimalayHimalayaa minemine iinn southernsouthern CaliforniaCalifornia isis nownow 1.5621.562 forfor W;w; birefringencebirefringence 0.000.0033 ttoo 0.004,0.004, darkerdarker onceonce mormoree producinproducingg fInefine qualityquality pinkpink andand multimulti areasareas hahadd ththee higherhigher valuesvalues;; SGSG aboutabout 2.66;2.66; absorpabsorp colourecolouredd tourmalintourmalinee crystalscrystals.. DetailDetailss ooff thethe historyhistory tiotionn similarsimilar toto thathatt ofof naturanaturall emeralemeraldd plupluss 477n477nmm inin ofof ththee minminee areare givengiven.. M.O'D.M.O'D. ththee c direction;direction; googoodd redred throughthrough ChelseaChelsea fIlter.filter. InclusionsInclusions plentifulplentiful,, wisp-likewisp-like veilsveils,, irregulairregularr opaopa HUGHES,HUGHES, RW,R.W., 1987.1987. TheThe plasticplastic coatingcoating ofof gemsgems.. queque fluxflux oftenoften withwith peripheralperipheral 'frames''frames' ofof includedincluded Australian Gemmologist, 16,16, 77,, 259-61259-61,, 9 figfIgss inin crystals,crystals, tubetubess oorr rodrodss parallelparallel ttoo thethe c axis,axis, colourcolour colour.colour. zoneszones duedue ttoo growtgrowthh stages,stages, includeincludedd phenakitephenakite,, etcetc.. AmongAmong cheapcheap stonesstones fromfrom BurmaBurma werewere facetedfaceted SuperfIcialSuperficial resemblanceresemblance ttoo poopoorr quality,quality, heavilyheavily- quartz,quartz, colourlesscolourless starstar corundum,corundum, andand palpalee jadeitejadeite includedincluded naturanaturall emeraldemerald cancan causcausee problemsproblems.. VeilVeilss coatecoatedd withwith reredd oror greengreen plastiplasticc toto imitateimitate muchmuch andand wisp-likwisp-likee inclusionsinclusions areare diagnosticdiagnostic.. RR.KM.. K. M. mormoree valuablevaluable gemsgems.. MagnificatioMagnifIcationn revealedrevealed peelingpeeling ooff plasticplastic,, gagass bubblesbubbles,, swirlsswirls ofof colourcolour,, etcetc.. RKM.R.K.M. GÜBELINGUBELIN,, E.,E., 1987.1987. DiagnosDiagnosee dedess nouvellenouvelless synthsynth esesèses d'émerauded'emeraude.. (Diagnosis(Diagnosis ofof neneww synthesessyntheses ooff KANEKANE,, RE.,R.E., 1987.1987. InamorInamorii syntheticsynthetic cat's-eyecat's-eye emerald.emerald. Revue de Gemmologie, 92, 92,5-7,1 5-7,111 figsfigs inin alexandritealexandrite.. Gems & Gemology, 23,23, 3,3, 158-62,158-62, 5 colourcolour.. figfIgss inin colour.colour. FeaturesFeatures ooff thethe LenniLennixx syntheticsynthetic emeraldemerald areare KyoceraKyocera CorporationCorporation hahass produceproducedd ththee fIrstfirst describedescribedd andand illustrateillustratedd (the(the firsfIrstt ooff a setset ooff commercialcommercial cat's-eyecat's-eye alexandritealexandrite.. HistoryHistory ooff chrychry- papers)papers).. M.O'D.M.O'D. sosobery beryll synthesissynthesis isis outlinedoutlined.. ThisThis cat's-eycat's-eyee isis probablyprobably frofromm a CzochralskCzochralskii pullepulledd crystalcrystal.. BroadBroad GÜBELINGUBELIN,, E.E.,, 1987.1987. DiagnoseDiagnose dedess nouvellesnouvelles synthsynth eyeeye ofof moderatmoderatee intensityintensity,, greyish-greegreyish-greenn inin daylight,daylight, esesèses d'emeraude.d'émeraude. 2n2ndd partpart.. (Diagnosis(Diagnosis ofof newnew darkdark purplish-redpurplish-red iinn incandescentincandescent light,light, slightlyslightly syntheticsynthetic emeralds.)emeralds.) Revue de Gemmologie, 9393,, oilyoily dullness,dullness, otherwiseotherwise apparentlyapparently cleanclean.. FaintFaint 77-11-11, , 1919 fIgsfigs iinn colour.colour. *Reviewed*Reviewed iinJournaln Journal ofofGemmology, Gemmology, 1987,20,1987,20, 5,312-3.5, 312-3. 110 J. Gemm., 1988,21,2

six-ray star seen down eye-streak direction, this Quartz with included marcasite, pyrite, chalco- does not occur in the natural stone. Microscope pyrite, silver and gold, from Zacatecas, Mexico, is showed vague rippled striations parallel to the long being cut as beads and sold as solvernite. A new axis of the stone. Natural cat's-eyes contain ultra- ruby locality in Afghanistan is reported. Mr Bleck fine growth tubes or needles quite different from says that Sri Lankan rubies are being heated in an anything seen in these synthetics. R. K.M. open fire to drive off blue over-tones; and that some cat's-eye zircons have had the eye induced by KELLY, M.B., 1987. Notes from the Lab. Wahroon melting feldspar onto the rough back of the zircon gai News, 21, 3,13,1 fig. cabochon. R.K.M. An antique gold mounted suite was set with foil- backed yellowish-green and green cabochons KOIVULA, J.I., Ed., 1987. Gem news. Gems & which were identified as prehnite — possibly Gemology, 23, 4, 238-42, 6 figs in colour. imitating Chrysoprase. R.K.M. Diamonds from a kimberlite pipe are reported from Mato Grosso, the first such mine in Brazil. A KELLY, R., 1987. The art and skill of the lapidary: rare and complex diamond Mohs-Rose twin is cabochon cutting. Wahroongai News, 21 : (a) part illustrated. The 64.83 ct diamond described in Gem 1, 2, 18- 19; (b) part 2, 3, 10-11; (c) part 3, 5, news (Gems & Gemology, 23, 3) fetched 17-19. US$6,380,000 at Christie's. (a) The first paper of the series, (b) Advice on Itabira mine, Minas Gérais, is producing an selection of rough, (c) Selecting the best equipment impressive quantity of fine alexandrites when not for cabbing. Some sound advice from a very expert interrupted by strife among the local miners. cutter. R.K.M. 'Siberian' amethyst has been found at Rainbow Lode mine at Red Feathers Lakes, Colorado, some KELLY, R., 1987. Facets. Wahroongai News, 21, 6, in gem quality. Adularescence in amethyst from 10-11. Artigas, Uraguay, has been called the 'Lowell'effect Brief but sensible advice on this subject. R.K.M. after its discoverer. H.S. Pienaar has introduced the 'Stellenbosch Index', or SGI, as a new method of KEMP, J., 1987. Jade. Wahroongai News, 21, 8, teaching the basics of gemmology. A star sapphire 15-20, 1 fig. also had colour change from blue to blueish-purple An interesting paper which deals with nephrite in incandescent light. Natural strontium titanate and jadeite and with a long list of imitants. R.K.M. has been found in Mongolia. Thaumasite, a com plex hexagonal compound of hydrated calcium KOIVULA, J.I., 1987. Gem news. Gems& Gemology, silico-carbide and sulphur was found, in a South 23, 3, 172-6, 8 figs in colour. African shipment of minerals, in gem quality, but a A heavily cracked and included diamond had hardness of 3.5 makes it unsuitable for jewellery. A apparently been filled to minimize cracks. Re pocket of gem topaz has been found at Conway, portedly treated in Israel by high temperature and New Hampshire. pressure, with a secret filler; a number of such We are warned that short-wave UV filters can stones have been seen. A 64.83 ct pear-shaped deteriorate with time and become opaque. Newest diamond auctioned by Christie, Manson & Woods short UV lamps have 'life-time' filters. Efficiency in New York is illustrated. No price quoted. can be checked with scheelite, benitoite or [hopeful An iridescent andradite cabochon was bought in ly] 'even a small synthetic yellow lb diamond'. Hong Kong as black opal; colour play is in zones R.K.M. which echo the original rhomb-dodecahedron; a 44.59ct example is illustrated; this new gemmolo- KOIVULA, J.I., 1987. Goethite inclusion alteration gical material is thought to come from Sonora, during heat conversion of amethyst to citrine. Mexico; iridescent garnet was known before, but Australian Gemmologist, 16, 7, 271-2, 2 figs in this seems to be an outstanding example. Emeralds colour. impregnated with plastic have been found by a Heating amethyst to 350°C changed golden Japanese laboratory; more durable than oiling, the goethite inclusions to brown/red hematite with unknown plastic can still penetrate only where some fracturing of the host quartz due to release of cracks reach the surface of the stone. Kunzite from a water. Such hematite pseudomorphs plus fracturing new source in Sri Lanka is reported. 'Rainbow indicate heat treatment. R.K.M. moonstones' from India have been identified, by Dr Hänni of Basel, as labradorite feldspars. Orangeish- KOIVULA, J.I., 1987. Pronounced flow structure in brown quartz cat's-eyes from Belo Horizonte, Australian opal. Australian Gemmologist, 16, 7, Minas Gerais, show exceptionally fine chatoyancy, 257-8, 1 fig. in colour. sometimes with a hint of asterism. A boulder opal showed clear evidence of flow J. Gemm., 1988,21,2 111

