Gemmology Volume 29 No. 4

The Journal of

Volume 29 No. 4 Gemmology October 2004

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

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President: EA[obbins

Vice-Presidents: N WDeeks, R A Howie, D G Kent, RK M itchell

Honorary Fellows: Chen Zhonghui, RA Howie, KNassau

Honorary Life Members: H Bank, DJ Callaghan, E J Gubelin, E A lobbins, J I Koivula, I Thomson, H Tillander

Council: S Burgoyne, AT Collins, TMJ Davidson, SA Everitt, RR Harding, L Hudson, EA [obbins, I Mercer, J Monnickendam, MJ O'Donoghue, EStern, P J Wates, V P Watson

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Branch Chairmen: Midlands - G M Green, North East - N R Rose, North West - D M Brady, Scottish - B Jackson, South East - C H Winter, South West - R M Slater

Examiners: AJAllnutt MSc P~D.FGA, L Bartlett BSc MPhii FGA DGA, Chen Meihua BSc PhD FGA DGA, S Coelho BSc FGADGA, Prof A T Collins BSc PhD, AG Good FGA DGA, D Gravier FGA, J Greatwood FGA, S Greatwood FGA DGA, G M Green FGA DGA, He Ok Chang FGA DGA, GM Howe FGA DGA, B Jackson FGA DGA, B Jensen BSc (Geol), TA [ohne FGA, H Kitawaki FGA cGJ, Li Li Ping FGA DGA, MA Medniuk FGA DGA, T Miyata MSc PhD FGA, M Newton BSc DPhil, CJE O ld ershaw BSc (Hans) FGA DGA, HLPlumb BSc FGA DGA, NR Rose FGADGA, R DRoss BSc FGA DGA, J-C Rufli FGA, EStern FGA DGA, S M Stocklmayer BSc (Hans) FGA, Prof I Sunagawa DSc, M Tilley GG FGA, R K Vartia inen FGA, P Vuillet a Ciles FGA, CM Woodward BSc FGA DGA, Yang Ming Xing FGA DGA

The Journal of Gemmology

Editor: Dr RR Harding

Assistant Editors: MJ O'Donoghue, P G Read

Associate Editors: Dr C E S Arps (Leiden), G Bosshart (Horgen), Prof A T Collins (London), J Finlayson (Stoke-on-Trent), Dr J W Harris (Glasgow), Prof R A Howie (Derbyshire), Dr J M Ogden (London), Prof A H Rankin (Kingston upon Thames), Dr JE Shigley (Carlsbad), Prof D C Smith (Paris), E Stern (London), Prof I Sunagawa (Tokyo), Dr M Superchi (Milan)

Production Editor: MA Burland

Vol 29, No.4, October 2004 IS5N: 1355-4565 193 Pearls from the lion's paw scallop

Kenneth Scarratt1 and Henry A. Hänni2

1. AGTA Gemological Testing Center, New York, NY10017, USA e-mail: [email protected] 2. SSEF Swiss Gemmological Institute, Basel, Switzerland e-mail: [email protected]

In memory of Alexander E. Farn, former Director of the London Chamber of Commerce DPPS Laboratory, Vice President of the Gemmological Association and Gem Testing Laboratory of Great Britain, author and gentleman.

Abstract: Pearls from the Lion's Paw scallops Nodipecten (Lyropecten) nodosus L. 1758 and Nodipecten (Lyropecten) subnodosus Sowerby 1835 are rare and have only recently come to the notice of the gemmological community. They are non-nacreous but differ in surface appearance and composition to other non-nacreous pearls such as the Conch and Melo varieties. The surface appearance is comprised of a patchwork of cells with each cell being formed from three sub-cells. The orientation of these sub-cells and the low magnification fibrous appearance of structures within them give the scallop pearl a peculiar surface sheen. SG and Raman data indicate that the perfectly round 5.91 ct scallop pearl described is composed in the main of calcite rather that being dominated by aragonite as is the case for the Melo and Conch pearls. In addition the chemistry, infrared, and UV/visible spectra for the 5.91 ct scallop pearl are described. These data are compared with similar data from lion's paw shells and detailed submicroscopic structures are described for the shells.

Keywords: lion's paw scallop, Nodipecten magnificus, Nodipecten nodosus, Nodipecten subnodosus, USA

Introduction Not frequently seen but relatively well Strombus gigas (Farn, 1977; Fritsch and known to gemmologists are those often quite Misiorowski, 1987; Moses, 2001), the clam valuable (Shigley et ah, 2000) natural pearls, pearl from Tridacna gigas (Anderson, 1971), formed within molluscs that do not produce the horse-Conch pearl from Pleuroploca nacre (Gutmannsbauer and Hanni, 1994; gigantean and the Melo pearl from any of the Hanni, 1999). Examples of these non- various Melo volutes (Brown and Kelly, 1990; nacreous pearls are the Conch pearl from Scarratt, 1992, 1996; Traub, 1999). The most

Figure 1: A Nodipecten subnodosus shell.

common of these rare non-nacreous pearls is earliest of times, both as a source of food and the spectacular variety produced by Strombus adornment. The shapes of the shells and wide gigas or the Queen Conch, and the rarest variety of colours and patterns have caused being the spectacular Melo pearls. Of late them to be a significant collector's item, to another non-nacreous pearl variety, the be the focus of scientific study, to serve as scallop pearl has become known and thus industrial symbols such as that of the oil far a very limited number recorded. The company Shell, and to feature as the centre following briefly describes Nodipecten piece of art forms. A particularly impressive (Lyropecten) nodosus L. 1758 (Atlantic Lion's art form where the focal point is the lion's Paw) and Nodipecten (Lyropecten) subnodosus paw shell (Figure 1) (so called as the shell Sowerby 1835 (Pacific Lion's Paw) and one resembles a lion's paw (Anonymous, 2003)) particular pearl that was produced by one may be seen in a brooch created by Cartier of these colourful scallops. Another scallop (Paris) ca. 1958 (Figure 2). The shell is pearl produced by the Atlantic Sea Scallop accompanied by turquoise and sapphires and (Placopecten magellanicus) has also been set in gold (Anonymous, 2004), the brooch recently described (Wight, 2004). being valued in the region of $28,000 (Fitzpatrick, 2002). The lion's paw scallop: Of the many scallops there are three its description, distribution bearing the common name Lion's Paw. One and habitats of these is the exceedingly rare Nodipecten magnificus (Sowerby, 1835) which is largely The scallops or pectens are bivalves that restricted to the Galapagos Islands (although have been a part of man's existence from the one was recently dredged off the coast of

J. Gemm., 2004, 29, 4, 193-203 193

Colombia (Hill and Carmihael, 2004)) and with the width and depth almost equal given this rarity is not a focus of this paper. (Figure 5). At a magnification of 10,000x The other two are Nodipecten (Lyropecten) there is no trace of organic material in or nodosus L. 1758 (Atlantic Lion's Paw) and between the fibres. Nodipecten (Lyropecten) subnodosus Sowerby From the SEM images of the shell (Figures 1835 (Pacific Lion's Paw), the largest pectinid 3, 4 and 5) it becomes clear that depending on in tropical waters and the one described as the direction of light the fibres will be in the probable source of the scallop pearl either a 'conducting' (ends of the fibres portrayed herein. N. nodosus is found in the towards the light) position and appear dark, seas off the south-eastern USA to Brazil and or 'reflecting' (other directions towards the N. subnodosus in the seas off western Central light) position and appear light. This America at depths between 25 and 150 m. phenomenon is also responsible for the Together the shell colours are exceptional shimmering silk-like appearance seen in both in their variety and depth (Hill and other shells that have a similar construction, Carmihael, 2004). The outer surface of the e.g. Strombus gigas and the Melo volutes. shell may be several shades of brown, In these shells too, bunches of fibres are in sometimes described as chocolate brown crossed orientation (Kamat et ah, 2000) and (Norris, 2003) and yellow to orange while the either reflect or conduct incoming light but in interior varies from pearly white to shades of this case producing the ubiquitous flame-like purple and brown (Figure 1). The outer pattern (Farn, 1977) well known for these surface of the N. nodosus shell most materials. commonly displays several rows of rounded nodular protuberances located on about eight Barrios-Ruiz reports (Barrios-Ruiz et ah, rounded ribs (although many from the 2003) that N. subnodosus was cultured in La southern Caribbean are smooth (Hill and Paz Bay (1995-1996) and noted that the Carmihael, 2004)) potentially differentiating culture is feasible. However, high water it from shells of N. subnodosus which temperatures in La Paz Bay in summer typically have no such protuberances. Both reduced growth and survival rates. the Atlantic and Pacific Lion's Paws have fan-shaped (typical of scallops in general) equal valves with unequal ears (Wye, 1991).

Scanning electron microscope studies give some insight into the architecture of the lion's paw shell. Classical nacre consists of fine tabular aragonite which provides the typical nacreous lustre. Non-nacreous shell material from Strombus gigas consists of aragonite fibres lying in bunches in crossed arrays (Kamat et ah, 2000). The scallop shell displays a different structure. A surface image shows fibres lying in bunches in different directions almost parallel to the surface (Figure 3). The thickness of the fibres is around 0.5 jum. An image of a broken section shows that under the surface the bunches of fibres still have a crossed orientation (Figure 4). At Figure 2: A brooch consisting of turquoise, sapphires and gold- higher magnifications the fibres can be seen set on a lion's paw shell, created by Cartier (Paris) ca. 1958; as geometrically not very well defined rods courtesy ofPrimavera Gallery, New York, photo Noel Allum.

Pearls from the lion's paw scallop A naturanaturall pearlpearl frofromm ththee lion'slion's pawpaw scallopscallop Materials andand methodsmethods WhilWhilee ththee authorsauthors havhavee beebeenn givengiven ththee opportunityopportunity ttoo viewview andand performperform limitedlimited examinationsexaminations onon several,several, thetheyy havhavee hahadd thethe opportunityopportunity ttoo completecomplete a detaileddetailed examinationexamination onon onlyonly oneone scallopscallop pearpearll whichwhich isis saidsaid toto bebe derivedderived fromfrom Nodipecten The data included in 00041596 C. nod 5Mm 2000x Un^a|e (Lyropecten) subnodosus. The data included in thisthis papepaperr areare gatheredgathered fromfrom thatthat oneone pearlpearl Fibres Fibres lyinglying ininbunches bunchesin indifferent differentdirections directions whichwhich isis perfectlperfectlyy roundround andand weighsweighs 5.915.91 c ctt almost parallel toto thethesUiface surfaceof of the thescallop scallopshell. shell. (Figures 6 andand 7).7). SeveralSeveral shellsshells ofof bothboth ththee AtlanticAtlantic andand PacificPacific lion'slion's pawpaw typetypess havehave alsoalso beenbeen examinedexamined andand thesethese datadata araree comparedcompared withwith thethe pearl.pearl.

AnalyticalAnalytical techniquestechniques employedemployed byby thethe authorsauthors includeinclude microscopymicroscopy usingusing gemmologicalgemmological microscopesmicroscopes atat magnificationsmagnifications rangingranging fromfrom 1515 toto 60x60x andand thethe LeicaLeica DMLMDMLM connectedconnected toto a RamanRaman microscopemicroscope aatt magnificationsmagnifications ofof upup toto 1000x.1000X. ScanningScanning electronelectron microscopymicroscopy ofof shellshell sectionssections wawass performedperformed atat thethe UniversityUniversity ofof BaselBasel (ZMB(ZMB SEMSEM Laboratory)Laboratory) withwith a PhilipsPhilips ESEMESEM XLXL 3030 FEGFEG withwith magnificationsmagnifications upup toto 10,000x;10,000x; 00041588 C.nod 30 Mm 500X u^Balel specificspecific gravitygravity (SG)(SG) determinationsdeterminations werewere Figure 4: A broken sectionsectionof of aascallop scallopshell shellshou» showsthat that determineddetermined hydrostaticallyhydrostatically usingusing aann under the surface thethe buncheshunches of fibres still have crossedcrossed appropriatelyappropriately fittedfitted MettlerMettler electronicelectronic balancebalance orientations. withwith waterwater atat roomroom temperature;temperature; UVUV / visiblevisible spectraspectra werewere recordedrecorded inin reflectancereflectance modemode usingusing a ZeissZeiss MCSMCS 500/501500/501 spectrometerspectrometer recordingrecording datadata forfor thesethese purposespurposes betweenbetween 250250 andand 800800 nm;nm; infraredinfrared datadata werewere obtainedobtained usingusing a Thermo-NicoletThermo-Nicolet AvatarAvatar 360360 FTIRFTIR spectrophotometerspectrophotometer utilizingutilizing a diffusediffuse reflectancereflectance accessoryaccessory (pearl)(pearl) andand a ThermoThermo- NicoletNicolet MagnaMagna 560560 usingusing a 4x4x beambeam condensercondenser (shell),(shell), bothboth atat a resolutionresolution ofof 4 cml:cm"1; RamanRaman datadata werewere recordedrecorded fromfrom a RenishawRenishaw RamanRaman systemsystem 10001000 spectrometerspectrometer incorporatingincorporating a 512512 nmnm argonargon ionion laser;laser; anandd qualitativequalitative chemicalchemical compositionscompositions werewere measuredmeasured usingusing anan EnergyEnergy DispersiveDispersive X-rayX-ray FluorescenceFluorescence SpectrometerSpectrometer (EDXRF)(EDXRF) Figure '5:5: At higher magnifications thethefibres fibres inin thethescallop scallop shellcanshell can be seenseen asas rodsrodswith with widthwidth andand depthdepth almosialmost manufacturedmanufactured byby EDAXED AX (DX95)(DX95) operatingoperating inin equal,equal, butbut neitherround neither roundnor norsquare, square,and and no!geomdrically not geometrically vacuumvacuum atat 3535 kVkV andand 450450 ~lA.juA . X-radiographsX-radiographs well defineddefined inin crosscross section.section. werewere producedproduced usingusing aa FaxitronFaxitron X-rayX-ray unitunit atat 9090 kVkV andand 33 rna.ma.

J.J. Gemm.,Gemm., 2004,2004, 29,29, 4,4, 193-203193-203 The LA ICPMS instrument used is a prototype excimer ArF laser (193 nm). Sample material is ablated (craters of 5-80 jum in diameter) and then flushed into an Elan 6000 quadrupole ICP mass spectrometer for 'simultaneous' multi-element analysis. The laser optics were developed in collaboration with Microlas (Göttingen). With this prototype instrument we can quantify as little as 0.01 ppm of trace elements in minerals, gemstones or archaeological Figure 6: The 5.91 ct scallop pearl on a scallop shell which shows the two colour samples from single spot zones at the rim and centre. ablations. displays a shimmering sheen effect Results particularly when viewed under a bright light. The first short gemmological reports Appearance appeared on these rare pearls in 1998 and Natural pearls from the lion's paw scallop, 1999 (Hurwit, 1998, 1999). A further general N. subnodosus, occur in a variety of shapes description appeared in 2004 (Federman, and colours and have been described as 2004). resembling high-fired pottery (Norris, 2003). They may be drop-shaped, oval, button, The inside of the lion's paw shell shows round, off-round or baroque, while the colour two colour zones indicating different range has been variously described as white materials; a wide ruffle-like margin at the to deep royal purple with varying shades of edge with a distinctive sheen which is an oranges, pinks and plum (Hurwit, 1998; orange to purple colour {Figures 6 and 8) and Anonymous, 2003). The surface of the pearls a white interior. The external mantle tissue

Figure 7a: A close-up of the 5.91 ct scallop pearl from the Figure 7b: A group of four scallop pearls of various qualities collection of Mr. Olivier Galibert and described in the text. and shapes (from the collection ofK.C. Bell)

Pearls from the lion's paw scallop 193

•Äüf"

$N(b^^*^

Figure 8: A wide ruffle-like margin with a distinctive sheen at the edge of a scallop shell

produces two materials as a function of age examination of the chemistry of the 5.91 ct (Gutmannsbauer and Hänni, 1994); the scallop pearl using EDXRF confirmed Ca as younger mantle tissue produces the being dominant with Sr also showing a pigmented purple material and at a significant presence. An examination of the genetically programmed moment in the life lion's paw shells revealed similar data. of the mantle tissue cell, this production In both the pearl and the shells examined, changes and the cell precipitates the white various trace elements were also recorded, material, with no pigment. but since some are possibly the result of contamination picked up since recovery, It thus depends upon the moment they are not reported here. of a pearls harvest, whether it is purple (produced by the mantle tissue in the juvenile A few shell samples (see Table I) were period) or white (produced by the epithelium analysed by LA ICPMS to compare their that has shifted to the second stage) or a trace element composition with that of combination of the two. The purple margin a Pacific lion's paw shell. LA ICPMS is on the shell is relatively wide when a method that is increasingly used in compared with the Pinctada or Pteria shells gemmology for the detection of low where the columnar growth produces smaller concentrations and for light elements rims. We can thus expect a large number of (Heinrich et al., 2003). In Table I concentrations lion's paw pearls to be of a plum colour with of some elements are shown, the figures (in only the older pearls having a white coating. microgram per gram - ppm) are mean values Chemical composition from three point analyses. The sample shell As is common with pearls of all varieties, of the Pacific Lion's Paw shows the highest scallop pearls are composed principally of magnesium concentration compared to all calcium carbonate (Hurwit, 1998). An other shells. With its low manganese content

j. Gemm., 2004, 29, 4, 193-203 1993 Table I: Trace element contents in (ppm) of some shell materials identified by LA ICPMS.

Lion's Paw P. maxima P. margaritifera Hyriopsis Unio A. plicata schlegeli (Pacific) (Australia) (Tahiti) (China) (China) (China)

Na 2119 6674 8019 2092 1857 2369 Mg 813 185 508 20 31 20 B 18 20 22 4 4 4 P 311 34 35 188 113 137 K 54 62 113 12 65 13 Mn 0.6 3 0.7 760 658 733 Sr 924 1077 926 666 2588 384 Ba 0.4 0.4 0.1 253 509 137

it is in line with other saltwater shell SC and X-radiography material. The SG of the 5.91 ct scallop pearl was Structure determined to be 2.65 which is rather low for The structure at the surface of pearls non-nacreous pearls. SGs determined for the produced by the lion's paw scallop is unique Melo pearls have been found to be fairly and upon sight is sufficient to identify the consistent and are generally 2.84 to 2.85 origin of such a pearl. The structure at the (Traub et al., 1999), although a few lower surface may be described as a segmented values down to 2.78 have been recorded. patchwork of cells, each cell comprising three However, these lower values can be attributed differently oriented sub-segments. Within to a greater amount of organic /less X-ray each sub-segment there is what appears to be absorbent material contained within these at low magnifications a 'fibrous structure' pearls. For Conch pearls Webster (Webster, (Figures 9 and 10) that is differently oriented 1994) gave an SG range of 2.81 to 2.87. From for each sub-segment. Light reflecting from this it has been suggested (Fritsch and these 'fibrous structures' produces a Misiorowski, 1987) that a composition for shimmering effect similar to that produced Conch pearls of 40% calcite and 60% aragonite by tiger's-eye and this is a unique feature of was likely, the individual specific gravities for this type of pearl. Although the light calcite and aragonite being 2.71 and 2.93 to shimmering effect is also seen in the shells of 2.95 respectively. The 2.65 SG recorded for the both N. nodosus and N. subnodosus (Figure 8) it 5.91 ct scallop pearl suggests a higher content is not in the segmented form as observed on of calcite than aragonite. This conclusion is the pearl. strengthened by the Raman data.

)-ÊÊ^^M

^|;.|«^f:*;;; •'•'y:'- -"yy^--'^ :'ï|,-;'

Figure 9: The structure at the surface of the scallop pearl may Figure 10: Within each sub-segment (see Figure 9) there is be described as a segmented patchwork of cells, each cell what appears to be at low magnifications a fibrous structure'. comprising three differently oriented sub-segments.

Pearls from the lion's paw scallop 193

90000

80000 ~\ 1123 70000

60000

50000

O U 40000 30000

20000 1087,

10000

0 300 800 1300 1800 2300 2800 3300

Wavenumber (cm-1)

Figure U: The Raman spectrum of the 5.91 et scallop pearl.

400000 1513 350000 1126 300000

250000

200000 O U 150000

100000

50000 1087 ^\ 0 —i , 1 1 1 \ , 1 1 1 i 1 1 1 1 1— 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3300 Wavenumber (cm-1)

-—White —Purple —Brown

Figure 12: Raman spectra of the purple, brown and white areas of the interior of a N. subnodosus shell.

While being the most powerful technique (natural or cultured) (Kennedy, 1998; in the arsenal of the gemmologist when Akamatsu et al, 2001) but these differences distinguishing natural from cultured pearls, are not necessarily obvious in non-nacreous X-radiography relies upon the differences in pearls. Non-nacreous pearls tend to have a X-ray absorbance between the alternating structure that consists of dense closely crystalline and organic layers that are packed crystal arrays without large amounts generally present within a nacreous pearl of organic material being present. Therefore,

J. Gemm., 2004, 29, 4, 193-203 193

(l) u c 50 ('J U (l) 40 t:;: (l) ~ 30

III 250 350 450 550 650 750 nanomctres

- Mauve area of shell - Yellow-brown area of shell - Scallop pearl

Figure 13: TIll' UV/visillie spectra recorded for the 5.91 ct scallop pearl and theyellow-Inmoll and purple areas of the scallop shell. .

in general non-nacreous pearls are opaque 2003; Withna1l, et al., 2003) present in the to X-rays and only occasionally show pearl. A peak of comparatively very weak the presence of organic material by intensity located at 1087 crrr! and which we X-radiography. As was to be expected, can attribute to calcite (Li and Chen., 2001; radiographs taken of the 5.91 ct scallop pearl Huang et al., 2003; Kiefert et al., 2004) was revealed only a small centrally placed dark also noted. The spectrum for this pearl differs arc partially surrounding a dark but from those recorded for other non-nacreous extremely small central core, and a few very pearls such as those produced by Strombus faint arcs towards the periphery of the pearl. gigas (the Conch pearl) and the Melo volutes While these structures were sufficient to (the Melo pearl). Both the Conch and Melo confirm that it was a cyst-type pearl and of pearls show peaks normal for aragonite natural origin the apparent small amount of (rather than calcite) at 1085 crrr! and 703 and organic material present could not explain these are also dominant over the carotenoid the low SG (Traub et al., 1999)but rather peaks. The Raman spectrum for the scallop supported the conclusion that calcite rather pearl is similar to that shown by natural that aragonite is the main component of this red coral. scallop pearl. The Raman spectrum of the 5.91 ct scallop Raman, UV/visible and infrared spectra pearl was compared with the spectra Raman spectra (Kiefert et al., 2001) for the produced from the white, purple and brown 5.91 ct pearl were collected from several areas on the interior of one N. subnodosus different areas and compared. All areas shell (Figure 12). The white area produced the examined produced the same spectrum with complete Raman spectrum typical of calcite primary peaks located at 1123, 1510,2239, with peaks at 281,713, 1087and 1433crrr! 2619and 3028 cm-l (Figure 11). These peaks and none indicating the presence of any are due to the carotenoids (Fritsch and carotenoids; the brown area showed Misiorowski, 1987;Moses, 2001;Huang et ai., relatively low intensity carotenoid peaks at

Pearls from the lion's paw scallop 193

1.4

1.2

(l) u t: :§ E 0.8 ctlJ r;: 0.6 1:: ~ 0.4

0.2

0 600 1100 1600 2100 2600 3100 3600 4100 4600 5100 5600

Wavenumber (cm')

- Purple area (If shell - Pearl

Figure 14: TIll' infrared spectra recorded for tilescallop pearl and lire purple area ofascallop shell.

1126, 1513,2241, 2623 and 3020 cm-I that scallop pearl had additional features at 1508 allowed the main calcite peak at 1087em-I to and 1457crrr". be clearly recorded. In contrast, the spectra from the purple area showed carotenoid Discussion peaks of such intensity (about six times the count rate) as to completely obscure the The shell of the lion's paw scallop is one of strongest calcite peak. the most beautiful of all seashells (Hill and Carmihael, 2004) and it is therefore not UVI visible spectra were recorded in surprising that any pearls produced by this reflectance mode for the 5.91 ct pearl, and for mollusc should also be beautiful. However, it white, purple and brown areas on the interior is surprising that given the beauty of the of one N. subnodosus shell (Figure 13). The shells and their desirability to collectors, that spectra recorded for purple areas of the knowledge of the scallop pearl has not shell's interior and that for the pearl showed reached gemmologists until recently. similar features. Broad but shallow absorption features were noted centred at 540 and 410 Pearls from the lion's paw scallop are nm. For the yellow-brown areas on the shell distinctive in so much as their surface two merging features were noted at structure is dissimilar to that of any other approximately 510 and 460 nm; and for the non-nacreous pearl. They are probably white areas, as to be expected, only a flat line composed predominantly of calcite rather with no features was recorded. than aragonite and the strength of the The infrared spectra were obtained from carotenoid Raman peaks (in relation to the both the 5.91 ct pearl and the purple area of a calcite peaks) is very distinctive. The lion's paw shell (N. nodosus) (Figure 14). combination of colour, structure and optical Above 1550cm-I both spectra were similar effects is unique among pearls and without with features at 1960,2018,2140,3932,4264, doubt as a gem material they are 4593 and 5133 cm-t. Below 1550crrr! the exceedingly rare.

