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VOLUME XVll SPRING 1981 \ .: I SPRING 1981 Volume 17 Number I

TABLE OF CONTENTS

EDITORIAL 1 An Introduction to the New Gems & Richard T. Liddicoat, /r.

FEATURE 2 Zabargad: The Ancient Island in the Red Sea ARTICLES Edward Gu belin 9 : An Update Kurt Nassau 20 A Simple Approach to Detecting Simulants !ill Hobbs

NOTES AND 34 The Hidden Beauty of : New Light on an Old Subject NEW yohn I. Koivr~la TECHNIQUES 37 Artificially Induced Color in -Citrine Kurt Nassau

REGULAR 40 Gem Trade Lab Notes FEATURES 47 Gemological Abstracts 56 Gem News 59 Book Reviews

ABOUT THE COVER: The elemen~soj gemology ore summed up in th~sclossic pose: , books, faceted stone (in this cnse, o 32.21 ct, oqriamorine), and nrriurol (here, on oquamorine jrom Ajghonistan, courlesy of the Los Angeles County Museum of Noturol History, Los Angeles, CA). Cover design by Peter lohns~on,photogrophy by Michoel Havstad. Composition for Gems & Gemology is done by Printed Poge Graphics, Fullerton, CA. The color sepnrotions ore done by Effective Grophics, Compton, CA. Printing is by Woverly Press, Eoston, MD.

" 1981 Gemological Institute of America. All rights reserved. EDITORIAL Editor-in-Chief Managing Editor Editor, Geni Trade Lab Notes STAFF Richard T. Lidtlicoat, jr. Alicc S. Keller Chuck Fryer Associate Editor 1660 Stcwart St. Editor, Geniologiwl Abstracts Peter C. Keller Santn Monica, CA 90404 Ilona Pvl. Dirlnrn Telephone: (213) 829-299 1 Associate Editor Editor, Book Reviews D. Vincent manso on Subscriptions Manager John I. I

PRODUCTION Art Director Cover Drsigii Photographer STAFF Susan Kingsbury Peter Johnston Mikc Havstad

EDITORIAL Robert Cro~vn~ngshicld Anthony K. Kampf Kurt Nassau REVIEW BOARD New York, NY Los Angeles, CA Bernarclsville, NI Pete Dunn John ICoivula Glenn Nord Woshir~gton,DC Sonta Mollico, CA Los An~eles,CA Dennis Foltz Lewis Kuhn Kick Shaw Srrn to Monica, CA New Yolk, NY Santo Monico, CA Chuck Fryer Sallie ~Morton Iohn Sinltnnltas Sonla Mollico, CA Son lose, CA Son Diegn, CA C. S. tIurlb~~t,Jr, George Rossman Cambridge, MA Posadeno, CA

SUBSCRIPTIONS Subscr~p~ionsin the U.S.A., ~tspossessions, and in Canada and Mexlco are priced as follows: $16.50 for one year (4 issues), $45.00 for thrce years (12 issues). Subscriptions sent elsewhere are: $20.50 for one year, $55.00 for three years. Special annual subscription rates arc available for all students actively involved in a CIA program: $12.00 U.S.A., its possessions, Canada, and Mexico; $16.00 elsewhere. Your student number mtisr be listed at the time your subscription is enteretl. Single issues may be purchased for $5.00 in the U.S.A., $6.00 elsewhere. A limi~ednumber of back issues of G&G arc also available for purchasc. Pleasc address all inquiries regarding subscriptions and the purcl~aseof slngle copies or back issues to the Subscriptions Manager.

NIANUSCRIPT Gems d Gemology welcon~esthc submission of articles on all aspects of the ficld. For a copy of the Suggestions for SUBMISSIONS Authors for preparing ~nanuscriptslor the journal, please contact thc Managing Editor. Lette~son articles published in Gems d Gelnology and other relevant matters are also weIcome.

COPYRIGHT Abstracting is permitted with credit to the source. Libraries are perm~ttedto photocopy beyond the Iinlits of U.S. AND REPRINT copyright law for private use of patrons, Instructors are per~nittedto photocopy isolated articles for noncomn~ercial PERMISSIONS classroon~use w~thoutfee. For other copying, reprint, or rep~~hlicatiollpermission, please contact the Managing Editor. Ge111s d Gentology is published quarterly by the Gemological Institute of America, a nonprofit educational organization for the jewelry industry, 1660 Stewart St., Santa Monica, CA 90404.

Any opinions expressed in signed articles are understood to be the vlews of the authors and not of the publishers. AN INTRODUCTION TO THE NEW GEMS & GEMOLOGY RICHARD T. LIDDICOAT, Jr. Editor-in-Chief

ommencing with this, the first issue of the 17th volume of Gems d Gemology, the C quarterly publication of the Gemological Institute of America has a new look, new size, and a commitment to become the most comprehensive periodical in the field of gemology. It seems fitting that this dramatic change will be effected during the 50th anniversary cele- bration of the founding of GIA by Robert M. Shipley in 1931. Since its inception in 1934, Gems d Gemology traditionally has followed a 6" x 9 format and almost always in 32 pages. Over the years, color has been used only sparingly. During these years, however, the jewelry industry has expanded rapidly and become increas- ingly sophisticated and well-educated. GIA is acutely aware of the greater need and desire of this industry and others involved in the field to be well-informed about new materials, new techniques, and other developments in gemology. With the new Gems d Gemology, we have increased the size of the journal almost four-fold- to 8%"x 1I", with a minimum of 64 pages per issue. Recognizing the integral role that color plays in dealing with gem materials, we have used color photographs throughout where pos- sible. Perhaps most important, to help ensure the accuracy and usefulness of the papers pub- lished we have called upon many of the prominent figures in the gemological community to serve on the journal's Editorial Review Board. All manuscripts submitted to Gems e?) Gem- ology now are reviewed by at least two members of the board in addition to the associate editors, Peter Keller and Vince Manson, and me. Only the meaningful articles will be published. Other editorial innovations have been made to increase the usefulness of this quarterly pub- lication. With news from Robert Crowningshield, Karin Hurwit, and Robert Kane, section editor Chuck Fryer has expanded and reorganized the Lab Notes column. GIA librarian Dona Dirlam, with the help of her large review board, has designed the Gemological Abstracts sec- tion to serve as the most comprehensive review available of articles relating to gemology. In addition to English publications, magazines in German, French, Spanish, Portuguese, and Jap- anese will be screened and abstracted on a regular basis. John Koivula will continue to provide a similar service for books in the field, and Stephanie Dillon will strive to present the latest information on current happenings in the gem world. As the journal of the Gemological Institute of America, Gems d Gemology will cover not only topics directly related to gems, but also those concerning jewelry arts, including design and manufacturing, as well as subjects related to the management of jewelry enterprises. Authors seeking publication of papers on any subject matter in the fields outlined above are encouraged to submit manuscripts to Gems d Gemology. Letters on articles published in the journal and other topics important to the industry also are welcome. It is the intention of the staff of Gems d Gemology to provide gemologists and gem enthu- siasts everywhere with the latest developments and most comprehensive coverage in the field.

GEMS & GEMOLOGY Spring 1981 1 ZABARGAD: THE ANCIENT PERIDOT ISLAND IN THE RED SEA

By Edward Giibelin

Reflecting on his 1980 visit to Zabargad, abargad is the oldest and longest-lznown source the author provides 11ti update on this zof gem (fig. 1); yet the island, just as relatively unknown island and the much as the it hoarded, has slid repeatedly into bcarrtiful peridots for which it has gained oblivion, only to be rediscovered over and over again and fame. He con~plementshis discussion of forgotten once more. The author visited this tiny island the geology of Zal?agad, the peridot in the Red Sea in March of 1980. Located about 60 miles occurrences, the mining techniques, and southeast of the RBs Bands peninsula, at 23" 36' 16" N the characteristics of the gemstone with a look ut the al~cienthistory of the island and 36" 11' 42" E (fig. 2))it is situated 16 lzm north of the and the etymological cliangcs Tropic of Cancer. Zabargad is only 3.2 lzm long and 2.4 surrounding the stone's current name, lzm wide, covering an area of 4.5 lzm2. There is hardly peridot. Although somewhat low on the any life on the island and no fresh water at all; one may hardness scale, this n~agnlficentgemstone justly describe it as a "desert island." In fact, apart from has regained popufrrr appreciation, and the low-growing shrubs, several giant turtles, and a few birds from Zabargud are still arnolig the such as wagtails, ospreys, and gulls, practically no flora finest in the world. or fauna exist on Zabargad. The highest ground is the so- called Peridot Hill (235 m above sea level), which to- gether with some smaller hills (135 m above sea level) forms the most impressive sight that the island offers the approaching seafarer (fig. 3). Despite the lack of vegeta- tion, the island is at its most beautiful when the yellow to dark brown toiles of the various roclzs and dump-heaps before the many pits brighten in the light of the morning sun. The adventurer with any imagination at all cannot avoid letting the pageant of history unfold (see box). - - ABOUT THE AUTHOR REGIONAL GEOLOGY Dr. Gubelin is a gernolog~stand honorary The occurrence of peridot on Zabargad is intimately professor at the University of Stellenbosch, related to the regional geology and the tectonic processes Sw~tzerland. that on a larger scale were responsible for the formation Acknowledgmenls: The author extends his of the Red Sea itself. As an extension of the East African genuine thanks to Professor Dr. Max Weibel of the lnstitute for and Petrography Rift Valley and part of the global rift system, the Red Sea of the Univers~tyof Zurich for his reading of the is a geologically young feature that evolved in the Ter- manuscript and hrs helpful commentary. Many tiary period of geologic time, 65 to 13 million years ago. appreciative thanks also to Dr. P. Bancroft of Fallbrook, Cal~fornia,who arranged the excursion The rocks seen on the island represent the results of and was an excellent companion. magmatic activity with associated metamorphism of "'~7 "'~7 98 1 Gemological Institute of America preexisting sediments and were all exposed through tec-

2 Zabargad GEMS 8: GEMOLOGY Spring 198 1 tonic uplift and erosion. Mafic igneous rocks THE PERIDOT (Badgley, 1965), which represent the bulk of the OCCURRENCES island, are of deep-seated origin. They are notable No detailed documentation of the peridot occur- for their low silica content and consist primarily rences on Zabargad has been made. An inter- of lherzolites, characterized by abundant olivine, esting review of available information is provided pyroxene, and amphibole. The metamorphic by Wilson (1976). rocks, in turn, consist of serpentinites, granu- It seems likely that peridots were once found lites, schists, and slates. The alluvial sediments on several parts of the island-in fact, almost and an extensive gypsum deposit are of more everywhere the peridotites outcrop. The finest recent origin. and largest gem crystals, it is believed, occurred The topography of the island reflects its tec- in such quantitites on the eastern slopes of Per- tonic history. The terrain is extremely irregular, idot Hill that mining was worthwhile. Here they the coastline consisting of fractured escarpment appear to have been recovered in vein-like areas terraces. Numerous coral banlzs and reefs occur of the serpentinized peridotite. The tiny veins in the surrounding waters. run in all directions so that in places they form

Zabargad GEMS h GEMOLOGY Spring 198 1 3 SITUATION MAP

bR4s Bands LPort Berenice

ZABARGAD r

Basalt dykes Peridotite (e.g. Iherzolite, dunite, etc.) Metamorphic rocks (e.g, serpentinite, etc.) m Alluvium (gravels, , etc.) Scale 1:10,000 Pliocene coral reef & raised beach 0 , ' $m -Gypsum ATRIANGULATION PT. ---- FAULT 36O12' & RUINS OF HOUSES + HORIZONTAL STRATA

Figure 2. Geologic map of the island of Zabargad. Inset shows the relationship of the island to the Egyptian mainland. an actual stockwork that occupies an oval region etched, they must have developed at the same of considerable extent. time or at a later stage. However, unless and until The peridot crystals must originally have fol- the island is investigated in its entirety miner- lowed and lined open cracks and fissures, inas- alogically and petrographically, such ideas must much as they were probably formed on the walls remain speculations. of fractures. As a result of tectonic movemenfs, Shortly before the visit of the author and his they were later broken from their original sites companion, a joint American-Austrian expedi- and included among the rubble of the cracks. In tion consisting of curators from the Vienna this author's view, however, this theory is only Museum of Natural History and the American valid if the transformation of the peridotite into Museum of Natural History in cooperation with serpentinite occurred metasomatically and before the Egyptian Geological Survey, and with the or during the formation of the peridot crystals; help of the El Nasr Phosphate Company, spent otherwise they too would have undergone serpen- several days on the island. It is to be hoped that tinization. Since the crystals are absolutely fresh new and valid knowledge can be expected from and well preserved, or at the most very slightly these investigators. At the old sieving places (fig.

Zabargad GEMS & GEMOLOGY Spring 198 1 merly, however, one could find peridot crystals up to 10 cm long, although those 2-4 cm in length were much more abundant. The Geolog- ical Museum in London owns a splendid step-cut peridot of 146 ct., while the largest known cut peridot weighs 310 ct. and is exhibited at the Smithsonian Institution in Washington, DC. Both of these magnificent samples came originally from the island of Zabargad. MINING The original mining methods consisted of prim- itive manual digging, whereby each individual vein wa~excavated (fig. 5). The miners worlzed

Figure 4. Sieving place in the foreground and dump-heaps in the background on the eastern slope of Peridot Hill.

4), in the prematurely abandoned sieve-heaps, and among the waste of the mines, the author and his companion found over a hundred fresh, transparent, well-preserved, in part broken but certainly cutable peridot crystals pale yellowish green to deep olive green in color. Conspicuous samples of the macroscopic paragenesis of these peridot crystals were green garnierite and fresh whitish to weathered grey cancrinite. The peridot Figure 5. tunnel dug into metamorphic crystals, pseudohexagonal after b(010) in form, rock to reach the deeper mafic rock (note the were between 5 and 15 mm along the a-axis. For- while bands of magnesite).

Zabargad GEMS & GEMOLOGY Spring 1981 5 FROM "TOPAZOS" TO PERIDOT: ZABARGAD AND ITS GEM SHARE A PLACE IN HISTORY, LANGUAGE, AND LORE Topazios is the name used by Greelz author Alexander Polyhistor to refer to an island on which are found whose color "resembles that of fresh oil." The great naturalist of ancient times, Pliny the Elder (23-79 A.D.), mentions the island "Topazios" in his work Naturalis Historia. He refers specifically to Icing Juba I1 of Mauretania (25 B.C.-23 A.D.) who reportedly states in his writings that this legendary island in the Red Sea was first explored during the reign of Queen Berenice (340-279 B.C.]. Pliny also refers to another report that pirates driven by adverse winds landed on an island in the Red Sea called Chytis or Cytis. Being in a famished condition, they sought herbs and roots in the ground and thereby fouild the first "topazos." Other names attributed to the island in ancient times include Island of Death (Nelzron)and Ophiodes ("snalze island," reported by Agatharchides of Knidos, 18 1- 146 B.C.). Not until the time of the Crusades did this mystery-bound scrap of land receive the name by which it is still mistalzenly lznown in the West, St. John's Island, and finally, Zabargad. For Pliny the Elder, topazos was a jewel that mainly occurs in green but may also be yellow. Probably there is some confusion here with chrysolite, "chrysolithos," which was also lznown in ancient times (Ezelziel 10, 9). During the period, chrysos meant golden, that is, yellow. Not until much later did the word experience an etyn~ologicalchange as the prefix chryso- entered common usage to describe a green stone (see , chrysoprase, chr ysopal, chr ysocolla, chrysolite, etc. 1. When in the early 18th century the name topoz was finally affixed to the fluorine-bearing aluminum that currently holds this title, a new name was needed for the green gemstone from Zabargad. In 1790, the sometime mineralogist A. G. Werner nained the olivine because of its typical olive-green color. In the same year, he published a description of chrysolite in Bergmanns /ournu1 3, stating that it was a mineral in its own right. A few years later, M. H. Klaproth was able to prove that olivine and chrysolite belong to the same family of . Although chrysolite was used by German and American ~nineralogistsfor over 100 years, this term has left general usage and is no longer accepted in English nomenclature for the gemstone. The English adopted Werner's name olivine, while the French gave preference to the new name peridot, which is derived from the Ara- bian word furidat, meaning gem. The latter is generally used today to refer to the gemstone, whereas the true name of the mineral is olivine (seeBall, 1950, Liischen, 1979, and Mitchel, 1979, for further information on the various names). Archaeological excavations in Alexandria have apparently unearthed valuable peridots. Faceted samples, which could only have come from Zabargad, have also been discovered in ancient Greece. In all probability, the fabulous stone that once adorned King Ezelziel from Tyrus (about 586 B.C.; Ezelziel 28, 13) was a peridot from Zabargad. Where so much treasure and beauty were to be found, the authorities kept a wary eye. Diodorus Siculus writes in the first century before Christ: "The Egyptians Izept the island under constant watch, and anyone who tried to approach the treasure island without permission-let alone to attempt to land and steal the peridots-was threatened with death." Thus, this island in the Red Sea became one of the most closely guarded regions of the ancient world, and its treasure was held secret for centuries, virtually hidden from the Western world from biblical times until the onset of the baroque period in the 17th century.