structure with curved layering of colour-play areas. fragments, is found in the argillaceous Raibler beds The phenomenon is not uncommon, but is rarely as which overlie the Wetterstein complex. M. O'D. obvious as this. R. K. M. OBENAUER, K., 1987. Über Merkmale des Quellens KOIVULA, J.I., 1987. Pyrite in Canadian ammonite. und Schwindens bei der Chalcedon- Bildung. Australian Gemmologist, 16, 8, 304-7, 4 figs in (On the role of swelling and contraction in colour. chalcedony formation.) Aufschluss, 38, 247-52,5 Pyrite is sometimes the replacing mineral in these figs (1 in colour). beautiful fossils [cf Dorset Lias, England]. The Details of the formation of chalcedony are given author describes it in ammonites from Alberta, with especial reference to the way in which growth Canada, and has taken the trouble to prove the allows the material to expand and contract. M.O'D. mineral chemically. The Canadian fossils are pro tected by law, so complete fossils may not be used O'DONOGHUE, M., 1987. Gems and gemmology. for jewellery, although broken ones can be so used. Watchmaker, Jeweller & Silversmith, September R.K.M. 1987,51-3. Chief attention is paid to amber, jet and their LOOCK, G.W., 1987. Chrysoberyll aus Orissa, In simulants; there are also notes on synthetic jadeite dien. (Chrysoberyl from Orissa, India.) Lapis, and synthetic ruby, a substitute for lapis lazuli and 12, 12, 11-15, 14 figs (8 in colour). details of interesting specimens on display at the Fine crystals of chrysoberyl, mostly twinned, are 1987 Tucson gem and mineral fair. At the fair it was found at a number of mines in the State of Orissa, reported that tsavolite had virtually disappeared India. Well-formed trillings are fairly common and from the market and that chatoyant kornerupine other minerals of ornamental interest include was being offered as chatoyant quartz. amethyst, zircon and topaz. M.O'D. (Author's abstract.) M.O'D.

NASSAU, K., 1987. Irradiated gemstones - could O'DONOGHUE, M., 1987. Adelstenar som Försvin- the ice be hot? Lapidary Journal, 41, 5, 41-6, 3 ner i Natten. (Gemstones that pass in the night.) figs (1 in colour). GME Bulletinen, Stockholm Gemmologiska Form The possibilities of gemstones retaining latent ing, 1987/1,12-13. radioactivity after treatment to alter or enhance A brief description of manganoan sugilite is colour are discussed. Actual amounts of radiation given. so far observed are minimal but care needs to be (Author's abstract.) M.O'D. taken with some topaz, spodumene and diamond. M.O'D. OLLIVER, J.G., 1987. A review of jade in South Australia. Australian Gemmologist, 16, 8, 283-6, 9 NASSAU, K., VALENTE, G.K., 1987. The seven figs, 6 in colour. types of yellow sapphire and their stability to This deals with Cowell nephrite deposits. Geo light. Gems& Gemology, 23, 4, 222-31, 8 figs in logy; estimated potential of this 6 x 3km area are colour. discussed optimistically. R. K. M Deals in detail with (1) light stable natural yellows; (2) natural or irradiated yellows with fading READ, P.G., 1987. Birth of a science. British Jeweller, colour centre; (3 & 4) iron-containing unheated and June 1987,74-7,90,5 figs in colour. heated yellows which are stable; (5) yellows To coincide with the hundredth anniversary of obtained by surface diffused Fe or Ni - stable; (6) the British Jeweller, this article traces the develop synthetic yellows - stable; (7) irradiated synthetics ment of the science of gemmology over the last 100 - unstable. Unexpectedly natural yellows can fade years in terms of the personalities of the period, the when heated to less than 200°C, but colour can be emergence of gem test instruments, newly dis restored by exposure to light. R. K. M. covered gem species and the evolving techniques of gemstone synthesis and identification. NIEDERMAYR, G., 1986. Bleiberg, Carinthia, (Author's abstract) P.G.R. Austria. Mineralogical Record, 17, 6, 355-69, 33 figs (12 in colour). ROBERT, D., 1987. A propos d'une analyse d'é- Bleiberg is one of Europe's classic locations for meraude synthétique. (Concerning an analysis of lead and its minerals. The gemmologist, however, a synthetic emerald.) Revue de Gemmologie, 93, will be most interested in the occurrence of 12. lumachelle, first described in 1793. This material, Further notes on the Lennix emerald are given to whose play of colour comes from fossil shell supplement the points made by Gübelin in his 112 J. Gemm., 1988,21,2