J. Gemm., 2004,29,4, 193-203 193 Guillong, M., and Horn, I., 2003. Quantitative Acknowledgements multi-element analysis of minerals, fluid and melt The authors gratefully acknowledge the inclusions by Laser-Ablation Inductively-Coupled Mass-Spectrometry. Geochim. Cosmochim. Acta., 67, cooperation and assistance of their colleagues 3473-97 in the AGTA and SSEF Laboratories; Olivier Hill, L., and Carmihael, P., 2004. The World's Most Galibert is thanked for allowing the full Beautiful Seashells, 7th edn. World Publications, Tampa, FL examination of the 5.91 ct scallop pearl Huang, F., Yun, X., Yang, M., and Chen, Z., 2003. Pearl described; Jeremy Norris for sight of several cultivation in Donggou, Ezhou, Hubei, and scallop pearl samples of all shapes, sizes and cathodoluminescence of cultured pearls. colours plus stimulating discussions on the The Journal of Gemmology, 28(8), 449-62 subject as well as donation of a N. subnodosus Hurwit, K., 1998. Gem Trade Lab Notes: Non-nacreous 'pearls'. Gems & Gemology, 34(4), 288 shell; K.C. Bell for the loan of several samples Hurwit, K., 1999. Gem Trade Lab Notes: Update on (see Figure 7b) some of which will eventually non-nacreous pearls. Gems & Gemology, 35(2), 140 be used for destructive analysis; and the Kamat, S., Su, X., Ballarini, R., and Heuer, A.H., 2000. authors are indebted to Wes Rankin for the Structural basis for the fracture toughness of the shell of the Conch Strombus gigas. Nature, 405, gift of a N. nodosus shell. The Primavera 1036-40 Gallery of Madison Avenue, New York, is Kennedy, S., 1998. Pearl identification. The Australian thanked for allowing, as owners of the item, Gemmologist, 20(2), 2-19 the reproduction of Figure 2. We thank Kiefert, L., Hänni, H., and Ostertag, T., 2001. Raman Dr T. Pettke, SFIT, Institute of Isotope Spectroscopic Applications to Gemmology. In: Handbook of Raman Spectroscopy, from the Research Geochemistry, Zürich, Switzerland, for the Laboratory to the Process Line, Lewis, H.G.M.E.I.R. LAICPMSdata. (Ed.). Marcel Dekker, New York/Basel Kiefert, L., Moreno, D. McL., Arizmendi, E., Hänni, H., and Elen, S., 2004. Cultured Pearls from the Gulf of References California, Mexico. Gems & Gemology, 40(1), 26-38 Li L., and Chen Z., 2001. Cultured pearls and colour-changed Akamatsu, S., Li T.Z., Moses, T.E., and Scarratt, K., 2001. cultured pearls: Raman spectra. Journal of The current status of Chinese freshwater cultured Gemmology, 27(8), 449-55 pearls. Gems & Gemology, 37(2), 96-113 Moses, T., 2001. Gem Trade Lab notes: Conch 'pearl', Anon., 2003. Scallop pearls. http://www.allnaturalpearls. highly unusual necklace layout. Gems & Gemology, com/scallop.htm 2003, December 37(3), 213 Anon., 2004. Cartier, Paris shell pin. http://www.primaveragallery.com/jewel.aspNorris, J., 2003 2004,. Scallo p pearls. May http://www.oasispearl.com/scallop.html 2003, Anderson, B. W., 1971. More notes from the Laboratory: December Pearls from the Giant Clam. The Journal of Scarratt, K., 1992. Notes from the Laboratory: Orange Gemmology, 12(6), 206-8 Conch pearls. The Journal of Gemmology, 23(3), 137-8 Barrios-Ruiz, D., Chávez-Villalba, J., and Cáceres-Martínez, Scarratt, K., 1996. Pearls and corals from Asia. C., 2003. Growth of Nodipecten subnodosus Gemmologia Europa VI, CISGEM, Milan, 12-27 (Bivalvia: Pectinidae) in La Paz Bay, Mexico. Shigley, J.E., Dirlam, D.M., Laurs, B.M., Boehm, E.W., Aquaculture Research, 34(8), 633 Bosshart, G., and Larson, W.F., 2000. Gem localities Brown, G., and Kelly, S.M.B., 1990. A rare baler shell of the 1990s - calcareous concretions. Gems & pearl. Australian Gemmologist, 17(8), 307-8 Gemology, 36(4), 309-10 Farn, A.E., 1977. Notes from the Laboratory: Pink Traub, J., Zucker, B., Content, D., and Scarratt, K., 1999. Conch pearl. The Journal of Gemmology, 15(7), 361-2 Pearl and the Dragon: A Study of Vietnamese Pearls Federman, D., 2004. Gem profile: scallop pearl: Baja and a History of the Oriental Pearl Trade, Content, Beauty. Modern Jeweler, April, 38 Derek J., Rare Books Incorporated, Houlton, Maine, Fitzpatrick, K., 2002. Splash! Marine-inspired jewelry. USA http://www.departures.com/wg/wg_0702_seajewels.html Webster, R., 1994. Gems: Their Sources, Descriptions and accessed May 2004 Identification., 5th edn. Butterworth-Heinemann, Fritsch, E., and Misiorowski, E., 1987. The history and Oxford gemology of Queen Conch pearls. Gems & Gemology, 23(4), 208-21 Wight, W., 2004. Scallop pearls from Digby, Nova Gutmannsbauer, W., and Hänni, H.A., 1994. Structural Scotia, Canada. Canadian Gemmologist, 25(1), 18-29 and chemical investigations on shells and pearls of Withnall, R., Chowdhry, B.Z., Silver, J., Edwards, nacre forming salt-and fresh-water bivalve molluscs. H.G.M., and de Oliveira, L.F.C., 2003. Raman spectra The Journal of Gemmology, 24(4), 241-52 of carotenoids in natural products. Hänni, H.A., 1999. Sur la formation de nacre et de http://www.cephbase.utmb.edu/refdb/pdf/7824.pdf perles. Revue de Gemmologie A.F.G., 137, 30-6 Accessed August 2004 Heinrich, C.A., Pettke, T., Halter, W.E., Aigner, M., Wye, K. R., 1991.The Encyclopedia of Shells. Quato Audedat, A., Günther, D., Hattendorf, B., Publishing plc, London.

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J. Gemm., 2004, 29, 4, 204 205 A treatment study of Brazilian garnets

Sigrid G. Eeckhout1, Antonio C.S. Sabioni1 and Ana Claudia M. Ferreira2

1. Department of Physics/ICEB, Federal University ofOuro Preto, Minas Gerais, Brazil 2. Department of Mining and Geology, Federal University of Paraíba, Brazil

Abstract: Over the past decade, there has been noticeable growth in interest in coloured stones worldwide, which has led to an increase in gem exploration, production and marketing. Since garnet displays a very large variety of colours, it deserves further attention. Although reports on enhanced gemstones are widespread in the gemmological literature, very few studies have been performed on the enhancement of garnets. We report the first systematic, scientific treatment study on Brazilian garnets from known geological localities, including thermal and diffusion treatment. Iron-containing species become opaque and produce a 'silvery skin'. Light yellow grossular turns to orange similar to that of Imperial-topaz. Other garnet varieties have stable colours, confirming the absence of colour centres. A preliminary diffusion treatment of some rough grossular has produced attractive green and orange stones. Since orange gemstones are becoming increasingly popular and since the diffusion-treated green grossulars resemble some emeralds in colour, they may be of economic importance in the future if quantities are confirmed to justify commercial mining.

Introduction Colour is one of the most important (Shigley et ah, 2000) and Brazil (Ferreira, aspects of the beauty of a gemstone and it is 1997) have sparked renewed interest in the a significant contributor to a gemstone's rare orange variety. Grossular garnet is found value. Members of the garnet family have in various colours, with the varieties hessonite been used as gems since prehistoric times, (cognac) and tsavorite (green) being the most and they are found in a wide range of popular. Uvarovite, the rarest of the familiar colours. Red pyrope and almandine are garnets, is seldom used as a gem. It is the probably the most common and most widely only garnet variety that does not occur in used gem varieties. In recent years, purplish- Brazil (Delaney 1996). Colour-change garnets red rhodolite garnet has become increasingly found in Madagascar change from blue-green popular. Andradite is the most lustrous of all in daylight to purple in incandescent light garnets and has three gem varieties, viz. (Schmetzer and Bernhardt, 1999). green demantoid, yellow topazolite, and opaque, black or dark red melanite. New Many Brazilian museums have garnet finds of spessartine in Namibia, Nigeria specimens but their locations are usually

40W 4W

48°W 42°W

16°S

Araçuai Teöfilo Poaî â )e Otoni

8W ^öy^f^t) Barra doCuieté 16°S -0~ Beio Horizonte

ü Romaria Mine

Minas Gerais

Figure 1: Maps of parts of Brazil indicating localities of the studied garnets.

poorly described. Furthermore, details of the enhancement is the most common and easiest geological environment or the mineralogical type of treatment for gems. Furthermore, the affinities of Brazilian garnet occurrences results of heat-treatment on most stones are reported in the literature are very scarce. stable and permanent under normal As a consequence, the range of Brazilian conditions of wear. In the following stage garnets, including pyrope, almandine- some selected grossular garnets were pyrope, almandine-spessartine, spessartine, diffusion treated and preliminary results spessartine-almandine, grossular and the were obtained. gem-varieties rhodolite and hessonite, will be outlined before describing our Materials and methods experimental work. Occurrence and geology of garnet samples Since gem treatment is a field of high Garnets occur in many geological environ potential wherein less attractive gemstones ments in Brazil. These include metamorphic are transformed to more desirable stones by rocks, igneous rocks, pegmatites, kimberlites various methods such as chemical treatment, and in sediments as detrital grains (Deer et ci., heating and irradiation, a range of garnet 1982). However, gem-quality garnets have varieties was assembled for study. Although been found in only two of these environments, reports on enhanced gemstones are namely pegmatites and alluvial deposits, and widespread in the gemmological literature recovered as a byproduct of some other (e.g. Nassau, 1994; McClure and Smith, 2000, gemstone mining objective (Delaney 1996). and references therein), very few studies have Localities of the studied garnets are shown in been performed on the enhancement of Figure 1. garnets. During the first stage of our experimental work on gem garnets from Pyrope Brazil, heat treatments were performed on Pyrope is one of the main locator minerals representative samples, since thermal in diamond prospecting. Pyrope garnets have

J. Gemm., 2004, 29, 4, 205-214 been recovered from the Romaria mine (originally called Âgua Suja) which is now defunct, on the Marrecos Ranch, SW of Monte Carmelo, Minas Gérais state. The geology of the Romaria mine has been described by Svisero et al. (1981). Almandine-pyrope The almandine-pyrope garnets are from the Fazenda Balisto, Municfpio Peixe, WSW of Sao Valério da Natividade, Tocantins state. They possess an unusual, attractive, purplish-red colour and are therefore called rhodolite in the jewellery trade (Wegner et al., 1998). They are found in alluvial gravels and their source is not yet known. Figure 2: Samples of rough spessartine with diameters up to 2.5 cm and spessartine-almandine garnets with colours Almandine-spessartine varying from reddish orange and orange to yellowish orange. The almandine-spessartine garnets are from the Serra dos Marimbondos granitic pegmatite, Carnaüba dos Dantas, Seridö district, Rio The pegmatite is situated in the Eastern Grande do Norte state (Ferreira, 2001, pers. gemmological province (Pinto and Pedrosa- comm). The garnets are concentrated in ore- Soares, 2001). shoots with feldspar, quartz and muscovite. Grossular Spessartine Grossular samples were collected from (1) Gem-quality spessartine samples have the Barra do Cuieté pegmatite, Governador been recovered from the Alto Mirador Valadares district, Minas Gérais state and (2) granitic pegmatite, Seridö district, NE of the Ägua Fria skarn, Santa Luzia, Paraiba state Carnaüba dos Dantas, Ermo village, Rio (Tavares et al., 2000). The Barra do Cuieté Grande do Norte state (Ferreira, 1984,1997; pegmatite belongs to the Eastern gemmological Ferreira et al, 2000). The highly fractured, province, whereas the Agua Fria skarn belongs complex and internally zoned Alto Mirador to the lithium-rich Borborema sub-province of pegmatite belongs to the lithium-rich the northeastern gemmological province (Pinto Borborema sub-province of the northeastern and Pedrosa-Soares, 2001). Transparent cognac- gemmological province (Pinto and Pedrosa- red grossular (hessonite) samples were found Soares, 2001). The garnets occur in fracture in the tailings of an old mine in Ägua Fria. fillings and in open cavities or pockets and the colours range from reddish orange and yellowish orange to orange. (Figure 2). Characterization of samples For the garnets listed in Table I, refractive Spessartine-almandine indices were measured with an Eickhorst Spessartine-almandine varieties were Gem Led refractometer on faceted stones collected from the substitution bodies of the (12 for the spessartine samples and 3 for the Poaiâ pegmatite. Sao José da Safira district, other compositions) and specific gravities Minas Gérais state. The Poaiâ pegmatite is were obtained from rough stones (10 for the one of the most important garnet-bearing spessartine samples and 4 for the other pegmatites of the Sao José da Safira district varieties) by hydrostatic weighing. and the gemstones possess orange-red, reddish-orange or cognac colours (Figure 2) Three selected crystals of each garnet (Cassedanne and Cassedanne, 1977). type mentioned in Table I were characterized

A treatment study of Brazilian garnets 193 Table I: Chemical composition and physical properties of Brazilian garnets.

Variety Pyrope Almandine- Almandine Spessartine Spessartine Grossular pyrope spessartine almandine Locality Romaria mine Fazenda Serra dos Alto Mirador Poaiâ pegmatite Barra do Balisto Marim bondos pegmatite Cuieté pegmatite pegmatite

Colour red purplish red red reddish orange yellowish reddish reddish cognac light orange orange orange orange colour yellow n Not measured >1.79 >1.79 >1.79 >1.79 >1.79 1.755- 1.755- 1.755- 1.740 1.760 1.760 1760 SG 4.17 4.08-4.11 4.17 4.11- 4.11- 4.11- 4.16- 4.16- 4.16- 3.86 4.22 4.22 4.22 4.18 4.18 4.18 Wt.% Chemical composition

Si02 40.03 37.88 36.97 36.74 36.82 36.71 35.21 35.17 35.16 37.55 Ti02 0.29 0.03 0.02 0.15 0.20 0.06 0.01 0.02 0.00 0.04 A1203 21.13 21.79 21.35 21.12 21.19 21.14 20.80 20.68 20.75 21.01 FeO 9.12 36.49 28.37 2.69 2.72 1.23 11.94 17.44 14.54 1.47 Fe203 0.00 0.00 0.00 0.30 0.30 0.13 0.00 0.00 0.00 0.00 MnO 0.43 0.04 11.98 38.06 38.28 40.41 30.90 25.85 28.47 0.03 MgO 21.33 4.54 1.55 0.85 0.86 0.50 0.00 0.00 0.00 0.05 CaO 4.24 0.06 0.42 0.22 0.20 0.39 0.15 0.21 00.19 37.35 Cr203 2.32 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Total 98.89 100.83 100.66 100.13 100.57 100.57 99.01 99.37 99.11 97.50 | Mol% Pyrope 71.7 18.3 6.3 3.3 3.3 2.0 0.0 0.0 0.0 0.3 Almandine 17.0 81.7 64.7 6.7 6.7 3.0 27.3 40.4 33.3 3.0 Grossular 10.3 0.0 1.3 0.7 0.7 1.0 0.3 0.3 0.3 96.7 Spessartine 1.0 0.0 27.7 89.3 89.3 94.0 72.4 59.7 66.4 0.0

Note: FeO obtained by microprobe was calculated as FeO + Fe203 based on the results of a Mössbauer study, and this for all samples.

by powder X-ray diffraction with a Rigaku to ensure that no other elements with an Geigerflex diffractometer using CuKoc abundance above the microprobe detection radiation and graphite monochromator. limit were present preliminary, qualitative Additional diffraction patterns were runs in wavelength-dispersive mode were recorded on powders, which were scraped performed on three spots of each sample in from the surface of heat-treated pyrope, the complete spectral area. The structural almandine-spessartine and spessartine- formulae were calculated on the basis of almandine garnets. 12 oxygen atoms. To do this, total iron obtained by microprobe was converted to Chemical analyses were performed on FeO and Fe 0 based on the results of a thin sections of one selected, rough sample 2 3 Mössbauer study on similar samples of all of each type mentioned in Table I using a garnet types. Mössbauer spectra (MS) were JEOL JXA-8900RL electron microprobe collected at room temperature (RT) using (15 kV and 20 nA). The standards used a conventional, constant acceleration were albite for Si, olivine for Fe and Mg, spectrometer in conjunction with a 1024 rhodonite for Mn, anorthite for Al and Ca, multi-channel analyzer. Mössbauer rutile for Ti and Cr 0 for Cr, and raw data 2 3 experiments were additionally performed were corrected using the ZAF program. at room temperature on hessonite samples Several line scans across each sample were which previously had been subjected to made to look for any chemical zoning. heat treatments in air at 800°C for four Data were collected from five points on hours and at 600°C for seven days. spessartine samples and from ten points on other samples. The elements determined For the UV-Vis spectroscopic were Si, Fe, Mg, Mn, Ca, AI, Cr and Ti, and measurements, platelets 1mm thick were

j. Gemm., 2004, 29, 4, 205-214 193 cut from representative rough samples of 6. in an oxygen saturated atmosphere each garnet mentioned in Table I. The platelets (Po2 = 1 atm) at 900°C for four hours were cut from the samples used for the 7. in an argon saturated atmosphere chemical analyses. The platelets were (P = 1 atm) at 900°C for four hours polished on both sides to obtain a thickness Ar and ranging from 0.25 to 0.35 mm. To facilitate handling, small crystals were embedded in 8. in a reducing atmosphere (PH = 1 atm) epoxy, which was later removed by at 900°C for four hours. dissolution in acetone. All platelets were The hessonite sample was further heated checked optically for the absence of both in air for seven days at 600°C, and rough liquid and solid inclusions. UV-Vis spectra rhodolite was heated in air at 600°C for 24 were measured, before and after treatment, hours and at 800°C for four hours. After using a Hitachi U-3501 spectrophotometer in cooling down in air, each heat-treated the spectral region 300 to 1100 nm. garnet was compared with the non-treated, In order to identify the diffusion-treated, reference sample. rough, non-transparent grossular stones, the In subsequent experiments, four Rutherford back-scattering technique was representative light yellow grossular rough used. This is a non-destructive, analytical samples were subjected to diffusion tool that uses elastic scattering of 1-3 MeV treatments. The diffusion-treatment process charged particles to analyse the surface usually involves embedding rough or and the outer few micrometres of solids. fashioned stones in a powder consisting of a colouring agent such as iron oxide, within Treatments a corundum crucible. The crucible is then subjected to heating in a furnace at relatively Heating experiments were performed in high temperatures (900°C). Before the oxidising, inert and reducing atmospheres diffusion experiments on the four stones one and at various temperatures up to 1000°C. was kept as a comparator for the diffusion- For the heating experiments, a batch of 9 to treated garnets, one was put in iron oxide, one 10 representative, rough stones from each of in chromium oxide and one in cobalt oxide; the following types was assembled: pyrope, only a very small amount of material was almandine-spessartine, reddish-orange and used in each crucible, and they were then yellowish-orange spessartine, cognac placed in a furnace at 900°C for 44 hours. coloured spessartine-almandine, grossular and hessonite. Only the pyrope and grossular samples were not of gem quality. Results One representative sample of each variety Characterization of the natural garnet samples and colour was not treated, and was retained Chemical composition as a comparator for the heat-treated garnets. X-ray diffraction confirmed that all the The heating experiments were conducted samples studied belong to the garnet family, under the following conditions: and the compositions determined and summarized in Table I confirm this. 1. in air at 800°C for four hours Physical properties 2. in air at 900°C for four hours The refractive index, n, and the specific 3. in air at 1000°C for four hours gravity, SG, of most of the garnets studied are summarized in Table L The pyrope samples 4. in air at 900°C for 24 hours studied are small and well rounded. The 5. in an oxygen saturated atmosphere almandine-pyrope garnets show distinctly

(p02 = l atm) at 800°C for four hours weathered surfaces, but the dodecahedral

A treatment study of Brazilian garnets 192130

Figure 3: Rough garnet species before (upper row) and after (lower row) heat treatment at 800°C for four hours in an oxygen saturated atmosphere (P0 = 1 atm). The following stones are depicted from left to right: reddish-orange and yellowish-orange spessartine, hessonite, almandine-spessartine, grossular, cognac colour spessartine-almandine and pyrope. The average size of the stones is 0.5 cm in diameter.

habit remains visible. The almandine- almandine samples are transparent, have spessartine garnets occur as anhedral or vitreous lustre and possess few or no intergrown crystals with diameters of up to inclusions. No colour-change phenomena 10 cm. The majority of the spessartine garnets were observed when viewed in natural and are euhedral with well-developed crystal incandescent light. faces, commonly dodecahedral {011} or trapezohedral {112}; they show lively and Spectral features brilliant colours varying between reddish UV-Vis spectroscopy was used to orange, orange and yellowish orange (Figure 2). determine the causes of colour differences The spessartine-almandine garnets occur as both within and between the garnet varieties. dispersed crystals within the primary Characteristic absorption peaks for the minerals (quartz, microcline, muscovite, various types of garnets studied are listed in biotite and K-feldspar) or as gem-quality Table II. All pyrope, almandine-pyrope, and aggregates, up to several decimetres, within almandine-spessartine spectra are characterized the substitution bodies which are composed by a broad band at -570 nm, a band at 526 of quartz, K-feldspar, albite, muscovite and nm, and a broad band at 505 nm. A sharp lepidolite. The spessartine and spessartine- absorption band at 410 nm and shoulders at

Table II: Characteristic absorption peaks in spectra of the Brazilian garnets studied.

Pyrope Almandine- Almandine Spessartine Spessartine- Hessonite Assignment pyrope spessartine almandine

Absorption maxima (nm)

1 370 • Fe3+ 1 <390 ultraviolet charge transfer J 410 Mn2+ 421 Mn2+ | 429 Mn2+

1 459 Mn2+ + Fe2+ | 482 Mn2+ 505 • • • Fe2+ 526 • • • Fe2+ 529 • • Mn2+ + Fe2+

-570 • • • Fe2+

J. Gemm., 2004, 29, 4, 205-214 193 Table III: Results of garnet heat treatment.

Pyrope Almandine- Reddish- Yellowish- Cognac colour Grossular Hessonite pyrope Orange Orange Spessartine- spessartine Spessartine almandine

Inairat800°C for 4 hours silvery silvery lustre lustre Inairat900°C for 4 hours

In air at 1000°C for 4 hours silvery opaque with opaque with Imperial- lustre burned no changes no changes burned topaz no changes Inairat900°C appearance appearance colour for 24 hours

PQ = 1 atm at 800°C for 4 hours

P0 = 1 atm at silvery silvery 900°C for 4 hours lustre lustre

PAr = 1 atm at 900°C for 4 hours

PH = 1 atm at no changes no changes no changes no changes 800°C for 4 hours

421, 429, 459, 482 and 529 nm characterize the stones remained unchanged; UV-Vis spectra spectra of the spessartine and spessartine- also remained unchanged. After heat almandine garnets. Furthermore, a broad treatment in air at 1000°C for four hours and absorption below 390 nm extends into the at 900°C for 24 hours, these iron-rich varieties visible region. The strong band at 370 nm is become opaque and have a completely the main characteristic of the absorption burned, charcoal-like appearance, which spectrum of hessonite. remains even after recutting or repolishing. The powder X-ray diffraction spectrum of such a 'burned' stone indicates that no crystal Garnet treatment structure changes occurred and that no Heat treatments hematite was formed. After heat treatments (Table III), both in Following a report that some rhodolite oxidizing (in air or in an oxygen saturated garnets change from purple to a hessonite- atmosphere of PQ = 1 atm) and inert type brown on heating at about 600°C atmospheres (P = 1 atm), on Brazilian Ar (Nassau, 1994), we additionally conducted pyrope, almandine-spessartine and heating experiments in air on rhodolite. After spessartine-almandine garnets, a silvery heating at 600°C for 24 hours, no differences lustre was observed over the whole surface of were detected and the absorption spectrum each heat-treated stone. This silvery lustre is before and after heat-treatments remains caused by formation of a hematite coating, the same. which was confirmed by powder X-ray diffraction. The silvery lustre is more It is apparent from Table III, columns 4, spectacular on heat-treated almandine- 5 and 8, that the heating experiments spessartine and spessartine-almandine than performed on spessartine and hessonite on pyrope (Figure 3). In a reducing caused no change of colour (see also Figure 3), atmosphere, however, no changes were and there were no changes in their UV-Vis observed and the colours of the treated spectra. On the basis of the Mössbauer

A treatment study of Brazilian garnets 193

results, the small amount of total iron in the non-treated hessonite contains 48% Fe3+, that in the hessonite heated at 800°C for four hours contains 51% Fe3+ and in the hessonite heated at 600°C for seven days the iron is 55% ferric. So, although no changes in colour were detected after the treatments, there was slight oxidation of the iron.

In all treatments except that in a reducing atmosphere, light yellow grossular turns to orange, showing the Imperial-topaz colour (see Table III, column 7 and Figure 3). The stone ligure 4: Light yellow, orange and green grossular. remains light yellow after treatment in a The orange and green colours were obtained after diffusion treatment of the light yellow material with Fe and Co, strongly reducing atmosphere (PHl = 1 atm). respectively. The stones have a diameter of about 8 mm.