6 Zabargad GEMS &k GEMOLOGY Spring 1981 Figure 6. Peridot crystal on 1 its original matrix, self- collected by the author. 1 The crystal is approxi- 1 mately 1.2 cm x 1.1 cm.

downwards until the vein, usually at a shallow DESCRIPTION AND depth, became sterile or contracted. However, the PROPERTIES peridots were not found where they had crystal- Gem peridot lies compositionally between the lized. They were always loosely attached to the end members forsterite (MgzSi04)and fayalite walls of the veinlets and could easily be removed (Fe,SiO,) of the olivine isomorphous series (Mg, from their position. Wilson (1976) noted that he Fe),[SiO,], in which the two divalent cations knew of no peridot crystal that he could in good Mg and Fe can replace each other diadochally. conscience claim was found directly grown on its The peridots from Zabargad contain 8%-10% mother-rock. However, the author of this present FeO (FeO + MgO amount to approximately 64%; article was so lucky as to find a piece of matrix Wilson, 1976). The crystals are elongated along about the size of a child's fist with a fully grown, the a-axis so that the brachy pinacoid b(010), well-developed peridot crystal attached (fig. 6). which is markedly striated vertically to the During the years before World War I, from c-axis, forms the largest face. The gradations in about 1906 onwards, the island of Zabargad was color of this summer-green gemstone (the birth- generally lznown as the source of peridot, and stone for August), as well as the variations in its mining rights were monopolized by the Khedive, other physical properties, are caused by the the Turkish viceroy in Egypt. Within a four-year content (see Troeger, 1956, p. 54) and other com- period, more than $2 million in peridot (present ponents. The color tones of the finest qualities day value) was found and sent to for cut- correspond with the DIN color chart 6164, page ting. The chief problem on the island then, as 24, colors 24:6:2;24:6:3 to 24:6:4 of the color now, was the lack of fresh drinking water for the norms Xc34.2; YC43.7; Z,10.2 or Xc23.0; Y,29.4; miners. The mining company overcame this dif- Zc6.9 or Xc15.2; Y"19.5, and Zc4.6. Refractive ficulty by erecting a large gasoline-powered water indices vary little, from 1.650 to 1.654 for na and condenser (of which a few rusty parts .are still between 1.686 and 1.690 for ny, with a constant lying around today). In 1922 the Egyptian govern- value for np only a little below the middle of the ment gave the mining rights to the Red Sea two extreme readings. The high Mining Company. In the years that followed, remains constant at 0.036, as does the until the outbreak of World War 11, this company (3.34)which is only 0.01 above that of pure meth- brought out a considerable amount of peridot. In ylene iodide, in which peridot remains sus- 1958, the deposits were nationalized by Egyptian pended or sinks slowly. Pleochroism is weak but President G. A. Nasser. perceptible as pale green along cu, green along P,

Zabargad GEMS & GEMOLOGY Spring 1981 7 and light green along y. The absorption spectrum Despite its somewhat low hardness of 6%-7 reveals the iron content by means of three char- (lying just below the critical border of gemstone acteristically placed bands in the blue to blue- hardness, 7), this magnificent gemstone with its green region at 453, 473, and 493 nm. agreeable sparkle and its glimmer like damp moss Diagnostically important are the rounded in the evening , has today once more plate-like and wafer-thin healing seams or gained appreciation and popularity. residual drops, in the approximate center of which a black grain of chromite is situated. Their appearance may be likened to that of a water-lily REFERENCES leaf, and they are consequently termed "lily pads." Agatharchides (150 A.D.) De Mare Erythmeo. Badgley PC (1965)Structr~rol and Tectonic Principles. Harper & Row, New York. CONCLUSION Ball SH (1950)A Roman Book on Precious Stones. Gemolog- ical lnstitute of America, Los Angeles. Since mining on Zabargad has failed to remain Liischen H (1979)Die Namen der Sieine, 2nd ed. Ott Verlag lucrative, other sources have filled the demand Thun, Munich. for peridot. Relatively great numbers of large, at- Mitchell RS (1979)Mineral Names, What Do They Mean! Van Nostrand Keinhold Co., New York. tractive peridots from Kyaukpon, above Mogok Pliny GS (Elder) (70 B.C.) Naturalis Historlo, Vol. 37, Chap. 0 in Burma are still reaching the market. Today's JL.9 second largest supplier of cutable gem peridots is Siculus D (50 B.C.) Bibliothecae Historicae, Book 3, Chap. 39. Troeger WE (1956-67) Optische Besrimmung der gesteinsbil- near San Carlos, in Arizona, followed up by a de- denden Minerale, 3rd. ed. E. Schweizerbart, Stuttgart. posit at Sondmore in Norway, which produces Wilson WE (1976) Saint John's Island, Egypt. Mineralogical peridots that are slightly lighter in color and very Record, Vol. 7, pp. 310-314. A German version of this article was published in the Ger- brilliant when faceted. In addition, some small man magazine Lapis-A Monthly for Amuteurs of Minerols fragments of peridot are said to come from Hawaii. and Gemstones, Vol. 5, No. 10, pp. 19-26.

8 Zabargad GEMS 8: GEMOLOGY Spring 1981 CUBIC ZIRCONIA: AN UPDATE By Kurt Nassau

Soon after it was first marketed in 1976, ubic zirconia was discovered as a natural mineral in colorless cubic zirconia became the C 1937, when two German mineralogists, von Staclz- dominant diamond imitation, with elberg and Chudoba (1937), were examining a highly current production of approximately 60 metamict given to them by B. W. Anderson. The million carats per year. Although cubic zircon contained some tiny crystals which they identified zirconia was discovered as a natural by X-ray diffraction as the cubic form of mineral in 1937, crystals usable for (or zirconia), a compound lznown as when in faceting were first produced ill 1969 and it was not until a practical sltull-melting the monoclinic form. So little did von Staclzelberg and technique was developed in the USSR in Chudoba think of this discovery that they did not even 1972 that commercial production became assign a name to the new mineral. As a result, it is lznown feasible. This article reviews the sl

Cubic Zirconia GEMS & GEMOLOGY Spring 1981 9 Figure I. A large slzull-melting apparatus being operated by George Braml~all.Courtesy of the Ceres Corp., Walthnm, MA. fortunately, these changes reverse on cooling and of melting the material without a to ob- the starting material forms once again. The ad- tain crystals more than 15 nlm (0.6 inch) long, of dition of stabilizers such as CaO, Mg.0, or Y,O:, composition 87.5% Zr02, 12.5% Y203.Only a few prevents these transformations on cooling: cubic properties of the crystals appear to have been zirconia then remains the stable form down to measured at that time, however, and the potential room temperature. Details of the different forms remained unrecognized. A somewhat modified of zircoilia are given in the Appendix. and greatly enlarged form of this apparatus was Crystals of cubic zirconia in a usable size were used by Alelzsandrov, Osilzo, Prolzliorov, and Ta- finally reported in 1969 by Roulin, Vitter, and tarintsev at the Lebedev Physical Institute of the DCportes of France. They used a difficult form USSR Academy of Sciences in Moscow (1973).

10 Cubic Zirconia GEMS & GEMOLOGY Their technique, called "slzull melting," is de- scribed in detail in the next section. Crystals one inch (2.5 cm) and larger in diameter can be grown with a modern embodiment of this arrangement (fig. 1) without excessive difficulty. The impetus for this work had been the hope-unfulfilled-of finding improved materials for or opto-elec- tronic uses, but measurements of the crystals showed a material that was hard, colorless, and with optical properties that approximate the bril- liance and fire of diamond better than any pre- vious diamond imitation. With its introduction into the gem trade late in 1976, cubic zirconia as a diamond imitation immediately created a huge demand as well as considerable anxiety. As with the introduction of every diamond imitation before it (Nassau, 1980a), some jewelers who did not know how to recognize the new material were unable to pro- tect themselves. Nevertheless, examination tech- niques have now been adapted to readily distin- guish cubic zirconia from diamond, and new instruments have appeared to assist the gemolo- gist-jeweler in this task, as outlined in the Appendix. As with YAG ( aluminum ), which was overproduced and pealzed about 1972 (Nassau, 1980a),we are now seeing a rapid rise in Figure 2. Schematic of one form of skull-melting the production of cubic zirconia accompanied by apparatus; only some of the fingers a rapid fall in the price. This supply-and-demand are shown. movement, together with the recent introduction of colored forms of cubic zirconia and the curious patent situation, is also discussed in the following sections.

THE SKULL-MELTING TECHNIQUE FOR GROWING CUBIC ZIRCONIA The technique of crystal growth by solidification from the melt in a container is one of the easiest and least costly ways of obtaining large crystals. When, however, a material has as high a melting point and is as reactive as cubic zirconia, no con- tainer can be found to hold the melt, and a "self- contained melt," "cold crucible," or "autocruci- ble" arrangement must be used. The technique described here was patented by Joseph F. Wenclzus and coworlzers (19771, now one of the major man- ufacturers of cubic zirconia as the Ceres Corpo- ration, Waltham, MA. The apparatus shown in figures 2 and 3 con- sists of a cup-like arrangement made up of a circle Figure 3. The split halves of a small slzull- of fingers, water-cooled by complicated in- melting apparatus.

Cubic Zirconia GEMS & GEMOLOGY Spring 1981 11 ternal plumbing. There are small gaps between the fingers. Surrounding this apparatus is a water- cooled copper coil activated by a radio-frequency HIGH- FREOUENCY generator, typically operated at a frequency of 4 WATER- COOLED MHz and at power levels as high as 100 1zW. The small gaps between the metal fingers en- able the radio-frequency energy to pass into the cup, which is initially filled with zirconia powder mixed with the required stabilizer. The powder is an electrical at room temperature; it will not begin to heat until after the addition of some pieces of zirconium metal, which are then rapidly heated by the radio-frequency field. As the zirconia adjacent to the zirconium metal heats up, it also begins to conduct and melts in a matter of minutes. The zirconium metal reacts with the in the air to produce more zirconia. All the zirconia soon melts, except for a rela- tively thin sintered shell or slzin that remains solid because it is cooled and prevented from melting by contact with the water-cooled fingers. In this way the molten zirconia is contained within a jacket of its own powder, which also pre- vents contamination from the metal. More zir- conia, again containing the required stabilizer, is added to the molten material to fill the skull to the desired level. A porous crust forms over the top of the melt, as shown in section A of figure 4, and helps to reduce heat loss. The contents are kept molten for some hours to ensure uniformity, as well as to permit the vaporization of some im- purities. The cup is then lowered very slowly out of the heating coil, typically over a 12-hour pe- riod. Useful crystal growth begins at the bottom of the melt. As can be seen in section B of figure 4, crystals nucleate and form parallel columns near the bottom and grow upwards. They con- tinue to grow until the whole melt has solidified, as in section C, whereupon the power is shut off. The growth process under way is shown in fig- COOLING COOLING ure 1, and half of a "skull"-the solidified crys- "7 1 WATER OUTLET tals with the surrounding crust-is shown in fig- LOWER1 NO ure 5. A "," a purposely added impurity, MECHANISM had been used to produce yellow cubic zirconia , , in this growth run. Light tapping will separate the crystal columns, which as in figure 6. An- Figure 4, The process of solidification during nealing, typically at 1400°C (2552OFL in air or in skull-melting crystal growth. A = formation o/ oxygen may be used at times to remove residual a porozls crust over the top the melt, B = strain to remove any discoloration resulting from early growth of parallel columns of crystal a slight oxygen loss, or to adjust the valence states nucleate, and Ci = final stage, with the entire of impurities. melt solidified hy the crystal growth.

12 Cubic Zirconia GEMS & GEMOLOGY Spring 1981 THE CURRENT STATUS OF COLORLESS CUBIC ZIRCONIA Starting from a small amount in 1976, within just four years production has grown to an estimated 13 tons (12,000 lzg or 60 million carats] of cubic zirconia per year at the end of 1980. Correspond- ing to the figures for rough material, the annual production of faceted material is estimated at about 3 tons (2700 lzg or 13.5 million carats) per year. During this same time period, the wholesale price per faceted has fallen from an initial US $40 or more to US $4 or less, varying of course with the quality of the material and the faceting, as well as with size, shape, and quantity. Figure 5. Half of a large skull of yellow cubic It is interesting to compare the production zirconia cryslals grown using the technique data for cubic zirconia with the data for synthet- described in figure 4. Courtesy of the Ceres ics previously used as diamond imitations, as Corp., Waltham, MA. shown in table 1. Annual production of cubic zir- conia has already well surpassed the YAG peak At first, a slzull 3 inches (7.5 cm) in diameter of 1972 which, it must be remembered, repre- was considered the state of the art for cubic zir- sented overproduction, was more than the market conia crystals, but today slzulls 12 inches (30 cm) could absorb, and resulted in the discontinuation in diameter and weighing 150 lbs. (68 kg), such as of production by a number of manufacturers. A the one shown in part in figure 5, are produced. reasonable guess would be that the equivalent These yield about 100 lbs. (45.5 lzg or 227,000 car- stage for cubic zirconia is close at hand. A factor ats) of usable rough. Individual crystals are well that may prevent this from happening is the ap- over one inch (2.5 cm) wide and several inches parent opening up in recent months of the Euro- long; stones several hundred carats in weight have pean market, where previous diamond imitations been faceted. The economy of large-scale produc- never achieved significant popularity. tion is significant, although the rather high cost Many jewelry retailers at first showed a strong of the high-purity starting material is not much resistance to handling cubic zirconia, but expe- affected by such a scale-up. rience has now demonstrated that the simulant has had no significant effect on diamond sales, occupying instead a separate niche in the jew- eler's range of goods. The available data for 1977 permitted an estimate of the retail value of all diamond imitations sold in the United States of about $20 million, compared to about $2000 mil- lion for (Nassau, 1980a). Although by . now the sales figure for diamond imitations has grown significantly, so has the figure for dia- monds, and the 1% ratio of diamond-imitation sales to diamond sales has probably increased only a little. Major manufacturers of cubic zirconia in the U.S. include the Ceres Corporation of Waltham, MA (marketing through MSB Industries of New York City); ICT Corporation of Shelby, MI; Singh Industries of Randolph, NJ; the LambdalAirtron Division of Litton Systems of Morris Plains, NJ; :igure 6. Columnar crystals of cubic zirconia and Commercial Crystal Laboratories of South me inch (2.5 cm) across. Amboy, NJ. Outside the U.S. there is production

Cubic Zirconia GEMS & GEMOLOGY Spring 1981 13 TABLE 1. The historical sequence of synthetics used as diamond imitations. Year of Peak annual initial production of rough Synthetic use (in carats) Year of peak