paper in Revue de Gemmologie, 92. M.O'D. up to 5.23 ct and 6 faceted stones up to 0.90 ct. The paper is the first report on these in gemmological ROUGHGEMS LTD., 1987. Charoite. Wahroongai literature. News, 21, 12, 29. Colours range from dark brownish-yellow, An account of this rare, one locality, attractively through bright yellow to greenish-yellow, grown in grained violet-purple hydrated calcium-potassium- a multi-metal melt which is both flux and catalyst. silicate metasomatic rock. A beautiful addition to De Beers say that no faceted stones have been the ornamental materials list which could be more marketed, nor do they intend doing so. Growth widely exploited. R. K. M. experiments have been directed entirely towards high technological needs. However, some Sumito RUNDLE, EA., 1987. Colour grading coloured mo synthetic diamonds have appeared on the open stones. Wahroongai News, 21, 7, 2-8. market so identification has considerable signifi An excellent review of the problems and difficul cance. ties of this subject, and of two American col- Gemmologically the De Beers diamonds can be orimetric methods of defining colour: the GIA detected as synthetic by short-wave fluorescence, ColorMaster and the American Gemological Labor which is yellow in the brownish and greenish atories' Color Scan Charts. R. K.M. stones, with slight phosphorescence in the latter; by absence of absorption lines expected in natural RUSKONE, E., 1987. La taille des pierres de couleur^ yellow stones; by geometric zoning of colour and of (The cutting of coloured stones.) Revue de internal graining; by clouds of minute white inclu Gemmologie, 92,15. sions which fog some of the darker stones; by some The first part of a paper on the cutting of larger inclusions of flux metal; and by crystal coloured stones. The history of the process is surface defects, which may be found as naturals on introduced. M.O'D. cut stones, which are specific to the synthetics. Infrared spectra indicate that the synthetics are all RUSKONE, E., 1987. La taille des pierres de couleur, type lb, rare in natural yellow diamonds, which are 2nd part. (The cutting of coloured stones.) Revue usually type la. de Gemmologie, 93, 13-17, 4 figs in colour. The authors are confident that synthetic dia General discussion of the history and techniques monds of this type can be detected with ease, but employed by the lapidary. M.O'D. express some reservations whether diamonds with lower nitrogen content, e.g. the more difficult SCHÄFER, W., 1987. Himmlische Tränen. (Heavenly colourless stones, should they ever be made on a tears.) Schmuck und Uhren: 10, 35-8; 11, 36-8, 7 commercial scale, would be detectable. [It seems figs (1 in colour). only fair to emphasize that production of synthetic A description of the emerald mines of Colombia. diamonds in cuttable gem quality does seem still to M.O'D. be a very expensive undertaking, possibly justified only for use in vastly important scientific applica SCHMETZER, K., HENN, U., 1987. Synthetic or tions. To date that seems to be the object of these imitation? An investigation of the products of exercises.] R.K.M. Kyocera Corporation that show play-of-color. Gems& Gemology, 23, 3, 148-51, 3 figs in colour. SNOW, J., 1987. Care and use of gemmological Investigates whether these are synthetic opal or instruments. Wahroongai News, 21 : (a) 2, 10-11; opal simulants. Authors found that they contained (b) polariscope, 3, 9-11; (c) the figure-o-scope, no water and therefore do not match natural opal. 4,14-15,3 figs; (d) the refractometer, 5,14-15; (e) They propose they should be called simulants and the microscope, 6,10-11. not synthetics. R. K. M. (a) Logically, Mr Snow starts with the eye, for without this natural organ gemmology could hard SHIGLEY, J.E., FRITSCH, E., STOCKTON, CE., ly exist. He then gives sound advice on the use of KOIVULA, J.I., FRYER, C.W, KANE, R.E., the hand lens, (b) Sound, basic instruction on the HARGETT, D.R., WELCH, C.W., 1987. The gemo polariscope and good advice, (c) An Australian logical properties of De Beers gem-quality synth version of the conoscope, similar to the polariscope etic diamonds. Gems& Gemology, 23, 4, 187-206, but using oblique light to give interference figures. 23 figs in colour. Line drawings do not convey the expected figures With so many eminent authors this has to be an too well, (d) More very sound advice, this time on important paper. the refractometer, from an expert gemmologist. (e) GIA Research Department examined 14 synthe Brief but sensible advice on the microscope. tic type, lb diamonds grown by De Beers, 8 crystals R.K.M. J. Gemm., 1988,21,2 113

SNOW, J., 1987. The Chelsea filter. Wahroongai Describes the Bilki saw which has 120 close-set News, 21, 8, 8. blades vibrating 1400 times a minute, producing A short account of this well-known gemmological opal slices about 0.25mm thick. The ultra-thin aid. The author says that natural emeralds appear blades are charged with silicon carbide grit and wear pink or green through the filter. [In my experience very rapidly. Basically this is an update of the emeralds which do not show pink give an ash-grey primitive mud-saw. [The line diagrams would be residual colour, not green, despite what textbooks more readily understood if annotations could be may say. Any 'emerald' appearing green through the typed instead of scribbled freehand ! ] R. K. M. filter is not an emerald ! ] R. K. M. SUNAGAWA, L, 1986. Morphology of diamonds. SNOW, J., 1987. Helpful hints with practical work. Morphology and Phase Equilibria of Minerals, Wahroongai News, 21, 9, 26-7. Sofia: IMA Vol. 2,195^207. Logical approach to testing three different stones Observations on morphology and surface micro- with further suggestions for such problems. All topography of diamond crystals of three different good sound advice. R. K. M. origins are summarized and the observations are critically analysed in the light of present under SNOW, J., 1987. The Kerez effect. Wahroongai standing of the growth mechanisms and morpholo News, 21, 12, 15-18. gy of crystals. The three types of diamond are: (1) A full account of a multiple RI effect seen in natural diamond, including both single-crystals certain tourmalines, which the abstracter reported and polycrystalline aggregates. Both ultramafic in 1967 and named after the friend who had first suites (in kimberlite) and eclogite suites are discus noticed it. Others have written about it since and are sed. All natural diamonds are grown from the quoted here. Suggestions are made for a possible solution phase of silicate compositions under di further investigation, including attempts to repro amond stable conditions; (2) synthetic diamond duce the effect by controlled heating of tourma grown by static high P under diamond stable lines. [The dark green tourmalines exhibiting this conditions. They are grown from metal-carbon multiplicity of readings are rare, possibly from a solution phases; (3) synthetic diamond grown by unique locality, and it is perhaps unwise to assume pyrolysis or chemical vapour deposition processes that heat, however applied, will necessarily give rise of CH4 or C2H2 under P < 1 atm. and high T to the effect in any suitably coloured tourmaline.] conditions. They are grown under diamond un R.K.M. stable conditions from the vapour phase. Analysis of growth rates vs chemical potential provides SNOW, J., BROWN, G., 1987. LWUV fluorescence of information concerning the mutual relations gemstones: a photographic review. Australian among polycrystalline aggregates, dendritic, hop Gemmologist, 16, 8,269-300,16 figs in colour. per and polyhedral crystals. Analysis of morpholo About 100 gems were grouped by species with gical characteristics of single crystalline diamonds their imitants and photographed in white fluores and their surface microtopographs are based on the cent light and then in long-wave UV light. The extent to which their morphologies deviate from resultant pairs of slides are often informative — the theoretical morphology. J. M. H. possibly of the variability of fluorescent colour, which may be responsible for the often differing THEMELIS, T., 1987. Diamonds from Venezuela. descriptions of the phenomenon in various tests. Lapidary Journal, 41, 4, 59-69, 5 figs (1 in R.K.M. colour). Maps and descriptions are given for Venezuelan STEIN, I., 1987. Opal triplets. Wahroongai News, 21, diamond. M.O'D. 8,21-2. An account which suggests that moulded glass THEMELIS, T., 1987. Burmese taaffeite. Lapidary tops (frangible!) are largely being used in place of Journal, 41, 5,19,2 figs in colour. quartz in making these cheap versions of opal. Among the inclusions noted are red crystals, R.K.M. perhaps of spinel; various parallel acicular crystals of unknown species and fingerprint or feather-like STEIN, I., 1987. Opal triplets, cutting by hand. droplets resembling those in Burmese blue sap Wahroongai News, 21,9,15-17,4 figs. phire. Colourless transparent hexagonal crystals Advice on cutting and assembly. R. K. M. with a slightly rounded outline were noted in another specimen. M.O'D. STEIN, I., 1987. Machine cutting of opal triplets. Wahroongai News, 21, 10, 17-18, 5 figs. THEMELIS, T, 1987. Girasol effect. Lapidary Jour- 114 J. Gemm., 1988,21,2