Diffusion treatments The preliminary diffusion treatments 1998). All values fall within the ranges produced an orange diffusion layer on the mentioned by Stockton and Manson (1985). pale yellow grossulars in the presence of either Fe or Cr oxide and a green diffusion Spectral features layer in the presence of Co oxide. The The UV-Vis absorption spectra of pyrope, diffusion-treated pale yellow grossular stones almandine-pyrope and almandine-spessartine in oxides of iron or chromium show an are characterized by common iron bands Imperial-topaz colour, comparable to that of (Schmetzer et al., 2001). These are a broad the heat-treated grossulars. band at -570 nm, a band at 526 nm and a broad band at 505 nm and according to Frentrup and Langer (1982), the Fe2+ ions Discussion in the eight-coordinated site produce the near-red colour. The structural formula of garnet is generally represented as X Y2Si30 , where X 3 12 The spectra of all spessartine and and Y refer respectively to eight- and six-fold spessartine-almandine garnets in our study coordinated cationic sites. The X sites are are characterized by iron and manganese occupied by rather large, divalent cations, bands (Schmetzer et al., 2001). They show a generally Ca2+, Mn2+, Fe2+ or Mg2+, whereas sharp absorption band at 410 nm [Mn], and the Y sites are occupied by smaller trivalent broad or weak maxima at 421 [Mn], 429 [Mn], cations, such as Al3+, Fe3+, V3+ or Cr3+. When 459 [Mn + Fe], 482 [Mn] and 529 [Mn + Fe] each site is occupied by only one type of ion, nm. The broad absorption below 390 nm, the result is identified as an end member of extending into the visible region, is due the garnet mineral group. to ultra-violet charge transfer, caused by Physical properties electron transfer from O2- ligands to a central The measured refractive index, n, and Fe3+ metal ion (Rossman 1988). Frentrup specific gravity, SG, of the garnets studied, and Langer (1982) further suggested that as listed in Table I, correspond well with a broad band at 370 nm, present in synthetic published data (Deer et al., 1982; Ferreira, spessartine, might additionally point to the 1997; Tavares et al., 2000; Wegner et al., presence of ferric iron in octahedral

J. Gemmv 2004, 29, 4, 205-214 193

coordination. The overall shapes of the The Imperial-topaz colour caused by absorption spectra correspond very well with heating pale yellow grossular (Table III) the one of synthetic spessartine (Frentrup and may well be caused by a change in the Langer, 1982). Comparison between the three valence state of iron, but due to its very low 193 spectra reveals, however, that the small concentration this could not be confirmed differences in colour within the spessartines by Mössbauer spectroscopy. The grossular cannot be explained fully from the spectra. remains light yellow after treatment in a A qualitative correlation between the strongly reducing atmosphere. presence of chromophore atoms (iron and manganese in the present case), microprobe Diffusion treatments analyses, and the colour of these spessartines The diffusion treatments produced an might be that the reddish hue is due to the orange diffusion layer on the rough grossular presence of somewhat larger amounts of iron stones in the presence of Fe and Cr and a (Table I). The absorption band at 370 nm of green diffusion layer in the presence of Co. hessonite is due to the presence of Fe3+ at the Oxides of cobalt are typically used to produce dodecahedral sites and causes the cognac a blue diffusion layer which, when applied to colour (Frentrup and Langer, 1982). an orange stone, produces the green colour. Pollack (1999) recently reported that diffusion Heat treatments treatment on light yellow garnet in the A silvery lustre was observed on pyrope, presence of Co produces stones which are almandine-spessartine and spessartine- green to blue-green. Rutherford Back almandine after heat treatment in air, in an Scattering reveals that the coloration occurs oxygen-saturated atmosphere (P0 = 1 atm) as a layer near the surface, hence recutting and in an inert atmosphere (PAr = 1 atm) or repolishing of the surface may seriously (Table III). Friedman (1988) was the first to affect the stone's appearance. It is important report that on heating almandine in air, the to keep in mind that the properties described surface acquired a silvery lustre. This author are based on a very small amount of sample attributed the silvery lustre to the formation material. Furthermore, experimentation is of specular hematite, but did not confirm it. continuing with the goal of confirming In the present study all powders scratched the results and of increasing the depth of from the surfaces of heat-treated pyropes penetration of the diffused layer. Generally and almandines were confirmed as hematite. speaking, the higher the temperature This means that garnet decomposes at the maintained and the longer the period used surface to form hematite. The fact that the for the heating, the greater will be the depth silvery lustre is more spectacular on of colour. However, at excessively high heat-treated almandine-spessartine and temperatures, the surface may be damaged. spessartine-almandine than on pyrope (Figure 3) can be related to the somewhat lower iron content of the pyrope (Table I). Conclusions In a reducing atmosphere, however, no Orange stones are an increasingly popular transitions were observed and the colour choice in jewellery, and the imperial-topaz of the treated stones remained unchanged. colour derived from light yellow grossular offers potential for economic interest. Although Mössbauer experiments However, the amounts of this mineral in performed at room temperature on hessonites gem-quality likely to be available from Brazil pointed to slight oxidation of Fe2+ to Fe3+ in are relatively small and would not justify the garnet lattice after heat treatment, this commercial mining on this basis alone. had no effect on the already distinct colour Consequently, enhancements of most garnets of the stones. are unlikely to really threaten the gem trade.

A treatment study of Brazilian garnets 193 garnet end members synthesized at high pressures. The heat-treated, iron-containing garnet In: Schreyer W. (Ed). High-pressure researches in varieties are easily detected, even by the geoscience. E. Schweizerbartsche unaided eye, since they become opaque Verlagsbuchhandlung, Stuttgart, pp 247-58 and produce a 'silvery skin'. For the other Friedman, D., 1988 Specular heat-treatment garnet. Australian Gemmologist, 16, 477 varieties, it is more difficult to make a McClure, S.F. and Smith, C.P., 2000. Gemstone enhancement decision between the treated and natural and detection in the 1990s. Gems and stones as they are most likely due to small Gemology, 36(4), 336-59 internal modifications. For the rough, non- Nassau, K., 1994. Gemstone enhancement: history, science and state of the art. 2nd ed. Butterworth-Heinemann transparent, diffusion-treated grossulars, Ltd. Oxford. Rutherford Back Scattering reveals that Pinto, C.P., and Pedrosa-Soares, A.C., 2001. Brazilian the coloration occurs in a surface layer. gem provinces. Australian Gemmologist, 21, 12-6 Pollack, R., 1999. Pat. US 5 888 918, March 30, 1999 Rossman, G.R., 1988. Vibrational spectroscopy of hydrous components. In: Mineralogical Society of References America Reviews in Mineralogy, 18, 193-206 Schmetzer, K. and Bernhardt, H.-J., 1999. Garnets from Cassedanne, J.P., and Cassedanne, J.O., 1977. Les garnets Madagascar with a colour change of blue-green to de Poaiá - Brésil. Revue de Gemmologie 52, 2-4 purple. Gems and Gemology, 35(4), 196-201 Deer, W.A., Howie, R.A., and Zussman, J., 1982. Schmetzer, K., Hainschwang, T., Kiefert, L. and Rock-forming minerals, Vol. 1A: Orthosilicates, Bernhardt, H.-J., 2001. Pink to pinkish orange Longman, London, 919 pp Malaya garnet from Bekily, Madagascar. Gems and Delaney, P.J.V., 1996. Gemstones of Brazil: Geology and Gemology, 37(4), 296-308 occurrences. Rem Revista Escola de Minas, Ouro Shigley, J.E., Dirlam, D.M., Laurs, B.M., and Boehm, Preto, 123 pp E.W., 2000. Gem localities of the 1990s. Gems and Ferreira, A.C.M., Ferreira, J.A de M., and Tavares, J.F., Gemology, 36(4), 292-335 2000. O pegmatito Alto Mirador: descricao e mineralogia, Stockton, C.M., and Manson, D.V., 1985. A proposed XVIII Simpósio de Geologia do Nordeste, Recife, new classification for gem-quality garnets. Gems 16, 157 pp and Gemology, 21(4), 205-18 Ferreira, J.A. de M., 1984. Caracterização gemológica e Svisero, D.P., Felitti, W., and Almeida, J.S., 1981. estudos geoeconomicos de espécies raras de minerais Geologia da mina de diamantes de Romaria, gemas do Alto Mirador, Rio Grande do Norte. município de Romaria. M.G. Mineração e Monographia do curso de pós-graduação Metalurgia, 44, 425, 4-14 lato-sense em Gemologia, Universidade Federal Tavares, J.F., Ferreira, A.C.M., and Ferreira, A. de M., de Minas Gerais/Conselho National de Pesquisa 2000. Uma grande grossulária gema em tactito. Ferreira, J.A. de M., 1997. Gemas raras do Seridó: I Simpósio Brasileiro de Tratmento e Caracterização de espessartitas e gahnitas do Alto Mirador. Jornal das Gemas, Ouro Preto, 67 pp Pedras, 10, 18-21 Wegner, R., Ramos de Brito, A., Karfunkel, J., Henn, U., Frentrup, K.-R. and Langer, K., 1982. Microscope and Lind, Th., 1998. Granate aus der Umgebung absorption spectrometry of silicate microcrystals in von São Valério, Tocantins, Brasilien. Zeitschrift der the range 40,000-5,000 cm-1 and its application to Deutschen Gemmologischen Gesellschaft, 47(3), 147-52

I. Gemm., 2004, 29, 4, 205-214 215 193 The nature of channel constituents in hydrothermal synthetic emerald

Rudolf I. Mashkovtsev* and Sergey Z. Smirnov

Institute of Mineralogy and Petrography, SB RAS, 630090, Novosibirsk, Russia * Corresponding author, e-mail: [email protected]

Abstract: Hydrothermal synthetic emeralds manufactured by Biron, Regency and Tairus have been distinguished from natural and synthetic emeralds using chemical analysis and infrared (IR) spectroscopy. Polarized IR spectra have been obtained from plates. Hydrothermal synthetic emeralds possess infrared absorption features not present in natural emeralds, and these features have been investigated. We infer that the system of five narrow bands in the 3000-2600 cm-1 region is related to the dimer formation of HCL molecules, which have been incorporated in the channels parallel to the c-axis during growth of Biron and Regency emeralds. In Regency emeralds, a double band with maximum at 3295 and shoulder near 3232 cm-1 and a broad band-between 3000 and 2500 cm-1 are attributed to + hydrogen-bonded NH4 ions. In Russian hydrothermal synthetic emeralds the strong infrared spectral features related to molecular water are generally similar to those of some natural emeralds but there are also broad bands due to Ni2+ and Cu2+ ions in the near-infrared regions which enable one to distinguish Russian hydrothermal synthetic from natural emeralds. Other bands unrelated to water in hydrothermal synthetic emeralds are also discussed.

Keywords: ammonium ion, emerald, HCl molecule, IR spectroscopy

Introduction The hydrothermal syntheses of emeralds testing by such techniques as absorption and have much in common with the growth of infrared (IR) spectroscopy and / or energy- natural emerald. As a consequence of dispersive X-ray fluorescence (EDXRF) improving techniques, identification of analysis should be used for conclusive synthetic stones has become increasingly diagnosis of synthetic gems (Koivula et al., difficult. As the gemmological properties of 1996; Schmetzer, 1996). The application of hydrothermal synthetic emerald overlap these tools is based on the distinction of the those of natural emerald, the most conclusive minor impurity contents of natural and results are obtained by the microscopic synthetic emeralds. In synthetic emeralds there examination of their inclusions. However, are impurities which have not been detected even this technique becomes ineffective when in any natural emeralds. For example, chlorine the emerald is clean or does not have is present as a structural constituent in the diagnostic inclusions. Therefore, advanced Biron and Linde or Regency hydrothermal

synthetic emeralds, as well as in recent distinguishing natural from synthetic Chinese synthetic emeralds (Hänni, 1982; emeralds, as practical problems in the Stockton, 1984; Kane and Liddicoat, 1985; examination of large faceted gems arise from Schmetzer et al, 1997). In some Colombian low transparencies in the mid-infrared range emeralds, chlorine has been found but only (4000 - 3400 cm-1) where the absorption as a brine component and, probably, in NaCl peaks of the water molecules are located. 193 crystals in three-phase inclusions (Bosshart, There are also difficulties in taking oriented 1991). Recently, using a micro-proton-induced spectra in the near-infrared range (8000 - X-ray emission (micro-PIXE) technique for 5000 cm-1). Two polarized spectra bulk analysis of an inclusion-free region in corresponding to the two principal optical some Colombian, Zambian and Brazilian directions in the crystal are needed if one is emeralds, chlorine was found as a structural to clearly distinguish the two types of water component but in lower amounts than in Biron molecules (Wood and Nassau, 1967,1968; hydrothermal synthetic emeralds (Yu et al., Schmetzer et al., 1997). Furthermore, in some 2000). Measurable amounts of nickel and emeralds from Colombia the absorption due copper were found in Lechleitner fully to type II water is weaker than in most synthetic and Russian hydrothermal synthetic natural emeralds (Zecchini and Maitrallet, emeralds (Hänni, 1982; Schmetzer, 1988; 1990). 1998). Also, Lechleitner and Russian hydrothermally-grown synthetic emeralds Spectroscopy in the visible and IR regions show the absorption bands associated with is a powerful method for gem identification both type I and type II water molecules and research (Fritsch and Stockton, 1987; (Schmetzer and Kiefert, 1990). Fortunately Fritsch and Rossman, 1987,1988). To date, however, additional measurements in other papers concerning the spectroscopic distinction spectral ranges enable one to solve these of natural from synthetic emeralds include problems. A very sharp absorption at 2357 Wood and Nassau, 1968; Leung et ah, 1986; cm-1 is characteristic of natural emeralds Stockton, 1987; Schmetzer and Kiefert, 1990; (Zecchini and Maitrallet, 1998), an absorption Diaz et al., 1994; and Zecchini and Maitrallet, which is due to carbon dioxide within the 1998. The method is promising because the natural crystal (Wood and Nassau, 1967, technique is non-destructive, extremely rapid, 1968). Lechleitner and Russian hydrothermal and comparatively inexpensive. synthetic emeralds can be identified by either The main features in the IR spectra of visible-range absorption spectroscopy natural emeralds are the presence or absence (Schmetzer, 1988,1990) or by the weak of absorption features from two types of absorption features in mid- and near-infrared water molecules (type I is observed in alkali- ranges (Stockton, 1987; Koivula et al, 1996). free emerald and type II is bound to alkalis) There are distinct absorption features in the incorporated in channels parallel to the c-axis range from 3400 to 2600 cm4 of Biron and (c-channels) of the beryl structure (Wood and Linde hydrothermal emeralds (Leung et al, Nassau, 1967,1968; Flanigen et al, 1967; 1986; Stockton, 1987; Zecchini and Maitrallet, Nassau, 1976; Schmetzer and Kiefert, 1990). 1998) and in Chinese hydrothermal emeralds Flux-grown emeralds have no spectral (Schmetzer et al, 1997). features in the range of water absorption, as has been revealed by previous authors. Linde We have tentatively assigned a doublet at and Biron hydrothermally-grown synthetic 3295 and 3232 cm-1 to ammonia, and a system emeralds have absorption bands associated of five strong bands in the 3000 - 2600 cm4 with only type I water molecules, whereas range to various forms of HCl molecules the natural emeralds have absorption bands which are incorporated in the c-channels of of both type I and II water molecules (Wood Biron and Regency hydrothermal synthetic and Nassau, 1967,1968; Schmetzer and emeralds (Mashkovtsev, 1996; Mashkovtsev Kiefert, 1990). But the absorption of water and Solntsev, 2002). Also Schmetzer et al molecules is a poor criterion to use in (1997) associated an identical system of

]. Gemm., 2004, 29, 4, 215-227 193 absorption bands with the chlorine-bearing with a microscope attachment which was hydrothermal synthetic emeralds (Biron, used to focus the beam when faceted stones Chinese, and Linde or Regency). In the were being measured. In this study the beam present paper we wish to gain an insight into was directed perpendicularly to table facet of the cause of the IR spectroscopic features of the stone on the microscope stage. hydrothermally-grown emeralds in the range The emerald specimens were analyzed for between 10000 and 2000 cm4, in the main, Na 0, FeO, V 0 , C^O^ NiO, CuO, A1 0 , using data obtained from polished plates 2 2 3 2 3 Si0 , and Cl by a Camebax Micro electron of emerald. 2 microprobe at an operating voltage of 15 kV and beam current of 20 nA. Samples of Biron Materials and methods hydrothermal synthetic emerald were also qualitatively studied using secondary ion Samples of the major commercially- mass spectroscopy (SIMS) using a Cameca produced hydrothermal synthetic emeralds S-6 ion microprobe. and of natural emerald from the Ural Mountains, Russia, have been tested to obtain their IR absorption spectra. Detailed Results investigations were performed on 11 rough Chemical composition and 10 faceted stones. Biron synthetic emerald was represented by four halves of Elements substituting major beryl components gem-quality rough crystals, sawn parallel to (Si, Al and Be) seed, of 17.20 to 107.40 ct and five faceted Microprobe and wet chemistry analyses stones of between 1.370 and 1.750 ct. Two of emeralds studied are presented in Table L slices from different rough crystals and one One can conclude from Table I that the most 1.46 ct emerald-cut samples of Regency important impurities in the emeralds are the (Linde) hydrothermal synthetic emerald were chromophoric elements Cr, V and Fe. Tairus examined. Tairus hydrothermal synthetic synthetic emeralds commonly have negligible emeralds from Novosibirsk, Russia were V and higher Cr contents in comparison to represented by 4 oval mixed cuts weighing Biron synthetic emerald. Tairus synthetic between 0.2 and 0.5 ct and by many rough emeralds also contain traces of Ni and Cu crystals. As there is no difference in chemistry which are commonly acquired during growth of the growth processes for crystals of types 1 by solution from the walls of the steel and 2 according to the Tairus Research autoclaves. Detailed zone analyses revealed scientists (see also Koivula et a/., 1996), we that in Tairus synthetic emeralds the Cr203 used only type 1 emeralds as representative and FeO contents gradually decreased away for recent commercial Tairus production. from the beryl seed, while in Biron synthetic Natural emeralds from the Urals (Malyshev emeralds there was a more uniform element mine) were represented by three rough distribution across the overgrowth. crystals and one 1.161 ct rectangular faceted Almost equal Cr and V contents are one of stone. Polarized spectra were obtained the most important chemical features of the from 0.6 to 3.3 mm thick plates cut from Biron synthetic emeralds. They are also rough crystals. extremely low in iron and this contrasts with Mid-infrared absorption spectra were the Tairus emeralds which contain significant obtained using a Brucker IFS 113v Fourier quantities of this element (Table I). No other transform infrared (FTIR) spectrometer in the elements are present that can substitute for Al range 4500-2000 cm"1 and a Specord M80 in the octahedral site of the beryl structure. (Karl Zeiss, Jena) spectrometer in the range 4000-2000 cm-1. Near-infrared spectra Natural emerald from the Malyshev mine were obtained using a SF-20 (LOMO, St. has a low Cr203 content in contrast to the Petersburg) spectrometer in the range 10000- Biron and Tairus synthetic emeralds. The -1 4000 cm . The FTIR spectrometer is equipped highest Cr203 content of intensely coloured

The nature of channel constituents in hydrothermal synthetic emerald ~

TableI;:Chemicalcompositionsof synthetic and natural emeralds.

Biron syn the tic eme rald" Tairu s sy nthetic emerald "O. Ural

Wt.% R29(6) R30(4) R32(7) R34(13) R35(22) 420 361 /1 310 309 U IO) U2(l)

Si0 2 66.35 66.63 66.75 65.66 65.46 65.90 65.70 66.00 65.80 63.99 64.86

AI20 3 17.91 18.66 18.29 18.16 17.87 15.3 1 16.36 16.00 16.40 16.63 16.89

Cr203 0.625 0.110 0.288 0.498 0.653 0.61 0.22 0.39 0.23 bd l 0.165

V20 3 0.756 0.132 0.348 0.874 0.917 bd l bdl bd l bdl bd l bd l

0 0 0 BeO nd nd 13.72 13.63 • nd 13.80 13.60 13.50 13.30 nd nd

FeD bd l bdl bdl bd l bd l 2.54 2.05 2.32 0.28 0.28 0.28

MgO bd l bdl bd l bd l bd l bd l 0.05 0.02 0.04 1.74 1.29

NiO bd l bd l bdl 0.023 bd l 0. 15 0.20 0.10 0.10 bdl bdl

CliO bdl bd l bd l bdl 0.034 0.10 0.00 0.00 0.00 bdl bdl

Na20 bdl bd l bd l bd l bd l 0.06 0.07 0.01 0.00 1.1I 0.82

Cl 0.329 0.386 0.410 0.378 0.397 bd l bd l bd l bd l bd l bd l

LOI nd nd nd nd nd 1.00 1.20 1.10 1.20 nd nd

Total 86.00 85.9-1 99.80 98.71 85.37 99.47 99.45 99.44 99.27 83.75 84.32

.,... C'.. bdl- belourdetection limit; 3 ,3 nd - not determined, L01- loss on ignition; Ul - palecolouredzorn'of Ural emerald, U2 - intenselycolouredzone of the same crystal; ,~

,tel

,-I>- *- averagecomposition:number of probepointsare shownin parenthesis; ~ ** - BeOconcentrationsfor R32 and R34 weredetermined by wet chemistry; Vo i...... - wet chemistry analysesof Tairus emerald; Li20 content is 0.1 wt.%, MnO andK20 contents arearoundthe detectionlimit. N " Cland V20 3 weredeterminedby electron microprobeandappearedto bebelowthe detection limit. 193

U fi Figure 1: The mid-infrared spectra of natural emerald from •ced o the Urals (1) and hydrothermal CA synthetic emeralds Biron (2), Regency (3), and Tairus (4, 5). Note that the Tairus hydrothermal synthetic emerald spectra were obtained from two stones with different orientations of their table facet relative to the optic axis, namely angles of 30 degrees (4) and 60 degrees (5) to the optic axis. 4500 4000 3500 3000 2500 2000 Wavenumber (cm-1)

Ural emeralds of about 0.2 wt. % was measured analogous to Biron synthetic emerald, contains in the studied sample (Table I). A similar relatively high MgO (Bank et al, 1989).

maximum Cr203 content (up to 0.5 wt.%) might be expected from the reports by Vlasov Elements occupying channel sites in the and Kutakova (I960), Schmetzer et al (1991) beryl structure and Schwartz (1991). In contrast, average The most important chemical feature of the

Cr203 contents of Tairus and Biron synthetic Biron synthetic emeralds is the relatively high emeralds are 0.54 - 1.24 wt. %. The average CI content, which is consistent with previous

Cr203 content of Biron synthetic emerald work (Hänni, 1982; Stockton, 1984; Kane and (0.11-0.65 wt.%) is close to the upper limit Liddicoat, 1985; Bank et al, 1989; Yu et al, of that of Ural stones. The colours and 2000). It is worth noting that all the studied compositional zoning can be characteristic synthetic emeralds are low in or free of alkalis, features of natural emeralds, and the while the Ural emeralds have relatively high

Cr203 contents of Ural emeralds do vary Na20 contents. significantly from zone to zone, resulting in contrasting intense and pale colours. On the Infrared spectroscopy basis of the reported (Schmetzer et al.,1991) The infrared spectra of the faceted stones and our own data (Table I), we conclude that are demonstrated in Figure 2. High absorbances the FeO content of Ural emerald is comparable are generally present in the range of the water with the lower limit of Tairus synthetic absorption bands between 3400 and 3900 cm-1 emerald and is much higher than that of for large faceted stones. Also atmospheric C0 Biron synthetic emerald. 2 has hindered the measurements in the range MgO may be present in Tairus emeralds in between 2300 and 2400 cm4 when using quantities up to 0.1 wt.%, but its average is the microscope attachment of the FTIR 0.04 wt.%. Biron synthetic emeralds usually spectrometer. So for faceted emeralds the do not contain detectable MgO, but it is worth narrow range from 2400 to 3400 cm-1 is more noting that Pool synthetic emerald, which is accessible for measurements. To measure

The nature of channel constituents in hydrothermal synthetic emerald 193 Table II: The main features ofIR spectra of hydrothermal synthetic and Ural emeralds and their appearance in emeralds of different origin.

Peak Polarization Emerald type location relative to Biron* Regency* Tairus* Ural* Assignment** cm"1 c-axis

2360 1 s C02 [a] 2624 1 m w-uo HCl [b] 2744 1 m w-uo HCl [b] 2816 II vs s-w HCl [b] 2888 1 m w-uo HCl [b] 2988 _L s m-uo HCl [b] 3230 II m-w s-m H20II [a] + 3232 1 sh NH4 [b] 3295 II, J- s-m NH4+ [b] 3520 1 w w w m H201 [a] 3560 _L w w H201 [a] 3600 II VW vw m s H20II [a] 3608 II w w w OH [d] 3650 1 w m H20II [a] 3700 II s s s vs H2OI [a] 3888 1 m m m s H201 [a] 4065 II w w H20II [b,e] 5097 1 w w w w H201 [a] 5271 J_ m s-m H20II [a] 5274 II s s s s H201 [a] 5460 _L m m m m H201 [a] 5520 II w HCl [b] 6494 II m-uo Ni2+ [c] 6820 II m m m m H201 [a] 6990 1 w w w w H201 [a] 7042 1 w OH [b] 7072 II w w OH [d] 7092 1 w H20II [a] s 7143 II s s s H201 [a] 7320 1 m m m m H201 [a] 8475 X m-uo Cu2+ [c]

* m - moderate, s - strong, w - weak, vw - very weak, vs - very strong, uo - unobserved, sh - shoulder ** References: [a] Wood and Nassau (1967,1968); [b] Mashkovtsev and Solntsev (2002) and this work; [c] Solntsev (1981); [d] Mashkovtsev and Lebedev (1992); [e] Koivula et al (1996)

polarized spectra in the range 2000 to 2600 - 3000 cm4 are always present in Biron 10000 em-1 (Figures 2 and 3), emerald plates emeralds (cf. Leung et ah, 1986; Schmetzer cut from the crystals were used. et al, 1997; Zecchini and Maitrallet, 1998). This system of bands may be so weak in Regency The main spectroscopic data are listed in emeralds that only the central band at 2816 Table II. The well-known bands related to cm-1 may be observed on the background of type I water molecules were observed in the other broad bands between 2400 and 3050 cm-1 spectra of all the samples. Type II water peaks (Figure 2A). Regency emerald spectra also are clearly present in Ural and Tairus emeralds, display a double band with the maximum but in Biron and Regency emeralds, absorption at 3295 and shoulder near 3232 cm-1 and traces related to type II water are weak or not a broad band between 3000 and 2500 cm-1 present. Five absorption bands in the range with a transmission window near 2870 cm1.