Sapphire After 1905 ? ? About 1920 ? ? 1948 750,000 1955 1955 1,500,000 1968 YAG 1968 40,000,000" 1972" GGG 1975 Small 1976 Cubic zirconia 1976 60,000,000b 1980-1 981

aPrernature peak due to overproduction. bMay still be increasing. in Moscow, USSR (marketed in the U.S. through Some of these names are registered trade- Clayhill Resources of New York City); at V. marks, others are not. It is important to note that, Djkvahirdjian S.A. of Monthey, Switzerland [at by themselves, zirconium and cubic zirconium first erroneously reported as using flux-growth are misnomers, since they would refer to zircon- [Nassau, 19761); as well as recent production in ium metal! Also, some sellers are using the end- Taiwan and undoubtedly elsewhere. The rough ing "-Z" with other terms, possibly to imply material is faceted all over the world, but until cubic zirconia when this may not, in fact, be the recently almost all has been used in the U.S. De- material at hand. spite the great improvement of cubic zirconia The stabilizer used in cubic zirconia is usually over YAG (in brilliance) and over strontium ti- Y,03, although CaO has also been used. The phase tanate (in hardness), both of these other simulants diagrams indicate that up to 65 weight percent continue to be manufactured and sold, albeit on YzO3 or up to 14 weight percent CaO could be a considerably smaller scale. used in cubic zirconia. Too much stabilizer Claims are sometimes made that one manu- results in a softer and less brilliant product, how- facturer's cubic zirconia is better than another's, ever, and amounts much smaller than those in- for example, in respect to turning dark in normal dicated in the phase diagrams are used for the use. Although some bad batches were undoubt- commercial product, as described in the Appendix. edly produced in the early days, currently there Now that large crystals of cubic zirconia are is no significant difference in the behavior of the readily available at a relatively low cost, scien- high-grade material produced by the various man- tists are once again studying the material for pos- ufacturers. Similarly, inclusions are virtually ab- sible technological uses, thus coming full circle sent in top-grade material. to the original purpose for growing the crystals! Names used for marketing cubic zirconia Cubic hafnia-hafnium oxide (HfO,) stabi- include: lized with Y,03-has also been described in the CZ Diamonique I11 cubic zirconia patents. This has about the same Cerene Diamonite or as cubic zirconia, but with an Cubic Z Diamondite even higher specific gravity. Since hafnia is much Cubic Zirconia Djevalite more expensive than zirconia, cubic hafnia is not Cubic Zirconia I1 Fianite likely to be used as a diamond imitation. Cubic Zirconium Phianite or Cubic Zirconium Phyanite THE CUBIC ZIRCOMA PATENTS Oxide or Dioxide Shelby In December 1972, the USSR group of V. I. Alelz- Diamon-Z Singh Kohinoor sandrov and coworkers applied for patents in the Diamond-QU Zirconia U.S. and other countries, the relevant claim being Diamonair I1 Zirconium cubic zirconia stabilized with 10% to 30% ytt- Diamonesque Zirconium Yttrium rium oxide. British patent 1,373,888 was pub- Diconia Oxide lished on November 13, 1974, and German patent

14 Cubic Zirconia GEMS & GEMOLOGY Spring 1981 2,261,85 1 appeared on July 1 1, 1974. The U.S. pa- son (Arizona) Gem and Mineral Show, where all tent application was abandoned and then refiled available colored cubic zirconia rough was quiclzly in March 1977, was again abandoned and then re- bought up by amateur as well as professional cut- filed in January 1978; it issued on May 8, 1979, ters. The attractiveness of the colors lies in their as U.S. patent 4,153,469. coupling with a high refractive index and disper- Meanwhile, additional patents had been ap- sion, and can be seen to some extent in figure 7. plied for in January 1975, leading to British patent The optical constants of most colored gem- 1,491,362, published on November 9, 1975, and stones-, , , amethyst, ci- German patent 2,501,800, published on July 22, trine, , etc.-have relatively low values, and 1976. The relevant claim in these patents was cu- their attractiveness resides predominantly in the bic zirconia stabilized with 5% to 10% yttrium color. With colored cubic zirconia, however, there oxide. Such a claim may also have been involved is considerable brilliance, or "life," in addition to in one of the U.S. refilings; if so, it was apparently the color; this liveliness can be transmitted only not allowed. It should be noted that the items poorly in even the best photograph. being patented are the chemical composition of A listing of the colors produced by specific do- cubic zirconia crystals, not the growth technique. pants (purposely added impurities) is given in After the issuance of the U.S. patent in 1979, table 2, and the dopant compounds used to pro- some retailers hesitated to purchase domestically duce desired colors appear in table 3. The nature produced material. At least one U.S. producer (the of the color can change with the concentration of Ceres Corp.) guaranteed its customers that it the dopant as well as with its oxidation state, and would defend them in any suits that might arise combinations of are used to obtain de- from this patent. A suit based on this patent has, sired shades. Just some of the colors produced by in fact, been filed; as of this writing it is still un- one manufacturer are shown in figures 7 and 8. decided. It should be noted that most cubic zir- The manner in which allochromatic transition conia produced in the U.S. is believed to be made metal impurities produce colors is described else- with somewhat less than the 10% minimum where (Nassau, 1974-75, 1980a, and 1980b). claimed in the patent. Even if this argument were The most frequently used colors at present are rejected, there is the fact that the patent contains (1)the amethyst to lavender to lilac range, (2)the no mention of the cubic zirconia stabilized with yellow (canary)to orange to reddish-brown range, 12.5% Y,03 reported in 1969 (Roulin et al.) and and (3)pinlz. Colored cubic zirconia produces fac- shown in large crystal form in a French film made eted stones that are much inore "lively" than the at that time; this would seem to imply that a analogous amethyst or purple sapphire for the court test of the validity of the patent might well first color group and citrine, padparadsha sap- result in an invalidation. phire, imperial topaz, or garnet for the second. Prices for colored rough are somewhat higher than COLORED CUBIC ZIRCONIA for the colorless. At present, these colored stones Aleksandrov and coworlzers gave details on the seem to be used primarily for fad-type medium- manufacture of colored cubic zirconia in their priced fashion jewelry. The quantity of colored 1972 patent application. Until recently, however, cubic zirconia produced is still quite small but is most manufacturers have concentrated on lzeep- increasing rapidly and may soon represent a sig- ing color out of their crystals, since even trace nificant portion of the marlzet. Attractive intense amounts of impurities such as iron can produce greens, blues, and reds have not been produced a yellow hue, undesirable in a diamond imitation. thus far. Some experimentation persisted, though, partic- Were it not for the relative rarity of colored ularly to find good ruby red and emerald green diamonds and the fact that most people are not colors, neither of which seems to have been familiar with them, these colored cubic zirconias achieved thus far. Along the way, significant would provide excellent imitations for naturally amounts of yellow and other colored material ac- occurring canary, pinlz, blue, and green diamond. cumulated. Some was faceted by amateurs for the Jewelers should indeed be aware that, with the fun of it and was found to be very attractive. correct shade and intensity of color, these cubic A major breakthrough in the market for col- zirconias could easily be mistaken for colored ored cubic zirconia was apparent at the 1979 Tuc- diamonds.

Cubic Zirconia GEMS & GEMOLOGY Spring 1981 15 Figure 7. Faceted cubic zircoz~ias;the largest is 9 mm across. CourLesy of the Ceres Corp., Waltham, MA, and MSB Industries, New York, NY.

TABLE 2. Colors produced by specific dopants added TABLE 3. Dopanls used in cubic zirconia to give to cubic zirconia." desired colors. Dopant Symbol Color Color range Dopants used Yellow-orange-red Yellow-orange-red CeO,, Ce203 Olive Yellow-amber-brown CuO, Fe203,NiO, Pr203,TiO, Lilac Pink Er203,Eu203, Ho203 Copper Yellow Green-olive Cr203,Tm203, V203 Pink Lilac-violet C0203, MnOa, Nd203 Pink Holmium Pink l ron Yellow PROSPECTS FOR THE FUTURE Brown-violet Lilac In chapter 1 and the epilogue of my book (Nassau, Yellow-brown 1980a), there is an extensive discussion of the Amber sources of new synthetics as well as of the way Green in which these sources have been changing over Yellow-brown Green the years. Today, only the most difficult of the syntheses have not yet been achieved and, as crys- aTypically at the few tenths of a percent level; the color tal growth techniques have become ever more achieved may depend on the oxidation state of the dopant. sophisticated, the search for new crystals has be- come more costly and time consuming.

16 Cubic Zirconia GEMS & GEMOLOGY Spring 1981 Figure 8. Colored cubic zirconia rough; the largest piece is 2.5 inches (6.5 cm) long. Courtesy of the Ceres Corp., Waltham, MA.

It is, therefore, hardly a coincidence that the tials more fully. So it may not be all that soon most recent diamond imitations-YAG, GGG that a potential successor to cubic zirconia will ( garnet), and cubic zirconia- arrive. all originated as spin-offs from technological re- Further qualifications arise from two factors. search. The use of YAG as a laser material is well First, the optical constants of cubic zirconia are lznown, GGG was developed as a substrate for sufficiently close to diamond in a material of ad- magnetic bubble memories, and cubic zirconia equate hardness and wearability that a large im- was studied as a possible laser or opto-electronic provement cannot be expected. This was hardly material. Is it then lilzely that this source will true of any of the previous diamond imitations. produce another material that might provide a Second, the cost involved in developing and mar- diamond imitation that is superior to cubic zir- keting a new synthetic or imitation is never small conia? and, given the existence of a highly satisfactory I believe the answer to this question is yes, but material in the marketplace, may not be justifi- a qualified yes. Although such a material will able in terms of the potential returns. (One may undoubtedly appear sooner or later, it must be re- note the difficulty synthetic flux-grown alized that technological research for new mate- have had in achieving market penetration in com- rials has slowed significantly. In part, this is petition with the Verneuil-grown product; they because present needs have been largely filled and recently came close to success by posing as nat- the areas left to be explored are becoming smaller; ural rubies with forged GIA certificates!) All in in part, it is because existing materials are being all, it would seem that cubic zirconia is lilzely to studied intensively so as to utilize their poten- be with us for quite some time.

Cubic Zirconia GEMS & GEMOLOGY Spring 1981 17 APPENDIX: TECHNICAL AND Inclusions. Small particles (Nassau, 1976, 1977, and GEMOLOGICAL DATA 1980a; Liddicoat and Koivula, 19781, gas bubbles (Nas- AND IDENTIFICATION sau, 19761, and a curious striated appearance (Nassau, 1976, 1977, and 1980a) can sometinles be seen but are Composition. Typically zirconia (zirconium [diloxide, absent in good-quality material. ZrO,] containing about 10 mol. percent yttria (yttrium oxide, Y,0,,] or 15 mol, percent lime ( oxide, Effect of Exposure to and Other Irradia- CaO). Zirconia can exist in several polymorphic struc- tions. Variable , may be completely ab- tures, as listed in table 4. sent; often turns brown, depending on cluality, nature, and length of irradiation. Good-quality material will Structure. Same as that of fluorite, CaF,, with Zr in again fade to colorless when placed in sunlight for a few place of Ca and 0 in place of F. This structure, shown hours and will not darken in sunlight, that is, "solarize." in figure 9, consists of a simple cubic arrangement of with every other cube occupied by a Zr. Each 0 is surrounded by four Zr, each Zr by eight 0. When ZrO, is stabilized with either Y203or CaO, there are fewer than two oxygens per metal atom, and some oxy- gens are missing: one 0 for every two Y or one 0 for every Ca, as is implied in the typical formulations Zr0.9,,Y0.1001.93and Zro.8,Ca0.1501.8j.Sonle Zr and some dopants may have only seven or six 0 around them in- stead of the usual eight; this changes the crystal field and, accordingly, the color (Nassau, 1974-75, 1980a, 1980b).

Crystal Symmetry. Cubic; class, 41m321m;, Fm3m.

Optical Properties. Refractive index, 2.15 to 2.18; no birefringence, singly refracting; , 0.058 to 0.066.

Mechanical Properties. Hardness, 8.0 to 8.5 (a slight in hardness appears to be present; this is possible even in the cubic system and also occurs in AT EACH CORNER: 0 I diamond); specific gravity, 5.6 to 6.0; no ; con- I choidal to uneven fracture; somewhat brittle; good wearability. Figure 9. The of cubic zirconia.

TABLE 4. The polymorphs of zirconium oxide. Temperature Unit cell Specific Structure range (°C)a parameters (A) gravity

Monoclinic P2,Ic Up to 1100 a = 5.15, b = 5.21 5.83 c = 5.31, P = 9g023' Tetragonal P4dnrnc 1100 to 2000 a = 3.64, c = 5.27 5.86 Hexagonal (?) About 1900 a = 3.60, c = 5.90 (5.88) 6.13 Cubicb Fm3m 2300 to 2750 a = 5.26 5.64 Cubicc Fm3m Up to melting a = 5.12 6.00 Cubicd Fm3m Up to melling a = 5.12 to 5.16 5.60 to 6.00

"The exact lemperatures depend on the impurilies present and the amounts thereof. bThe unslabilized high-temperature form of pure ZrO,. "The natural stabilized material of von Stackelberg and Chudoba (7937). dThe synthetic stabilized material.

18 Cubic Zirconia GEMS W GEMOLOGY Spring 1981 Distinction from Diamond. Several articles in this 1976-79b). Although there are some limitations, one journal have dealt with various aspects of this problem of the many reflectivity meters should give a clear dis- (Liddicoat and Koivula, 1978; Nassau, 1978-79a, 1978- tinction (Liddicoat and Koivula, 1978; Nassau, 1978- 79b, 198 1; Nassau ancl Schonhorn, 1977-78; Shaw, 79b). Finally, the wetting contact angle (Nassau and 1978). The distinction is obvious to the trained, aware Schonhorn, 1978-79) provides a distinction when the eye. In a loose stone, the high specific gravity is readily GEM Diamond Pen or one of a number of other pens apparent. Flatness of faces and sharpness of edges are is used (see Shaw, 1978, for a discussioil of the GEM not foolproof criteria, and girdles apparently showing Diamond Pen, and Nassau, 1978-79b, for a discussion ~lilaturals"have been observed on cubic zircoilia (Lid- of that and other pens), but surface coatings may have dicoat and Koivula, 1978; Nassau, 1978-79b). The to be removed. As always, the gemologist must guard uniquely high of dianlond pro- against the possibility of a doublet. vides an uilan~biguousidentification of diamond when a well-compensated instrument such as the Ceres Dia- mond Probe (Nassau, 1978-79a) is used, but soille care Size, Weight, and Shape. Proportions aid cuttiilg tech- is required with a simpler instrument such as the niques have beell discussed (Kerr, 1979).A graph for the pocket-sized Ceres Czecl

REFERENCES Aleksandrov VI, Osiko W, Prokhorov AM, Tatarintsev VM Nassau K (1979)The size and weight of diamond and diamond (1973) Production of refractory single crystals and molten imitations. Gems d Gemology, Vol. 16, pp. 203-204. ceramics by a new method. Vestnik Aknd Nauk USSR, Nassau K 11980a) Gems Made by Mr~n.Chilton Book Co., Vol. 12, pp. 29-39. Radnor, PA. Kerr B (1979)Fashioning cubic zirconia. Gems el Gernology, Nassau K 11980bl The causes of color. Scientific American. Vol. 16, pp. 155-157. Vol. 243, pp. 106-123. Liddicoat RT Jr., Koivula JI (1978) Synthetic cubic stabilized Nassau K, Schonhorn S (1977-78) The contact angle of water zirconia. Gems d Gemology, Vol. 16, pp. 58-60. on gems. Gems d Gemology, Vol. 15, pp. 354-360. Nassau K ( 1974-75) The origins of color in gems and minerals. Roulin Y, Vitter G, Deportes CC (1969) New device for melt- Gems d Gemology, Vol. 14, pp. 354-361; Vol. 15, pp. 2- ing without a crucible. Fusion of high melting iri a 1 I, 34-43. multitubular furnace. Revue Internr~tionaledes Hotltes Nassau K (1976) A new diamond imitation: cubic zirconia. Ten~perutureset des Refmctaires, Vol. 6, pp. 153- 157. G'erns d Gemology, Vol. 15, pp. 143-144. Shaw li (1978) The new diamond pen. Gems d Gernology, Nassau K (1977) Cubic zil.conia, the latest diamond imitation Vol. 16, pp. 92-95. and skull melting. Lr~piclary/ournal, Vol. 31, pp. 900-904, Stackelberg M von, Chudoba K (1937) Density and struc- 922-926. ture of zircon, 11. Zeitschrift fur Krista11ographie. Vol. 97, Nassau K ( 1978-793) A test of the Ceres diamond probe. Gems pp. 252-262. d Ge~nology,Vol. 16, pp. 98- 103. Wenckus JF, Menashi WP, Castonguay A 11977) Cold crucible Nassau K (1978-79b) Distinguishing diamond from cubic zir- system. United States Potent 4,049,384, filed April 14, conia: old and new tests for the identification of diamond. 1975, issued September 20, 1977. Gems 01 Gemology, Vol. 16, pp. 1 1 1-1 17.