nal, 41,6,19,2 figs in colour. WALKER, G.S., 1987. A new 'spot reading' techni A particular colour effect seen in some Mexican que for the refractometer. Australian Gemmolo opal is described. M.O'D. gist, 16,7,253-6,2 figs. For distant vision RI tests, suggests using a THROWER, C, STEANE, D., 1987. Notes onTasman- pinhole diaphragm held close to the eye and viewing ian gemstones. Australian Gemmologist, 16, 6, from about 6cm instead of 30cm. Spot and scale are 223-4. both in focus and more of the scale is seen. R. K. M. Large very dark sapphires from Weld River area were too flawed and twinned for heat treatment to WARD, F., 1987. Jade, stone of heaven. National lighten colour. Upper Gordon River stones also Geographic, 172, 3,282-315,37 figs in colour. strongly twinned with some asterism. No gem Attractively illustrated general overview of the quality. Colours light blue to black. jade minerals and methods of fashioning them. Fragments of alexandrite found with sapphires M.O'D. at Weld River, some with chatoyancy. Low quality turquoise found at Back Greek, at WILKS, E.M.,WILKS, J., 1987. Cleavage surfaces of Beaconsfield and on north-west coast, usually as diamond. Industrial Diamond Review, 47, 1, 17- thin veins in slate, porous with white soft patches. 20. R.K.M. The (111) cleavage surfaces are generally smoother on the so-called Type II diamonds than TILLANDER, H., 1987. Diamantschliff im on the much more common Type I diamonds. Such 17. Jahrhundert. (Diamond cutting in the seven variations are due to the quite large variations of teenth century.) Jahrbuch der Kunsthistoriken crystal structure arising from the presence of Sammlungen in Wien, 81,169-84,191 figs. impurity atoms, and reflected in the irregular The essay describes the development of diamond pattern of growth banding. R.A.H. cuts in the 17th century. Cuts developed during the period include the Taille en Seize, V-cut and the WILKS, E.M., WILKS, J., 1987. An unusual form of Hybrid half-rose cut. The rose cut itself is also coated diamond. Mineralogical Magazine, 51, 5, discussed. M.O'D. 743-6. On polishing an (001) surface on a colourless TRT'IYAKOVA, L.I., BENAVIDES, K.S., 1987. dodeca hedral diamond of gem quality from Zaire, (Mineralogical and spectral colorimetric studies a marked step was observed between the central of emeralds from Chivor and Muzo deposits, and outer regions. This distinction into core and Colombia.) Zapiski Vses. Min. Obshch., 116, 6, coat was confirmed by X-ray topography and SEM 713-18. (Russian with English abstract.) techniques, and by differences in abrasion resist A series of emeralds from the Chivor and Muzo ance and orientation of cleavage. These differences deposits has been studied and their chromatic are ascribed to quite different growth conditions. characteristics established. Although there is some R.A.H. overlap, spectral differences are clearly seen be tween the emeralds from these two Colombian deposits. The chromophores are Cr+ and V+. R.A.H. J. Gemm., 1988, 21, 2 115

Book Reviews

APOSTOLESCU, R., 1987. Caleidoscop minéralogie. among others. Considerable historical material is (Mineral kaleidoscope.) Editura Technica, provided and the photographs are of high quality. Bucuresti, pp.246, illus. in black-and-white and Many are themselves of historical interest as their in colour. Lei 22.50. [In Rumanian.] subjects include personages of previous genera Dépite the popular sound of the title, this is a tions. This is a well-produced book and well worth serious mineralogical textbook with very valuable the very reasonable price. There is an excellent references to Romanian minerals and their locali bibliography. M.O'D. ties. Gem quality minerals are described and illustrated in colour at the end of the book. There is HADDLETON, M.E., 1987. The Jewellery Quarter a bibliography and a chapter with questions and history and guide. YBA Publications, Birming answers. M.O'D. ham, pp.39, illus. in colour. Gratis. A most delightfully produced guide to the happi BALFOUR, I., 1987. Famous diamonds. Collins, ly rejuvenated Jewellery Quarter of Birmingham. London, pp224, illus. in black-and-white and in M.O'D. colour. £15.00. Based on a series of articles appearing in India- HARTMAN-GOLDSMITH, J., 1986. Chinese jade. qua, this excellent book covers many of the best- Oxford University Press, Hong Kong, pp. xvi, known diamonds with illustrations and copious 81, illus. in black-and-white and in colour. £6.95. historical notes. There is a table to the world's Forming part of the series Images of Asia, this largest stones, giving details of the stones and their short book is of good quality, describing the main whereabouts where known, a glossary and a useful features of the use made of the jade minerals by the bibliography. Although there are many accounts of Chinese. Particular reference is made to the nature celebrated diamonds extant, this one is carefully of the artefacts and there is a useful bibliography. written and is based on records whose authenticity M.O'D. is sound. The price is most reasonable for so attractive and interesting a book. M.O'D. LUZZATTO-BILITZ, O., 1987. Antique jade. Cassell, London, pp.153, illus. in colour. £4.95. BIRÄU, O., CIUHANDU, A., VANGHELI, D.A., 1986. Translated from Antiche giade, published in 1966, Safirul si rubinul. (Sapphire and ruby.) Editura this is a good short guide to jade artefacts and is well Facia, Timisoara, pp.170, illus. in black-and- illustrated. M.O'D. white. Lei 19.50. [In Romanian.] An exhaustive treatise on the ruby and sapphire MATTHES, S., 1987. Mineralogie. (Mineralogy.) varieties of corundum with particular reference to Springer-Verlag, Berlin, pp. xvii, 444, illus. in crystal structure as determined by X-rays. There is black-and-white. DM69.00. an excellent bibliography. M. O'D. The second edition of a work first published in 1983, the text deals not only with the major mineral FIELQ L., 1987. The Queen's jewels. Weidenfeld and species but gives a detailed account of mineral Nicolson, London, pp.192, illus. in black-and- formation and rock types. Thus it is in no sense a white and in colour. £18.00. replacement of Dana's Manual of mineralogy but More than one book has been assembled from rather a text which guides the reader through a good photographs of the personal jewellery of Her Majes deal of material found normally only in journals. ty the Queen but this is the most satisfactory one to The section describing minerals starts the book and appear so far. This book, too, includes a section on the remainder of the text covers the three major rock jewellery which is properly the property of the state types, their petrology and mineralogy. as the crown jewels are also described. Each section has its own bibliography and there The jewellery is described by stone so that there are some useful crystal drawings as well as high- are sections on rubies, sapphires and diamonds, quality photographs. M.O'D.