J. Gemm., 2004, 29, 4, 215-227 193

a 6ll

,.... 50 E ~ C ·Ill RAL ·u<:> (;: 1; 0 30 u TAIRUS <:J u C r::; .Q... 20 BIRON 0 .Q'" < 10 REGENCY

-lSOO -lOOO 3S00 3000 2500 200ll b 60

50 'E ~ c 40 <:i ~ <:i 0 30 URAL u <:i ;:= TJ\IRUS ~ .Q 20

a BIRON .Q'" -c 10 REGENCY

4S()(] 4000 3S00 3000 2500 2000 Wavenumber (cnr')

Figure 2: Mid-infrared extraordinary-ray (a) andordinary-ray (b) spectra of thin plates of Regency (thickness t==0.65 mm), Biron (t=0.95 mm), Tairus (t=1.4 mm) hydrothermal synthetic emeralds andnatural emerald from the Urals (t=0.6 mm). The main spectral features shown are discussed in thetextandlisted in TableII.

In comparing the most intense bands in natural related to water (see Figures 1 and 2); this and Tairus emeralds, these are similar except system of bands between 2700and 3105 crrr! that in the Ural emeralds, there is an intense was obtained from Tairus faceted stones band at 2360 crrr! related to the COz molecule (Figure 1), but only certain of these were (Wood and Nassau, 1967, 1968). In synthetic observed in thin plates (Figure 2). Also, the emeralds, this peak is vanishingly small or Tairus emeralds are the only emeralds to absent. In Tairus emeralds there are the bands contain the broad bands at 6494 cm-l and at at 4065 and 3230 cm-l which relate to type II 8475 crrr! related to optical transitions in Niz+ water (Wood and Nassau, 1967;Koivula et al., and Cu2+ ions respectively (Solntsev,. 1981; see 1996), and there are weak peaks in the region also Koivula et al; 1996). The band at 3608crrr! around 2300 cm-l as well as in the region is present in all three synthetic emeralds. Weak between 2700 and 3105 cm-! which are not peaks visible near 7000 crrr! include the line

The nature of channel constituents in hydrothennal synthetic emerald 193

-1 Wavenumber (cm1) at 7042 cm in Biron emerald and -1 10000 6000 5000 one at 7072 cm in Tairus and _J L J 1 _J natural emeralds {Figure 3). The relative thickness of the Biron plate enabled the weak band at 5520 cm-1 to be detected.

Discussion I Impurities It has already been stated (Stockton, 1984) that composition of synthetic emeralds is of great importance in their identification. In this context, the components, which either are not present in natural mineral-forming solutions, or can not be incorporated in beryl structure under natural conditions are of the greatest interest, and chlorine is one example. CI is one Wavelength, nm of the most important constituents of natural mineral-forming solutions. The concentrations of Wavenumber (cm:1) chlorides in the mineral-forming 10000 8000 6000 5000 _J I J I I medium of a schist-type emerald deposit average about 5-10 wt. % (Moroz and Vapnik, 1999), and in evaporite type deposits, concentrations are typically as high as 38 wt. % (Cheilletz et ah, 1994). Very high salinities (up to 38 wt. % of NaCl) have also been t detected in fluids at the Gravelotte schist-type deposit in South Africa (Nwe and Morteani, 1993). In contrast, CI contents of most natural emeralds determined by PIXE (proton-induced X-ray emission) methods typically are very low, about 0.01 - 0.09 wt. % (Yu et ah, 2000), although in some Colombian, Zambian and Brazilian

1000 1500 2000 emeralds, contents can be as high Wavelength, nm as 0.12 - 0.18 wt. % (Yu et ah, 2000). Thus a content of more than Figure 3: Near-infrared extraordinary ray (a) and ordinary-ray (b) 0.2 wt. % CI is a very powerful spectra of the same plates as shown in Figure 2 except that the Biron indication that the emerald is 2+ plate is 3.3 mm thick. Note the broad absorption bands due to Ni and hydrothermal synthetic. Cu2+ ions in Tairus emerald, the additional peak at 5520 cm-1 due to HCl in Biron emerald, and other peaks which are discussed in the text and listed in Table II.

J. Gemm., 2004, 29, 4, 215-227 193

Using our own data on composition of the molecules (single HCl, dimer and trimer) and emeralds and data available from the literature, state that all five of the absorption bands in synthetic emeralds may be roughly divided the 2600 - 3000 cm-1 region are related to the into two groups: low-chlorine and high- HCl dimer (two bound HCl molecules). In a chlorine. Typically low-chlorine are flux solid Ar matrix at a temperature of 20 K, emeralds, excluding some Gilson and Lennix the spectrum of the HCl dimer has one stones (see Yu et ah, 2000), Russian very weak band at 2855 cm-1 and another -1 hydrothermally-grown emeralds and most strong band at 2817.5 cm , which depends 193 natural emeralds. In this study CI was not only slightly on the matrix (Mailard et ahß detected in Tairus synthetic or in Ural 1979). Therefore we assume that the emeralds, thus they belong to low-chlorine strong band at 2816 cm-1 observed in emeralds. High-chlorine emeralds include chlorine-bearing hydrothermal synthetic hydrothermally-grown Linde or Regency, emeralds is related to the HCl dimer (the Biron and new Chinese synthetic emeralds. band near 2855 cm-1 in our case is probably It is known that hydrochloric acid and alkali too weak to be observed). The two pairs of chloride water solutions were used to grow the bands (one at 2624 and 2988 cm-1 and Linde or Regency synthetic emeralds another at 2744 and 2888 cm"1) are near- (Nassau, 1976). It has also been found that symmetrical about the main band at 2816 cm-1, alkali chlorides are the major salt constituents whereas the intensities of the bands at 2624 of nail-head and spicule-like fluid inclusions cm-1 and at 2744 cm-1 are always weaker than in Biron synthetic emeralds (Smirnov - those of their counterparts at 2888 and at unpublished data). Although there are no 2988 cm4. We assume that these so-called obviously appropriate sites within the beryl combination bands have resulted from the structure that chlorine ions could occupy, hindered rotation (or libration) of the HCl the high Cl-contents in synthetic emeralds, dimer about two axes of the dimer determined by electron microprobe or PIXE compound. The full justification will be analyses, indicate that CI is a structural published elsewhere. Here we note only that impurity rather than a constituent of inclusions. in a similar way the libration of molecular We therefore suggest that channels in the water gives rise to the combination bands beryl structure are the only appropriate sites at 3520 and 3888 cm4, which are near- for chlorine. symmetrical about a strong band at 3700 cm-1

and are related to the type I H20 (Wood and IR spectroscopy Nassau, 1967). The uneven intensity and From infrared spectroscopic data we slightly asymmetrical disposition of these conclude that five bands in the range 2600- combination bands about the main band are 3000 cm-1 observed in Biron and Regency explained by a dissimilar mechanism of their emeralds are related to HCl molecules excitation (Herzberg, 1945). arranged in the channels of the beryl structure Hence we suggest that the system of the (Mashkovtsev, 1996; Mashkovtsev and Solntsev, bands in the 2600-3000 cm4 region is related 2002). Schmetzer et ah (1997) also associated to an L-shaped dimer of two HCl molecules this group of bands with chlorine content. {Figure 4). The extraordinary-ray near-infrared In support of this conclusion it was noted spectra show a narrow absorption band at that (i) in these emeralds chlorine was 5520 cm4 related to an overtone (it is a replica invariably detected by Hänni (1982), Stockton of the main band at nearly double the (1984), Kane and Liddicoat (1985) and by frequency but with very weak intensity) of other authors (see Table I), and (ii) the dimer HCl vibration at 2816 cm4 (see Figure 3). vibrational frequencies of various forms of HCl molecules trapped in inert matrices It is known that for the growth of Linde stretch from 2700 to 3000 cm-1 (Hallam, 1973). hydrothermal emeralds, ammonium halides Here we want to refine the early assignment were used (Nassau, 1976). Furthermore, the (Mashkovtsev, 1996) to various forms of HCl Tairus experimental beryl, synthesized

The nature of channel constituents in hydrothermal synthetic emerald 193

et ah, 2002) but these bands were not detected in beryl because they are veiled by lattice vibrations. The IR spectrum in the range from 5000 to 4000 cm-1 for a thick plate of Tairus emerald was also obtained (Mashkovtsev et ah, 2004) and revealed a weak peak at 4651 cm-1 (related to an overtone of a water molecule (Wood and Nassau, 1967)) superimposed on a background band with a broad maximum centred near 4770 cm-1; this is probably a result of the linear combination of the ammonium bending mode (typically near 1680 and 1450 cm4) and the stretching mode at 3295 cm-1. Furthermore we can explain the origin of the broad band between 3000 and 2500 cm-1 with a transmission window near 2870 cm-1 in the following way (Mashkovtsev et ah, 2003; Mashkovtsev et ah, 2004). Ammonium can be regarded as a proton donor; it results in a hydrogen-bonded complex with oxygen in the lattice and forms an O-H bond (see Figure 4) which gives rise to an absorption continuum in the range 3000 - 2500 cm-1. Fermi resonance Figure 4; The proposed model for ammonium ion and HCl produces a transmission window in this -1 molecules in the structural c - channel of beryl. Shown are continuum at 2870 cm because of interaction the H-Cl bond of one HCl molecule which is hydrogen- with a sharp overtone of the bending mode bonded with another HCl molecule, and the O-H bond of near 1450 cm"1 (Wood, 1973). structural oxygen which is hydrogen-bonded with an ammonium ion. The narrow peaks at 3608 and the overtone at 7072 cm-1 (Figures 2 and 3) have been hydrothermally in an NH4C1 salt solution, observed previously in Russian hydrothermal shows IR spectral features similar to those of synthetic beryls and assigned to OH groups a Linde emerald (Mashkovtsev and Solntsev, (Mashkovtsev and Lebedev, 1992). Analogously 2002). Hence we have proposed that the band the band at 7042 cm4 observed in Biron at 3295 cm-1 (with shoulder at 3232 cm"1) and emeralds (Figure 3) may be an overtone of the the broad band between 3000 and 2500 cm-1 main band near 3600 cm-1. In this region the + are related to NH3 molecules and NH4 ions, main band is masked by the intense water respectively, in the structural c-channels. This absorptions. Aines and Rossman (1984) showed conclusion was supported by careful study of how to distinguish the spectrum of the H20 + the NH3 radical observed after y-irradiation molecule from that of an OH group in the 7000 -1 by the use of electron paramagnetic resonance and 5200 cm region. In contrast to H20 (Mashkovtsev and Solntsev, 2002). However, molecules the OH groups have no bending more data are needed for unambiguous vibrations with a frequency near 1600 cm-1, determination of the cause of all the above- which give, together with stretching vibrations 4 mentioned bands. Besides the stretching near 3600 cm for H20, the combination band bands between 3000 and 3400 cm-1, in the near 5200 cm-1. In our case there are no weak IR spectra there are characteristic bending peaks near 5200 cm4 associated with the intense 1 modes at 1630, 968 and 930 cm" for NH3 bands related to the type I and type II molecular molecules and at 1680 and 1450 cm4 for water. The presence or absence of the bending- + 4 NH4 ions (Nakamoto, 1978; Likhacheva related absorption near 1600 cm is the primary

J. Gemm., 2004, 29, 4, 215-227 193

criterion of distinction between H20 and OH. Conclusion According this criterion the band at 7042 cm-1 So far as we know, HCl (the system of observed in Biron emeralds may be assigned the bands in the range between 2600 and to an OH group, and the difference in the 3000 cm4) and ammonium (double band near frequencies of this (7042 cm4) and the 3300 cm4 and broad band between 3000 and Tairus emerald (7072 cm-1) may relate to 2500 cm4 with transmission window near 2870 substitution of OH for oxygen at different cm4) molecules have not been found in positions in the emerald structure. natural beryls. It is known that ammonium Visibility of an additional system of the halides and acid media are used in the growth weak bands between 2700 and 3105 cm4 in of synthetic emeralds (Nassau, 1976). Tairus emeralds (Figure 1) depends on the Therefore, detection of HCl and ammonium in orientation of cut stones relative to the incident the IR spectra of emeralds serves to identify light and, probably, has been camouflaged in them as hydrothermal synthetic emeralds. other emeralds by intense absorption bands Incorporation of different impurities in the in this range. This system may be related to beryl structure originates from the chemical the overtones of beryl lattice vibrations. The reagents and autoclaves used for crystal Tairus emerald is the only synthetic emerald growth by different manufacturers, so, if which displays the bands at 3230 and 4065 required, hydrothermal synthetic emeralds of cm4; these are related to type II water (cf. the different well-known manufacturers Stockton, 1987; Koivula et al., 1996). should be distinguishable. In Biron hydrothermal emeralds for example, strong Obviously the detection of the weak bands in the range from 2600 to 3000 cm4 due absorption bands in cut stones depends on to HCl molecules are visible, and Regency sensitivities of the instruments used, (Linde) emeralds show an additional strong dimensions of the gems and on the orientation double band near 3300 cm4 due to ammonium of the polished facet to the incident light. (Figures 1, 2 and Table II). The important So although Koivula et al. (1996) did not distinguishing features of Russian reveal any weak band at 7072 cm4, their mid- hydrothermal synthetic emeralds are the broad infrared spectra did show a peak at 3608 cm4 bands in the near-infrared range due to Cu2+ in Russian synthetic emeralds. Although the and Ni2+ ions which result from dissolution of Tairus emeralds studied here failed to show a the autoclave walls (Figure 3, Table II). Now the number of bands around 2300 cm4 reported use of IR spectroscopy is a powerful tool in by Stockton (1987) and Koivula et al. (1996), separation of natural from synthetic emeralds. there are a sufficient number of strong However, it is still preferable to combine the distinguishing features to enable separation techniques of trace-element analysis, of natural from Russian hydrothermal microscopic study and spectroscopic method synthetic emeralds. The broad bands in the for the unequivocal determination of whether near-infrared range, which we attributed an emerald is synthetic or natural. to Ni2+ and Cu2+, have been reported by Koivula et al (1996). In some modern Tairus emeralds the peaks are small, indicating only traces of Ni and Cu. In the visible range Acknowledgements spectra, any bands relating to Ni2+ and Cu2+ The authors thank the following for the loan are camouflaged by the intense bands due of material for this study: A.S. Lebedev to Cr3+, Fe3+ and Fe2+, especially when the (Institute of Mineralogy and Petrography, concentrations of Ni2+ and Cu2+ are small Novosibirsk), V.G. Thomas and S.D. (cf. Schmetzer, 1988). In this case, it is more Pantsurkin (joint venture 'Tairus', productive to measure the near-infrared Novosibirsk). This work was supported by range which lacks interfering bands. RFBR grant 03-05-64555.

The nature of channel constituents in hydrothermal synthetic emerald 193

Mailard, D., Schriver, A., and Perchard, J.P., 1979. Study References of hydracids trapped in monoatomic matrices. Aines, R.D., and Rossman, G.R., 1984. Water in minerals? I. Near infrared spectra and aggregate structures. A peak in the infrared. J. Geophys. Res., 89, 4059-71 J. Chem. Phys., 71, 505-16 Bank, H., Henn, U., and Lind, Th., 1989. Synthetische Mashkovtsev, R.I., 1996. The application of spectroscopy smaragde aus Australien (synthetische 'Pool to discern natural from synthetic emeralds. emeralds'). Zeitschrift der Deutschen Gemmologischen In: Annual Meeting of the Russian Mineralogical Gessellschaft, 38, 11-16 Society, St. Petersburg, 47-48 [in Russian] Bosshart, G., 1991. Emeralds from Colombia (Part 2). Mashkovtsev, R.I., and Lebedev, A.S., 1992. Infrared J. Gemm., 22(7), 409-25 spectroscopy of water in beryl. J. Struct. Chem., 33, Cheilletz, A., Feraud, G., Giuliani, G., and Rodriguez, 930-3 C.T., 1994. Time-pressure and temperature Mashkovtsev, R.I., and Solntsev, V.P., 2002. Channel constraints on the formation of Colombian emeralds: constituents in synthetic beryl: ammonium. An 40Ar/39Ar laser microprobe and fluid inclusion Phys. Chem. Minerals, 29, 65-71 study. Econ. Geol., 89, 361-80 Mashkovtsev, R.I., Paukshtis, E.A., and Thomas, V.G., Diaz, J., Lorenzo, A., Sole, J.G., Jaque, F., Hoyos, M.A., 2003. The state of molecules and ions in the structural and Vara, I., 1994. Optical spectroscopy as a tool to channels of synthetic beryl. In: X-ray discern natural and synthetic emeralds. Proceedings Diffraction and Crystal Chemistry of Minerals. Book of the 16th General Meeting of the International of Abstracts of the XV International Conference, Mineralogical Association, Pisa, Italy, p. 96. St. Petersburg, 182-3 Flanigen, E.M., Breck, D.V., Mumbach, N.R., and Taylor, Mashkovtsev, R.I., Stoyanov, E.G., and Thomas, V.G., A.M., 1967. Characteristics of synthetic emeralds. 2004. The state of molecules and ions in the Am. Mineral, 52, 744-72 structural channels of ammonium-bearing synthetic Fritsch, E., Stockton, C.M., 1987. Infrared spectroscopy beryl. J. Struct. Chem. 45, 62-9 in gem identification. Gems & Gemology, 23(1), Moroz, I., Vapnik, Ye., 1999. Fluid inclusions in emeralds 18-26 from schist-type deposits. Can. Gemm., 20, 8-14 Fritsch, E., and Rossman, G.R., 1987. An update on Nakamoto, K., 1978. Infrared and Raman spectra of color in gems. Part 1: Introduction and colors inorganic and coordination compounds. Wiley, caused by dispersed metal ions. Gems & Gemology, New York:, 281 pp 23(3), 126-39 Nassau, K., 1976. Synthetic emerald: the confusing Fritsch, E., and Rossman, G.R., 1988. An update on history and the current technologies. J. Cryst. color in gems: Part 2: Colors involving multiple Growth, 35, 211-22 atoms and color centers. Gems & Gemology, 24(1), Nwe, Y.Y., and Morteani, G., 1993. Fluid evolution in 3-15 the H2O-CH4-CO2-NaCl system during emerald Hallam, H.E., 1973. Molecules trapped in low-temperature mineralization at Gravelotte, Murchison molecular matrices. In H.E. Hallam, Ed., Greenstone belt, Northeast Transvaal, South Africa, Vibrational Spectroscopy of Trapped Species: Infrared Geochim. Cosmochim. Acta, 57, 89-103 and Raman Studies of Matrix-Isolated Molecules, Schmetzer, K., 1988. Characterization of Russian Radicals and Ions. Wiley-Interscience, London hydrothermally-grown synthetic emeralds. 68-132 J. Gemm., 21(3), 145-64 Hänni, H. A., 1982. A contribution to the separability of Schmetzer, K., 1990. Two remarkable Lechleitner natural and synthetic emeralds. J. Gemm., 18(2), synthetic emeralds. J. Gemm., 22(1), 20-32 138-44 Schmetzer, K., and Kiefert, L., 1990. Water in beryl - Herzberg, C., 1945. Infrared and Raman Spectra of a contribution to the separability of natural and Polyatomic Molecules, D. Van Nostrand, Inc. synthetic emeralds by infrared spectroscopy. New York. J. Gemm. 22(4), 215-23 Kane, R. E., and Liddicoat, R.T., 1985. The Biron Schmetzer, K., Bernhardt, H.-J., and Biehler, R., 1991. hydrothermal synthetic emerald. Gems & Gemology, Emeralds from the Ural Mountains, USSR. Gems & 21(3), 156-70 Gemology, 27(2), 86-99 Koivula, J.I., Kammerling, R.C., DeGhionno, D., Reinitz, Schmetzer, K., 1996 Growth method and growth-related I., Fritsch, E., and Johnson, M.L., 1996. Gemological properties of a new type of Russian hydrothermal investigation of a new type of Russian hydrothermal synthetic emerald. Gems & Gemology, 32, 40-3 synthetic emerald. Gems & Gemology, 32 (1), Schmetzer, K., Kiefert, L., Bernhardt, H.-J., and Beili, 32-9 Z., 1997. Characterization of Chinese hydrothermal Likhacheva, A. Yu., Paukshtis, E.A., Seryotkin, Yu. V., synthetic emerald. Gems & Gemology, 33(4), 276-91 and Shulgenko, S.G. 2002. IR spectroscopic characterization Schwarz, D., 1991. Die chemischen Eigenschaften der of NH4-analcime. Phys. Chem. Minerals, Smaragde. III Habachtal/Osterreich und 29, 617-23 Uralggebirge/UdSSR. Zeitschift der Deutschen Leung, C.S., Merigoux, H., Poirot, J.-P., and Zecchini, Gemmologischen Gessellschaft, 40, 103-43 P., 1986. Use of infrared spectrometry in gemmology. Solntsev, V.P., 1981. Nature of color centers and EPR in In: Proceedings of the 13th General Meeting of the beryl and chrysoberyl. Trudy Instituta Geologii i International Mineralogical Association, Varna, 1982, Geofiziki, Akademiya Nauk SSSR, Sibirskoe Otdelenie, Vol. 2, publ. Sofia 1986, 441-8 499, 92-140 [in Russian].

J. Gemm., 2004, 29, 4, 215-227 193 Stockton, C.M., 1984. The chemical distinction of natural of beryl and emerald by visible and infrared from synthetic emeralds. Gems & Gemology, 20(3), absorption spectroscopy. Am. Mineral, 33, 777-800 141-5 Wood, J.L., 1973. The vibrational spectra of hydrogen-bonded Stockton, C.M., 1987. The separation of natural from complexes. In: Ed. By J. Yarwood, synthetic emeralds by infrared spectroscopy. Spectroscopy and Structure of Molecular Complexes. Gems & Gemology, 23(2), 96-9 Plenum Press, London and New York, 303-85 Vlasov, K.A., and Kutakova, E.I., 1960. Izumrudnye Kopi Yu, K.N., Tang, S.M., and Tay, T.S., 2000. PIXE studies of (Emerald Mines). Moscow: AN USSR. 252 pp emeralds. X-Ray Spectrometry, 29, 267-78 [in Russian]. Zecchini, P., and Maitrallet, P., 1998. Que peut apporter Wood, D.L., and Nassau, K., 1967. Infrared spectra of la spectrographie infrarouge dans l'Étude des foreign molecules in beryl. J. Chem. Phys., 47, Émeraudes? In: Giard, Ed., L'émeraude. 2220-8 Connaissances Actuelles et Prospectives, Association Wood, D.L., and Nassau, K., 1968. The characterization Française de Gemmologie, Paris 81-96

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The nature of channel constituents in hydrothermal synthetic emerald 192283 A new definition of optic axis for gemmology and the four kinds of optic axis

Richard H. Cartier

Toronto, Ontario, Canada [email protected]

Abstract: Longstanding misuse of terminology in gemmological literature and course notes has allowed an inaccurate definition of optic axis to confuse understanding of this simple and fundamental concept. The problem is addressed with the proposal of a succinct new definition for optic axis. A review of anisotropic optics and discussion of the four kinds of optic axis explains how the proposed definition accords with optics theory.