Cubic Zirconia GEMS & GEMOLOGY Spring 198 1 19 A SIMPLE APPROACH TO DETECTING DIAMOND SIMULANTS

By [ill Hob bs

This article offers a step-by-step approach iamond simulants need not frighten the gem iden- to the identification of the most D tifier. Quiclz methods of identification are available, problematic diamond sim ulants. The with many clues requiring only a trained eye. Although optical and physical properties of certain clues when used alone cannot establish the iden- diamond are contrasted to those of tity of the stone, often two or three of these clues con- colorless , synthetic sidered together will to the identification of the gem cubic zirconia, gadolinium gallium garnet, and yttrium aluminum garnet. If material. Even if the clues available are insufficient for the testing methods discrlssed in this positive identification of the material at hand, other tests article are used, none of the above have been developed that at least prove whether or not materials should be mistaken for the stone in question is a diamond. diamond. The intent of this article is to provide a step-by-step approach to the identification of colorless diamond sim- ulants. The methods and techniques described are not new, but they have been arranged in such a way here to present a relatively simple, systematic approach to dia- mond identification. Basically, the approach involves the following: Train your eyes to recognize as many visual char- acteristics of simulants as possible. A "trained eye" may spot a possible simulant without the use of laboratory equipment.

ABOUT THE AUTHOR Know and use basic tests to identify the type of diamond simulant. Even though your primary con- Ms. Hobbs is a colored stonelgem identification instructor in the resident program of the cern is probably not to name the simulant, it is Gemological lnstitute of America, helpful to be able to provide your customer with Santa Monica, CA. such information. Acknowledgments: The photographs were taken by Michael R. Havstad and the line illustrations in 3. Stay abreast of the development of new instru- property charts A and B were drawn by Peter ments that identify loose or mounted diamonds. Johnston, Gem Media, Gemological lnstitute of While in most cases such devices do not identify America, Santa Monica, CA. the type of simulant, they are very helpful at the Author's note: Strictly speaking, the word stone repair or take-in counter, where employees may should be used to refer only to natural materials. For simplicity, the term is used here to refer to not have the training to recognize diamond simu- simulants as well as to diamond. lants by their visual characteristics or with the "1987 Gemological lnstitute of America basic tests.

20 Detecting Diamond Simulants GEMS & GEMOLOGY Spring 198 1 Of all the techniques available for diamond visual characteristics reflect differences in the op- separations, perhaps the most important is the tical and physical properties of the various trained eye. If a machine fails, or if you cannot materials. perform other verifying tests, your eyes may alert you to a possible simulant. The training requires The "Read-Through" Effect. The visual trait that a great deal of practice and continual updating, is often noticed first in round-brilliant-cut stones but visual examination can be performed any- is the read-through effect. When the various dia- where, anytime. mond simulants are tilted or placed table-down This article focuses on the identification of on paper, each one "reads through" differently; the four diamond simulants that cause the most that is, each simulant allows a different amount confusion for the jeweler: (1) strontium titanate, of light to be transmitted through the stone at (2) synthetic cubic zirconia [CZ),(3) gadolinium different angles. This trait is related to the stone's gallium garnet (GGG),and (4)yttrium alumiilum refractive index, critical angle, and proportioning. garnet (YAG).All of these stones share two prop- Fancy shapes (e.g., marquise, oval, pear) usu- erties with diamond: each is over the limits of the ally read through to some extent regardless of the conventional refractometer, and each is singly re- material involved (the proportioning of fancy cuts fractive in optic character. The properties of dia- allows for greater light transmission). Properly mond and these four diamond simulants are listed cut in a round-brilliant shape, however, diamond in property chart A. The stones are listed in order and strontium titanate will generally not read from highest to lowest refractive index. The prop- through, while CZ, YAG, and GGG will. When erties of these materials are arranged from left to the stones are placed in order of ascending re- right in the order in which they are presented in fractive indices, the succession is as follows: YAG, this discussion. GGG, CZ, strontium titanate, and diamond. YAG Other significant materials that have been has the lowest refractive index and diamond the mistaken for diamond are listed in property chart highest. (An easy way to remember the order is B. They are: synthetic rutile, zircon, synthetic by associating the first letter of each of the stones sapphirelsynthetic , synthetic spinel, with this phrase: You Go Crazy Staring at Dia- , and assembled stones. For convenience, monds). If a diamond and the above four diamond these stones and their properties are arranged the simulants are cut to approximately the same size same as chart A. All these materials are more and proportion, the stones with the lowest re- easily identified than those in chart A because fractive indices can be read through most easily. they either have refractive indices within the If the stones are placed table-up in a tray, the range of the conventional refractometer or they read-through effect is apparent when the stones are doubly refractive. Chart B is, then, supple- are tilted. In figure 1, this effect is seen where an mental information. The following article as- orange paper has been placed in back of the stones sumes that the reader is familiar with the prop- to make the effect more visible. Note that the erties of the materials listed on chart B, and does orange paper can easily be seen through YAG, but not have difficulty identifying them. For more not through diamond. At different angles, the information on these stones, refer to the newly "read-throughJJ character of each stone varies. revised CIA Diamond Assignment number 36. However, only when the tray is tilted to the angle where the stones almost spill will diamond trans- VISUAL CHARACTERISTICS mit the orange of the paper. And, at that point, THAT SEPARATE DIAMOND the amount of orange that can be seen through FROM DIAMOND SIMULANTS the diamond is still less than for any of the other As yet, no diamond simulant has been developed materials. Again, the amount of orange seen in that fully duplicates the appearance of a diamond. each of the five stones gradually increases in re- A diamond has unique optical and physical prop- lation to the refractive index of each. erties that make its appearance distinctive. The read-through effect can be particularly The four diamond simulants that cause the helpful when examining a parcel of round-bril- most confusion for the jeweler-CZ, GGG, stron- liant-cut diamonds. Simply line the stones table- tium titanate, and YAG-have many visual traits up, and then tilt the paper away from you. The that are unlike those of diamond. The different lining or cotton inside the parcel paper should il-

Detecting Diamond Simulants GEMS & GEMOLOGY Spring 198 1 21 PROPERTY CHART A DIAMOND AND COLORLESS SIMULANTS

Refractive Read Color on Externall Internal Specific Reflection Typical Gemstone Index Througha Dispersion Pavilion Hardness Characteristics Gravity Pattern Fluorescenceb

Bearding, natural Weak to strong Orange or with trigons, blue (Iw and None, if 0.044 blue on a grainings, sw); may ~iamorid properly cut 3.52 few cleavage, El fluoresce any included crystal color

Strontium None, if Spectral 0.190 colors, Gas bubbles 5.13 Generally ine. titanate properly cut widespread

None to weak- Negative moderate orange Synthetic Orange crystals, lined or (Iw); none to weak- cubic Slight 0.060 over most partially lined 5.95 moderate yellow, zirconia of pavilion with zirconium oxide powder or greenish yellow (SW) None to moderate Gadolinium None, or orange (Iw); orange Gas bubbles, Moderate ;.05 moderate to gallium 0.045 over most metallic platelets strong orange to garnet of pavilion pinkish orange (sw)

None to Yttrium None, or moderate blue over aluminum Gas bubbles Strong most of garnet pavilion orange (sw)

'This techniqueIS meaningfulonly with round-brilliant-cutstones. bl~= long-wave ultraviolet light; sw = short-waveultraviolet light. PROPERTY CHART B COLORLESS DIAMOND SIMULANTS

Refractive Read Color on Externall Internal Specific Reflection Typical Gemstone Index Througha Dispersion Pavilion Hardness Characteristics Gravity Pattern Fluorescenceb

Synthetic rutile Various (yellow 2.61 6-2.903' None 0.330 spectral 6-6% Gas bubbles 4.26 wlors Generally ine. body widespread color)

- -> Blue over Zircon most of Liquid in two- (high 1.925-1.984' Moderate 0.038 pavilion; 7% phase Or 4.70 None to weak fingerprint yellow (Iw & sw) property) may exhibit 0 pattern orange

Synthetic Gas bubbles, Blue over ps"" 4.00 None to weak Sapphire 1.762-1.77OC Very strong 0.018 most of possibly in thread-like bluish white (sw) Synthetic pavilion :n corundum pattern

Synthetic Blue over ki Moderate to spinel 1.730 Very strong 0.020 most of 8 Gas bubbles 3.64 ' $7, ii strong bluish pavilion -+. .A white (sw) -,-'--

'* 0.009- Gas bubbles, -- concave facets, 0.098 Variable wlors Glass 1.48-1.70 Extreme (usually Variable mold marks, 5-6y2 flow lines, 4.50 about white overtones orange-peel 0.037) effect Separation Same to plane; gas Variable; possibly bubbles near % on Variable different on crown and Variable cement, crazing Variable Variable Variable stones crown and pavilion in cement; pavilion variable inclusions "This technique is meaningful only with round-brilliant-cut stones. Vw = long-wave ultraviolet light; sw = short-wave ultrav~oletl~ght. cDoubly refractive. ?,' b

d A------Figure I. Diamond and its simulants will have different degrees of transparency, or read- through effect, if all are well- I-

read through is. Also, the greater the tilt, the clearer the read I through is. Order from left to right (high to low R.I.): diamond,

even a small amount of read through may aid in identification because diamond and strontium ti- tanate do not read through in this position. (Syn- thetic rutile will also not read through, but it is easily identified on the basis of its other visual characteristics, as per property chart B). In short, the read-through effect is a quick "indication" test, that is, a test that does not prove, but leads to, the identity of the material. It can be performed with simple aids such as a rlgure 2. Zhe read-ttlrougn effect is seen on stone cloth, a business card, or parcel paper. The well-proportioned round brilliants when they results are consistent provided that all the are tilted on a light background, such as a stone clotl~.Order from right to left: diamond, stones are well-proportioned round brilliants. strontium titanate, CZ, GGG, YAG. YAG, GGG, and CZ will wash out or read through, while diamond and strontium titanate will not.

luminate the effect. Also, the stones do not have to be specially aligned before the results are vis- ible. When a loose stone is placed in a stone cloth, the same results are evident. As you tilt or rock the stone inside the cloth, the degree of read through becomes evident (fig. 2). The read-through effect can also be seen when the stones are placed table-down over a busi- ness card (fig. 3). With YAG, the letters of the business card are easily seen through the stone; the letters appear a bit magnified and slightly rounded, but they are still very readable. As the Figure 3. The read-through effect is also noted refractive index of the material increases, read when round-brilliant-cut stones are laced through becomes progressively more difficult. table-down over a printed page. Order from left Through GGG, the letters appear twisted; through to i.ight: diamond, strontium titanate, CZ, CZ, they are almost indistinguishable. However, GGG, YAG.

24 Detecting Diamond Simulants GEMS & GEMOLOGY Spring 1981 Figure 4. Spectral colors seen as a result of dispersion. Magnified 10X.

To obtain meaningful results, the tester should With regard to the two materials that do not have comparison stones, or have sufficient expe- show read through, the dispersion of strontium rience with diamond simulants to recognize the titanate (0.190)is over four times that of diamond different degrees of read through of the various (0.044)-a difference not easily overlooked. Stron- stones. tium titanate is literally "on fire," while diamond displays a moderate amount of spectral colors. Dispersion and the Monochromatic Flash. If the Of the three diamond simulants that do dis- stone is a properly cut round brilliant and has no play read through-YAG, GGG, and CZ-none read-through effect, it is most likely diamond or has the dispersion of strontium titanate. YAG has strontium titanate. At this point, the difference the lowest dispersion value (0.028)and the spec- in the dispersion values of the two stones will tral colors are hardly visible. In appearance it al- easily separate them. most resembles a low-lead-content glass; the lack Dispersion is the ability of a substance to cause of dispersion and extreme read through make YAG light to divide into its spectral colors. For exam- a lifeless simulant. GGG does not appear to have ple, when light is transmitted through a prism, a much dispersion. Its value (long thought to be series of colors-red, orange, yellow, green, blue, 0.038, but recently verified as 0.045; Nassau, 1980, indigo, and violet are seen, as illustrated in fig- p. 148) is very close to that of diamond, yet the ure 4. Angular pieces of glass that hang in a chan- spectral colors do not seem as prominent. CZ, delier often display dispersion. A cut stone has however, has a good deal more dispersion than the same ability to break up light into these colors, diamond. The spectral colors are always evident, although the distinctness of the colors that em- but the amount of dispersion is such that the anate varies with the material. stone is not always distinguishable from diamond Studies have determined the amount of dis- (0.060 vs. 0.044) on this basis alone. In the event persion in each of the diamond simulants (see that there continues to be some uncertainty, the property chart A). How do the numerical values stone could be examined for a monochromatic relate to the visual effect? The visual approxi- color on its pavilion, as explained below. mation of dispersion takes more time to master On many of the gem simulants, one spectral than does read through; however, once mastered, color predominates on the back (pavilion) of the it can help to build a case for the identity of the cut stone, creating an umbrella effect. The color material. The best way to judge dispersion is to is the result of dispersion, and the breadth of its reflect light off the surface of the stone and look circumference is the lzey to its usefulness as a closely at the crown and bezel facets. visual aid. The monochromatic sheen can be seen

Detecting Diamond Simulants GEMS &; GEMOLOGY Spring 1981 25 Figure 5. Dispersion: orange commonly covers a Figure 6. Dispersion: blue often covers a large large area on the pavilion of CZ. Magnified area on the pavilion of YAG. Magnified lox. lox. in reflected or transmitted light. The unaided eye might notice the color as light is reflected off the pavilion of the gemstone. Under a microscope, it is easily seen with dark-field illumination, that is, light directed at the gem from the side. Posi- tion the stone table-down, and gently tilt it in different directions. Colorless cubic zirconia generally exhibits an orange flash over most of its pavilion surface (fig. 5). At times, the color seems restricted to one-half of the pavilion until the stone is gently rocked, in which case the orange usually extends over the other half as well. This orange effect is prevalent on most cuts of cubic zirconia. GGG may also exhibit an orange-flash effect, but gen- Figure 7. Dispersion: orange and blue extend erally the orange is not as extensive. over only a few facets of diamond. Magnified YAG often shows a blue color on one-half of lox. its pavilion surface (fig. 6). The results are not as consistent as with cubic zirconia, but they may still aid in identification. (The only other dia- mond simulants to exhibit the blue effect are mond simulants have been examined for read within the limits of the refractometer, i.e., syn- through and the effects of dispersion. These vis- thetic sapphire and synthetic spinel.) ual traits can be seen in a glance. Just a quick look Diamond usually does not display a mono- and turn of the stone can yield a great deal of in- chromatic color over most of its pavilion surface. formation to a trained observer. However, since It may show blue or orange, but in most cases these characteristics do not prove the identity of these colors extend only across one or two facets the material, a loupe is useful as we proceed to (fig. 7). Thus, the significance of the monochro- the next steps of identification. matic effect lies not only with the color present, but with the breadth of the color on the pavilion Junctions.When a stone is examined using surface as well. a loupe, one of the first external characteristics In the identification process thus far, the dia- worth noting is the sharpness of the facet junc-

26 Detecting Diamond Simulants GEMS & GEMOLOGY Spring 198 1 Figure 8. The facet junctions of diumond zlszlally Figure 9. GGG often hus rounded facet appear sharp and well defined because of the jrlnctions becarlse it has a hardness of only 6 Yz. stone's exteme hardness. Magnified 30 X. Magnified 40 X. tions. Because of diamond's extreme hardness (10 on the Moh's scale], its facet junctions are usually sharp and precise (fig. 81, whereas stones under 7 on the Moh's scale (e.g., GGG at 6'/2 and strontium titanate at 5-6) have a tendency to- ward rounded facet junctions (see figure 9). Dia- mond's facet junctions may become abraded over time, but they will not appear rounded. Because of its relative softness, strontium ti- tanate usually has heavily abraded facet junctions as well. CZ and YAG, on the other hand, have hardness values over 8, so their facet junctions appear relatively well defined. Again, though, Figure 10. The girdle of a diamond often has a mat, waxy appearance. Magnified 40x. CZ can be separated from diamond by the orange-flash effect, and YAG1s laclzluster appear- ance malies it distinctive. The roundness or sharp- ness of facet junctions is best seen in reflected light.

Girdle Area. Next, a trained eye might glean infor- mation from the girdle area, provided that it is not faceted. The girdle of a diamond appears mat and waxy after bruting. As illustrated in figure 10, it is not dull, like ground glass, but has the shiny appearance of wax (Bruton, 1973, p. 341). The gir- dles of most diamond simulants are polished. However, if they are not, the girdle appears quite dull, similar to that of unpolished glass. The gir- dles of simulants may look frosty, but never waxy. The girdle surface has neither the fine-grained look of a carefully turned diamond nor the poorer, A 1 coarser look of a diamond subjected to rapid brut- ,4 ing. In addition, sometimes the girdle of a dia- Figure 11. The girdle of a diamond may show mond is "bearded," that is, marlzed by hairline bearcling, or hairline feathers that extend into feathers that extend into the stone (fig. 11). The the stone. Magnified 30x.