PIETRACAPRINA, A., BRIZZI, G., 1986. La Sardegna e SPENCER, C, 1986. Mineral wealth of S audi Arabia. i suoi minerali. (Sardinia and its minerals.) Edit Immel Publishing, London, pp.128, illus. in rice Mediterrança, Cagliari, pagination irregular, colour. £23.50. illus. in colour. Price on application. Among the minerals with possible ornamental Minerals from Sardinia are described in application found in Saudi Arabia are peridot, alphabetical order, each entry containing full de fluorite, selenite, gold, azurite, malachite, chryso- tails of the mineral concerned with notes on colla, tourmaline, garnet, amazonite and quartz. occurrences. Gem minerals include amethyst, M.O'D. fluorite and vesuvianite. Maps of important occurrences follow the descriptive section and then SYCHOVA, N., 1984. Traditional jewellery from Soviet come notes on minerals and crystals in general, Central Asia and Kazakhstan. Sovetsky Khu- with a glossary. There is a short bibliography. The dozhnik, Moscow, pp.179, illus. in colour. Price book is very well produced and particularly wel on application. come. M.O'D. This is a well-illustrated and printed book with a text in Russian and English. Coral and turquoise are widely used and many stones are set in silver. A wide SCHUBNEL, H.-J., 1987. Pierres de lumière et objets variety of styles has been chosen to give the reader a précieux. (Shining stones and precious objects.) good idea of the range used over the period Editions Arthaud, Paris, pp.257, illus. in colour. described and there is a short bibliography, in F 495.00. Russian only. M.O'D. Though there are a number of books presenting fine jewelled artefacts with a general supporting SUNAGAWA, I., 1987. Materials science of the earth's text, this one is very well produced with many of the interior. Terra Scientific Publishing Company, pictures new to publication. The book commences Tokyo, and D. Reidel Publishing Company, with a description of the use of gemstones in Dordrecht, pp. xv, 653. Illus. in black-and- prehistory and among primitive societies, proceed white. Price on application. ing to the introduction of later objects from both This major work contains chapters on the East and West; particular attention is paid to the mechanism of crystal growth and on the morpholo pieces emanating from Central America and this gy of natural and synthetic diamond crystals. These section also contains an account of gemstone carv chapters are followed by others on surface microto- ing. The remainder of the book discusses gem- pographic and X-ray topographic study of stones themselves with a useful note on gemstones octahedral crystal of natural diamond from Siberia in commerce. There is a short bibliography. M.O'D. and on synthesis researches of diamond. M.O'D. J. Gemm., 1988, 21, 2 117

Proceedings of the Gemmological Association of Great Britain and Association Notices

OBITUARY Mr Xaver Sailer, FGA (D.1960 with Distinc Mr E.J. Burbage, FGA (D.1927 with Distinc tion), died on 18 December 1987. tion), London, died on 18 January 1988, after a long With the death of Xaver Salier gemmology has illness. His collection of gemstones and minerals lost one of its brightest stars. Very knowledgeable, will remain on display at Haslemere Museum. always helpful, his death is a sad loss to all those who knew and worked with him and to the industry as a Mr Leslie F. Cole, FGA (D.1937 with Distinc whole. He is survived by his wife, Doris, and tion), London, died on 6 December 1987 within a daughter Silvia. few days of his 81st birthday. A service was held at Xaver Salier was a self-made man. He was born in St Anthony's Church, Nunhead. Schmiedeweiden in Bavaria on 26 May 1904, lost Fifty years ago Leslie Cole passed his examina his mother at the age of seven and his father at the tion in gemmology with distinction. It was a year age of twelve during the First World War. After when the list of successful candidates was almost leaving grammar school in Nürnberg, he went to the entirely male and represented the coloured stone Technical Goldsmiths College in Pforzheim, and trade in many aspects of collectors, dealers and from then on worked in the jewellery trade. In 1951 specialists. It was the era when Chelsea Polytechnic under Professor Schlossmacher he took his German was the venue of trade gemmology, the classes were gemmological examinations and in 1960 he became entitled 'Mineralogy for jewellers'. Leslie was ac an FGA. Xaver Salier was an Honorary President of quainted with not only Chelsea Polytechnic but also the German Gemmological Association, and an with the Northern Polytechnic and Sir John Cass honorary member of the Finnish and Japanese College. A close associate and friend of Robert gemmological associations. He also contributed to Webster, he assisted at classes over a very long various committees, including the nomenclature period and to within a year or so of his death. commission of CIBJO. He was also a member of the Council of the Together with his wife Doris he offered generous Gemmological Association for many years; one hospitality to his many friends. His house in could say that Leslie Cole served the trade and Rottach/Egern is a delight. I am very saddened by gemmology for a lifetime. During the war years he the loss of an honourable man and good friend. E. S. served as a Special Constable in the war-torn capital. His retail experience included Wordleys the specialist shop in Birchin Lane in the City of GIFTS TO THE ASSOCIATION London. His daughter has happy memories of The Council of the Association is indebted to accompanying her father on his Saturday morning E. A. Thomson (Gems) Ltd, London, for the gift of clock winding tours of duty. After the closure of two oval fluorolith cabochons. Wordleys he joined the old established jewellers Jay Richard Attenborough in Oxford Street. His last NEWS OF FELLOWS position was with Arthur Saunders of Southampton After 38 years with the Gemological Institute of Row. America and the GIA Gem Trade Laboratory, Bert He will be remembered by generations of stu Krashes announced his retirement near the end of dents of the London scene and by fellow Council 1987. He will continue to serve on the Board of members. His lifetime as a gemmologist spanned Governors of the GIA. the vintage years of Anderson, Payne, Webster, Bert Krashes was born in New York City on 23 Andrews and Wheeler, embracing the very gamut of April 1923. He is married to Charlotte Frankel and gemmology. A.E.F. has three sons and a daughter.