Keywords: birefringence, double refraction, optic axis, polarization

Introduction The common definition of optic axis The proposed new definition for optic axis is: in gemmology, 'a direction of single Optic axis: a propagation direction in a refraction in a doubly refracting crystal1', birefringent medium that by some criterion is unsatisfactory because light at normal has zero birefringence. It is a direction where incidence in this direction would not birefringence (BI) = 0 in a medium with BI>0. refract at all, so refraction is irrelevant. Even when it is reworded to eliminate the refraction/ refringence2 confusion, 'an Isotropic and isotropic direction in a birefringent medium' does not leave an opening for minerals with anisotropic media 3 optical activity . This inadequate wording A brief iteration about isotropic and would not allow, for example, that quartz has anisotropic media may be a logical place to an optic axis. Careful consideration of optical start. The measure of refringence4 (optical properties in biaxial media will show that, density) is refractive index (RI), and materials unlike the simpler uniaxial media, there are that have more than one RI are said to be no isotropic directions in a biaxial medium. birefringent. The numerical difference There is clearly a need for a new definition between the lowest and the highest RI along of optic axis that is in accord with modern one propagation direction is called the understanding of optics. A definition that birefringence (BI) of that reading. A test in uses the phrase 'single refraction' is simply another direction through that same medium wrong, and a definition that specifies can yield other RI values with a changed isotropic excludes some uniaxial and all birefringence particular to that new direction biaxial material. tested. Each direction through the medium

will have its own birefringence value. When birefringence (BI=0). The qualifying by some referencing the medium (rather than one criterion in the definition of optic axis allows specific test direction) all possible test insertion of specifics to enable distinction of directions are considered. The 'birefringence' different kinds of optic axes. (BI) of the medium is presumed to mean There are four different kinds of optic axis; 'maximum birefringence'. The BI of the stone each is definably monorefringent. will almost always be greater than the BI of one direction tested. 1. An isotropic propagation direction in a To understand the interaction of light with biréfringent medium8. an anisotropic medium, one must consider 2. An optically active propagation direction the vibration direction of the light. It must be with nil birefringence for linearly appreciated that randomly vibrating light can polarized light. be sorted by a medium into one portion of light having specifically definable vibration, 3. A ray direction in which mutually and another portion of light vibrating in a perpendicular vibrations travel at the direction perpendicular5 to the vibration of same velocity. the first portion. Where birefingence is 4. A propagation direction in which all observed, the different RI readings are vibrations travel at the same wave- related to different vibration directions in the normal velocity. medium. For each propagation direction, the birefringence is for mutually perpendicular5 Materials with tetragonal, hexagonal, or directions of vibration. Light vibrating in trigonal structure have9 either the first or the specifically definable directions is called second type of optic axis. Materials with polarized light. orthorhombic, monoclinic or triclinic symmetry, have10 both the third and the For most biréfringent media, the mutually fourth kinds of optic axes. perpendicular vibrations that each medium produces will be two sets of plane-polarized light. One set of linear vibrations will be at 90° to the vibration of the companion set. Uniaxial minerals For most directions of propagation through In uniaxial media, the direction parallel the medium, each direction of vibration to the c axis differs from and is 90° to the interacts differently with the medium in directions in the plane of the 'a' axes. terms of velocity of transmission, which In biaxial media, all the crystal axes differ. interactions result in birefringence. The To visualize the optical properties of a numerical value of birefringence will vary medium it is helpful to consider the shapes according to the propagation direction tested of wave fronts of light as they progress. because vibrations are limited to within the The relationship between the wave front, wave front6 in transverse relationship7 to the the direction of travel, and the direction of direction of travel. vibration can be understood by considering the activity of the light at one point on the Optic axes wave front. There will always be at least one direction Imagine that a single-point light source through a biréfringent medium where the inside the medium produces a momentary numerical value of birefringence is zero. flash of light, somewhat like a pinpoint This special propagation direction in a size photographic flash bulb. Using our biréfringent medium is an optic axis. imagination to stop time a little while after As stated above, an optic axis is a our pulse of light is produced, we can picture propagation direction in a biréfringent the shape of the wave front at any particular medium that by some criterion has zero moment as it progresses through the medium.

A new definition of optic axis for gemmology and the four kinds of optic axis 231930

n i'V \!""A>.. i i H IK U^

y, ^ Uniaxial negative wave fronts ^ (with optic axis top to bottom in the plane of the page Uniaxial positive wave fronts O = origin \ = wave tangent plane ^ = ray (propagation direction) -- = wave front at the fourth wavelength X = vibration in the plane of the page circular is ordinary elliptical is extraordinary •.••*•• = vibration perpendicular to the page

Figure 1: Uniaxial wave fronts: (a) positive, and (b) negative. The optic axis is top to bottom in the plane of the page.

The three-dimensional shape of the regardless of direction of vibration. Every progressing wave fronts is called the vibration will continue at the velocity ray-velocity surface in optics terminology. imposed by the réfringence with no change in the sense of vibration; that is the vibration Figure 1 shows a central cross-section of direction will not be altered by the medium. wave fronts of light radiating from a point This direction is isotropic. light source and travelling in a uniaxial medium (positive (a) and negative (b)) with Quartz the direction of vibration indicated once every wavelength and the shape of the wave To show the wave fronts and vibration front shown by dashed lines at the fourth directions for the more complex case of wavelength. With the optic axis set top-to- quartz, a perspective view of a wedge section bottom in the plane of the diagram, each is more helpful than a cross-section. For diagram shows the direction of propagation Figure 2, which shows the vibration directions for rays vibrating in a plane perpendicular for dextrorotatary and laevorotatary quartz12, to the optic axis, for rays vibrating in a plane imagine that the single point light source is at parallel to the optic axis and for rays floor level in the corner of a room that is vibrating in a plane at 45° to the optic axis. completely filled, wall-to-wall and floor to In simple cases, such as zircon, beryl, calcite ceiling, with quartz crystal structure. The or tourmaline, the two wave fronts are in optic axis is oriented parallel to the edge contact with each other at two diametrically where the floor and a wall meet on our left as opposite points that locate the optic axis. we look down into the corner. Stopping time All normally incident light in this propagation a moment after a pulse of light is produced, direction will travel (without refracting)11 we can see the shape of the wave fronts with no optical variation for differing against the floor and the two walls. Either vibration directions. In terms of réfringence, of these sections together with the missing every ray will travel at the same velocity seven comparable sections would show

j. Gemm., 2004, 29, 4, 228-234 193

O = origin = linear vibration K^ = circular vibration \ ïï ~ e^iptica^ vibration ^ \ ^

Optic Axis Optic Axis

Figure 2: Vibration directions in quartz.

a fully rounded three-dimensional shape orthohombic, monoclinic, or triclinic indicating proportional velocity from the structure. When these lower-symmetry centre for all vibration directions. structures are tested it is found that birefringence does vary from maximum The vibration direction of the light is to zero, however. shown in six points on each of the two wave fronts. The vibration direction for light For these cases narrow and more specific travelling perpendicular to the optic axis is language is needed to define a special linear13, the vibration direction for light direction that can be termed an optic axis. travelling along the optic axis is circular14, There are two different directions that can be and the vibration direction for other defined as monorefringent in biaxial media; directions of travel is elliptical15. one relates to light rays and the other to light waves. These two directions are the third and In this helical medium, two circularly fourth kinds of optic axis. polarized rays with opposing sense of rotation yield circular birefringence in one In every biréfringent medium, there will be propagation direction, but this circularly at least one direction of propagation through biréfringent direction is monorefringent with the medium where mutually perpendicular respect to the wave-normal velocity16 of vibrations can progress along the same path linearly polarized light. For this, the second at the same velocity. In uniaxial media this kind of optic axis, velocity is the same defined direction coincides with the one optic regardless of the direction of linear axis, but in the lower symmetry media two vibration, whilst the direction of linear directions within the optic plane17 satisfy this vibration changes over the course of definition. These materials are said to be transmission. This rotation of the direction biaxial. This direction is monorefringent with of linear vibration is called optical activity, respect to ray velocity and is the optic axis for which is produced by the circular light rays. In optics texts it is called the birefringence. secondary optic axis. This direction is easier to recognize in a wave-front diagram but, as Biaxial minerals will be shown, has optical properties that make it deserve the status of secondary. These first two kinds of optic axes, which are seen in uniaxial media, are too highly For every biréfringent medium, there will symmetrical to be found in media with be at least one direction into the medium

A new definition of optic axis for gemmology and the four kinds of optic axis 193

where vibrations in all normally incident vibration and not necessarily in the ray light continuously share the same wave- direction. The wave front containing the tangent plane as the light progresses through vibration perpendicular to the optic plane is the medium. In uniaxial media this defined circular, so that wave-normal continues in a direction coincides with the one optic axis, straight line from the origin. The wave front but in the lower symmetry media two containing the vibration in the optic plane is directions within the optic plane satisfy this an ellipse, so that vibration direction sets the definition and the biaxal label is reinforced. wave-normal in a different direction. This direction is monorefringent with respect The special directions defined in terms to wave-normal velocity and is the optic axis of the continuously coinciding plane of for light waves. In optics texts this direction vibrations have been called 'primary optic is called the primary optic axis, or just the axes' or just 'optic axes'. It may be helpful optic axis. to consider them as the external optic axes. It may be helpful to consider the directions Figure 4 shows a centre section through the defined in terms of equal ray velocity as the wave fronts in the optic plane with one optic internal optic axes. Figure 3 shows18 a centre axis direction detailed. The other external section in the optic plane through the wave optic axis is sloped in from the other side at fronts of light travelling in a biaxial medium. that same angle. Two rays with mutually perpendicular vibrations are travelling along one internal This optic axis direction is oblique, within optic axis sloped to the right; the other the optic plane, and normal to the wave- internal optic axis has that same slope to the tangent plane shared by both wave fronts. left through the other point where the two Collimated light incident at the normal in the wave fronts cross. This internal optic axis is a direction of the external optic axis19 will direction shared by the rays for two mutually experience conical refraction upon passing perpendicular vibration directions. The ray through an incident surface at AB. Vibrations vibrating in the optic plane and the ray in the principal vibration direction for ß vibrating perpendicular to the optic plane travel straight on. Vibrations in all other travel at exactly the same velocity in this directions are refracted as the vibrations direction through the biaxial medium. travel in shared parallel planes through the Even though they are travelling at the same medium. In the Figure 4 side view, vibrations velocity, each vibration has a different wave- 90° to the page are ß. In the end view, normal. It must be remembered that the vibrations in the tangent shared by all the wave-normal is perpendicular to the circular wave front sections are ß as they

= optic axis direction = origin = vibration in optic plane = vibration 90° to page = wave front (ray velocity) = wave normal (for each vibration direction)

Figure 3: Internal (secondary) optic axis.

J. Gemm., 2004, 29, 4, 228-234 193

side view (the optic plane)

= optic axis direction = gamma vibration direction * = vibration 90° to page = wave front (ray velocity surface) ^ = vibration in plane of page = wave tangent plane O = origin J = ray direction

Figure 4: External (primary) optic axis wave-front diagram.

continue past the origin of the ray-velocity vibrations, whilst it is doubly refracting surfaces depicted in the side view. because of the different wave-normal directions (although the angle between the diverging refracted rays would be smaller Discussion than the angle between the internal wave- normals). The idea of a doubly refracting Practical testing related to optic axes optic axis sounds self-contradictory, but that involves examining material from an exterior clearly is the case here. perspective. Looking in from the outside, The case of a doubly refracting external optic axes are being observed. monorefringent direction in biaxial media External optic axes are defined as also reinforces the importance of monorefringent with respect to wave-normal differentiating double refraction from velocity, and wave-normal directions are birefringence2. This peculiar state of affairs easiest to consider in understanding underlines the suitability of considering the refraction. External optic axes are the optic internal optic axes as secondary. Discussions axes for waves of light, and waves actually of biaxial optic axes, therefore, usually exist. Internal optic axes are the optic axes sensibly refer to only the two external for rays of light, and rays do not exist except optic axes. in our imagination. It is therefore understandable that external optic axes are For readers having difficulty with the routinely considered as the optic axes while subtle difference between the two kinds of the internal optic axes are considered biaxal optic axes, a careful comparison of the secondary. optic axis direction shown in Figure 4 (side view), with the secondary optic axis shown in Curiously, the internal optic axis is Figure 3, should help clarify the concepts. monorefringent because it provides one For most people a ray is relatively easy to velocity for mutually perpendicular visualize, so the direction of the secondary

A new definition of optic axis for gemmology and the four kinds of optic axis 191933 random direction within a plane perpendicular to optic axis shown in Figure 3 makes sense. the direction of propagation. It also holds for all Wave fronts are more difficult to visualize, anisotropic cases including polarized light (with so the optic axis depicted in Figure 4, as linear, circular, or elliptical polarization) and a flat perpendicular to shared wave tangent planes, vibration plane that is tilted from being perpendicular to the ray direction (to conform with the requires careful consideration to understand wave-tangent plane). that this direction differs (by a small angle) 8. This first kind of optic axis is monorefringent from the secondary optic axis direction. (exhibits zero birefringence) for all criteria that are not self-limiting. That is, for any kind of polarized Finally, correct use of terminology can help light, for ray velocity, and for wave-normal velocity avoid misunderstanding. The contraction this optic axis is a propagation direction that will exhibit zero birefringence. 'DR' should be expunged from future texts 9. One of (so uniaxial because when looking for one and articles in favour of 'BF. 'Doubly kind of optic axis only one will be found). refracting' or a variation of this phrase is 10. Two of each (so biaxial because when looking for usually a misuse of terminology that clouds one kind of optic axis two of that kind will be found). the issue by confusing a property of a 11. Much literature has referred to this as a direction of medium with action taken by light. The word 'single refraction' but such wording is clearly inaccurate 'refract' (and all variations of it) should only when no refraction takes place. 12. After G.R. Fowles, Introduction to modern optics, 2nd and always refer to light, not a medium. edn, reprinted 1989. Dover Publications, New York. If a medium is biréfringent, some of the light Figure 6.19, p.190 (with correction) it transmits experiences double refraction. 13. Companion vibrations have mutually perpendicular If double refraction of light is observed, the vibrations. 14. Companion vibrations have reverse sense of medium is biréfringent. It is incorrect to refer rotation. to a medium as 'doubly refracting' because 15. Companion vibrations have reverse sense of the medium does not bend, it is only the light rotation and the ellipses' major axes are mutually that bends. perpendicular. 16. Wave-normal velocity is velocity in that direction perpendicular to the wave tangent plane. In References isotropic media, in uniaxial optic axes, and in anisotropic propagation directions that coincide 1. Webster, R., edited by Read, P.G., 1994. Gems. 5th with a principal vibration direction, this corresponds edn. Butterworth-Heinemann Ltd., Oxford, p. 668 with the ray direction. 2. Cartier, R.H., 2002. Birefringence vs. double 17. The optic plane is that plane that contains both the refraction divergence. Journal of Gemmology, 28(4), highest RI (γ) and the lowest RI (α) vibration directions. 223-6 3. Optical activity, which is the rotation of linearly 18. Figure 3 also shows the wave-normal for each of polarized light during transmission, occurs along the rays travelling along the internal optic axis. the optic axis of a uniaxial crystal structure that The ray direction of the refracted external rays will spirals around in one direction (such as quartz), depend, of course, upon the slope of the exit surface. in different crystal systems where units of internal The exit surface cannot be tangent to both wave structure can be described in terms of mirror isomerism fronts at the same time, so the external rays cannot (such as the optic axes of Rochelle salt) or be along the internal wave-normal. If, for example, enantiomorphism (such as the four triad axes in the exit surface is tangent to the elliptical wave sodium chlorate), and can also occur in amorphous front at the internal optic axis, then the ray vibrating media that include left- or right-handed molecules in the circular wave front will refract toward the (such as fluids containing some organic molecules ray at the wave-normal for the elliptical wave such as sucrose). See: E.E. Wahlstrom, Optical front. If the exit surface is tangent to the circular th Crystallography, 5 edn, chapter 13 wave front at the internal optic axis, then the ray 4. Wahlstrom, E.E., 1979. Optical crystallography. 5th vibrating in the elliptical wave front will refract edn. John Wiley & Sons, New York. p. 50, first toward the wave-normal for the circular wave paragraph front while the other ray travels straight on. Other 5. (and/or of reverse sense, if rotation is involved) slopes of the exit surface will cause both rays to 6. The two-dimensional space containing the vibration refract, and they will always be travelling with an is usually represented by a flat plane. If the angle between them significantly less than the wave front is not flat, the plane of vibration is represented angle between the internal wave-normals. by a flat plane tangent to the wave front 19. Every ray direction is reversible, so the double-headed at the point under consideration. This is called the depiction of rays allows that this diagram wave-tangent plane. could be interpreted as showing light travelling 7. The phrase 'transverse relationship' holds for the from the origin 'O' to exit through the surface 'AB' isotropic case, where the vibration may be any and then travel as collimated light.

J. Gemm., 2004, 29, 4, 228-234 192335 Abstracts

agent. The resulting unusual, olivine- spectroscopy. Diamonds free mineral association and the host D.A. ZEDGENIZOV, H. KAGE, V.S. Gem News International. diamonds are interpreted as products of extensive carbonation of the SHATSKY AND N.V. SOBOLEV. B.M. LAURS (ED). Gems & peridotite. G.L.B. Mineralogical Magazine, 68(1), Gemology, 39(4), 2003, 322-46. 2004, 61-73. The gemmological properties of Diamond geezer. Micro-inclusions (1-10 iim) in 55 three famous blue diamonds (the Hope, J. MCCALL. Geoscientist, 14(3), diamonds of cubic habit from the Blue Heart and Heart of Eternity) are Udachnaya kimberlite have been shown described, together with those of 2004, 10-11. by IR and Raman spectroscopy to Short review of the history of natural yellow diamond with Ni-related contain a multiphase assemblage which diamond recovery in India. M.O'D. optical centres. R.A.H. includes carbonates, olivine, apatite, graphite, water and silicate glasses. Diamond formation and Diamond crystals. These micro-inclusions preserve the source carbonation: mineral T. MOORE. Mineralogical record, high internal pressure and give confi 35(1), 2004, 9-63. dence that the original materials were associations in diamonds from trapped during growth of the host Notes on the crystallization of Namibia. diamond. These internal pressures, diamond are followed by descriptions extrapolated to mantle temperatures, lie I. LEOST, T. STACHEL, G.P. BREY, and illustrations of diamond crystals within the stability field of diamond; the J.W. HARRIS AND I.D. from various parts of the world. Many relatively low temperatures are typical are linked to individual mines. M.O'D. RYABCHIKOV. Contributions to for the formation of cuboid diamonds. Mineralogy & Petrology, 145(1), In contrast to previous data for African On unusual deep-violet 2003, 15-24. diamonds, the micro-inclusions in the Udachnaya cuboids are extremely Mineral inclusions in diamonds microcrystals of diamonds carbonatitic in compostion, (H 0)/(H 0 from Namibia document a range of from placers of Ukraine. 2 2 + C0 ) ~ 5-20%, with an observed mantle sources, including eclogitic, 2 M.N. TARAN, V.M. KVASNYTSYA assemblage of micro-inclusions similar websteritic and peridotitic parageneses. AND K. LANGER. European journal to some types of carbonatites. The low Based on unusual textural features a water and silica content testify that the group of inclusions showing websteritic, of Mineralogy, 16(2), 2004, 241-5. material in the micro-inclusions of the peridotitic and transitional chemical Ukrainian deep-violet diamond Udachnaya diamonds was near-solidus features is assigned to an 'undetermined crystals have a distinctive broad absorp 1 carbonatitic melt. R.A.H. suite' (12% of the studied diamonds). tion band centred at -560 ran (17850 cm- The mutual characteristic of this group or 2.21 eV). The intensity of this band is is the occurrence of lamellar inter- almost two orders of magnitude greater growths of clinopyroxene and orthopy- than that in a light rose diamond from roxene. In addition, the 'undetermined Yakutia. Although previously this band Gems and suite' is associated with a number of was attributed to the N-V centre uncommon phases: in one diamond because the absorption spectrum of the Minerals negative N-V centre in irradiated and MgC03 is enclosed by clinopyrozene. Recent discoveries at the Other minerals that form touching unannealed type lb diamonds is known inclusions with the pyroxene lamellae to have an absorption band with a Jeffrey mine, Asbestos, maximum at a similar wavelength, this are: 1) a Si02 phase observed in three Quebec. assignment is not confirmed. At ~ 77 K, diamonds, together with CaC03 in one 1 M. AMABILI, A. MIGLIOLI AND R of them, 2) phlogopite and a Cr-rich the 17850 cnr band displays no fine 'titanite' (probably lindsleyite). The structure that unambiguously shows SPERTINI. Mineralogical record, 35, inclusions document a metamorphic that it cannot be the band at ~ 2.2 eV, 2004, 123-35. path of decreasing P and T after entrap commonly attributed to the N-V centre. A short history of the Jeffrey mine, ment in diamond. First, homogeneous This band is probably caused by 'plastic Asbestos, Quebec, Canada, describes low-Ca clinopyroxenes were entrapped deformation', typical of pink diamonds a number of gem-quality minerals, at high T, then they exsolved orthopy- from the Argyle field. R.A.H. including orange grossular, clear colour

roxene and probably also Si02 (coesite) less grossular with emerald-green cores on cooling along a P, T trajectory that Carbonatitic melts in cuboid (a speciality of this location) and pink did not allow garnet to be exsolved. diamonds from Udachnaya grossular. Emerald-green, deep violet Phlogopite, carbonates and LIMA and multi-coloured vesuvianite are also phases are the result of overprint of a kimberlite pipe (Yakutia): described. Collecting at the mine, peridotitic source rock by a carbon-rich evidence from vibrational always restricted to professionals, has

now ceased due to safety problems as The origin of precious opal - have SG between 2.0-2.65, RI1. 43-1.46, full-scale mining has ceased. M.O'D. a new model. H 5.5-6.5. M.O'D. B. DEVESON. Australian L'opale d'Ethiopie: Achate aus Nordwestsachsen: Gemmologist, 22(2), 2004, 50-8, 1 gemmologie ordinaire et carac 14 Fundstellen. map, 1 illus. téristiques exceptionelles. W. BECK, U. THONFELD AND This new model for the formation of precious and potch opal is based on the J-P. GAUTHIER, F. MANDABA H. PRAWITZ. Lapis, 29(2), 2004, association between opal and natural MAZZERO AND E. FRITSCH. Revue 29-34. artesian springs called mound springs. de gemmologie AFG, 2004,149, Fourteen locations are described for The Lightning Ridge opal field lies on a agate in the NW of Saxony, Germany. line of such springs, and active and 15-23. Many specimens are of ornamental extinct mound springs are found in the Details of gem opal from Ethiopia quality. M.O'D. general proximity of several sedimen are given; SG 1.39-2.06, RI 1.40-1.46. tary opal fields in New South Wales, Values are affected by porosity. The opal South Australia and Queensland. Where shows a play-of-colour against a Crazy Lace-ein the mound spring waters have the brownish background. Traces of stron bemerkenswerter Achat aus appropriate chemistry (i.e. alkaline with tium, lead and niobium have been Mexiko. a high silica content), a mechanism is found in some specimens. Internal suggested in which the physico-chem features are described; parallel lines W. BECK, Lapis, 29(6), 2004, 26-7. ical properties of the water are changed probably associated with grain bound An ornamental agate with elaborate so that suitable silica spheres and then aries may turn out to be helpful in white markings and known as 'Crazy linear chains of these spheres are distinguishing these opals. The opal- lace' is described from the Santa Rita formed. A final component of the new bearing sites are located approximately claim in the Sierra Santa Lucia, north model is the presence of suitable voids 250 km from Addis Ababa in the west Chihuahua, Mexico. Some lined with clay that can act as a semi province of Shewa. Opal is found as examples are pseudomorphous permeable membrane to concentrate rhyolitic nodules which are often near- after calcite. M.O'D. and purify the silica spheres by ultra spherical and may reach 20 cm. M.O'D. filtration and dialysis. RG.R. Achate aus Nordwestsachsen: New interpretation of the 14 Fundstellen. origin of tiger's-eye. Recent study of fluid W. BECK, U. THONFELD AND P.J. HEANEY AND D.M. FISHER. inclusions in corundum of H. PRAWITZ. Lapis, 29(2), 2004, Geology, 31(4), 2003, 323-6. Tiger's-eye is an attractive and 29-34. Sri Lanka. M.D.RL. FRANCIS, H. MATSUEDA, popular gemstone. For more than Fourteen locations are described for a century, textbooks and museum J. TORIMOTO, P.G.R. agate in the NW of Saxony, Germany. displays have identified the material as DHARMARATNE AND G. GIULIANI. Many specimens are of ornamental an archetype of pseudomorphism, i.e. quality. M.O'D. Gemmologie. Z. Dt. Gemmol. Ges., the replacement of one mineral by 52(4), 2003,163-76.10 photo another with the retention of the earlier graphs, 1 map, 4 diagrams, bibl. Topaz from Killiecrankie, mineral's shape. This new study has It was possible to confirm the theory revealed that the textures responsible Flinders Island, and other Bass that fluid inclusions in Sri Lankan for the shimmer of tiger's-eye do not Strait islands. corundum contained more or less pure represent pseudomorphic substitution of quartz after pre-existing crocidolite R.S. BOTTRILL, R.N. WOOLLEY C02 and that the most common daughter minerals included were asbestos. Rather, it is argued that tiger's- AND A.B. FORSYTH. Australian graphite and diaspore. The necking eye classically exemplifies synchronous Gemmologist, 22(1), 2004, 2-9,1 observed was similar to that found in mineral growth through a crack-seal vein-filling process. RB.L. illus., 1 map. Malawi material. The fluid inclusions Flinders Island is one of the were classified into four categories Furneaux group of islands in Bass Strait according to shape, size and microscopi Sapphire-blue kyanite between Tasmania and the Australian cally visible contents of the voids. from Nepal. mainland. The main occurrence of A model was formulated to describe colourless to pale-coloured gem topaz U. HENN. Australian the fluid inclusions in relation to the on Flinders Island is in the fossicking formation of corundum in Sri Lanka.E.S. Gemmologist, 22(1), 2004, 35-6, 5 area around Killiecrankie Bay at the illus. north-eastern end of the island. Gem Kyanite is known to be an important topaz crystals, locally known as Le contexte minéralogique des rock-forming mineral, but gem-quality Killiecrankie diamonds, have been recov specimens are relatively rare and mostly ered in some abundance from around gisements d'opale de la région used as a collector's stone. Attractive the Bay since at least 1803. Some of the de Säo Geraldo do Araguaia, intense blue kyanite of high trans topaz occurs as well formed, pale- Etat de Para (Brésil). parency was recently brought into the coloured glassy crystals, but most are gemstone market from a new occurrence moderately to highly rounded and J-P. GAUTHIER, D.B. ROSA, S. in Nepal. The faceted stones investi frosted in the alluvial deposits. The RANTSORDAS AND J-C. SAMAMA. gated are of up to 12.2 ct in weight and primary deposits are in cavities in Revue de gemmologie AFG, 149, possess the typical physical characteris granitic pegmatite veins up to a metre tics of blue gem kyanite. RG.R. or more wide. Details are given of the 2004,11-14. chemistry, crystallography and the Opal of ornamental quality is typical inclusions of the topaz described from the area of Säo Geraldo Spinel from Kayah State crystals. P.G.R. do Araguaia, Para, Brazil. Specimens (Myanmar).