Detecting Diamond Simulants GEMS & GEMOLOGY Spring 1981 27 Figure 12. A natural, or part of the original Figure 13. Trigons are growLh markings that are crystal surface, is often found on or near the often found on a natural and, to the experienced girdle of a diamond. Magnified 35 X. observer, prove diamond. Magnified 40 X.

feathers are actually tiny fractures caused by rapid The chief reason for using a loupe is to find bruting. If seen, bearding signifies a diamond. inclusions, which may prove whether or not the A natural is a part of the original crystal sur- stone is man-made. With the emphasis on dia- face and is often seen on or near the girdle. Its mond certification today, most of us are acutely unique luster distinguishes it from the rest of an aware of the typical inclusions of diamond, such unpolished girdle (fig. 12). To the experienced as cleavages, fractures, knots, and included crys- eye, a natural, too, signifies a diamond. tals. While inclusions do not increase the value Growth marlzings may confirm the process of a diamond, they can be extremely valuable in under which the crystal grew and verify that the identifying one. stone is, in fact, a diamond. Several growth mark- Most of the diamond simulants in the mar- ings are characteristic of diamond. Trigons, or tri- ketplace today are flawless, since manufacturers angular etch marlzs, may be seen on a natural, have perfected the techniques of crystal growth. parallel to an octahedral face (fig. 13). Lines, or If inclusions are seen, they are generally tiny parallel grooves, are seen on those naturals that white or highly reflective dots composed of var- originate from a dodecahedra1 facej while square ious materials. In YAG, GGG, and strontium ti- or rectangular depressions indicate a cube face. tanate, the tiny dots are usually gas bubbles, in Attempts have been made to duplicate these which case high magnification may be needed to natural marlzings, but thus far the results have resolve them. In cubic zirconia, the whitish in- not been realistic. For example, attempts have clusions are small negative crystals that are lined, been made to duplicate the appearance of trigons or partially lined, with a white powder that is by marlzing triangles on the girdle of diamond probably unmelted zirconia oxide (Liddicoat and simulants; instead of having the layered appear- Koivula, 1978, p. 58). They may appear singly, or ance of natural etch marlzs, however, the simu- in rows. The only other significant inclusions lated marlzings appear to lie in one plane. found in diamond simulants are the triangular or hexagonal platelets seen in GGG. Inclusions. After the external characteristics of Thus, if the material has inclusions typical the material have been noted, the next step in only of natural stones, there is no doubt about the identification is to examine the interior under stone's identity. If tiny, round, high-relief inclu- magnification. sions are seen, the stone is probably man-made.

28 Detecting Diamond Simulants GEMS & GEMOLOGY Spring 1981 Figure 14. If visible, polishing marks on a Figure 15. Polishing marks on diamond diarnond travel in different directiol~son simulants usually travel in approximately c~djoiningfdcets because of the slone's a he same direction on adjoining lncets. directional hordness. Magnified 20 X. Magnified 20x.

If the material has no inclusions, other tests can render the necessary proof.

Polishing Marks. When examining the stone for inclusions, polishing marlzs might be noted. Pol- ishing marlzs are a series of close, parallel lines on the surface of a facet. Polishing marlzs are not always seen on dia- mond because its hardness allows for an excellent polish. If seen, the polishing marlzs will travel in different directions on adjoining facets (fig. 14). Because of diamond's directional hardness, facets are polished in the direction of the dodecahedra1 faces. By contrast, the polishing marks on a diamond simulant will usually travel in approximately the same direction on adjoining facets. The uniform lines indicate a softer material and represent a Figure 16. An experienced eye may see grain mechanized process in which the concern of the lines on diamond, which verifies the stone's producers is primarily mass production (fig. 15). natural origin. Magnified 35 X.

Grain Lines. Straight, parallel lines that might be natural origin of the gem material, since only a confused with polishing lines may be the result natural gemstone could exhibit such markings. of graining (fig. 16). Grain lines appear in the di- rection of twinning, or gliding, and are character- BASIC TESTS TO IDENTIFY THE istic of diamond. The lines are usually seen on TYPE OF DIAMOND SIMULANT the surface, but they may also be internal. In ad- If the stone has no distinguishing visual charac- dition, graining may take on various shapes (Kane, teristics and positive proof is still wanting, then 1980). Regardless of the form, graining proves the several tests can be performed to verify the type

Detecting Diamond Simulants GEMS & GEMOLOGY Spring 198 1 29 of diamond simulant. The most important in- volve specific gravity determinations and special TABLE 1. Relationship of specific gravity to size in diamond and cubic zirconia. immersion techniques. - Diameter Specific Gravity Determinations. Specific gravity Carat weight is defined as the ratio of the density of one sub- Diamond Cubic Zirconia stance to the density of another substance which 1 6.5 mm 5.5 mm is used as a standard when both are ob- tained by weighing the substances in air. The de- termination of specific gravity is extremely help- ful since diamond has a much lower value than any diamond simulant on property chart A. Spe- the stone is per carat, and vice versa. Thus, since cific gravity is estimated by heft, or by the use of diamond has a lower specific gravity than its sim- heavy . Precise measurements are obtained ulants, the diamond simulants will all be smaller, on a hydrostatic balance. per carat, than diamond. Skilled gem identifiers can gauge the density When the stones in question are round bril- of CZ and GGG in their hands, since GGG's den- liants, the relationship can be charted as shown sity is twice that of diamond and CZfs density is in table 1. Two variables are needed for each over one-and-one-half times greater than that of stone: the diameter and the weight. When a dia- diamond. The diamond simulants that feel clos- mond and a diamond simulant weigh the same, est in density to diamond-YAG and possibly each will possess a different diameter; conversely, strontium titanate-can be distinguished on the a diamond and a diamond simulant with the same basis of the visual characteristics described above. diameter will not weigh the same. The figures Heavy liquids can also help approximate spe- may not work perfectly, but they will point to the cific gravity. Simply drop the stone in question in identity of the material. methylene iodide (density of 3.32) and note the rate at which the stone sinks. Diamond will sink Immersion Techniques. B. W. Anderson has much more slowly than any of its simulants. It guided gemologists to a new technique for iden- appears to float to the bottom, while the diamond tifying diamond simulants. Initially, he discov- simulants plummet. If a known diamond is not ered that diamond simulants have different de- available, the rate of sinking can be compared grees of visibility when placed table-down in im- using a synthetic corundum (specific gravity of mersion liquid. Stones with refractive indices 4.00).All the diamond simulants in property chart greater than that of the liquid appear to have dark A will sink faster than synthetic corundum. The borders around the girdle and light facet edges, use of methylene iodide will at least prove while stones with refractive indices lower than whether a stone is a diamond. A set of compari- that of the liquid have light borders around the son stones can be used to help identify the spe- girdle and dark facet junctions. These differences cific diamond simulant. in relief are best seen when the cut stones are An accurate specific-gravity measurement can immersed in 3.32 liquid table-down in a glass- be accomplished by a direct weighing method in bottomed cell that is strain-free. The cell should which the stone is weighed first in air and then be slightly above its resting surface with light in water to determine the weight lost in water. placed directly over the stones. The specific gravity is found by dividing the ma- Interestingly, not only do the majority of the terial's weight in air by the loss of weight in diamond simulants have dark borders when im- water. The stones can be weighed on a diamond mersed in heavy liquid, but as their refractive in- balance that has been adapted for hydrostatic dices increase, the width and darkness of the ring measurements. The results prove the identity of around the girdle also appear .to increase. Thus, the material, although the measurements are not as mentioned earlier, if the diamond simulants as accurate for stones under one carat. were aligned according to refractive index, YAG would have the lowest relief, since its refractive Relationship of Specific Gravity to Size. The index is closest to that of the liquid, with GGG, higher the specific gravity of a stone, the smaller CZ, strontium titanate, and diamond (in that or-

30 Detecting Diamond Simulants GEMS & GEMOLOGY Spring 1981 Figure 17. The higher the refractive index of the stone, the more distinct the stone is when immersed in methylene iodide and the darlzer and wider the shadow around the girdle is. Left to right (high to low K.I.): diamond, strontium titanate, CZ, GGG, YAG.

Fig1u.e 18. When light is placed over stones immersed in methylene iodide, ench stone shows a different reflection pattern. Top row (left to right): dinmond, strontium titr~nate. Bottom row: CZ, GGG, YAG.

der) demonstrating increasing levels of relief (see bright rays that radiate from the middle of the fig. 17). stone and extend beyond the girdle outline. How- Since relief in itself usually will not lead to ever, the rays in strontium titanate show spectral the specific identity of the gem material, a new colors as a result of the material's great dispersion application of the Anderson principle has been and usually extend a bit farther than those of developed to provide this information. The tech- diamond. nique is the same; that is, the stones are im- CZ has a dark area round the girdle, but it is mersed in a glass cell and a light is placed over- not circularly defined. The middle of its pattern head. However, the stones are viewed from the is bright like that of GGG, but contains distinc- side instead of from directly overhead. Viewed at tive sharp, star-like images that extend halfway a 45" angle from the resting surface, different into the dark area. The reflection pattern of GGG stones will exhibit different reflection patterns is doughnut-like, with a thick, dark girdle border (fig. 18). While viewing contact photographs of and a bright interior in which the facet edges are immersed stones, Anderson noted the differing light but somewhat rounded and blurry. The re- reflections, but he did not specifically apply the flection pattern of YAG is characterized by a com- principle to the identification of diamond simu- paratively thin, dark girdle border and bright facet lants (Anderson, 1971, p. 35). Careful study has edges. shown, however, that when two or more diamond In most instances, the reflection pattern will simulants of the same cut are compared, each has identify the dialnond simulant. Since GGG and a unique reflection pattern. Round brilliants with zircon have similar patterns, the optic character good proportions seein to provide the best results. of the stone should be checked before it is im- The reflection patterns of diamond and stron- mersed. In addition, the patterns may be affected tium titanate are similar in that they both exhibit by the distance between the light source and the

Detecting Diamond Simulants GEMS & GEMOLOGY Spring 198 1 3 1 stone as well as by the distance between the cell lant, but they are very usefui at the repair or take- and its resting place. If a penlight is used to create in counter to determine whether or not the stone the pattern, the optimum distance between the in question is a simulant. The two most conclu- light source and the stone is approximately three- sive instruments are the GEM Diamond Pen (Gem quarters of an inch, and between the cell and its Instruments Corp., Santa Monica, CA) and the resting place is approximately one-quarter of an diamond probe. inch. Lately, we have noticed that these reflection GEM Diamond Pen. The GEM Diamond Pen patterns can be revealed without immersing the effectively separates diamond from the above sim- stone. The ramifications of this technique are ulants on the basis of diamond's unique surface being studied to see if it can be applied to mounted tension. Surface tension refers to the ease with goods. which a loose diamond can be picked up by a damp finger; most simulants do not possess this Fluorescence. Fluorescence is useful only as a property. supplemental test in gem identification, since the The effects of surface tension are illustrated by fluorescence of the diamond simulants is not very placing a small drop of liquid on the surfaces of constant. It may be helpful, though, to note a diamond and a diamond simulant simultane- whether the fluorescent reaction is stronger un- ously. The liquid spreads on the surface of the der long-wave or short-wave ultraviolet light. diamond, while it beads on the surface of the sim- Diamond generally fluoresces stronger under long ulant. The GEM Diamond Pen uses a nondrying wave than under short wave, while most simu- colored liquid to demonstrate the property quickly lants fluoresce stronger under short wave. and easily. The characteristic fluorescence of diamond is TOensure an accurate test, the stone's surface weak to strong blue under long- or short-wave should be well polished and clean. Hold the pen ultraviolet light. However, it may be inert or flu- perpendicular to the testing surface. In a quick oresce a variety of other colors. even stroke, run the tip of the pen across the sur- GGG's typical fluorescence is a moderate to face. In this position, the pen will allow only a strong orange (or pinkish orange) under short-wave metered amount of liquid to flow. A common ultraviolet light. The fluorescence is generally mistake is to hold the instrument in the same constant, although some stones have been inert. position as a writing pen, in which case too much The fluorescence of CZ is variable. When the liquid is deposited on the surface. material first appeared on the market, the typical Magnification may be needed to examine the fluorescence was orange under long-wave ul- drop of liquid. The reaction may be affected by traviolet light and yellow or greenish yellow un- abrasions or coatings on the surface, which can der short-wave ultraviolet light. It has since been be removed by a polishing compound included in shown that CZ may be inert or may fluoresce a the GEM Diamond Pen kit. In addition, a dia- number of other colors. mond doublet would fool the pen unless surfaces YAG and strontium titanate are usually inert, on both the crown and pavilion were checlzed. although YAG has been known to fluoresce a However, the test can be performed on both loose weak orange. Because of its inconsistency, fluo- and mounted goods and, if used properly, provides rescence should be used only in conjunction with positive proof of diamond. other tests. Chemical impurities, foreign mate- rials, and strain may alter the typical fluorescence Diamond Probe. The diamond probe yields the of a stone. fastest, most consistent results as to whether the material is diamond. Unlike the Diamond Pen, it INSTRUMENTS THAT SEPARATE is based on a bulk property that is not subject to DIAMOND FROM DIAMOND SIMULANTS miscalculations. The probe measures the thermal IN MOUNTED GOODS conductivity of diamond. Diamond's ability to If the gemstone is mounted, or if a person has not conduct heat is greater than that of any known been trained to use the above tests, instruments simulant, as evidenced by the fact that diamonds are available to separate diamond from its are colder to the touch than any simulant and simulants. The results do not identify the simu- become warm more quickly when worn. Simi-

32 Detecting Diamond Simulants GEMS & GEMOLOGY Spring 198 1 larly, moist breath evaporates much more quickly ulant, and they may lead to the precise identity on a diamond. of the material at hand. If the visual character- A typical thermal conductivity unit consists istics are not satisfactory, an estimate of specific of a small box with a pen-like probe attached to gravity coupled with the visual traits will often the unit by a cord. The only requirements for the separate diamond from its imitators. use of the unit is that the stone be at room tem- If a specific identification is needed, hydro- perature and that the probe pen be held perpen- static measurements can provide the proof, or the dicular to the testing surface. Position the pen, B. W. Anderson reflection technique will identify push lightly, and note the reaction. If the tip of simulants that are cut to certain proportions. the probe touches a diamond, the needle on the Last, the Diamond Pen and diamond probe scale points to "diamond"; if it touches a dia- conclusively identify a loose or mounted dia- mond simulant, the needle points to the "simu- mond. Even if the visual characteristics are ob- lant" area. structed, and the stones cannot be weighed or The diamond probe cannot distinguish among immersed, these instruments will reassure the all diamond simulants because they do not all gem identifier. At present, no diamond simulant differ significantly in their ability to conduct heat. duplicates the optical and physical properties of Some of the recently marketed probes have indi- diamond. Until is manufac- cator marks for the important simulants; how- tured for commercial use, if ever, diamond should ever, YAG and GGG are generally too close to pose no problem in identification. separate. If the machine is working properly, it is im- possible to mistalze diamond. To ensure that the machine is operating properly, press the tip of the probe against one of the checlz areas, or compare reactions with known stones. Thin coatings on REFERENCES the stone's surface should not affect the readings. Anderson BW (1971)Gem Testing, 8th ed. Butterworth & Co., Only a diamond doublet can confuse the ma- London, England. chine. The results have been found to be accurate Bruton E (1973)Diamonds, 2nd ed. Chilton Book Co., Radnor, PA. for both loose and mounted stones. Kane R (1980)The elusive naturc of graining in gem quality diamonds. Gems e) Gemology, Vol. 16, pp. 294-314. CONCLUSION Liddicoat RT jr. and Koivula jI (1978) Synthctic cubic stabi- lized zirconia. Gems d Gemology, Vol. 16, p. 58. There is no good reason to misidentify a diamond. Nassau K (1980) The optical constants of G.G.G. ]ounial of Visual characteristics alone should reveal a sim- Gemmology, Vol. 17, p. 148.