Mr Krashes was a bombardier in the United On 18 November 1987 Mr Michael O'Donoghue, States Eighth Air Force during World War II. He MA, FGS, FGA, organized and chaired a British became a prisoner of war, after being shot down and Library Seminar on Earth Science Information wounded over Europe. His formal education in Sources. cluded the New York City public school system, On 5 March 1988 Mr O'Donoghue gave a lecture New York University, and the Gemological Insti entitled 'Gemstones' to the Kent Group of the tute of America, from which he was graduated in British Iris Society. 1949. Mr Krashes joined the staff of the GIA and the GIA Gem Trade Laboratory in 1949. He soon MEMBERS' MEETINGS developed a reputation as an outstanding teacher, London and became a much sought after speaker for the On 8 March 1988 at the Flett Theatre, Geological American Gem Society conclaves and for jewellers' Museum, Exhibition Road, South Kensington, groups all over the United States and Canada. London SW7, Dr Margherita Superchi gave an illustrated lecture entitled The treasures of Milan Cathedral, the use of a pot-stone from Val Malenco and the alabaster of Volterra'. Dr Superchi's pre sentation was dedicated to the memory of Xaver Sailer of Munich, West Germany, who died in 1987 (obituary p. 117).

Midlands Branch On 15 January 1988 at Dr Johnson House, Bull Street, Birmingham, Mr Alan Jobbins, FGA, gave an illustrated lecture entitled The gemstones of Brazil'. On 19 February 1988 at Dr Johnson House Mr Alan Clark, FGA, of the Gem Testing Laboratory of Great Britain, gave an illustrated lecture entitled 'Future gemmology?'. On 18 March 1988 at Dr Johnson House Mr D.J. Callaghan, FGA, Chairman of the Gemmological Association, gave an illustrated lecture entitled 'From gem to jewel'. North West Branch On 20 January 1988 at Church House, Hanover Bert Krashes. Street, Liverpool, Mr W Stringer gave a talk entitled 'Diamonds'. In addition to earning his Graduate Gemologist On 17 February 1988 at Church House Mr diploma from the GIA, he also became a Certified Jonathan Condrup of Sothebys gave a talk entitled Gemologist through the American Gem Society. In 'Antique cameos'. 1953 Krashes passed with Disinction the Diploma On 16 March 1988 at Church House Dr John Examination of the Gemmological Association of Franks gave a talk on the Munich Gem Fair. Great Britain. In 1970 he was made an honorary vice president of the Gemmological Association of COUNCIL MEETING Canada. Together with his longtime colleague, At a meeting of the Council held on 18 February Robert Crowningshield, Bert Krashes was hon 1988 at the Royal Automobile Club, Pall Mall, oured by the American Gem Society in 1983, by the London SW1, the business transacted included the presentation of its prestigious Robert M. Shipley election to membership of the following: award. In his many years of dedicated service Bert Fellowship Krashes seamed the respect and admiration of Aresti, Tony, London. 1987 those who had the opportunity to work with him. Bernât, Marcos, Barcelona, Spain. 1987 The diamond and jewellery industries have been Brennan, John D., Birmingham. 1969 enriched by his presence. Chiu, Man K.A., Kowloon, Hong Kong. 1987 Corduff, Rosalie ET, Stoke-on-Trent. 1987 • • • Dale, Ann F, Kenner, La., USA. 1987 J. Gemm., 1988,21,2 119

Dalmau Bafalluy, Mo Nieves, Barcelona, Spain. Hughes, Thomas H., Castro Valley, Ca., USA. 1987 Ishikawa, Kyoko, Richmond. Drukker-Loth, Julia J.M., Huizen, Netherlands. Jain, Sanjay, London. 1987 Jassinger, Alexandre I. J., Epsom. Dufficy, Margaret H., San Rafael, Ca., USA. 1987 Kwok, Suk Har, Hong Kong. Ferrer Coma, Montserrat, Barcelona, Spain. 1987 Kyriakidou, Katerina A., London. Filion, Marie M., Montreal, Que., Canada. 1987 Law, Patricia M., Cambridge. Hakola, Arto K., Tornio, Finland. 1987 Lipton, Lindsay, London. Lam, Jim M.K., Kowloon, Hong Kong. 1987 Liyanage, D.C.S., Ashford Common. Marsh, Lesley F, Harare, Zimbabwe. 1987 McGowan, Marion, London. Maupu, Françoise J., St Rambert en Bugey, France. Meade, Christopher, Cleckheaton. 1987 Mussche, Eduard, Brussels, Belgium. Metaxas, George C, London. 1987 Newbould, Hans P.M., Surbiton. Minner, Loren M., Belen, New Mexico. 1987 Nunn, Robert A., Chesham. Nakamori, Katsuyuki, Saitama-Ken, Japan. 1987 Page, Steven, Hillingdon. Offord, Nigel J., Chandlers Ford. 1987 Parsons, Ann S., Keirising. Pitkanen, Marja-Leena A., Lahti, Finland. 1987 Pattni, S., Southall. Roucouna, Catherine, Athens, Greece. 1987 Pedersen, Gunhild, Nattland, Norway. Saminathan, Kannika, Ipoh, Malaysia. 1987 Petty, Mary A., London. Scott, Doreen M., Liverpool. 1987 Piyasirikul, Soonthorn, Bangkok, Thailand. Silverman, Sivan J., Watertown, Ma., USA. 1987 Pople, Cecilia, Godalming. Tang, Ho C.M.T., Hong Kong. 1987 Roberts, Anne M., Crawley. Tapia Canadell, Laura, Barcelona, Spain. 1987 Sadler, Anthony, Loughton. Thevathasan, Nuala A., Colombo, Sri Lanka. 1987 Schunko, Christian, Oslo, Norway. Wirman, Anna L., Salts jo-Boo, Sweden. 1987 Shukla, Manjot, London. Zwack, Geraldine M., Bangkok, Thailand. 1987 Sim, Evelyn, London. Sinclair, Anne L.K., Haslemere. Ordinary Membership Skrablin, Lada-Lucia, London. Admet, Alessandro, Milan, Italy. Slater, Garth, Hallingbury. Ahad, Sayed, Brentford. Solheim, Jan, B0nes, Norway. Alfano, Angelo, London. Soriano Clemen te, Marta, Spain. Andrews, Fern A., London. Sparks, Deborah A., Ruislip. Bassett, Marlene J., London. Speake, Michael H., Tadworth. Bignotti, Fabrizio, London. Spencer, Stephen R., Nottingham. Brink, Carl F, Crystal Falls, Mich., USA. Suzuki, Yoshio, Tokyo, Japan. Cerrone, Mo., Hitchin. Teixeira, Luis EC, Woking. Clark, Diane E., Letch worth. Thurlow, Stephen N.G., Billingshurst. Coote, George E., Sevenoaks. Torrens, Robert M., Crieff. Coulthard, Joan M., Windermere. Tsouji, Nao, Richmond. De Bevere, Dirk, Sutton. Urvik, Hilde, Oslo, Norway. De Michèle, Vincenzo, Milan, Italy. Whitby, Victoria M., Hindhead. De Silva, Edirimuni J.B., Singapore. Winblad, Cathrine, Stockholm, Sweden. Dry den, Kenneth E., Spalding. Wu, Mei, London. Duprez, Bruno, Linselles, France. Elliott, Lucy E.C., London. MEETING OF OFFICERS Emden, Lee, High Wycombe. At a meeting of the Officers of the Association Fong, Phoay H., Penang, Malaysia. held on 1 March 1988 the following were elected to Foster, W. James, Arroyo Grande, Ca., USA membership: Gaston, Giuliani, Brasilia, Brazil. Genis Sol, Eduard, Girona, Spain. Fellowship Gower, Sarah-Jane, Yiewsley. Gotoh, Takeshi, Amsterdam, Netherlands. 1977 Graham, Barry D., Glasgow. Harding, Richard W, Solihull. 1984 Gullerud, Hanne, Nesoddtangen, Norway. Hash, Daniel W, Watrous, Sask., Canada. 1987 Hamblin, Frederick T., Brighton. Hanna, David, Inverness. Ordinary Membership Hirst, Jenny E., London. Baxter, Graham S., Plymouth. Holmes, Irene V., Tadworth. Bucy, Rodger, Ellicott City, Ma., USA. 120 J. Gemm., 1988,21,2