J. Gemm., 2004, 29, 4, 235-240 193

U.T. HLAING. Australian at Tory Channel in the Marlborough Mineralogia polonica, 34(1), 2003, Gemmologist, 22(2), 2004, 64-6,1 Sounds). These farms are geographically 27-36. isolated from each other to minimise the Gem-quality moonstone is described map, 1 illus. risk of loss of stock due to algal bloom from pegmatites in the Karkonosze area A sample of gem-quality mainly and other natural disasters. The paper of the Sudety Mountains, Poland. The pink to red spinels from Kayah State in provides information on the history of nature of the K-feldpar structure deter the east of Myanmar was given to the the abalone and then describes the tech mines the shade of blue seen: thus author for testing and evaluation. nologies and methods used by the Eyris micromezoperthite gives a pale blue, Kayah State is one of the smallest states Company to culture and harvest half microperthite blue and cryptoperthite in Myanmar and is bounded on the east pearls. Criteria used to grade the pearls violet-blue. The quality of the moon by Thailand, to the south and west by are also illustrated and briefly stones is said to be the equal of good Karen State and to the north by the described. P.G.R. Shan State. The approximate location of Sri Lanka material. M.O'D. this new alluvial deposit is indicated in the paper and on the accompanying Achate aus der Sierra Pintada, Gem News International. map, and details are given of the area's Argentina. geology. P.G.R. B.M. LAURS (Ed.). Gems & P. JECKEL AND M. HENKEL. Lapis, Gemology, 39(4), 2003, 322-46. 28(10), 2003, 33-7. A 23 x 14.5 mm crystal and five Amino acids in the nacre layers Agate of strikingly deep red and cabochons of afghanite (the latter of shell from Magnavicula white patterning is described from loca speckled with inclusions of lazurite) are tions in the Sierra Pintada, Argentina. reported as is a variety of rough and penguin and blister pearls from A brief description of the occurrences polished quartz crystals ('platinum 7 Sanya, China. is given. M.O'D. quartz ) containing blades of brown or HUANG FENGMING, CHEN. tan brookite coated with precisely oriented needles of rutile. A 3.84 ct ZHONGHUI, ZHOU YING AND Der Stein des Regenbogens: faceted yellow stolzite and a 147 ct YANG MINGXING. Australian 'Rainbow Calsilica'. golden orange scapolite are also described, along with new synthetic Gemmologist, 22(1), 2004, 29-31, L. KIEFERT, J. HÄNNI, P. 1 table. opal varieties and carved plastic imita VANDENABEELE, L. MOENS AND tion 'scrimshaw' walrus tusks. R.A.H. The compositions and contents of amino acids in the nacre layers of shells V.M.F. HAMMER. Gemmologie. Z. of the oyster Magnavicula penguin from Dt. GemmoL Ges., 52(4), 2003 Pezzottaite from Ambatovita, Sanya, China, and in blister pearls 151-62. 7 photographs, 4 produced in the same oyster, were Madagascar: a new gem determined using a Model 835-50 diagrams, bibl. (English material. Hitachi automatic meter. Comparison abstract) B.M. LAURS, W.B. SIMMONS, G.R. measurements were also taken from The spectacularly colourful gem ROSSMAN, E.R QUINN, S.F. cultured freshwater pearls from Ezhou, material from Mexico was offered on Hubei, and cultured seawater pearls the market as 'rainbow calcilica', MCCLURE, A. PERETTI, T. from Indonesia and Beihai, Guangxi, 'calcilica' and 'fossilized clay'. It was ARMBRUSTER, RC. HAWTHORNE, China. Tabulated results showed that marketed as a natural material with A.U. FALSTER, D. GÜNTHER, M.A. the shells and blister pearls of the pictures of the mine and certified by a Magnavicula penguin from Sanya both laboratory in Arizona. Examination by COOPER AND B. GROBÉTY. Gems & contained similar amino acids. Other Raman spectra showed the material to Gemology, 39(4), 2003, 284-301. measurements showed that the total be artificial, partly coloured by artificial Pezzottaite, ideally Cs(Be2Li) concentration of amino acids in the pigments and stabilised by a waxy Al2Si6018, is a new Cs, Li-rich member nacre layer close to the hinge line is resin. E.S. of the beryl group. It was discovered in higher than that of amino acids in the a granitic pegmatite near Ambatovita in margins of the shell. Blister pearls Pink gem quality orthoclase central Madagascar. The limited number produced by the Magnavicula penguin of transparent faceted stones and cat's- contain the highest concentration of from the Mogok Stone Tract, eye cabochons that have been cut amino acids in all the tested samples. Myanmar. usually show a deep purplish-pink colour. Pezzottaite can be distinguished P.G.R. U.H.KYI AND U.K. THU. from beryl by its higher RI (typically £ Australian Gemmologist, 22(1), 1.607-1.610, m 1.615-1.619) and D of 3.09- Culturing abalone half-pearls. 2004, 29-34, 4 illus. 3.11 g/cm3. The IR and Raman spectra P. HUTCHINS. Australian Although transparent pink ortho and XRD pattern are also distinctive, Gemmologist, 22(1), 2004,10-20, clase is rare, particularly in Myanmar, while the visible spectrum is similar to a pink gemstone discovered in the that of morganite. The colour is prob 19 illus. rough in the Mogok Stone Tract was ably caused by radiation-induced colour New Zealand is presently the one of 3+ studied and found to be a facetable centres involving Mn . R.A.H. at least two successful abalone pearl orthoclase feldspar. This paper provides culture operations utilising the New details of the feldspar's physical/optical Zealand paua, Haliotis iris. Roger Beatie, properties, XRD features and trace Iridescence of a shell of Pteria Managing Director of the Eyris Blue element analysis. RG.R. Sterna (Gould 1851): an optical Pearl Company, is responsible for the creation of the Eyris cultured half pearl and structural investigation. after becoming interested in farming Moonstone from the Y. Liu, K.N. HURWIT AND L. paua. He currently has three pearl farms Karkonosze pegmatites (the TIAN. Gemmologie. Z. Dt. (in the Whangamoe inlet on New Zealand's Chatham Islands, in Akaroa Sudety Mountains, Poland). Gemmol. Ges., 52(4), 2003,145- Harbour on the Banks Peninsular, and W. LAPOT AND E. SZELEG. 50, 7 photographs, bibl.

Gems and Minerals 193 The shells of the pearl-producing growth of ruby with fuchsite and penecontemporaneous with formation Pteria sterna show strong iridescence, kyanite. The material comes from India, of the host rock; in the other two usually green and purple, but also violet but is not dissimilar to material from regions hydrothermal activity from a blue and golden yellow. The aragonitic Zimbabwe and Mashishimala in South second volcanic event may have nacre layers are characterized by growth Africa. The suggested name is occurred. R.A.H. lines or grooves which form diffraction corundum fuchsite; the combination of reflection gratings. The density of these red (ruby), green (fuchsite) and blue grooves changes with the position (kyanite) is very attractive. L'émeraude de la Vallée within the shell. Change of the groove Some transparent yellow-brown to de Binn. density corresponds directly to a change orange-brown rough weighing up to 5 g in the strength of the iridescence. E.S. and a faceted specimen weighing 3.19 ct T. MUMENTHALER AND A. FREY. were examined and found to be bastna- Schweizer Strahler, 4, 2003, 4-11 Inclusions in Vietnamese Quy site. The material comes from a new and 24-30. source in the Peshawar district of Chau ruby and their origin. Emerald of near-gem quality is Pakistan. It is hexagonal with a low described from the Binn valley, Valais, P.V.LONG, H.Q.VINH AND hardness of 4-4 Vè and is a rare earth Switzerland where aquamarine has also N.X.NGHIA. Australian carbonate. It is named after a locality in been found. Speculations on origin are Sweden. E.S. Gemmologist, 22(2), 2004, 67-71, presented. Illustrations in this French issue differ from those in the German 10 illus. version on pp 24-30. M.O'D. Samples of rubies from Quy Chau, What's new in minerals. Vietnam, were collected for this study T. MOORE. The Mineralogical by the authors during several field trips. record, 35, 2004, 249-63. Agates and géodes from the The characteristics of the inclusions Among crystals and gemstones Khur area, Central Iran. were examined by optical microscopy, exhibited at the Tucson Show of 2004 and their compositions were analysed were: a dark greenish-blue euclase M. NAZARI. Australian by Raman scattering and SEM. The crystal from Colombia measuring near Gemmologist, 22(1), 2004, 21-8, 38 abundant inclusions listed in the paper 18 cm, pink scapolite crystals from illus. (27 on separate insert). are quite diverse in chemical composi Badakhshan, Afghanistan, a colourless The Khur agates of Central Iran tion, suggesting the possibility of two natrolite crystal about 3.9 cm, Mont St have long been celebrated for their fine origins - by metamorphism or by Hilaire, Quebec, Canada, and blue blue banding and this paper is the first metasomatism. RG.R. scheelite crystals from Baia Sprie scientific study of the agates and their (formerly Felsöbanya), Maramures, associated minerals. These minerals Romania. M.O'D. Heliotrop in Sachsen... und have been identified either visually, Fluoritachat. microscopically, and/or by XRD, SEM Lab Notes. and EDS. The numerous colour illustra M. LÜTTICH. Lapis, 28(12), 2003, T.M. MOSES, I. REINITZ, S.R tions are individually supported by 44-5. descriptive texts. RG.R. Ornamental-quality opaque green MCCLURE AND M.L. JOHNSON chalcedony with red flecks and agate (Eds). Gems & Gemology, 39(4), with fluorite banding are described 2003, 314-21. Zagi Mountain, Northwest from areas of Saxony, Germany M.O'D. Items noted include artificially Frontier Province, Pakistan. coated diamonds, a bluish-green H. OBODDA AND P. LEAVENS. The The Trimouns quarry, Luzenac, dichroic emerald, a high-RI violet-blue Ariège, France. glass (n 1.700) simulating tanzanite, blue Mineralogical record, 35, 2004, sapphires treated to give an unusual 205-20. F. MARTY. The Mineralogical colour zoning and filled cavities in a cut Bastnasite-(Ce) of gem quality is record, 35, 2004, 225-47. spinel. R.A.H. described from Zagi Mountain, which is Among mineral species occurring as located about 5.5 km SE of Warsak crystals of possible ornamental quality Moganite and water content as Dam on the Kabul River in the at the Trimouns quarry, Luzenac, Ariège, Peshawar District, North West Frontier France, is bastnasite-(Ce). M.O'D. a function of age in agate: an Province, Pakistan. Crystals and an XRD and thermogravimetric orange-red transparent faceted stone are Gemmological Notes. study. illustrated; transparent rutile and orange zircon are also found in the area. C.C.MILISENDA. Gemmologie. Z. T. MOXON AND S. Rïos. European The rutile contains Hg as a trace Dt. Gemmol. Ges., 52(4), 2003, Journal of Mineralogy, 16(2), 2004, element, a composition not previously 123-6. 4 photographs. 269-78. reported. M.O'D. Some translucent, apple green rough The crystallite size, and the content material weighing between 1 and 3 g of moganite, molecular surface water was found to be opal, said to come from and internal water in agates from Der Pegmatit von a locality near the border of Croatia and volcanic host rocks ranging from 38 to Anjiahamiary bei Fort Macedonia. SG 2.08-2.10. Some other 1100 Ma have been measured. Water is Dauphin, Madagaskar. green opal was submitted with similar shown to be involved in the transforma appearance, but with much lower SG tion of moganite into chalcedony; the F. PEZZOTTA AND M. JOBIN. Lapis, (1.33-1.37); this material melted when maximum amount of moganite found in 29(2), 2004, 24-8. touched with a hot needle and was agate was 14%, but after ~ 410 Ma it is A pegmatite located at found to be artificial. Some emerald only present in trace amounts. Changes Anjiahamiary, NE of Fort-Dauphin, imitations on the market proved to be in the degree of crystallinity of agates Madagascar, has produced gem-quality dyed quartzes. from 10 host rocks < 412 Ma have been tourmaline group species (liddicoatite Some cabochons weighing approxi determined; for eight regions, agate and rossmanite) in pink, green and blue mately 5 g each were made of an inter- genesis appears to have been roughly colours. M.O'D.

J. Gemm., 2004, 29, 4, 235-240 192339 Ratsel im breenendheissen is one of the few places in the world value. Results of experiments at various Sand: das libysche Wustenglas. where such beautiful specimens are temperatures in an oxygen atmosphere found. This paper describes the occur suggest that Vietnamese rubies should C. PINTER AND H. STEHLIK. Lapis, rence and gemmological properties of be treated only at 1500-1600°C to 28(10), 2003,11-6. the rare mineral. A group of crystal convert them into more valuable rubies Natural transparent lemon-coloured specimens and two faceted specimens of enhanced colour and clarity. Higher glass is found as lumps in the Libyan are illustrated. P.G.R. temperatures will only yield slightly desert. Specimens are described and bluish-red rubies. All samples exhibited their origin speculated upon. M.O'D. Geochemie und Petrologie von better clarity after the treatment, which enhanced the colour of the stones but Smaragdvorkommen - could not eliminate inclusions. P.G.R. Ungewohnliche Turmaline Erfahrungen aus dem vom Erongo, Namibia. Smaragdbergbau in Sambia What's new in minerals. P. RUSTEMEYER. Lapis, 28(11), und Simbabwe - Teil 2: VARIOUS AUTHORS. Mineralogical 2003, 29-41. Sandawana, Simbabwe. Tourmaline of ornamental quality is record, 35, 2004, 143-79. K.C. TAUPITZ. Gemmologie. Z. Dt. described from the Erongo massif in Among gem and ornamental-quality Namibia, north-west of Windhoek. Gemmol. Ges., 52(4), 2003, 127- specimens described from various Crystal forms and habits are investi 44, 4 maps, 1 diagram, 2 tables, mineral shows in Europe and North gated and colour zoning effects illus bibl. America are elbaite from Paprock, trated. M.O'D. Kunar, Afghanistan (in the specimen Detailed article about the local shown the outer green zone has been geological conditions around selectively removed), near-transparent Mineralien der Sandawana. The two occurrences of amazonite, clear pink scapolite and Turmalingruppe. Sandawana in Zimbabwe and Kafutu in clear light green diopside, also from Zambia are compared. E.S. Anwendungsmoglichkeiten in Afghanistan. Pakistan has produced Technik, Haushalt und some greenish-grey fluorite octahedra Griin, gelb, rot und blau. Uber Medizin. from a locality in the Hunza area. Fine die Farbung von Titanit- orange-red 'imperial' topaz has been K. SCHMETZER. Lapis, 28(10), kristallen in alpinen Kluften. found in the Kolwezi area in the 2003, 38-50. Republic of Congo close to the border Minerals of the tourmaline group S. WEISS AND B. HOFMANN. Lapis, with Zambia, and sherry-brown topaz is find many uses other than ornamental 28(10), 2003, 30-2. reported from Pakistan. M.O'D. ones. Some technical, household and Titanite (sphene) crystals originating medicinal applications are described. in Alpine-cleft deposits show a variety M.O'D. of colours whose origin is discussed. M.O'D. Instruments and Red beryl from Utah: a review and update. Sphenkristalle aus der Techniques J.E. SHIGLEY, T.J. THOMPSON AND Laghetti-Amphibolitzone, Naretgebiet, Schweiz. The sclerometer and the deter J.D. KEITH. Gems & Gemology, 39(4), 2003, 302-13. S. WEISS AND F. RIZZI. Lapis, mination of the hardness of The Ruby Violet (or Red Beryl) mine 28(10), 2003, 17-29. minerals. in the Wah Wah Mts of Beaver County, Crystals of sphene and accompa U. BURCHARD. Mineralogical Utah, is the only known commercial nying minerals are described from the occurrence of gem-quality red beryl in amphibolite zone at Laghetti, Ticino, record, 35, 2004, 109-20. the world. It is found along fractures Switzerland. Other Swiss locations for While Mohs' scale is still used for (often clay-filled) in a topaz rhyolite, sphene are described. M.O'D. determining the approximate scratch and crystallized as a vapour-phase hardness of minerals the sclerometer was developed in the 19lh century to mineral from the reaction of rhyolite- The early history of the derived gases, vapours originating from give a more precise value of hardness. heated groundwaters and pre-existing Mineralogical Record. Different models are described and minerals and volcanic glass in the rhyo J.S. WHITE. Mineralogical Record, illustrated. M.O'D. lite. The production over the past 25 35(1), 2004, 73-85. years is estimated to have been >60 000 The origins and development of the ct, of which about 10% were facetable. Record are described by its founder, John R.A.H. S. White. M.O'D. Synthetics and

Crocoite. Quality enhancement of Simulants S.PSORREL. Australian Vietnamese ruby by heat L'opale de synthese. Gemmologist, 22(2), 2004, 59-63, 1 treatments. J-P GAUTHIER. Revue de map, 7 illus. P. WlNOTAI, P. LlMSUWAN, I.M. Tasmania has long been famous TANG AND S. LIMSUWAN. gemmologic AFG, 149, 2004, 24-6. among mineralogists and geologists for The difference between synthetic its specimens of crocoite, a brilliant Australian Gemmologist, 22(2), and natural gem-quality opal is orange to red lead chromate. Its fame 2004, 72-77, 8 illus. reviewed. Hexagonal markings within may now spread as the result of crocoite A suitable heat treatment specifically colour patches continue to be the distin being chosen as Tasmania's Mineral designed for a particular ruby must be guishing features of the synthetic Emblem. Apart form Russia, Tasmania used to enhance both its quality and product. M.O'D.

Synthetics and Simulants 191924243300 [Growth of diamond from [About mechanism of the Gem-quality synthetic diamonds

solution in the CaCo3 melt.] fibrous structure appearing in grown by a chemical vapor A.F. KHOKHRYAKOV, Yu.M. cubic diamond crystals.] deposition (CVD) method. BORZDOV. YU.N. PAL'YANOV AND V. M. SON IN, D. G. BAGRYANTSEV, W. WANG, T. MOSES, x.c. AG. SOKOL. Proceedings of the AI. CHEPUROV AND J.-M. LINARES, J.E. SHIGLEY, M. HALL Russian Mineralogical Society, DEREPPE. Proceedings of the AND J.E. BUTLER. Gems & 132(2),2003,87-95 (Russian Russian Mineralogical Society, Gemology, 39(4), 2003, 268-83. with English abstract). 132(2), 2003, 95-8 (Russian with Brown to grey and near-colourless Diamond nucleation and growth English abstract). single-crystal type IIa synthetic kinetics on the [100] and [111] faces of The growth of diamond crystals at diamonds grown commercially using a chemical vapour deposition technique seed diamond crystals in the CaC03-C high P in the Fe-Ni-C system was system were studied in a non-pressing studied in terms of a T decrease of -1 have gemmological properties that are device of 'cross-cut sphere' type at 7 2° I sec. A phenomenon has been distinct from those of both natural GPa and 1700-1750°C in experiments detected of octahedral crystals re-facing diamonds and HPHT-grown synthetic of 10 min to 18 h duration. The growth via the transformation of numerous tiny gem diamonds. The tabular crystals of [100] develops in the diffusion cubic sub-individuals on their faces. range from up to 1 ct or more and a few limiting regime, and growth on [111] is Data show that this is possibly the millimetres thick, and consist of an over determined mainly by the kinetics of formation mechanism of natural cubic growth on a natural or synthetic superficial processes. Evolution of the diamond crystals with a fibrous struc diamond substrate. Faceted CVD surface accessories on the [111] faces ture. This is based on the growth of synthetic diamonds generally cannot be was traced from triangular frame cubic sub-individuals parallel to one distinguished from natural diamond defects up to large trigonal pyramids. another in the 1111} direction with the (unless portions of the substrate are still Comparison with similar Si and Ge formation of subparallel fibres. Because present). In a gemmological laboratory, patterns shows that the trigonal pyra of this phenomenon, sectors of cubic however, they can be identified by the mids are complex twins. The only growth become enlarged while the octa combination of a strong orangey-red stable cubic forms of diamond growth hedral growth sectors are declining; the fluorescence seen with the DiamondView

in the CaC03-C system are tetragontri main cause of this change in the growth deep-UV imaging system, a character octahedron faces; among them only mechanism is the sharp increase of istic anomalous birefringence (strain) {322) faces achieve the habit scale of supersaturation in the crystallization pattern and distinctive features in their development. R.A.H. media provided by the falling T. R.A.H. IR absorption spectra. R.A.H.

Abstractors

G.L. Barron G.L.B. P.B.Leavens P.B.L. EG. Read EG.R. R.A. Howie RA.H. M. O'Donoghue M.O'D. E. Stern E.5.

Book Review

Rock-forming minerals. Vol. unfamiliar with the series will find guishing features (details of determina 4B. (Znd edn). Framework unexpected treasures. The authors state tive tests are given here), and paragen their criteria for a mineral's inclusion in esis, giving the rock types in which the silicates: silica minerals, the preface to the first edition (1962): mineral is found and outlining some feldspathoids and the zeolites. [the text will include] only those characteristic mineral assemblies. A W.A DEER, R.A HOWIE, W.S. minerals which, by their presence or concise table of properties precedes each absence, serve to determine or modify entry and a list of references ends it. WISE AND J. ZUSSMAN, 2004. The the name of a rock. In their preface to Many will find it pleasing that "light Geological Society, London. pp the second edition the editors make the microscopy remains the basic petrolog xiv, 982. Hardcover ISBN 1 point that a far greater sophistication in ical tool underpinning all other determinative methods has enabled 86239 144 O. £62 (to Fellows of methods" but clearly the use of electron them to improve the quality of informa microprobe analysis and, to take one the Geological Society). tion formerly available. This is particu Minerals of especial interest to example quoted in the preface to the larly true of chemical compositions. readers of The Journal include quartz new edition, of environment-controlled and opal, petalite, leucite, species of the For the most part each mineral or specimen stages, will lead to a far sodalite group and the scapolite group; group is considered in five distinct deeper understanding of mineral forma mineral collectors will welcome the parts. These are structures, chemistry, tion and determination. For any serious revision of the zeolite group. Readers optical and physical properties, distin- study of minerals, 'DHS' is vital.M.O'D.

J. Gemm., 2004, 29, 4, 235-240 191924331 Proceedings of the Gemmological Association and Gem Testing Laboratory of Great Britain and Notices

New appointments at Gem-A

President We are delighted to announce that at the Annual General Meeting held on Tuesday 14 September E Alan Jobbins was elected President of the Association for the term 2004-2006. E Alan Jobbins BSc CEng FIMM FGA was Curator of Minerals and Gemstones at the Geological Museum in London from 1950 to 1983. During these years he acted as consultant to a wide range of enquirers from which a series of research papers developed. These included, among many others, a major study of East African garnets, the first papers characterizing the structure and identification of synthetic opals, the discovery of a new mineral magnesio-axinite and the field study of the E Alan Jobbins, President Barwell meteorite fall. His many overseas assignments (for the United Nations and the includes 32 years as a gemmological British Government) included setting up lecturer at the Sir John Cass College a gemmological laboratory in Rangoon, (now the London Metropolitan University), Burma (now Myanmar) and the subsequent some 20 years as an examiner for the training of a cadre of students who Association's gemmology examinations successfully passed the Gemmology and eight years as Editor of The Journal of Diploma examinations; a major study of Gemmology. He is a popular lecturer and the Pailin ruby and sapphire deposits in has presented papers in some 30 countries Cambodia with recommendations for around the world. In 1986-89 he was improved working methods; an assessment privileged to be a member of the team of diamond and opal deposits in Piaui State, which conducted the first gemmological Brazil; a survey of the Sri Lankan gemstone examination of the English Crown Jewels. industry to improve cutting techniques These researches were published as part and many other projects. In 1988 he of a major two volume catalogue. He is gave a series of lectures and initiated an Executive Member of the International gemmological training with new laboratory Gemmological Conference and is currently facilities at the China University of President of the Society of Jewellery Geosciences in Wuhan. In the UK his record Historians.

Chief Executive Officer Scottish Branch Dr Jack Ogden, a Fellow of Gem-A and On 26 September a gold panning field trip a founder member of the SJH, has been to Tyndrum was arranged. appointed Chief Executive Officer of Gem-A On 6 October at the British Geological on the retirement of Terry Davidson on 1 Survey, Murchison House, West Mains Road, November 2004. A report of the appointment Edinburgh, Guy Clutterbuck gave a talk was published in the September 2004 issue of entitled 'The coloured stone business from Gem & Jewellery News. a global perspective'. On 19 October at the Hunterian Museum, Honorary Life Member University of Glasgow, Neil Clark, the Curator Ian Thomson, who retired from the of Palaeontology at the Hunterian Museum, Council at the Annual General Meeting gave a talk on the inclusions in amber. after serving for 14 years, has been awarded an Honorary Life Membership in South East Branch recognition of his substantial contribution On 22 August at Gem-A headquarters at 27 and commitment to the Association. Greville Street, London ECl, David Lancaster gave a presentation entitled 'Can provenance Members' Meetings be valued?' London South West Branch On 27 July at 27 Greville Street, London On 12 September at the Bath Royal ECl, an Extraordinary General Meeting was Literary and Scientific Institution, 16-18 held, a report of which appears below. Queen Square, Bath, Maggie Campbell The EGM was followed by a talk by Terry Pedersen gave a presentation and practical Davidson on the jewellers of Bond Street. session entitled 'Organics in the afternoon'.