Detecting Diamond Siinulants GEMS & GEMOLOGY Spring 1981 33 NOTES AND NEW TECHNIQUES

THE HIDDEN BEAUTY OF AM~ER: NEW LIGHT ON AN OLD SUBJECT By Iohn I. Koivula

While many aspects of he nature of amber and its This journey into amber's hidden microscopic organic ~nclusionshave been reported in the world begins with a simple spherical void, a bub- literature, virtually nothing has been recorded about ble. Anyone who has studied amber under the the inorganic-minerul, liquid, and gas-inclusioi~s microscope has seen bubbles suspended in its "hidden" amid the better-documented life forms. golden depths. But the microscopist's eye is usu- This article takes a microscopic look at the gas ally drawn away from any bubbles present to the bubbles and crystal forms tllat also belong to more captivating inclusions of flora and fauna. In amber's inner world. With the use of polarized light, the a~lthoralso documents strain centers in the fact, if a piece of amber does not contain insects amber, ~ncludingmovements made millions of years or other fossilized life forms, it is seldom given ago by animals trapped in the resin. a second glance with the microscope. This sin- gular fixation on life forms has kept an intriguing portion of amber's inclusion world from the gem- ological community. At first glance, except for minor differences in shape, the bubbles found in amber appear to be The gemological literature is filled with a wealth essentially the same. However, careful study un- of information on amber and its inclusions. Seem- der the microscope reveals that many have unique ingly countless and exhaustive studies on the characteristics. Figure 1 shows a gas bubble dis- subject have been carried out by well-qualified, torted by the flow of the resin before it solidified. highly slzilled paleozoologsts, paleobotanists, and The bubble plays host to a transparent euhedral gemologists. Their Izeen observations have led to crystal of an unlznown solid, possibly quartz the identification of thousands of varieties of flora (Flamini et al., 1975). Figure 2 shows a group of and fauna as inclusions in amber, and more will white crystals that appear to adhere to the lower- undoubtedly be discovered as the search contin- front inner surface of this somewhat spherical ues. Through the application of spectro- bubble. The crystal group subsequently moved to photometry and other sophisticated instrumen- the inner-back surface of the bubble, revealing it- tation (Langenheim, 19641, the very origins of the amber resin itself are now being studied. Consequently, when we scan the available lit- -- ABOUT THE AUTHOR erature, it seems that there is very little that re- Mr. Koivula is a senior research fellow at the mains to be written on the subiect of amber, But, Gemological Institute of America, Santa Monica, CA. to the close and careful observer, amid the often- readers of paper have observed any noted inclusions of flowers and insects a world of seeming/y unuscla/inclusions in amber, the author hidden beauty unfolds, a microscopic world never woald be delighted to hear of them. before reported in the gemology literature. O1981 Gemological Institute of America

34 Notes and New Techniques GEMS & GEMOLOGY Spring 198 1 It is an established fact that the physical bod- ies of all animal life are composed primarily of water. When insects or other fauna are trapped in amber, their internal organs deteriorate, leaving behind the fossilized exoslzeleton. Transparent, gem-quality amber is not porous, so any organic

Figure 1. Distorted by the flowing motion of its amber host, this bubble is unique in that it contains a well-formed crystal, possibly quartz. Magnified 65 X, dark-field illumination. self as a mobile solid. The photomicrograph of a bubble in figure 3 illustrates a three-phase inclu- sion in amber. The solid phase consists of tiny brownish-red pollen grains. The largest of these appear to be attached to the inner surface of the bubble, while the smaller grains move around in- side the bubble chamber, propelled by heat-con- ~i~ure3. The solid phase of this three-phase vection currents and water vapor. The liquid phase inclusion in amber consists of microscopic pollen grains, some of which stick to the inner is a droplet of ancient rain or dew. It can be seen surface of the void while others fly around. The easily in various stages of condensation on the liquid phase, seen here in various stages of inner surface of the gas bubble, the third phase. condensation on lhe inner surface of the gas bubble, is possibly a droplet of ancienl rain or dew. Magnified 40 X, dark-field illumination.

body fluids trapped within the insect's remains are left behind in the exoslzeletal void. If the exo- slzeletal shell is thin enough to allow the passage of light, then a small mobile gas bubble often can be observed rolling about inside the fauna host. In figure 4, we see one of these mobile bubbles trapped in the abdomen of an ant. Occasionally, small fragments of the exoslzeleton will float with the bubble, creating a three-phase inclusion. The application of polarized light to the study of amber reveals further heretofore hidden details. The spherical voids shown in the first photo in Figure 2. This gas bubble contains a group of figure 5 house two-phase, liquid and gas, inclu- whitish crystals that appears to be sticking to sions with a mobile gas phase in each. Under po- the bubble's lower front surfc~cebut revealed larized light, framed by bright interference colors, itself as a mobile solid. Magnified 40 X, oblique these inclusions show themselves as strain ten- illumination. ters in the amber. A close-up of a strain-center

Notes and New Techniques GEMS & GEMOLOGY Spring 198 1 35 Figure 4. The internal organs of this ont in amber have deteriorated, and only the body fluids remain in the exoslzeleton. A bubble of abdominal gas can be seen floating about. Magnified 30x, dark-field illumination. liquid-and-gas two-phase inclusion shows tiny liquid droplets that have condensed in the gas phase as a result of temperature-change and va- por-pressure alteration.

Figure 6. The death dance of three tiny bees. The final life movements of arthropods are often traced in amber, but only under polarized light do these final death throes become visible as vivid strain colors. Magnified IOX.

Polarized light may also disclose "hidden" de- tails in amber's fauna inclusions that often re- main invisible when other methods of illumina- tion, such as dark field, are used. If insects or other fauna are trapped alive by the resin, their final life movements-as they attempted to es- cape-are visible under polarized light in the form of vivid strain colors surrounding their bodies and legs. Figure 6 illustrates the death dance of three small bees. A case of not seeing the forest for the trees. It is obvious that there is more to amber than has previously met the gemologist's eye. These newly recorded facts only add to the unique nature of amber as a gem material. Figure 5. The bubbles in the top photomicrograph house two-phase, liquid and gas, inclusioi~swith mobile gas phases. Under polarized light, these inclusions show REFERENCES themselves to be strain centers in the amber. Magnified 35 X.Higher magnification reveals Flamini A, Graziani G, Grubessi 0 (1975)Inorganic inclusions in amber. Archaeomstry, Vol. 1, pp. 1 10- 1 12. tiny liquid droplets that have condensed in the Langenheim JH (1964) Present status of botanical studies of gas phase as a result of vapor-pressure amber. Harvard University Botanical Museum Leaflets, alteration. Magnified 60x. Vol. 2, No. 8, pp. 225-287.

36 Notes and New Techniques GEMS & GEMOLOGY Spring 198 1 ARTIFICIALLY INDUCED COLOR IN AMETHYST-CITRINE QUARTZ By Kurt Nassau

Adjacent amethyst and cltrine colors in the same crystal of quartz have been reported from So~rrhArner- ica, although there appears to be uncertainty as to the exact locality of origin. Such material has also been prodr~cedby synthesis. Several previous studies on the imp~~ritiescontained in natural and synthetic quartz and the effects of irrndiation and heating, as well as RE new heating and Irradiation experiments with the cur- rent natural amethyst-citrine quartz and with ame- L." thyst, are described. It is concluded that there are pres- ently no lznown tests to distinguish natural blcolor material that wns heated or irrudiated (or both) in nn- ture from natural amethyst heated or irradiated (or both) by man or from the ecluivaient synthetic material.

Figure 1. Natural amethyst-citrine quartz, 108.5 A new and rather unusual gem material has been carats (from the Los Angeles County Museum of reported recently, namely, the occurrence of Natural History collection). citrine and amethyst colors side by side in the same crystal of quartz. Brief descriptions have cott (1977). Briefly, citrine and amethyst are been given by Hehar (1980), Koivula (1980), and caused by the incorporation into quartz of dif- Vargas and Vargas (1980).The locality was origi- ferent types of iron; amethyst also involves irra- nally reported as being in the Rio Grande do Sul diation. The amounts of the two types of iron mining area of Brazil, close to the Uruguay border, present in a quartz crystal depend on the growth or in northern Uruguay itself; subsequently it has direction and on other growth factors, but either been reported to be in Bolivia (G. Vargas and J. type may be present by itself or they may both be Koivula, personal communications). The names present in variable ratios. It has long been lznown amethyst-citrine quartz, citrine-amethyst quartz, that the depths of the colors do not correlate with ametrine, trystine, and golden amethyst have the analyzed iron concentration; this is a result of been used for this material. The first of these is the presence of a third type of iron, which is not a clear and descriptive designation and will be color producing. used below. The well-cut stone shown in figure Many scientific studies have also been con- 1 clearly displays both colors. ducted over the years on the impurities contained Usually, a gemstone material is synthesized in natural and synthetic quartz, together with the after naturally occurring material provides the effects of irradiation and heating (Cox, 1977; stimulus for duplication attempts. In this instance, however, the author has had a piece of synthetic amethyst-citrine quartz in his possession for sev- ABOUT THE AUTHOR eral years without realizing its significance! This Dr. Nassau is a research scienlist residing in unusual specimen is shown in figure 2, where the Bernardsville, NJ 07924. purple amethyst and yellow citrine colors can be The author wishes to [hank Mr. Glenn Vargas of clearly seen. Thermal, CA, for supplying amelhyst-citrine quartz, and Mr. J. I. Koivula and Dr. D. V. Manson of the A general description of the growth of syn- Gemological Institute of America, Sanla Monica, CA, for thetic quartz has been given by the author supplying both amethyst-citrine quartz and the sectored (Nassau, 1980a and 1980b).The causes of color in amethyst sections. quartz have been reviewed by Nassau and Pres- :* 1987 Gemological Institute of America

Notes and New Techniques GEMS & GEMOLOGY Spring 1981 37 rhombohedron amethyst to leave citrine, but which did not bleach the major-rhombohedron amethyst material. According to the third scheme, heating could have affected the material in such a way that a subsequent irradiation might have colored only some parts, thus producing the observed end product. According to these alternative schemes, the important difference is not in the quantities of iron occupying the different sites, (although some such differences may be present], but in the behavior of the material with respect to heating. The determining factor is either the temperature at which the bleach (i.e., at which the color centers are destroyed) or the temperature of heat treatment after which the citrine can no Figure 2. Synthetic amethyst-citrine quartz crystal, longer be converted to amethyst. Such differences 3 cm long (author's collection). (e.g., in the bleaching temperatures) do occur in quartz (Nassau and Prescott, 1977), and sectored Cohen and Hassan, 1974; Hassan, 1972; Cohen, variation in properties has also been noted in 1975; Lehmann, 1975; and Nassau and Prescott, conjunction with the pleochroic anisotropy in 1977 and 1978). These studies, as well as some smoky quartz color centers (Nassau and Prescott, current experiments, suggest that several possi- 19781 and in amethyst (Cox, 19771. There are two bilities exist as to the origin of any specific piece questions that arise should one of these schemes of amethyst-citrine quartz. apply: (1)Was the heating or irradiation (or both) a naturally occurring event or was it performed NATURAL AMETHYST-CITRINE QUARTZ by man! and (2) Is this property unique to the In their reports, Hehar (1980),Vargas and Vargas locality or will amethyst from other localities (1980), and Koivula (1980) note six alternating produce the same result if suitably treated! regions, three each of amethyst and citrine, which clearly correspond to the major-rhombohedron HEATING AND IRRADIATION growth regions of typical amethyst and the minor- EXPERIMENTS rhombohedron growth regions of typical citrine. Specimens of the natural amethyst-citrine cur- There are three significantly different ways in rently in the trade were made available to the au- which such naturally occurring amethyst-citrine thor by the very lzind cooperation of G. Vargas quartz could have been formed. First, it is possi- and by J. I. Koivula and D. V. Manson of the GIA. ble that the quartz simply grew under such con- Parts of two specimens were irradiated in a ditions that the amethyst-forming iron was in- cobalt-60 gamma-ray cell to a dose of at least corporated under the major-rhombohedron faces, 1,000,000 rads. As a result, portions of some of while only citrine-forming iron entered under the the amethyst and citrine regions acquired an ad- minor-rhombohedron faces (some may, of course, ditional weak smoky tint. Heating to 350°C re- be present under the majors as well). Natural ir- moved this tint and restored the specimens to radiation would then produce this end product. their original state. There are, however, important alternative Parts of two different specimens were next possibilities involving different mechanisms. In heated in air in a furnace for two-hour periods the second suggested mechanism, both ame- first at 250°C and then at successively higher thyst-producing iron and citrine-producing iron temperatures at intervals of 50°C. The amethyst are present in all sectors of the quartz, and the sectors became yellow after the two hours at the naturally occurring irradiation has produced an 400°C step; the citrine regions were not affected amethyst color in all sectors. According to the by this heat treatment. A subsequent irradiation second scheme, the quartz next would have passed followed by heating to 350°C to remove smolzi- through a heating stage that bleached the minor- ness restored the original amethyst-citrine colors.

38 Notes and New Techniques GEMS & GEMOLOGY Spring 1981 In order to obtain comparison data, experi- ments were also performed on two specimens of sectored amethyst from Minas Gerais, Brazil, which were also obtained from the Gemological I Institute of America. These specimens exhibited alternating sectors of dark (major rhombohedron) and pale (minorrhombohedron) amethyst. Dupli- cation of the first irradiation experiment above gave essentially the same results: smolzy purple and pale smoky purple, with the smolzy compo- nent removed and the original state restored upon heating to 350°C. Heating the sectored amethyst to successively Figure 3. Amethyst-citrine quartz produced by higher temperatures, however, produced an unex- heating and irradiating sectored amethyst from pected result: the dark purple sectors became Brazil; 12 mm across. somewhat lighter but the pale purple sectors turned yellow at 400°C. To the eye, this material Since the sectored amethysts tested were now had exactly the same appearance as the merely randomly chosen, it is lilzely that much amethyst-citrine. Subsequent irradiation and such material from a variety of sources can be heating to 350°C restored the original all- treated to produce amethyst-citrine, including amethyst state. This process corresponds to the man-made quartz. There are no lznown tests to second mechanism discussed above, but the end distinguish the origin of color of natural inaterial product is unlike the current amethyst-citrine, that was heatedlirradiated in nature from natural which did not convert to all-amethyst even after amethyst heatedlirradiated by man or from the 20 megarads of cobalt-60 gamma rays. equivalent synthetic material. Heating of these same sectored-amethyst sec- tions to the slightly higher temperature of 450°C bleached all the amethyst sectors to yellow. A REFERENCES subsequent irradiation followed by heating to Cohen AJ (1975)On the color centers of iron in amethyst and 350°C reproduced not only the appearance of the synthetic quartz: a reply. American Mineralogist, Vol. 60, current amethyst-citrine, but also its behavior pp. 338-339. with respect to heating and irradiation: it could Cohen AJ, Hassan F (1974)Ferrous and ferric ions in synthetic a-quartz and natural amethyst. American Mineri7logist. no longer be returned to all-amethyst. A spec- Vol. 59, pp. 719-728. imen of this treatment-produced amethyst-citrine Cox RT (1977) Optical absorption of the d" ion Fe" in pleo- (see figure 3) has been returned to the Gemolog- chroic amethyst quartz, lournal of Physics C: Solid State Physics, Vol. 10, pp. 4631-4643. ical Institute of America for archival purposes. Hassan F 11972) Amethyst. Mineralogical Record, Vol. 3, pp. Iron analyses were not performed because such 221-225. analyses cannot distinguish among the three Hehar WC (1980)The discovery of golden amethyst. Lapidary ]ournal, Vol. 34, pp. 582-583. types of iron but only give the total iron present; Koivula J1 (1980) Citrine-amethyst quartz. Gems eJ Gemol- this total has not provided useful information in ogy, Vol. 16, pp. 290-293. previous studies. Lehmann G (1975) On the color centers of iron in amethyst and synthetic quartz: a discussion. American Mineralogist, Vol. 60, pp. 335-337. DISCUSSION Nassau K (1980aJ Gems Made by Mon. Chilton Book Co., The above experiments show that the amethyst- Radnor, PA. Nassau K [1980b) The history and present status of the syn- citrine combination in quartz can be obtained by thetic quartz family. Lapidary 1ournal. Vol. 34, pp. 718- heat-treating sectored amethyst from Minas Ger- 726 and 956-963. ais, Brazil, in either one of two ways: (1)a medium Nassau, 1<, Prescott BE (1977) Smoky, blue, greenish yellow, and other irradiation-related colors in quartz. Mineralogi- heating step produces the change, but this can be cal Magazine, Vol. 41, pp. 301-3 12. reversed by irradiation; (2)a more intense heating Nassau K, Prescott BE (1978) Growth-induced radiation-de- followed by irradiation and a second, gentle heat- veloped pleochroic anisotropy in smoky quartz. Americnn Mineralogist, Vol. 63, pp. 230-238. ing also produces the change, but the product can Vargas G, Vargas M (1980) A new quartz gem material. Lop- no longer be returned to all-amethyst. idory ]ournal, Vol. 34, pp. 1504- 1506.