Butler, David J., Malmo, Sweden. Carter, Geoffrey J., Carshalton. Crevoshay, George, Newton, Mass., USA. Doran, Sean E, Liverpool. AMENDMENT Harris, Raymond H.L., London. Misson, Gary P., Oxford. TO PROGRAMME Monachino, Melinda, San Francisco, Ca., USA. Nootenboom, Apollonius, Kingsland. OF LONDON Nyah, Koufie, London. Ogden, Anne-Marie, Bristol. EVENING Pender, Patricia, Southport. Pyne, Anne M., Bristol. MEETINGS 1988 Rana, Ghulam A., London. Schwarz, Dietmar, Ouro Preto, Minas Gérais, Would members please note that the Brazil. meeting that was to have been held on Thevanayagam, Michael A.H.K., Washington. Tuesday 24 May has been cancelled. The October meeting at which Clive R. CORRIGENDA Burch will be giving a lecture entitled On p. 49 above, first column, for 'Brillo, Douglas', A review of inclusions in synthetic read 'Brill, Douglas'. gemstones' will be held on Monday 10 On p. 52 above, 2nd column, Katsuyuki Naka- October 1988 and not on 11 October as mori, Saitama-Ken, Japan, was omitted from the notified in the January issue ofthe Journal. list of those who qualified in the Diploma section of the 1987 Examinations in Gemmology.

Letter to the Editor

From James E. Shigley and Carol M. Stockton

Dear Sir, In order to set the record straight, we are sending The article 'Blue spinel from the Hunza valley, you linearly-scaled spectra (in absorption, this time) Pakistan' by R.R. Harding and F. Wall that was from the same four stones originally illustrated. We published in the July/October 1987 issue of The would be grateful if you could publish this letter and Journal of Gemmology includes a comparison of the these four spectra in order to provide a better spectra of these new blue spinels with that of a comparison for those obtained by Harding and Wall cobalt-containing one published in our article as well as for future gemmological researchers. As 'Cobalt-blue gem spinels'in the Spring 1984 issue of far as we can tell, under the circumstances, compari Gems& Gemology. Figure 2 of Messrs Harding and son of the spectra of the Hunza valley blue spinels Wall's article clearly shows that their spectra and our with that (now comparable) of the type I cobalt- do not correspond. However, this is because the containing blue spinel from Sri Lanka reveals the spectrum from our 1984 article has a non-linear presence of cobalt as a colouring agent as well as wavelength scale similar to that seen in a prism chromium and (possibly) titanium, as stated by spectroscope. The spectra published in the 1984 Harding and Wall. article were obtained from an old single-beam spectrophotometer system that has since been superseded at GIA Research by a Pye-Unicam 8800 Yours etc., dual-beam instrument. Nevertheless, we must James E. Shigley and Carol M. Stockton apologize for having neither explicitly stated that the scale in our 1984 article was non-linear nor having provided a better scale (simplified for lack of 10 December 1987 space, as we recall) in our original figure, although GIA Research Department, Santa Monica, Ca., the non-linearity could be deduced by correlating USA. labelled bands with those of the hand spectroscope images printed alongside.

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WWee loo lookk afte afterr aJ Jall you yourr insuranc insurancee PROBLEMPROBLEMSS For nearlFor nearlyy a centur a centuryy T. H. T.Marc H. Marchh has builhast buillan an whethewhetherr it be ithome be home,, car, boacar,t boat or pensio or pensionn plan .plan . outstandinoutstandg reputatioing reputationn by helpin by helpingg peopl peoplee in business In business.. We woulWe WOuldd be please be pleasedd to giv toe giveadvic advicee and and As LloydAs 1I0ydss broker brokerss we ca wen offecan roffer speciall speciallyy tailore tadilored quotationquotalionss for al forl you allr yourneed needss and delighteand delightedd to visi tot visit policieposliCi foesr th fore retail Ihe retail, wholesale. wholesale, manufacturin, manufacturingg and and your yourpremise prems iisesf require if requiredd for thi fors purposethis purpose, withou, withoutt alliedallied jeweller fewelleryy trades trades. Not. onlNoty only can wcane helwep help you wityouh with obligationobligation. , all aspectall aspectss of you ofr yourbusines bussiness insuranc insurancee but w bute ca wen can For aFor fre ea freequotatio quotationn ring ringMik eMike War Wardd or Ji orm JimPitma Pitmann also alsotake takecare careof al lof you allr yourothe rother insuranc insurancee problems problems,, on 01-6061282on 01-6061282. ,

T. HT.. MarcH. Marchh an dand Co .Co, Ltd Ltd. , SaintSa Dunstan'int Dunstan'ss House House, Care, yGarey Lane ,Lane, LondoLondonn EC2 VEC2V 8AD. 8ADTelephon. Telephonee 01 -60 01-606126 1282 82 & Lloyd'lloyd'ss Insuranc Insurane Brokerce Broske rs J. Gemm., 1988,21,2 125

ROCKMENT LIMITED

Specialising in Sapphires and Rubies

63-66 Hatton Garden, London EC1N 8LE

Telephone: 01-242 5586 Telex: 263042 GemroxG.

ADVERTISING IN Have you a worn prism? THE JOURNAL OF Arrangements have now been made to offer a speedy repair/overhaul service for GEMMOLOGY Rayner refractometers*. So if your refractometer glass prism is The Editors of the Journal invite cracked, chipped or marked, or the advertisements from gemstone refractometer just is not operating and mineral dealers, scientific satisfactorily, simply send it to instrument makers, publishers the Gemmological Association for overhaul. This will include completely and others with interests in the stripping the unit down, checking and gemmological, mineralogical, replacing, if necessary, damaged internal lapidary and jewellery fields. lens system parts, replacing the top glass prism with a harder glass and generally Rates per insertion, excluding cleaning and realigning optics to VAT, are as follows: ensure many more years of use. Whole page Half page Quarter page The cost is just £51.00 plus postage and £180 £100 £60 VAT where applicable. Enquiries to Mrs M. Burland, Gemmological Association of Advertising Manager, Great Britain, Saint Dunstan's House, Gemmological Association, Carey Lane, London EC2V 8AB. Saint Dunstan's House, Carey Lane, London EC2V 8AB. * Please note that it is not possible to repair some of the old 'black style' refractometers as they are now obsolete. 126 J. Gemm., 1988,21,2