Midlands Branch On 24 September at the Earth Sciences Annual Report Building, University of Birmingham, Edgbaston, Professor A T Collins gave The following is the Report of the Council a lecture entitled 'Colour in natural and of the Gemmological Association and Gem artificial diamonds'. Testing Laboratory of Great Britain for the year ending 31 March 2004. North East Branch On 26 July at Evans of Leeds Ltd, Officers, Councils and Committees Millshaw, Alan Hodgkinson gave a talk and Gem-A The Gemmological Association and practical workshop entitled 'Putting the Gee Gem Testing Laboratory of Great Britain is a back into gemmology'. company limited by guarantee and is governed by the Council of Management. On 19 October at Evans of Leeds Ltd, The Council of Management was Millshaw, Martin Vainer gave a talk with the strengthened by the election of L M Hudson title 'Fancy diamonds?!' FGA, an American financier and private investor with international banking and North West Branch investment portfolio experience. On 15 September at Church House, J Kessler retired as chairman of the Trade Hanover Street, Liverpool 1, Alan Liaison Committee. W Roberts and J Evans- Hodgkinson gave a talk and workshop Lombe were elected chairman and vice- entitled 'A few of my favourite things'. chairman respectively of the Committee. On 20 October at Church House Marcus C Winter and P Dwyer-Hickey continued as McCallum gave a talk entitled 'Pearls: the Chairman and Vice-Chairman respectively of trade industry today'. the Members7 Council. (Continued on p.246)

J. Gemm., 2004, 29, 4, 241-252 193

Gem-A Awards

Gem-A Examinations were held worldwide in June 2004. In the Examinations in Gemmology 258 candidates sat for the Diploma Examination of whom 92 qualified, including two with Distinction and 13 with Merit. In the Foundation Gemmology Examination, 178 candidates sat of whom 121 qualified. In the Gem Diamond Examination 95 candidates sat of whom 60 qualified, including ten with Distinction and seven with Merit. The Anderson Bank Prize for the best non-trade candidate of the year in the Diploma in Gemmology Examination, the Anderson Medal for the candidate who submitted the best set of answers in the Foundation Certificate examination which, in the opinion of the Examiners, are of sufficiently high standard, and the Hirsh Foundation Award for the best candidate of the year in the Foundation Certificate examination, have been awarded to Jiang Huijing, Zhuhai City, Guangdong, P.R.China. The Christie's Prize for Gemmology for the best candidate of the year in the Diploma Examination who derives his or her main income from activities essentially connected with the jewellery trade has been awarded to Anu D. Manchanda, Smethwick, West Midlands. The Deeks Diamond Prize for the best candidate of the year in the Gem Diamond Examination has been awarded to Emma l. McMillan, Dalkeith, Midlothian. The Tully and Bruton Medals were not awarded. The names of the successful candidates are listed below:

EXAMINATIONS IN GEMMOLOGY Gemmology Diploma Chandhok, Iasrneet Singh, New Delhi, India Qualified with Distinction Curtis-Taylor, Tracey, London Jiang Huijing, Zhuhai City, Guang Dong, Dong Xinzhi, Wuhan, Hubei, P.R. China P.R. China Drijver, Joyce M-L., Utrecht, The Netherlands Scott, John R.J., Vancouver, British Columbia, Fu Ming, Guilin, Guangxi, P.R. China Canada Gaskin, Clare Kathryn, Putney, London Gerber, Doris c., Zurich, Switzerland Qualified with Merit Gael, Amita, New Delhi, India Choi, Eun [unq, [eolanarn-Do, Korea Gray, Matthew N., Lismore, New South Wales, Landmark, Vicky, Harpenden, Hertfordshire Australia Lee Yu Mi, Gyeonggi-Do, Korea Hasegawa, Akemi, Akashi City, Hyogo Pref., Liao Baoli, Guilin, Guangxi, P.R.China Japan Manchanda, Anu Dippal, Smethwick, Hearnden, Rachel c., Sheffield, South Yorkshire West Midlands Hemlin, Colette, Anjou, Quebec, Canada Ramerison, Tokinomena A., Antananarivo, Hirst, Catherine, Harborne, West Midlands Madagascar Hsin Shih Meng, Wuhan, Hubei, P.R. China Ren Ming, Wuhan, Hubei, P.R. China Htin Lynn Aung, Yangon, Myanmar Sordini, Federico, Cagli, Italy Huang Qiulan, Wuhan, Hubei, P.R. China St John Lewis, Delyth, South Norwood, London Ideno, Yumi, Nishinomiya City, Hyogo Pref., Tsutsui, Kazumi, London Japan Wells, Miranda, Hartlebury, Worcestershire Inoue, Koichi, Suita City, Osaka, Japan Wong Ching Man, Discovery Bay, Hong Kong Kao Oi Shan, Patsy, Chai Wan, Hong Kong Zhang Kui, Wuhan. Hubei, P.R. China Khaing Win Win, Yangon, Myanmar Kueon, Sean-II, Bupyong-ku, Inchon, Qualified R. of Korea Agrawal, Puru, New Delhi, India Kwok Sau Mei, Halisa, Tai Po, Hong Kong Aki, Miou, Osaka City, Osaka, Japan Lai Mei Oi, Emily, Tuen Mun, Hong Kong Anderson, Tricia, Helen's Bay, Bangor, Lee Young Shin, Kyunggido, Korea N. Ireland Lee Jeong 1m, Seoul, Korea Aung, Htet Su, Yangon, Myanmar Lee Kyu Ho, [eonlanarn-Do, Korea Aura, Kimma, Espoo, Finland Li Mo Ching, Hong Kong Blanksma, Eelco, Arnhem, The Netherlands Li Yue, Shanghai, P.R . China Brard, [aqvinder Singh, Pinner, Middlesex Liu Baa, Wuhan, Hubei, P.R. China Broglie, Nicole, Zurich, Switzerland Liu Fang, Wuhan, Hubei, P.R. China

Proceedings of the Gemmological Association and Gem Testing Laboratory 01Great Britain and Notices 193 Gem-A Awards

Lovelock, Justina E., London Comerford, Elaine-Sarah, Dunhill, Lyons, Annabel H., London Co. Waterford, Ireland Manolia, Evgenia, Zografou, Greece Costello, Michael P., Pen-y-lan, Marsh, Claire, Stourbridge, West Midlands South Glamorgan Moe Tin Tin, Yangon, Myanmar Costin, Charlotte, Horsham, West Sussex Moore, Katherine, Symington, Ayrshire Cullen, James, Dublin, Ireland Pai, S. Vishnunarayan, Kerala, India Dawson, Jane, Ashbourne, Derbyshire Pang Shing Kwan, New Territories, Hong Kong Devitt, Isobel, Dublin, Ireland Pang Taotao, Guilin, Guangxi, P.R. China Eakins, June E., Heswall, Merseyside Piacenza, Maria Rene, Sutton, Surrey Eddery, Colette M., Dublin, Ireland Pumpang, Sureeporn, Nakoonpathom, Eeckhout, Tiphaine, Thomery, France Thailand Espinoza, Juls, Roseville, California, U.S.A.

Ruan Yaohua, Guilin, Guangxi, P.R. China Fellows, Andrew Sv Aldridge, West Midlands Sien Pe (a) Yang Cheng Pei, Yangon, Myanmar Fong Yan, William, Kowloon, Hong Kong Singh, Amrinder Pal, Nagar, Delhi, India Gibbons, Timothy B., Battersea, London Song Dong, Shanghai, P.R. China Gigg, Daryl B., Stevenage, Hertfordshire Stanyer, Natasha, Lewes, East Sussex Gillman, Scott, Sudbury, Massachusetts, U.S.A. Turku, |enni )., Helsinki, Finland Godfrey, Kay, Halstead, Essex Valvio, Raija L.M., Vaajakoski, Finland Gogna, Sanjeev, Distt Una, Himachal Pradesh, van Gorkom, Annemarie, Utrecht, India The Netherlands Goodwille, Zoe F., Battersea, London van Schaik, Persis L., Groot-Ammers, Hardwick, Christine J.E., Crail, Fife The Netherlands Heltzel, Christopher, Kilkenny, Ireland Visschers-Villerius, Cornelia, Heerde, Huang Shieh-Yen, Taipei, Taiwan, R.O. China The Netherlands Huang, Yvonne, Taipei, Taiwan, R.O. China Wai Yee Tak, Elise, New Territories, Hong Kong Huck, Perry, Stanford-in-the-Vale, Oxfordshire Welton-Cook, Elsa, West Kensington, London Hui Wan Man, Kwun Tong, Hong Kong Wessels, Jurie H.W., London Hunter, Sara, Athboy, Co. Meath, Ireland Williams, Benjamin J., Blockley, Gloucestershire Huth, Melvin G., Orangevale, California, U.S.A. Wofd, William, Joure, The Netherlands Kitching, Katherine, London Wong, Rosemary M.N., New Territories, Ko Hoi Fu, Kowloon, Hong Kong Hong Kong Kwok Men Yee, New Territories, Hong Kong Wong Chung Yan, Kowloon, Hong Kong Kyaw Cho Cho, Yangon, Myanmar Wu Shengfan, Wuhan, Hubei, P.R. China Kyaw Swar Htun, Yangon, Myanmar Xu Ping, Shanghai, P.R. China Kyaw Tun Aung, Yangon, Myanmar Yang Jiaru, Wuhan, Hubei, P.R. China Lai Sau Han, Winnie, Kowloon, Hong Kong Yang Ruochen, Wuhan, Hubei, P.R. China Lai Suk Kwan, Eleanor, Kowloon, Hong Kong Zhang Tao, Wuhan, Hubei, P.R. China Lawton, Sarah, Huncote, Leicestershire Lee Mi Yu, Gyeonggi-Do, Korea Gemmology Foundation Certificate Lee Kyu Ho, Jeonlanam-Do, Korea Qualified Lee Tin Wan, New Territories, Hong Kong Alcock, Kate, Byford, Hereford and Worcester Leung Chi Fai, Hong Kong Asavaroengchai, Suwanna, Bangkok, Thailand Leung Ka Lok, Kowloon, Hong Kong Barker, Matthew, Taipei, Taiwan, R.O. China Leung Ka Yi, Kowloon, Hong Kong Baskerville, Fenella, London Li On Kei, New Territories, Hong Kong Bayoumi, Nevin, London Lim Yee Lam, Hong Kong Chan Ching Han, New Territories, Hong Kong Lima Pontes, Beatriz, Rio de Janeiro, Brazil Chan Fung Ping, Kowloon, Hong Kong Lin Wai Kei, Tseung Kwan, Hong Kong Chau Lok Yuen, Amy, Kowloon, Hong Kong Lindstrom, Christina, Spanga, Sweden Chiu Shu-Fen, Taipei, Taiwan, R.O. China Liu Haimei, Guilin, Guangxi, P. R. China Chiu Ka Ming, Kowloon, Hong Kong Liu Xianyu, Guilin, Guangxi, P.R. China Choi Eun jung, Jeolanam-Do, Korea Lo Wing See, Kowloon, Hong Kong Chu Yan Yan, Joey, New Territories, Hong Kong Looney, Eimear, Dublin, Ireland Chu Hon Chung, New Territories, Hong Kong Lu, Shan, Kofu City, Yamanashi Pref., Japan Coene, Helena 1.1., Wezembeek Oppem, Malone, Helena, Portlaoise, Co. Laois, Ireland Belgium Marsh, Shona K., Birmingham, West Midlands

J. Gemm., 2004, 29, 4, 241-252 241953 Gem-A Awards

Maury-Laribiere, Volodia, Saint Trieix, France Tsoi Mei Yu, New Territories, Hong Hong Mera, Kanako, Toyonaka City, Osaka, Japan Underwood, Anthony D., Sumner, Texas, U.S.A. Miller, Jodie L., Hinckley, Leicestershire Voulgaris, Apollo, Athens, Greece Mo Mo Win, Yangon, Myanmar Ward, John E.C., London Munich, Lita E., Sacramento, California, U.S.A. Wong Lok Yin, Rocky, Kowloon, Hong Kong Murphy, Lawrence C, Sacramento, California, Wong Oi Chun, New Territories, Hong Kong U.SA Wongkar, Franky, London Naw Htar Phyu, Yangon, Myanmar Yamout, Sabah I., Leeds, West Yorkshire Newton, Naomi C, Birmingham, Yang Ping, Guilin, Guangxi, P.R. China West Midlands Zhong Lihong, Zhongshan, Guangzhou, O'Dwyer, Michael, Wicklow Town, Co. Wicklow, P.R. China Ireland Zong Yu, Zhongshan, Guangzhou, P.R. China Ogata, Etsuko, Suita City, Osaka, Japan Palmares, Richard P., Sale, Cheshire Gem Diamond Diploma Pan Han, Guilin, Guangxi, P.R. China Qualified with Distinction Pany, Emmanuel, Clotilde Reonion, France Chen Jianzhi, Wuhan, Hubei, P.R. China Peers, Sofia L.R., Leamington Spa, Warwickshire Edwards, Trevor, London Pelletier, Use, Montreal, Quebec, Canada Hanlon, Adrienne K., Ingol, Lancashire Pham Quoc, Sacramento, California, U.S.A. Hira, Vijender Singh, New Delhi, India Phisuthikul, Piyamaporn, Bangkok, Thailand Lam Kwi Peng, Singapore Poole, Jessica, Portadown, Co. Armagh, Lim Yee Lam, Hong Kong Northern Ireland Ren Chunhua, Wuhan, Hubei, P.R. China Powar, Krishna, Hockley, Birmingham, Surawy, Laura K., Haywards Heath, West Sussex West Midlands Tavelov, Dan, Moseley, West Midlands Pun Kwok Kong, Kowloon, Hong Kong Thomhill, Helen V., Sheffield, South Yorkshire Rakotoson, Eric, Montreal, Quebec, Canada Rana, Ashka, Sureshkumar, Vastapur, Gujarat, Qualified with Merit India Claydon, Louise, Carshalton, Surrey

Ravaoarimalala, Fanjaniaina Vv Antananarivo, Fisher, Abigail, London Madagascar Lau Siu Ying, Emily, Hong Kong Ra& Stuart, Gillingham, Dorset Pearson, Isabel J., Tilehurst, Berkshire Roïifiî-Belhadj, Khedidja, London Shaw, Sinead, London Ruan Qingfeng, Guilin, Guangxi, P.R. China Tan Mingwei, Wuhan, Hubei, P.R. China Russell, Marie, Bromsgrove, Hereford and Van Rooij-Roeloffzen, Marjolein, Almere Buiten, Worcester The Netherlands Sanders, Jacqueline, Towcester, Northamptonshire Qualified Sardjono, Grace W., New Territories, Chan Chee Pang, Hong Kong Hong Kong Chan Lim Chi, Hong Kong Saull, Elanor Nico, Stourbridge, West Midlands Chan Wing Tung, New Territories, Hong Kong Serafim, Evangelia, Glyfada, Greece Chan Ying Hon, New Territories, Hong Kong Shwe Li, Yangon, Myanmar Chan Yun Ping, Anna, Southall, Middlesex Sinclair, Michelle, Nottingham Chang Wing Chi, Vivian, Kowloon, Hong Kong Smithie, Sheila B., Boston, Massachusetts, Cheng Wai Yee, New Territories, Hong Kong U.S.A. Cheung Ching Ping, Candy, Kowloon, Sordini, Federico, Cagli, Italy Hong Kong Surangsuriyakul, Nualwan, Samut Prakarn, Chie, Christine, Hong Kong Thailand Ching Chin Pang, Kowloon, Hong Kong Takahata, Yoshichika, Takamatsu City, Kagawa Ching Chin Ping, Tung Chung, Hong Kong Pref., Japan Farrell, Ann Marie, Greenford, Middlesex Tarn Tin Sang, Daniel, Kowloon, Hong Kong Hui Wai Wai, Hong Kong Tang Yin Tung, Chai Wan, Hong Kong Huo Zhi Yong, Beijing, P.R. China Taylor, Daniel, Moseley, West Midlands Hynes, Lola, Dublin, Ireland Teng, Terry, West Hampstead, London Jelinska, Emma, London Tripathi, Pooja, Jaipur, Rajasthan, India Jones, Lorraine, Farnworth, Greater Manchester Tsang Kwai Ying, Yau Yat Tsuen, Hong Kong Kiamos, George K., Athens, Greece

Proceedings of the Gemmological Association and Gem Testing Laboratory of Great Britain and Notices 193 Gem-A Awards

Kwok Sau Mei, Halisa, Hong Kong Sowa, Ali Med, Tilbury, Essex Lawattanatrakul, Thidarat, London Szymanska, Zofia, London Leung Suk Kay, Hong Kong Thein Myint Myint, Whetstone, London Li Bo, Beijing, RR. China Thesia, Ashish P., Northolt, Middlesex Lin Yang, Beijing, P.R. China Van Rensburg, Stefan, Ealing, London Manolia, Evgenia, Zografou, Greece Wells, John, Bickerstaffe, Lancashire Pennington, Maria, Sprowston, Norfolk Whalley, Joanna, Walthamstow, London Rebmann, Olivier, Carlsbad, California, U.S.A. Xie Hui, Beijing, P.R. China Richmond, Sonia, Herne Hill, London Ye Hui Hui, Preston, Lancashire Romero, Michelle A., St Andrews, Fife Yeung Wing Chuen, Benny, New Territories, Simo Ooi Kok, London Hong Kong So Yiu Ki, Eric, Hong Kong Zhang Rui, Beijing, P.R. China Southam, Karen L., Oldbury, West Midlands Zhang Yilin, Wuhan, Hubei, P.R. China

(Continued from p.242) In January 2004 the death was reported London gemmology and gem diamond with great regret of Alexander E. Farn FGA, courses fully subscribed, with students a Vice President of the Gemmological coming from far and wide. Association since 1992. A range of courses and tutorials was held at the Greville Street Gem Tutorial Centre, Gem-A including a very successful new rough The financial year 2003/2004 proved to be diamond short course. Custom built trade even more challenging than the previous tutorials have continued. D.J. Garrod gave year. Business in the jewellery trade faced his popular short talks and tutorials at increasing competition from other 'Must various venues including Norway, Hong have7 products and saw the closure and Kong, Tucson and several locations around restructuring of many retail and Great Britain. manufacturing companies. Even so, A greater number of students attended Gem-A managed a modest increase over the gemmology and gem diamond budgeted income. examinations compared with the previous Monthly departmental meetings have year. The Anderson Bank Prize was awarded continued which ensure a continuous flow to Jessica Banks of London. The Christie's of up-dated information and the cross Prize for Gemmology was awarded to Xie fertilization of ideas. Jing of Shanghai, China. The Anderson Medal The 2003/2004 appeals to members and and Preliminary Trade Prize were both the UK trade resulted in 446 donations awarded to Antoinette Jackson of London. totalling £12,180. Donations of specimens, The Deeks Diamond Prize was awarded to including rough and cut stones, synthetics Lu Lili of Wuhan, China. Neither the Tully and simulants, has enabled the Association nor the Bruton Medal was awarded. to expand educational courses and The Presentation of Awards was again examinations. held at Goldsmiths' Hall where the President, Education Professor A. Collins, presided and welcomed The Education Office Team have worked the successful students and their families and tremendously hard over the past year, with friends, who had travelled from as far afield final development and promotion work on as Hong Kong, Japan, Canada, Sri Lanka and the new Foundation Certificate Course notes the USA, as well as those from the UK and and exam, preparation and launch of the new Europe. Anthony Hirsh presented the awards. bi-annual Five-month course, and the varied The new Hirsh Foundation Award of and new short courses and travelling £1000 per year had a well-attended press tutorials. The last year has again seen the launch at the Las Vegas show. The existing

J. Gemm., 2004, 29, 4, 241-252 193 Gifts

TheThe AssociationAssociationis ismost mostgrateful gratefulto tothe thefollowing foil forfor theirtheirgifts giftsfor forresearch '$ and teachingteaching purposes:pu

MaggieMaggie CampbellCampbell PedersenPedersenFGA, FGA, U.S.A.),U.SA),tourmaline tourmaline (Brazil),(Brazil), emerald emerald (Brazil),(Bra London,London, forfor anan imitationimitationtortoiseshell tortoiseshell calcitecalcitéslabs slabs(New (New Mexico),Mexico), ChathamChatham •"••«•^•ê decorativedecorative box.box. synethicsynethicemerald emerald (very(very early earlyproduction), production), andand aa largelarge packetpacket ofoftourmaline; tourmaline; organicsorganics MrsMrs K.K. Findlay,Findlay, Randburg,Randburg, SouthSouth Africa,Africa, includingincliÄlgwhale whale 'ivory','ivory', shellsshellsfrom fromTexas. Texas. inin memorymemory ofof herher husband,iwband, thethe latelate KennethKenneth FindlayFindtayFGA; FGA; aa portableportable diamonddiamond balancebalance inin MarkMarkSaul, Saul, Arusha,Arusha, Tanzania,Tanzania,for fora a aa traveltravèftbo boxx withwitha aset set of of weights,weights,a àBeck Beck selectionselectionof of roughrough specimensspecimensfrom fromTanzania Tanzania prismprism spectroscopespectroscopewith withwavelength wavelength scale,scale, includingincluding fivefive piecespieces of of vesuvianite, vesuvianite,two two aa BeckBeck UVUV spectroscopespectroscope 'and and aa BeckBeck samplessamples ofof kornerupinekornerupine displayingdisplayingstrong strong wavelengthwavelength reversionreversion spectroscope.spectroscope. pleochroism,pleochrot^ andand aapacket packetof ofactinolite actinolitefrom from thethe Tanga Tanga district.district. JohnJohn R.R. HihrbachFührbach FGA,FGA, Amarillo,Amarillo,Texas, Texas, U.S.A.,U.S.A.,for for aacollection collection ofof specimensspecimens AdrianAdrianS. S-Smith SmithFGA, FGA, Perth,Perth, Scotland,Scotland, includingincluding thethe following:following: roughrough specimensspecimens ofof forfor aa PerfectPerfect DiagramDiagram CD CD showingshowingdifferent different selenite,selenite, opalizedopalized chertchert (UV(UV fluorescent),fluorescent),an an typesiAÉÉp^face of facett arrangements.arrangements. obsidian slab (New Mexico),quartz and agate obsidian slab (New Mexico),quartz and agate ^AèAbee K.K. Suleman,Suleman, Arusha,Arusha, Tanzania,Tanzania,for for (Texas), peridot in lava (Moorea, Tahiti), (Texas), peridot in lava (Moorea, Tahiti), aa samplesample ofof metamorphicmetamorphic emeraldemerald sourcesource sugilite slabs (Africa), amethyst (Brazil and sugilite slabs (Africa), amethyst (Brazil and rockrock fromfromthe the ManyaraManyaraemerald emerald deposit,deposit, Zambia), corundum (Georgia, U.S.A), Zambia), corundum (Georgia, U.S.A.), Tanzania.Tanzania. turquoiseturquoise slabsslabs (New(New Mexico)Mexico) andand aa packetpacket Ian Thomson FGA, London, for a framed ofof miscellaneousmiscellaneous quartz,quartz, calcite,calcite, agate,agate, chertchert Ian Thomson FGA, London, for a framed cultured pearl collage. andand garnet;garnet; aa selectionselection ofof crystalscrystalsincluding including cultured pearl collage. rubiesrubies (India(India andand NorthNorth Carolina,Carolina, U.S.A.),U.S.A.), M.M. Walsh,Walsh, Beckenham,Beckenham, Kent,Kent,for fora a berylberyl (Colorado,(Colorado, U.S.A),U.S.A.), sapphiresapphire (Georgia,(Georgia, presentationpresentation setset of of CZCZ mastermaster cuts.cuts.

Anderson Medal is now a discretionary edition; a Gem-A Education leaflet produced award, on a similar basis to that of the for widespread circulation; and a new CD- Tully and Bruton Medals. ROM of Tutor Help and Advice, provided On the recommendation of the Board of for all ATC and Correspondence Course Examiners, S Greatwood and N Rose were tutors. appointed examiners for Foundation Several new Allied Teaching Centres are Certificate in Gemmology and Gem Diamond at various stages of development world theory respectively. R Lake was appointed to wide, under the eye of Ian Mercer, with shadow E Stern on the diamond examination. Brenda Hunt's coordination. The Education Review Meeting was held in Ian Mercer initiated the re-accreditation November and provided useful discussion of Gem-A courses with the QCA during the and exchange of views between tutors, year; this will include renewal of the levels lecturers, examiners and staff of the for our qualifications; to be followed by a Education Office. European-led credit transfer system. Lome Stather's development work on Gem-A hosted the Federation of European courses, examinations and promotion has Education in Gemmology (FEEG) General increased in scope and included bringing the Assembly and Seminar, from 22 to 25 Diploma in Gemmology notes into January. Ian Mercer oversaw the FEEG continuity with the new Foundation course Seminar, held at the Royal College of during the normal process of updating; the Surgeons of England, which proved to be development of a new promotional, annual a success, with the great organizational Education Prospectus, now into its second assistance of Mary Burland.