Notes and New Techniques GEMS & GEMOLOGY Spring 1981 39 EDITOR Chuck Fryer GIA, Sanla Monica CONTRIBUTING EDITORS Robert Crowningshield LAB NOTES Gem Trade Laboratory, New York Karin N. Hurwit Gem Trade Laboratory, Santa Monica Robert E. Kane Gem Trade Laboralory, Los Angeles

A NOTE FROM THE EDITOR AQUAMARINE This is the first Gem Trade Lab Trapiche Aquamarine? Notes column under [he new for- An unusual stone came into the New mat of Gems & Gemology. Al- Yorlz lab for identification. Figure 1 though the general style of the for- illustrates the green-blue melon-cut mer colrrmns will be retained, a few drop that appeared at first to be improvements have been made, in- merely a drilled aquamarine bead. In cluding the use of more color photos. reality, this stone has been cut from Previously, there were separate a trapiche-like crystal with six columns for the New York, Los An- separations [apparently carbona- geles, and Santa Monica branch ceous) and a clear central hexagonal labs. It will be my job to combine area, as shown in figure 2. Although the information supplied by each the stone displayed evidence of branch into one column. The New chromium in its absorption spec- York col.respondent will continue to trum, its color was unlike that of be Bob Crowningshield, vice presi- any trapiche emerald crystals we dent of GIA and director of the col- have seen. However, the chalced- ored stone section of the Gem Trade ony-lilze translucency and the black Lab. Bob Kane will keep the datu iilclusions seen in figure 2 do resem- Figure 2. End view of the from Los Angeles coming in, while ble characteristics common to tra- melon-cut aquamarine in Karin N.Hurwit supplies the items piche emerald. figure 1. Magnified lox. of interest from S~ntnMonica. Perhaps the /nost important long- range improvement is the arrange- ment of the material in alpha- betical order, by variety. Such an DIAMONDS arrangement makes it easier to pro- Cyclotron-Treated Diamonds vide an annual index of the stones coming into the labs and aids the Diamonds were first treated in a cy- reader in his or her search for more clotron to produce color nearly 40 information on particular stones. years ago. A color then seen some- Please note that all magnifica- what frequently in treated dia- tions given refer to the power of the monds, but seldom seen today, is a pleasing orange-brown. However, microscope at which the photo- graph was taken, not necessarily the cyclotron treatment, which imparts a shallow penetration of color, is final magnification of the printed image. an expensive and troublesome pro- cess. For these reasons, other meth- ods of artificially inducing color in diamonds have been developed, including atomic-pile treatment. Figure 1. Melon-cut aqua- Atomic-pile treatment penetrates "1981 Gemological Institute of America marine, approximately 35 cis. the diamond completely, resulting

40 Lab Notes GEMS & GEMOLOGY Spring 198 1 Figure 3. Cyclotron-treated diamond. Left = crown facets viewed through the pavilion, magnified 40~.Center = culet area viewed through the table, magnified 30x. Right = culet area and brown graining, magnified 12 X. in even color throughout the stone. Yorlz appeared watery when viewed This process has largely replaced from the side, which suggested that cyclotron treatment, and we seldom it was surface treated. However, it see cyclotron-treated diamonds in did not show the umbrella around the laboratory today. the culet or dark penetration zone Several months ago, however, a around the table and star facets cyclotron-treated diamond was sub- which are typical of such treatment. mitted to the Los Angeles lab for Finally, with immersion and later in determination of the origin of color. air we were able to determine that Since the color penetration was the stone was treated on one side of shallow, this particular diamond did the pavilion only, where a grid-like not exhibit the usual absorption penetration zone appeared when the spectrum with the typical 5920 A diamond was viewed through the line. upper girdle and bezel facets [see fig- The fact that the color is shallow ure 4). We have heard that in the and confined to a layer near thesur- early days of cyclotron treatment if face malzes cyclotron treatment eas- a stone fell from its fire-resistant ily detectable when the stone is ex- holder, operating procedures did not amined under magnification. As seen allow stopping the equipment to in the three sections of figure 3, this right it. It is rumored that just such diamond displayed a surface layer of an accident led to the discovery that Figure 5. Radiation stains on a intense color paralleling the edges of overexposed dark green stones could natural of a near-colorless facets on the crown and around the be heated to turn them brown, diamond (see arrows). culet that is very typical of cyclo- orange, or yellow. Magnified 45 X. tron-treatment. The first photo in figure 3 shows crown facets viewed from the pavilion. The area around Natural Radiation Stains the culet is seen in figure 3 center Radiation stains on diamond natu- as viewed through the table. The fi- rals are often associated with green nal pose in figure 3 shows, at lower stones, but they can occur on dia- magnification, the treatment-layer monds of any color. In the Fall 1979 zone at the culet, as well as brown issue of Gems d Gemology, we graining. mentioned a G-color round brilliant It should be noted that natural- with radiation stains on both of the color diamonds frequently display two naturals. Since that time, we brown graining. Light brown dia- have seen several diamonds, not monds with brown graining are green, that had this feature: Figure sometimes treated to darken their 5 shows a near-colorless and thus improve their ap- with two such small brown stains pearance; the graining, of course, is on a natural. Another diamond, of still present. Figure 4. Grid-like color M to N range in color, was also ob- A dark blue-green diamond ex- zoning in a cyclotron-treated served to have a stain on a natural. amined in both California and New diamond. Magnified 40~. Directly across from the natural

Lab Notes GEMS & GEMOLOGY Spring 1981 41 LL-I Figure 6. liadiation stain in a diamond natural. Figure 7. Flower-like inclusion in a diamond. Magnified 50 x. Magnified 15 X.

there was a stain remaining in the bruted girdle where the rough dia- mond slzin had been removed. The stain in the natural is intense in color and penetrates deep into the stone (see figure 6). Inclusions The cover of the Spring 1952 issue of Gems d Genlology featured a windowed diamond crystal with a beautiful flower-like iilclusion that shows both petals and sepals. This year we were shown a similarly

Figure 9. A uniquely glassy diamond natural. Magnifier1 35 X.

windowed crystal with a flower-lilze of this natural was very smooth and inclusion that has a brown tubule glass-like (see figure 9),almost as if which looks ever so much lilze a it had melted! There was absolutely stem or the stick for a pinwheel (see no evidence of any growth or etch figure 7). marlzs on the surface of the natural. We are at a loss to explain the No one in the Gem Trade Lab re- unusual inclusions in the round- members ever before seeing a dia- brilliant cut diamond shown in fig- mond natural with this appearance. ure 8. On examination under the microscope, they appeared to be Notes on hollow tubules, some brown or filled We admire the cutter of the orange with a brown material. cube diamond seen recently in New Yorlz (see figure 10). Gem-quality An Unusual Natural cube-shaped diamond crystals are Figrrre 8. Irregular trrbe-like The unique natural on a dia~nond almost unlznown, so in retaining the inclusions in ci' diamond. brought into the Santa Monica lab cube shape with very symmetrical Magnified 18 X. warrants a description. The surface beveling of the edges the cutter has

42 Lab Notes GEMS W GEMOLOGY Spring 1981 Figure I I. Top view of a Peruzzi-cut diamond, 2.00 cts. Figure 10. Cube-cut diamond, 1.13 cts.

Figure 12. Diagram of the Peruzzi cut. (Diagram courtesy captured the stone's beauty and of Robert A. P. Gaul, Diamond rarity. Dictionary, 2nd ed., Rare outside museums or royal Gemological Institute of collections are Peruzzi-cut dia- America, Santa Monica, CA, monds. We were privileged to re- 1977.) ceive for grading and photographing Peruzzi cut. such a stone weighing more than I 2.00 cts. (see figure 11). Presumably this style of cutting, detailed in fig- ure 12, was first employed by a a type I1 diamond in the darltroom, with the ultraviolet lamp perhaps a Venetian cutter in the 17th century, using short-wave ultraviolet light foot away. Figure 13 shows the and it led to the old-mine cut, the and a piece of placed be- transparency difference between a old-European cut, and finally the hind a porthole. Only UV light that type I yellowish marquise and a type modern brilliant. The stone we has passed through the stone can II,, pear-shaped diamond. graded had no culet, had a table per- affect the scheelite. If the scheelite centage of 46, and showed a depth glows, we test the stone further for percentage of 97.9. electrocoi~ductivity to determine EMERALD whether it is type 11,. Of course, 11, or Not 11, there is no permanent record of these An emerald sent to Santa Monica for Type I diamonds are opaque to short- UV transparency tests. To obtain a identification showed quite unusual wave ultraviolet (UV) light, while permanent record, place the stones stn~cturalcharacteristics. First, we type I1 are transparent. Type 11, dia- table down on the emulsion side of were surprised to see a significant monds are not electroconductive, but photographic paper and expose them difference in transparency when the type 11, are. Normally we check for for a very short time (two seconds) stone was viewed from different an- gles. As we loolzed at the stone through the table, the emerald was almost transparent; yet when we looked sideways at the pavilion fac- ets, the stone was oilly translucent, having the appearance of dyed green chalcedony. Magnification of this stone revealed a peculiar structure: straight, colored growth lines were crossed by lightly curved, wave-like bands (see figure 14).The stone was Figure 13. Ultraviolet transparency of a type I marquise con~pared of natural origin, possibly cut from to a type I1 pear-shaped diamond. a trapiche-type crystal.

Lab Notes GEMS & GEMOLOGY Spring 1981 43 Figure 15. Yellow inclusion in Figure 16. "Venetion blind" a synthetic emerald. banding in synthetic emerald. Magnified 25 X. Mognified lox.

ably like a cleavage that astonished occurred between bedding planes in Figure 14. Unusual growth us (see figure 17). Although mala- the stone and produced a flat, lines in'an emerald. Magnified chite has one perfect cleavage direc- smooth break. 63 x. tion, massive material usually does not show it. What had ha~~ened?-. The New York lab encountered This particular piece of , Cultured a synthetic emerald, reportedly of apparently was formed by the pro- Russian manufacture, with a refrac- cess of sedimentation. When the The Sailta Monica lab had the op- tive index of 1.560-1.563 and a low carving was damaged, the separation portunity to examine a necltlace specific gravity. The stone trans- mitted red on the spectroscope light but showed only weak long-wave ultraviolet fluorescence. The stone had fairly typical flux fingerprints and even contained a platinum crys- tal in the girdle. What was partic- ularly unusual was the presence of hi. .\ long needles, which we have always felt indicated natural origin. Nearly -.\ - as disturbing was the discovery of a cavity filled with yellow liquid in this otherwise obviously synthetic emerald (see figure 15). Elsewhere in the stone, the "Venetian blind" banding that is typical of a synthetic was visible (fig. 16). .-

MALACHITE A malachite carving of an oriental 1 lady holding a flower basket was sent to the laboratory for a damage re- port. Part of the flower basltet and the right hand of the lady had been Figure 17. Damaged malachite carving showing separation broken off, leaving a surface remark- between bedding planes; 2.5 cm x 7.5 cm x 10.5 cm high.

44 Lab Notes GEMS & GEMOLOGY Spring 198 1 consisting of bluish-gray cultured pearls with one "oddball" in the strand. The layered structure of shell was apparent in this single bead (see figure 18). Notice also the concen- tration of dye at the drill hole. It would seem that at one time this was crushed or received a blow that caused the nacreous outer layer to fall off, exposing the nucleus. A "faith-shaker" was a pair of earrings set with a bronzy-black, drop-shaped pearl and a similarly shaped white pearl. Both were cul- tured. However, the blaclt pearl fluoresced reddish brown-much stronger than any ltnown Tahiti blaclt cultured pearl we have seen. The history of the earrings pre- cluded the possibility that the black pearl could have been cultured in Tahiti waters. Incidentally, it is re- Figure 19. Neclzlace of unrlsual bronze-colored dyed cultured ported that a inuch wider range of pearls. hues has been produced in the cur- rent harvest there, so we may see RUBY colors other than the usual black, 7 dark gray, and light gray. Synthetic stones examined in the Figure 19 illustrates a neclzlace New Yorlz laboratory recently have set with bronzy-colored dyed cul- been cause for alarm. Thc first was 1 tured pearls. The shapes too are a flux-grown synthetic ruby report- unusual. edly of recent Chatham manufac- ture. It weighed more than 5 cts. and had fine flux fingerprints fairly well distributed with only one area of typical coarse flux. The alarming

characteristic was angular,-, silk-like I banding visible to the unaided eye (see figure 20). lndividual needles could not be discerned: rather. we observed precisely the effect we have seen when a Burma star ruby has been heat treated and the rutile needles are not quite absorbed. Mounted, it could readily be mis- identified, since the silk-lilze bands are not expected in synthetic stones. Figure 20. Angular banding in The stone was highly fluorescent and a flux-grown synthetic rrrby. was obviously not cut in the Orient. Magnified 30 X. Whether this stone indicates a change in the Chatham product or a one-time "flulte" has not been duced fractures to produce very established. believable fingerprint inclusions. It We have mentioned previously was therefore more expected than the process whereby ordinary syn- alarming to receive for identifica- thetic blue are heated in tion a synthetic Verneuil ruby Figure 18. Shell nucleus of a with an unknown liquid showing both curved striae and "fin- cultured pearl. Magnified 10~. that is then incorporated within in- gerprints" (see figure 2 1).

Lab Notes GEMS & GEMOLOGY Spring 198 1 45 Under short-wave ultraviolet light, most of the stones treated by induced surface coloration show a patchy fluorescence where the dif- fused color was removed when re- polished. However, a stone sent to New York by the Los Angeles lab did not fluoresce. When the stone was immersed, all facets showed - -- L 1 color except the girdle, which had Figurb G~.Star . been repolished and all diffused color Magnifietl lox. removed (see figure 22).

SPINEL It is not often that one has the op- portunity to see a star spinel. Imag- Figrlre 21. Curved striae and ine our surprise when two of them "fingerprint" inclusions in I arrived at the Santa Monica lab at synthetic ruby. Magnified 30~. the same time. We were especially SAPPHIRES pleased when it was apparent that one of the stones showed a four-ray Induced Surface Coloration star, while the other star had six legs of Natural Sapphires (see figure 23). The shortage of Sri Lanlzan sapphire rough suitable for heat treatment in Bangkok has evjdently led to the use of cut stones that are heated after packing in chemicals to diffusecolor ACKNOWLEDGMENTS into the surface. The method re- The photographs in figures 1, 2, 4, 8, 13, portedly is a variation of the one and 21 were taken by Bob Crowningshield outlined in U.S. Patent 3,897,529, in New York. A1 Roditi, also in New York, issued to Union Carbide Corp. in took the photographs in figures 7, 10. 11, 15,76,79, 20, and 22. Shane McClure of 1975. We first encountered such the Gem Trade Lab in Los Angeles did the stones a year ago in the form of an photography for figure 5, while Bob Kane orange sapphire, reported in the Fall Figure 22. Loss of color in the was responsible for the photos used in fig- d Iures 3 and 6. The specimens examined in 1979 issue of Gems Gemology. the Santa Monica lab were photographed Since then we have seen a number repolished girdle of a color- by John Koivula (figures 9, 14, and 78), of parcels containing variously col- treated sapphire. Magnified Mike Havstad (figure 17), and Chuck Fryer ored treated stones. lox. (figure 23).