ATTENTION: enesis Museums, Educational * Leaders in gemmological education, specializing in intensive tuition, from scratch to F.G.A. Establishments Diploma in nine months. We can claim a very high level of passes including Distinctions & Collectors amongst our students. I have what is probably the largest * We organize a comprehensive programme of range of genuinely rare gemstones in Study Tours for the student and practising gemmologist, to areas of gemmological interest, the UK-from Apophyllite to Zincite. including Antwerp, Idar-Oberstein, Sri Lanka Also rare synthetics, i.e. Scheelite, and Bangkok. Bismuth Germanate & Yttrium * Dealers in gemstones and rare specimens for both the student and the collector. Vanadate. * Suppliers of gemmological instruments, Lists available- especially the world famous OPL diffraction grating spectroscope, together with a range of (large s.a.e. appreciated) books and study aids. For further details of these and other activities, please contact:- A.J. FRENCH F.G.A. Colin Winter, F.G.A., or Hilary Taylor, B.A., Gem Dealer & Consultant F.G.A., at GENESIS, 21 West Street, Epsom, 82 Brookley Road Surrey KT18 7RL, England. Tel: Epsom (03727) 42974. Brockenhurst, Hants S042 7RA Telex: 923492 TRFRTG attn GENS. Telephone: 059023214 GEMDATA A computer program for gem identification The GEMDATA Package by Peter Read (see p. 66 for full details) is available through the Gemmological Association at £75.00 plus postage, packing and VAT* (*UK only at £11.25). Postal rates are as follows: £3.50, UK and Eire; £4.00, Europe; £6.00 rest of the world. To order your Package use the form below.

To: Gemmological Association of Great Britain, Saint Dunstan's House, Carey Lane, London EC2V 8AB. Please supply copies of the GEMDATA package. *I enclose remittance £ /debit my credit/charge card (please tick appropriate box) D E3 • £3 • MM D Diners Club Card No Expiry date Name Address Telephone No. . Signature Date. ^Delete as applicable J. Gemm., 1988,21,2 127

{JflKiatodriQA.

Dealer in fine,rar e and collectors' gemstones, carvings and mineral specimens. Dealers in Specialist supplier of jade, from archaic nephrite to imperial jadeite. the gem stones of Valuations of collections and of the world individual items undertaken. I wish to purchase gem and mineral Diamonds, Rubies, collections, engraved gemstones Sapphires, Emeralds, and (especially intaglios) and old books most coloured gem stones on gem related subjects. Pearls & Synthetics. Christopher R. Cavey, F.G.A. Bond Street Antique Centre, R.M.Weare 124 New Bond St., & Company Limited. London W.l. 67 The Mount York. England. Y02 2AX. Telephone 0904-621984. Telex: 57697 Yorvex.G Telephone: 01-495 1743 k=

MINERALOGY AND MUSEUMS London July 5-6 1988 An International Conference organized by the British Museum (Natural History) and the Mineralogical Society of Great Britain and Ireland. The Conference will discuss how the mineralogical work of museums can best serve the requirements of industry, science, universities, the amateur mineralogist and the general public. It will be of interest to all museum research workers, curators, designers, mineral collectors, gemmologists and educationalists. Three keynote speakers will lead sessions on the themes:-

COMMUNICATION ACQUISITION RESEARCH DIRECTIONS AND AND AND DISPLAYS CURATION NEEDS Dr H Bari Dr J S White Dr J AMandarino Strasbourg Smithsonian Institution Royal Ontario Museum

A number of invited speakers will also take part in these sessions which will be followed by an open session. Poster displays are welcomed. Registration will be £15 for members of the Mineralogical Society, otherwise £20.

Further details from:

Dr Paul Henderson, Mineralogy and Museums Conference, Department of Mineralogy, British Museum (Natural History), Cromwell Road, London SW7 5BD 128 J. Gemm., 1988,21,2

AN EXCITING NEW OPPORTUNITY IN GEMMOLOGICAL EDUCATION

The Gemmological Association has launched a whole new programme of short practical courses in gremmology.

The courses have been designed for the Association by Ken Scarratt and will be held at the Gem Testing Laboratory in London. The aim is to give practical instruction and experience to students studying gemmology, particularly those preparing to take the FGA examination by home study, and updates specialized courses for all gemmologists.

Various types of one-day courses are being offered during 1988, the dates of which are:

19 and 20 May Practical diamond grading examination revision 16 and 17 June Practical gem testing examination revision 5 July Organic gem materials, including amber and pearls 29 September Diamond grading 27 October Jade, turquoise, lapis lazuli and their simulants 24 November Ruby and sapphire

The National Association of Goldsmiths are also arranging courses on practical gemstone knowledge at the Laboratory. These are to be held on 13 May, 7 July and 7 October 1988.

Each course is limited to 8 participants and is offered at the low charge of £55 plus VAT (including lunch). The courses are open to all students and members of the Association who would like to take a short refresher course.

To book for the courses, please use the coupon below and enclose the necessary remittance.

To: Paula Jennings, Gemmological Association of Great Britain, Saint Dunstan's House, Carey Lane, London EC2V 8AB Please reserve place(s) for the course to be held on (Date). Enclosed is my remittance for £ The fee is £55 plus VAT (i.e. £63.25) per person, per course. NAME ADDRESS

Please use BLOCK LETTERS GEMMOLOGICAL ASSOCIATION OF GREAT BRITAIN

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

Historical Note The Gerrunological 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 ofGemmology 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. Gerrunological 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 can tent of the paper. It should be followed by gemmological interest for publication in the the names (with initials) of the authors and by J oumal. Articles are not normally accepted their addresses. A short abstract of 50-100 , which have already been published elsewhere words should be provided. Papers may be of in English, and an article is accepted only on any length, but long papers of more than the understanding that (1) full information as 10,fOOO 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.reas 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. e1sew here wi thou t 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; addi tional A4 paper. They should be typed with double copies may be supplied, but they must be line spacing wi th 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.2 April 1988

1 lK Journal of Gemmology

Contents

An important Australian contribution to gemmology R.K. Mitchell 67

Orientated lath-like inclusions of a new type in spinel K. Schmelzer 69

Synthetic Opal A. Hodgkinson 73

Observations on turquoise, lapis-lazuli and coral, and some of their simulants

S. TakiandM. Hosaka 74

A fishy 'gem'? R.K. Mitchell 81

More on Nelson's 'FMIR Body Colour' K. Nassau 82

Notes on the inclusions in a greyish kyanite A, Ghera, G. Graziani and E. Gubelin 83 Investigation of cat's-eye zircons from Sri Lanka M. Gunawardene and M. Gunawardene 88 Gemmological investigation of a large faceted east African enstatite John L Koivula, C. W. Fryer and J.E. Shigley 92

Lechleither synthetic rubies with natural seed and synthetic overgrowth K. Schmelzer and H. Bank 95

Colour-changing chromiferous tourmalines from East Africa H. Bank and U. Henn 102 A note on the Barkhausen effect K. Nassau 103

Crystalline and organic A. E. Farn 104

Another low cost accessory J.R.H. Chisholm 105

Gemmological abstracts 106

Book reviews 115

Proceedings of the Gemmological Association of Great Britain and Association Notices 115

Letter to the Editor 120

ISSN: 0022-1252

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