Proceedings of the Gemmological Association and Gem Testing Laboratory of Great Britain and Notices 193

Membership contributed much to Gem-A's American There was a slight decrease in Fellow, exposure; Colin Winter and Jerry Root Diamond and Associate membership during donated their time and knowledge in hands- the year, with Laboratory membership on Workshops. A book-signing event for 7 remaining static. Colin s new Student's Guide to Spectroscopy The Gem-A Branch network was expanded was a big hit during the show. The splendid in 2003 with the launch of the North East annual dinner gathering for members and Branch which held its inaugural meeting in friends of Gem-A USA brought in many Leeds on 10 October. The Midlands Branch international and American supporters to held eight meetings as well as their Summer hear our Gem-A USA Honorary Consultant, Supper Party and a 51st Anniversary Dinner, Gabi Tolkowsky who, as always, dazzled his and a one-day Conference in February with audience with passion for the trade while keynote speaker Stephen Dale. The North expressing the importance of gemmological West Branch held seven meetings. The education. Scottish Branch held eight meetings at venues The Stuller Annual Workshop was a in both Edinburgh and Glasgow, and their 'hands-on' gem identification event at Annual Conference in Perth at the beginning Lafayette Louisiana. This Gem-A USA of May with John Koivula of the GIA's Gem production was recognized as being the most Trade Laboratory as the keynote speaker. liked presentation by attendees. During the The South East Branch held seven meetings year Gem-A maintained their arrangements during the year at venues in Central London with two Allied Teaching Centres, with four and Guildford, Surrey. The South West further centres preparing to start ATC Branch held a meeting in Bath in September. operations. Additional ATC and Council is most grateful to the Branch Correspondence Course tutors were assigned. Officers and Committee Members who work The nationwide Jewelers of America so hard to present interesting and varied organization offers an annual $100,000 programmes of activities each year. scholarship program to qualifying members. Gem-A USA was qualified as a participant for Laboratory those JA members seeking gemmological Stephen Kennedy, head of the Gem Testing education. Laboratory, resigned in August 2003 to enable him to spend more time with his family. Publications He has continued on a consultancy basis The Journal of Gemmology underwent its working two days a week producing reports second major change of format since its first for coloured stones and pearls. Diamond publication in 1947 with an increase in size to grading continues to develop with an A4 in January 2004. This enables more scope increasing demand for the new Gem Testing for larger illustrations and more varied Laboratory of Great Britain report. There was presentation of the continuing technical an increase in the number of larger fine advances in gemmology. quality diamonds and also an increase in In the period April 2003 to March 2004, type Ha diamonds recorded. 19 papers were published with topics ranging T M J Davidson represented the laboratory from Sri Lanka multi-star quartzes to Scottish at the gem industry and laboratory marble, and from pearl cultivation in China conference in Tucson in February 2004. to the compositions of Thai rubies and Gem-A USA sapphires. Abstracts totalled 149 and there Our national office in the United States were 22 book reviews. The Assistant Editors, grew steadily, increasing in visibility with Associate Editors and abstractors are warmly workshops, lectures and exhibits at trade thanked for their continued support with shows including JCK Las Vegas, JA New York academic and technical expertise - more and and AGTA Tucson Gem Fair. Gem-A USA more appreciated these days as technologies became a member of AGTA and the Gem Fair continue to advance. The Mineralogical

J. Gemm., 2004, 29, 4, 241-252 193 Donations The Council is grateful to the following for responding to the appeal for donations. Donation levels were Circle of Benefactors (£5000 and above), Diamond (£1000 to £4999), Ruby (£500 to £999), Emerald (£250 to £499), Sapphire (£100 to £249) and Pearl (£25 to £99). The following joins those donors listed in previous issues of The Journal.

Pearl Donations Ikuo Sato FGA, Sendai-Shi, Miyagi-Ken, Japan

Hong Kong Jewellery and Watch Fair 2004 The Council is also most grateful to the following for their generous sponsorship of the Gem-A stand and seminars at the Hong Kong jewellery and Watch Fair:

Charles & Colvard (HK) Ltd, Central, Hong Kong vsAwv.charlesandcolvard.com Aaron Shum Jewelry Ltd, Kowloon, Hong Kong www.aaronshum.com Opalight Artcrafts & Gems Co. Ltd, Kowloon, Hong Kong www.opalight.com

Society is also thanked for their permission Gem Show giving delegates the opportunity to reprint mineralogical abstracts that are to browse and buy at the Show during the relevant to gemmology. R. Coleman (of lunch break. The keynote lecture 'An update Harley UK) is thanked for his part in on research activities at GIA' was presented developing the new A4 format in January by William E. Boyajian, President of the and making the publication much more GIA. Professor Henry A. Hänni gave a attractive. presentation on gem identification carried out Gem and jewellery News is published jointly at the SSEF Swiss Gemmological Institute, with the Society of Jewellery Historians and in Dr Jack Ogden explained how jewellery 2004 it too benefited from the change to A4 mounts could be scrutinized to authenticate size and publication in full colour. Another jewellery, Clive Wright gave an update on change was the acceptance of advertisements, the Kimberley Process and Paula Crevoshay which helps to offset the increased printing spoke about Crevoshay designs and using costs, and the whole project has benefited gemmology as a designer tool. Two of the from the expertise of Shelley Nott on the new Gem-A USA Advisory Board Members, Gail design and John Goodall on production. Levine and Theresa Shannon as well as As ever, Mary Burland has coordinated and Director A Dale, attended the conference to managed this development and continued show support for the Association in the UK. to pull together a wide range of stimulating A private viewing of the Crown Jewels at articles from both our regular contributors the Tower of London with Crown Jeweller and people new to gemmology. David Thomas, a visit to the DTC, and a private viewing and guided tour of the Conference Wernher Collection at the Ranger's House, The Annual Gem-A Conference was held Greenwich, were arranged for the conference for the second time at the Kempton Park delegates. The Council is most grateful to the Racecourse during the late autumn Rock 'n' Conference sponsors Marcus McCallum

Proceedings of the Gemmological Association and Gem Testing Laboratory of Great Britain and Notices 193

and T.H. March Insurance Brokers, and Staff and Supporters supporters Fellows & Sons, Dreweatt Neate, Three members of staff left and have and Malca-Amit (UK) Ltd. been replaced. There have been three additions to the staff: Hayley Smith joined Visits the education team as an examination and The annual visit organized by D J Garrod course administrator, Michell Henry was to the world-famous Idar-Oberstein gern employed in office services as a cleaner and centre in Germany was again very successful. Stephen Bennett was appointed IT person Visits to new venues in Idar and Oberstein responsible for routine PC software, network were organized, while our 'traditional' visits maintenance, Gem-A website upkeep in and around the twin towns were as and development, reporting to YJ Thien, popular as ever. along with Gem-A promotion, education development support including graphics Photographic Competition and CD Rom production, reporting to The 2003 competition on the theme 'All Lome Stather. shapes and sizes' drew a record number of Through the continued dedication and images of particularly high quality, and hard work of our staff we continue to several were selected to grace the 2004 strengthen the foundation and build for calendar. The winner was Zeng Chungguang the future of Gem-A. of Singapore, with runners-up Anthony de Goutière of Victoria, BC, Canada, and Luc Gemmological Instruments Ltd. Genot of Brussels, Belgium. Council is most Gemmological Instruments Ltd is a grateful to Harley (UK) for their sponsorship wholly-owned company of Gem-A. The of the three prizes and for their contributions company supplies gem-testing equipment of to conference expenses. good quality at competitive prices, ranging from stone tweezers to top-of-the-range Trade fairs and shows microscopes, books on gems, gemmology and Gem-A exhibited at International Jewellery gem-set jewellery, and a range of thematic London 2003 at Earls Court in September sets of gems for students. The turnover and with D Garrod giving a series of lectures. profit generated by GI Ltd were very similar T Davidson, I Mercer, D Garrod and L Stather to the figures for the previous year and reflect represented Gem-A at the Hong Kong the need for constant development and Jewellery Show in September, where a good improvement in a competitive market. attendance was enjoyed at our show booth Introduced in the second half of 2003/2004, and seminar. A Clark, D Garrod and L Stather and for which we have sole world attended Rock 'n' Gem Shows at Kempton distribution, was the Diamond Trading Park promoting Gem-A. Company's Diamonds CD ROM on Treatments, Synthetics and Simulants. The Finance world market for gemmological equipment For 2003/2004 Gem-A exceeded its remains highly competitive. We continue to budgeted turnover. Although a small search the world for the best equipment to increase on budgeted turnover was achieved, market at good and realistic retail prices. unbudgeted expenditures in cost of sales, consultancy and unforeseen costs in repairs and maintenance along with an increased Extraordinary investment in education expenditure planned to produce dividends in 2004-2005 reduced General Meeting our operating profit. We have continued to At an Extraordinary General Meeting held show improvement in our accountancy at 27 Greville Street, London EC1 on 27 July procedures and have reduced our debtors in 2004, the following Special Resolutions were Gem-A and Gemmological Instruments Ltd. approved:

J. Gemm, 2004, 29, 4, 241-252 193

THAT the Gemmological Association and Brennan, Aidan, Dundalk, Co Louth, Ireland Gem Testing Laboratory of Great Britain Cader, Lazhar, London should seek registered charity status. Cardosa Rodriques, Isadora, Surbiton, Surrey THAT the Gemmological Association and Chang Yuan-Cheng, London Gem Testing Laboratory of Great Britain Chawla, Jaspreetkaur, London adopts the Memorandum and Articles of Cheong Mun Fong, London Association dated 2 June 2004 as posted on Dowell, Vanessa CD., Cambridge their website at www.gem-a.info, subject to Duncan, Barry John, Littlehampton, West Sussex any changes required by the Charity Groenenboom, Peter, Arnhem, The Netherlands Commission, for application for registration Hafeez, Mohammed, Dewsbury West Yorkshire as a charity. Hague, Des, Sheffield, South Yorkshire Hazra, Dibyendu, West Bengal, India Membership Hemeryck, Marine, Brighton, Sussex Huck, Perry, Stanford-in-the-Vale, Between 1 July and 31 October 2004 the Oxfordshire Council approved the election to membership Johnson, Bede, Lewes, East Sussex of the following: Kashaka, Jean-Claude M., Surbiton, Surrey Katembwe, Joseph C, Southsea, Hampshire Fellowship (FGA) Kiilu, Kyalo, Mayfield, East Sussex Adzovic, Senada, Sarajevo, Bosnia Herzegovina, Leadbeater, Craig C, Dulwich, London 1997 Luckett, Martin J., Stafford, Staffordshire Aura, Kimmo T., Espoo, Finland, 2004 Lu Lu, Morden, London Aziz, Khalid, Karachi, Pakistan, 1987 McLeod, Samantha, Wellington Point, Chandhok, Jasmeet Singh, New Delhi, India, 2004 Queensland, Australia Hearnden, Rachel Claire, Sheffield, S Yorkshire, Masson, Neil, Bucksburn, Grampian 2004 Mitchell, Shirley D., Windsor, Berkshire Jennings, Rick, Roanoke, VA, USA, 1979 Mortimer, Laura H., South Ockendon, Essex Kao Oi Shan, Patsy, Hong Kong, 2004 Morton, Jacqueline A.C., Cambridge Li Mo Ching, Hong Kong, 2004 Munalula, Crispin, Harrow, Middlesex Michaelides, Mapia, Athens, Greece, 1999 Ota, Shinya, Acton Town, London Peters, Judith Anne, Falmouth, Cornwall, 1976 Pinckernelle, Kathia, Glasgow, Strathclyde Sillem, Hayaatun, London, 2004 Points, Jaqueline Elizabeth, Dorset Valvio, Raija, Vaajakoski, Finland, 2004 Sane, Hemant, Mumbai, India Visschers-Villerius, Conny, Heerde, Saull, Elanor N., Stourbridge, West Midlands The Netherlands, 2004 Sesay, David Emmanuel, London Wong, Chung Yan, Kowloon, Hong Kong, 2004 Shah, Nilay, Hatfield, Hertfordshire Wong Man Nea, Rosemary, Hong Kong, 2004 Shoaie-Nia Pouladi, Shabnam, Goring-by-Sea, West Sussex Diamond Membership (DGA) Thomson, Alison, Tiptree, Colchester, Essex Beattie, Rosamund, Manor Park, London, 1999 Tonkin Jukes, Claire, Newham, London Lam Wai Han, Hong Kong, 2004 Tun, Thura, Greenford, Middlesex Li Chi Wai, Kowloon, Hong Kong, 2004 Veitch, Tara MacNeil, London So Yiu Ki, Eric, Hong Kong, 2004 Wadhwa, Pritam. Harrow Wagner, Olivier, Hammersmith, London Associate Membership Woolfe, Diana P., Poole, Dorset Akar, Farah, Finchley, London Archibong, Elizabeth, London Laboratory Membership Anderson, Michael R., Chillerton, Isle of Wight Bamarra, Jaspac, London M. Abram Ltd, 75 Bond Street, London, W15 IRU Barrie, Brenda, Woking, Surrey Christopher Klean, Suite 28, 88/90 Hatton Berden, Angela CM., Balham, London Garden, London EC1N 8PI

Proceedings of the Gemmological Association and Gem Testing Laboratory of Great Britain and Notices 193

Transfers Van Rooij-Roeloffzen, Marjolein, Almere Buiten, Transfer from Diamond Membership The Netherlands to Fellowship and Diamond Wai Yee Cheng, Tsuen Wan, New Territories, membership (FGA DGA) Hong Kong Whalley, Joanna, Walthamstow, London Manchanda, Anu D., Smethwick, West Midlands St John Lewis, Delyth, South Norwood, London Transfer from Associate Membership Wells, Miranda E.J., London to Diamond Membership (DGA) Transfer from Associate Membership Hui Hui Ye, Preston, Lancashire to Fellowship (FGA) Rebmann, Olivier, Carlsbad, California, U.S.A. Sowa, Ali Med, Tilbury, Essex Aki, Miou, Osaka City, Osaka, Japan Szymanska, Zofia, London Anderson, Tricia K.W., Helen's Bay, Bangor, N. Ireland Brard, Jagvinder S., Pinner, Middlesex Subscriptions 2004 Curtis-Taylor, Tracey, London The following are the membership subscription Ideno, Yumi, Nishinomiya City, Hyogo Pref., rates for 2005. Existing Fellows, Diamond Japan Members and Associate Members will be entitled Landmark, Vivienne J., Harpenden, Hertfordshire to a £5.00 discount for subscriptions paid before Lee, Young Shin, Kyunggido, Korea 31 January 2005. Moore, Katherine H., Symington, Ayrshire Sane, Hemant. Mumbai, India Tsutsui, Kazumi, London Fellows, Diamond Laboratory Members and Members Transfer from Fellowship to Fellowship Associate Members and Diamond Membership (FGA DGA) UK £72.50 £250.00 + VAT Hynes, Lola, Dublin, Ireland Jones, Lorraine D., Farnworth, Lancashire Europe £80.00 £250.00 Lam Kwi-Peng, Singapore Richmond, Sonia, Herne Hill, London Rest of the World £85.00 £250.00 Thein, Myint Myint, Whetstone, London

J. Gemm., 2004, 29, 4, 241-252 253 1 1 :> Pearl Com! Amba Bead Nee..,'ces Carvings Cameos Mineral Specimens

! ". By appointment only ~ la Wickham Court Road, West Wickham, Kent BR4 9LN .i/;l- Tel: 020-87774443, Fax: 020-8777 2321, Mobile: 07831 843287 t N e-mail: [email protected], Website: www.ruppenthal.co.uk ~

Modern 18ctGem-set Jewellery

Tile JJtil annual Gem-A visit to Experience a IDAR-OBERSTEIN New Understanding Sunday 13 March two new books to Saturday 19 March 2005 by Richard Cartier FGA Major highlights of the tour include: Seeing • The Steinkaulenberg mine (the sou rce of local aga te and amethyst) The Light • Historic and modern gem-cutting workshops Understanding Optics Without the Mathematics • Gem carving and cameo cutting demonstrations • Mineral and gem museums Professional Jewellery There will also be arranged visits to gem deale rs and a wine tasting eveni ng at Gethman ri's Hotel . Appraising Second Edition Price £695 visit Heartier.c om For further deta ils visit the Gem-A website at or order from your www.gem-a.info or contact Doug Garrod on +44 (0)20 7404 3334 . Gem Association 192534 Before you choose your insurance make sure

you read the small print

At T.H March, every insurance package we supply is hacked by an experience no one else can match, For over a hundred years we have provided the expertise, reliability and i|ualiiy of service which has made us the premier insurance broker to lite jewellery trade

IAA, ^^ T.H.MARCH INSURANCE BROKER

London 10/12 Ely Place, London EC1N 6RY Tel 020 7405 0009 Fax 020 7404 4629 web www.thmarch.co.uk email [email protected]

Additional offices in: Birmingham 10A Vyse Street, Hockley, B18 6LT Tel 0121 236 9433 Fax 0121 233 4901 Glasgow Empire House, 131 West Nile Street, Gl 2RX Tel 0141 332 2848 Fax 0141 332 5370 Manchester 1st Floor, Paragon House, Seymour Grove, M16 0LN Tel 0161 877 5271 Fax 0161 877 5288 Plymouth Hare Park House, Yelverton Business Park, Yelverton PL20 7LS Tel 01822 855555 Fax 01822 855566 Sevenoaks Sackville House, 55 Buckhurst Avenue, Kent TN13 1LZ General Insurance Tel 01732 462886 Fax 01732 462911 251953 Museums, Educational Establishments, Collectors & Students ROCK I have what is probably the largest range of genuinely rare stones in the UK, from Analcime to Wulfenite. Also rare and trains modern synthetics, and inexpensive SHWVS crystals and stones for students. Computerised lists available with even Exhibitors displaying & selling a huge more detail. Please send 12 1st class range of minerals, fossils, stamps refundable on first order crystals & jewellery (overseas free).

Two special offers for students: New Teach/Buy service and free NEWMARKET RACECOURSE stones on an order. Newmarket, Suffolk A J. French, FGA 20 -21 NOVEMBER 7 Orchard Lane, Evercreech Somerset BA4 6PA BRIGHTON RACECOURSE Telephone: 01749 830673 Freshfield Road, Brighton Email: [email protected] 27 -28 NOVEMBER www.ajfrenchfga.co.uk

From sparkling crystals and spectacular minerals to Pearls ancient fossils; from gemstones in a whole spectrum of colours to jewellery containing them; from insects in Gemstones amber to beautiful carvings. It is impossible to list or describe them all so why not come and see for yourself. As the majority of exhibitors are collectors themselves they are more than happy to Lapidary Equipment talk about their speciality, and are both knowledgeable and interested. This makes a friendly atmosphere and a visit to the show even more enjoyable. There are up to 40 dealers exhibiting, with some of the UK's best-known dealers attending. The Showgrounds are easy to find being well signposted Since 1953 in the area.

CH. De Wavre, 850 B-1040 Bxl - Belgium

Tel : 32-2-64738.16 Fax : 32-2-6482036 E-mail : [email protected] All shows open 10am - 5pm (Trade & Public) j Admission: ! All other shows: Adults £2.50, Seniors £2.00 I www.gemline.org Children (8-16 yrs) £1.25 ! For further information please contact; HD Fairs Ltd 01628 621697 www.geofana.net Email; [email protected] www.rockngem.co.uk 192536 Forthcoming Events

10 November Exhibition tour: 'Hungary's Heritage: Princely treasures from the Esterhâzy Collection7 at Somerset House 16 November Scottish Branch: Gemstones of Mozambique. Roger Key 17 November North West Branch: Branch AGM and social evening 26 November Midlands Branch: Bring and Buy Sale and Quiz 4 December Midlands Branch: 52nd Anniversary Dinner 7 December Gem Discovery Club Specialist evening: Unusual gems with Marcus McCallum 2005 18 January Scottish Branch: Suffragette Jewellery. Liz Goring 28 January Midlands Branch: Diamond from crust to core. Dr Jeff Harris 22 February Scottish Branch: Diamonds - a research perspective. Dr Jeff Harris 25 February Midlands Branch: European jewellery from Elizabeth I to Elizabeth Taylor. John Benjamin

BRANCH CONFERENCES 2005

Midlands Branch Sunday 13 March - Barnt Green, Worcestershire Scottish Branch Friday 29 April to Monday 2 May - The Lovat Hotel, Perth South East Branch June - Colombo, Sri Lanka

When using e-mail, please give Gem-A as the subject:

*!5 London: Mary Burland on 020 7404 3334; +^ e-mail [email protected] ,•9a; Midlands Branch: Gwyn Green on 0121 445 5359; e-mail [email protected] +-» North East Branch: Neil Rose on 0113 2070702; u e-mail [email protected] +-) North West Branch: Deanna Brady 0151 648 4266 c Scottish Branch: Catriona Mclnnes on 0131 667 2199; o e-mail [email protected] South East Branch: Colin Winter on 01372 360290; e-mail [email protected] South West Branch: Richard Slater on 01635 553572;

L*S.!ääL».> jSl-'Sft^s ..i&iÄi Gem-A Website For up-to-the-minute information on Gem-A events visit our website on WWW.gem-a.info Guide to the preparation of typescripts for publication in The Journal of Gemmology

The Editor is glad to consider original articles Transparencies, photographs and high quality shedding new light on subjects of gemmological printouts can also be submitted. It is recommended interest for publication in The Journal. Articles are that authors retain copies of all illustrations not normally accepted which have already been because of the risk of loss or damage either during published elsewhere in English, and an article is the printing process or in transit. accepted only on the understanding that (1) full information as to any previous publication (whether Diagrams must be of a professional quality and in English or another language) has been given, prepared in dense black ink on a good quality (2) it is not under consideration for publication surface. Original illustrations will not be returned elsewhere and (3) it will not be published unless specifically requested. elsewhere without the consent of the Editor. All illustrations (maps, diagrams and pictures) Typescripts Two copies of all papers should be are numbered consecutively with Arabic numerals submitted on A4 paper (or USA equivalent) to the and labelled Figure 1, Figure 2, etc. All illustrations Editor. Typescripts should be double spaced with are referred to as 'Figures'. margins of at least 25 mm. They should be set out in the manner of recent issues of The Journal and Tables Must be typed double spaced, using few in conformity with the information set out below. horizontal rules and no vertical rules. They are Papers may be of any length, but long papers of numbered consecutively with Roman numerals more than 10 000 words (unless capable of division (Table IV, etc.). Titles should be concise, but as into parts or of exceptional importance) are independently informative as possible. The unlikely to be acceptable, whereas a short paper approximate position of the Table in the text of 400-500 words may achieve early publication. should be marked in the margin of the typescript. The abstract, references, notes, captions and tables should be typed double-spaced on separate sheets. Notes and References Authors may choose one of two systems: Title page The title should be as brief as is consistent with clear indication of the content of (1) The Harvard system in which authors' the paper. It should be followed by the names names (no initials) and dates (and specific pages, (with initials) of the authors and by their addresses. only in the case of quotations) are given in the main body of the text, (e.g. Collins, 2001, 341). Abstract A short abstract of 50-100 words is References are listed alphabetically at the end of required. the paper under the heading References.

Key Words Up to six key words indicating the (2) The system in which superscript numbers subject matter of the article should be supplied. are inserted in the text (e.g. ... to which Collins refers.3) and referred to in numerical order at the Headings In all headings only the first letter and end of the paper under the heading Notes. proper names are capitalized. Informational notes must be restricted to the A This is a first level heading minimum; usually the material can be incorporated in the text. If absolutely necessary B This is a second level heading both systems may be used.

First and second level headings are in bold and References in both systems should be set out are ranged left on a separate line. as follows, with double spacing for all lines.

Third level headings are in italics and are Papers Collins, A.T., 2001. The colour of diamond indented within the first line of text. and how it may be changed. J.Cemm., 27(6), 341-59

Illustrations High resolution digital files, for both Books Balfour, I., 2000. Famous diamonds. 4th edn. colour and black-and-white images, at 300 dpi TIFF Christie's, London, p. 200 or JPEG, and at an optimum size, can be submitted on CD or by email. Vector files (EPS) should, if Abbreviations for titles of periodicals are those possible, include fonts. Match proofs are essential sanctioned by the World List of scientific periodicals when submitting digital files as they represent the 4th edn. The place of publication should always colour balance approved by the author(s). be given when books are referred to. The Journal of Volume 29 No. 4 Gemmology October 2004

Contents

Pearls from the lion's paw scallop 193 Kenneth Scarratt and Henry A. Hanni

A treatment study of Brazilian garnets 205 Sigrid G. Eeckhout, Antonio C.S. Sabioni and Ana Claudia M. Ferreira

The nature of channel constituents in hydrothermal 215 synthetic emerald Rudolf I. Mashkovtsev and Sergey Z. Smirnov

A new definition of optic axis for gemmology 228 and the four kinds of optic axis Richard H. Cartier

Abstracts 235

Book Review 240

Proceedings of the Gemmological Association and 241 Gem Testing Laboratory of Great Britain and Notices

Cover Picture: A brooch consisting of turquoise, sapphires and gold set on a lion's paw shell, created by Cartier (Paris) ca. 1958; courtesy of Primavera Gallery, New York, photo Noel Allum. (See Pearls from the lion's paw scallop p. 793)

The Gemmological Association and Gem Testing Laboratory of Great Britain Registered Office: Palladium House, 1 -4 Argyll Street, London W1 F 7LD