46 Lab Notes GEMS & GEMOLOGY Spring 1981 GEMOLOGICAL ABSTRACTS

Dona M. Dirlam, Editor

REVIEW BOARD Karin N. Hurwit Richard J. Saindon Gem Trade Lab, Inc., Santa Monica GIA, New York Stephanie L. Dillon John I. Koivula Andrea L. Saito GIA, Santa Monica GIA, Santa Monica GIA, Santa Monica Bob F. Effler Noel P. Krieger Peter C. Schneirla GIA, Santa Monica GIA, Santa Monica GIA. New York Caroline K. Goldberg Shane F. McClure Frances Smith GIA, Santa Monica Gem Trade Lab, Inc., Los Angeles Gem Trade Lab, Inc., Los Angeles Joseph P. Graf Elise 6.Misiorowski R. Stephen Smith Gem Trade Lab, Inc., Santa Monica Gem Trade Lab, Inc., Santa Monica GIA, Sanla Monica Gary S. Hill Gary A. Roskin Carol M. Stockton GIA, Sanla Monica Gem Trade Lab, Inc., Los Angeles GIA, Santa Monica Jill M. Hobbs Michael L. Ross Evelyn Tucker GIA, Sanla Monica GIA, Santa Monica GIA, Santa Monica

COLORED STONES AND orientation may be verified if the stone contains straight, ORGANIC MATERIALS tube-like inclusions that align themselves parallel to Additional and corraborative data on violet gem sca- the c-axis. All the stones examined contained these in- polite probably from Eastern Africa. B. Jackson, clusions, which sometimes broaden out, resembling Iournal of Gemmology, Vol. 17, No. 4, 1980, cleavages. Given the similarities in color and in optical pp. 235-238. and physical properties, this material may be confused with amethyst. The two stones can be distinguished, The author describes a violet gem scapolite, probably however, on the basis of optic sign (scapolite, negativc from Kenya, that has unusually low refractive indices vs. amethyst, positive). RSS (1.536-1.541) and density (specific gravity of 2.65), and has the highest content recorded thus far in The alexandrite effect in minerals: chrysoberyl, garnet, natural scapolite. All the samples exhibited strong di- corundum, fluorite. K. Schmetzer, H. Bank, E. chroism: violet when viewed parallel to the c-axis and Gubelin, Neues lahrbuch fur Mineralogie colorless when viewed perpendicular to the c-axis. This Abhundlangen, Vol. 138, No. 2, 1980, pp. 147-164. As Schmetzer, Bank, and Gubelin state in the abstract, This section is designed to provide as complete a record the purpose o'f thei; study is to determine the condi: as possible of the recent literature on gems and tions required for change of color in various minerals. gemology. Articles are selected for abstracting solely at Following a helpful review of the literature on color- the discretion of the section editor and her reviewers, change materials, the experimental details of the ab- and space limitations may require that we include only those articles that will be of greatest interest to our sorption spectra and chemical analyses are presented readership. in this comparison of the spectroscopy and chemistry Inquiries lor reprints of art~clesabstracted must be of alexandrite and alexandrite-like minerals. addressed lo the author or publisher of the original Most of the paper is devoted to analyzing the results material. of these experiments for alexandrite and those , The reviewer of each article is identified by his or her , and fluorites that exhibit change of color. initials at the end of each abstract. Guest reviewers are Specifically, the authors discuss how the elements identified by their full names. present and the location of ions in the crystal structure 5)1981Gemolog~cal Institute of Amerlca relate to the absorption spectra and therefore to color.

Gemological Abstracts GEMS 8: GEMOLOGY Spring 1981 47 Lastly, the authors hypothesize from their investi- tion on the Canadian amber found at Cedar Lalze in gation that four features are characteristic of the ab- Manitoba and the Alaskan amber found along the Ketic sorption spectra of color-change minerals. The first is River near Point Barrow. spectral transparency from 15,000 cm-' to 16,000 cm-' The view that the source of all amber was resin from (red area]. The second is a strong absorption maximum a particular species of pine is disputed in a short section between 17,300 cm-' and 17,800 cm-' (yellow area). on the botanical origins of amber. With the use of in- Then another absorption maximum exists between frared spectrophotometry, the spectra of amber from 19,700 cm-' and 21,000 cm-' (green to blue area). Fi- various localities were compared with those of modern nally, there is a continuous increase in absorption from resins. The authors point out the information that may 21,000 cm-' to the limit of the visible area with- be gained from the insects and other arthropods, as well out additional minima. The authors note further that as the microorganisms such as nematodes and fungi, crystals green in daylight generally change to red in that have been discovered in amber. The article con- artificial light while bluish-green crystals change to cludes with a warning to be on guard against amber reddish-violet. Figures and tables of the spectral and substitutes. IIK colorimetric data are included as well as a substantial list of references. DMD The causes of color. K. Nassau, Scientific American, Vol. 243, No. 4, 1 980, pp. 124- 154. Alexandrite-like natural spinel from . K. In this article, Kurt Nassau gives a rather compre- Schmetzer and E. Giibelin, Neues luhrbuch fir hensive summary of five general color-causing me- Mineralogie Monatshefte, Vol. 9, 1980, pp. 428- chanisms that he has subdivided into 14 specific 432. categories. Within this framework, he discusses a wide In a continuation of their articles on alexandrite-lilze variety of color phenomena, ranging from the vibrant minerals, Schmetzer and Giibelin report on the inves- red of a ruby to the multi-hued iridescence of a com- tigation of a 1.87-carat spinel that shows a "remarkable mon oil slick. The interaction of light with change of colour from violet in daylight to reddish vi- is the unifying theme behind almost all causes of color. olet in artificial light." Through an analytic and spec- The opening sections of the article relate the energy troscopic investigation, the authors hoped to verify the hierarchy of light to the absorption and emission of ra- four features they have postulated as being character- diation by the atomic electrons. Nassau's treatment of istic of alexandrite-lilze materials: transmission in the the crystal field, molecular orbital, band structure, and red area of the spectrum, an absorption maximum in physical optical theories contains many interesting ex- the yellow region, transmission in the blue-green, and amples from the gem and mineral lzingdoms. Several an increase in absorption from the blue to the ultra- large diagrams, plus a few color photographs, supple- violet end of the spectrum. ment the verbal explanations. In addition to the normal amounts of Alto3 (alu- Some of the parameters, such as volts and minum oxide) and MgO ( oxide), the micro- the spectroscopic notations, will seem bewildering to probe analysis indicated the presence of FeO (iron the nonscientist, but a full understanding of those de- oxide), Cr20, (chromic oxide), and V,03 (vanadium tails is not necessary for grasping the main ideas. Any- trioxide]. The position of the maxima and minima one interested in an in-depth treatment of the origins bands in this spinel are different from a typical blue of color should not miss this excellent article. BFE spinel. The authors suggest that the overlapping of the absorption bands of Fe+' (iron) by the spectra of Connoisseurship in . B. Zuclzer, Connoisseur, Cr+"chromium) and V+"vanadium) produced this Vol. 204, NO. 819, 1980, pp. 52-58. displacement. Benjamin Zuclzer begins with a short summary of the A diagram is also given which plots chromacity co- history and lore of emeralds, from their limited use by ordinates for daylight and artificial light. The authors the Egyptians and Komans to the discovery by the conclude that this change-of-color spinel does exhibit Spanish of the vast resources held by the Incas in South the four common spectral features. DMD America. He then comments on the rarity of emeralds, which he feels is related to their unique chemical com- Amber-the New World's fossil . G. 0. Poinar, Jr., position. According to the author, the finest color of and F. Agudelo, Amtricas, Vol. 32, No. 10, 1980, emerald is "old-mine" green, a term that is supposedly pp. 31-41. derived from the color of the stones that were first sent After a brief introduction that mentions the classic am- back to Europe by the conquistadors. It is a color he ber locality of the Baltic Coast and brushes on amber's describes as a "deep, intense, velvety, almost blackish ancient uses and lore, this article discusses in some shade of green." detail the fossil resin deposits found in the Americas. The color, commercial potential, and characteristic It focuses on the amber deposits of the Dominican Ke- inclusions for emeralds from the major world sources public and Chiapas, Mexico, with additional informa- are presented. According to Mr. Zuclzer, no source cur-

48 Gemological Abstracts GEMS & GEMOLOGY Spring 198 1 rently compares with Colombia. Sandawaila emeralds infra-red spectra ant1 behavior following heat treat- (Zimbabwe] are often small and have a less intense ment, which reflects initial growing conditions. Three green, Zambian stones are blaclzish and often highly figures and four tables summarize the results for the included, while Brazilian stones are frequently craclted two groups before and after heating. The extensive bib- and oiled. Twenty-one colored photographs present liography will also be helpful to the reader. DMD typical emeralds from the various localities as well as Green from Gabanintha Western Australia. R. A. illustrate inclusions found in natural and synthetic Ball, Australian Journal o/ Gemmology, Vol. 1, stones. NO. 3, 1980, pp. 5-7. Although this article is not complete from a gem- Ball reports the occurrence of bright "emerald" green ologist's point of view, it is a very good introduction opal at Gabanintha, the principal copper center of the to emeralds and could be useful to the gem Murchison Goldfield. Noting that the opal is found in salesperson. RSS quartz associated with copper minerals, Ball suggests Estudio del material de inter& gemologico 'angel stone' that the opal results when olivine that has been con- (A study of a material of gemological interest-an- verted to serpentine is altered to magnesite and opal gel stone). J. M. NoguCs Carulla, C. de la Fuente through the agency of carbonated water. He concludes Cullell, L. M. Roberdeau, and J. M. Bosch Figueroa, that the green color results when opal absorbs copper. Gemologia, Vol. 1 1, No. 4 1 and 42, 1979, pp. 17- Five photographs are included in the article. It is 29. difficult to appreciate the two hand-specimen photo- "Angel stone" has been considered attractive and du- graphs because they are in black and white, not color. rable enough for use in jewelry. The authors report on Ball used three scanning electron micrographs to sug- a gemological study of the material. Angel stone is gest that the opal is actually in a transition stage microcrystalline, opaque, and pale pink. Its major con- between opal and , as evidenced by the "distinct stituent is the mineral palygorslzite, impregnated by agate type banding" shown in the photomicrographs. amorphous silica. The pink hue derives from man- In the summary, he cites Cassedanne and Cassedanne's ganese in the palygorslzite (which can also be grayish, (1975)account of the occurrence of green opal in Brazil yellowish, or whitish). The sample tested was crypto- and questions whether a parallel exists between the crystalline, with no directions or fracture planes. There two, iron causing the color in Brazil and copper causing were no cleavage surfaces or splinters; the fracture was the color in Australia. DMD conchoidal. Irradiation-induced colors in gemstones. K. Nassau, The study included X-ray diffraction, X-ray fluores- Lopidary lournal, Vol. 34, No. 8, 1980, pp. 1688- cence, thermal analysis, examination under the elec- 1706. tron microscope, and hydrostatic weighing. Hardness tests were performed with a photon~icroscope.It was Dr. Nassau begins by citing the increased availability concluded that the impregnation of the palygorslzite of irradiation facilities as the primary reason for the added appreciably to the hardness of angel stone (4.5, trend in artificial color change of this type. He then as contrasted to palygorskite's 2.0-2.5) as well as to its provides a thorough and understandable explanation of compaction, rendering it usable as gem material. the sources of irradiation, including visible light, ultra- For further information on palygorslzite, see Christ violet light, X-rays, and gamma rays. The discussion et al., "Palygorslzite: New X-ray Data," The American also details where each source of irradiation is to be Mineralogist, Vol. 54, Nos. 1 and 2, 1969, pp. 198- found and how samples are treated. In general, the low- 205. SLD energy rays [X-rays) and those particles that are nega- tively and positively charged penetrate poorly and sub- Explanations of the absorption spectra of natural and sequently color only the surface layer. More active synthetic Fe- and Ti-containing corundums. K. gamma rays and neutrons penetrate very well, produc- Schmetzer and H. Bank, Neues Iahrbuch fur Mi- ing uniform coloration. As long as the irradiation used neralogie A bhundlongen, Vol. 139, No. 2, 1980, pp. is energetic enough to cause the intended color change, 2 16-225. the nature of the source is unimportant. A table sum- Schn~etzerand Banlt examined the effects of heat treat- marizing the types of irradiation used to effect color ment on the absorption spectra of 154 natural sapphire change is supplied. crystals from corundum localities in 10 different coun- A color change induced by irradiation is, in most tries. Using three different spectrophotometers to mea- cases, due to the formation of a color center. Once a sure absorption spectra, the authors studied the alter- color center has been bleached, it may usually be re- ations of the absorption spectra and then drew turned to its original hue by further irradiation. If, conclusions about the mechanisms and valence of the however, the sample was overheated during bleaching, color-causing transition ions. re-creation of the irradiated color is impossible. For ex- While all sapphires show certain absorption bands, ample, amethyst that has been heated to citrine may they can be divided into two groups based on their be returned by irradiation to its original color provided

Gemological Abstracts GEMS & GEMOLOGY Spring 198 1 49 the temperature used has not been too great. The sta- average weight was 0.57 ct. The refractive index of this bility of a color center to light exposure-i.e., the re- material ranged from 1.764 to 1.792. The specific grav- sistance to fading-is the basis for three groups of ity ranged from 3.92 to 4.17. The authors concluded irradiation-produced color effects. A fourth irradiation that the six types of crystal inclusions noted in these effect, one that does not involve color centers, is also garnets were probably rutile, zircon, monazite, actin- described. The irradiation and bleaching behavior for olite, apatite, and ilmenite. ET topaz, , , kunzite, and quartz is sum- Nuggets of island sun. H. E. Rice and P. C. Rice, marized in a second table. Americas, Vol. 32, No. 10, 1980, pp. 37-41. The article represents a well-organized, up-to-date This short article offers a brief overview of the budding work on irradiation sources, color-center stability, and amber industry in the Dominican Republic. It describes how irradiation may be identified. It incorporates sev- the shops where amber can be purchased and mentions eral aspects of the large body of research on color and the methods used by local craftsmen to fashion raw treatment already credited to Dr. Nassau. PCS amber into polished gems and jewelry. The authors Ivory-popular but prone to many imitations. G. Brown, continue with a general description of some types of Ieweller Watchmalzer d Giftware, Vol. 65, No. 1, amber found in the Dominican Republic aild of mining 1980, pp. 22-23. methods used to recover the amber. It is interesting to Australia has not yet invoiced trade embargoes on carved note that although the Dominican Republic deposits ivory, which is very popular there. Its popularity has are considered to be recent discoveries, large-scale min- naturally resulted in sometimes successful efforts to ing was begun in 1949 and the first school for polishing unload imitations on retail jewelers; this article tells amber was established early in the 1950s. how to detect such imitations by visual inspection, hot The article concludes with a summary of how am- point, and microscopic examination of thin peelings. ber was formed and some mention of its inclusions. Eleven photographs serve to clarify the text. These per- lIK mit comparison of the "engine-turned" effect of ele- Royal lavulite discovered. B. Jones, Roc/

50 Gemological Abstracts - GEMS h GEMOLOGY Spring 1981 Madagascar. Named liddicoatite after GIA's well-ltnown do business with any government regardless of the pol- president, this type of tourmaline is found to have an itics of that government. unusually high calcium content. Wentling discusses However, the buying of diamonds for investment briefly the locations where liddicoatite has been found, purposes and the selling practices of the Soviet Union and describes the unusual color zoning that malzes this (which accounts for 20% of world production] are caus- type of tourmaline fascinating. NPK ing DeBeers to take additional steps to "restore order to the diamond world." To circumvent the impact that investor disenchantment could have on marlzet stabil- DIAMONDS ity, DeBeers is striving for greater concentration of power, which clearly includes cutting and polishing as Battle lines form on lasering disclosure. H. Huffer, /ew- well as advertising and sales. Technological develop- elers' Circnlar-IZeystone, Vol. 151, No. 10, 1980, ments supported by DeBeers in sawing, cleaving, brut- pp. 42-44 ing, and polishing have generated the greatest amount Associate Editor Helene Huffer reports on jewelry in- of negative response from some of the traditional dia- dustry reactions to the most recent position talten by mond leaders. Similarly, they question the direction the Jeweler's Vigilance Committee (JVC]on disclosure DeBeers is talzing through its subsidaries and "coop- of laser drilling in diamonds. As proposed in the "Dia- erative, efficient companies" in the distribution and mond and Gemstone" sections prepared for the Federal sale of polished diamonds. Clearly, the greatest impact Trade Con~missionas part of the revised Trade Practice of this will be on the smaller business people, whether Guidelines, lasering need not be disclosed. JVC Dia- cutters, middle-level dealers, or independent jewelers. mond Committee Cochairman Leo Kaplan stated that XIS because Indians and Israelis are now lasering melee, it would be "too cumbersome" to check each stone. Some very important but little known historic dia- Huffer interviewed other important leaders in the monds. E. B. Tiffany, Zeitschrift der Deulschen jewelry industry, including Sydney DeYoung of J.&S.S. Gemmologischen Gesellschuft, Vol. 29, No. 1 and DeYoung, GIA1sG. Robert Crowningshield, and Robert 2, 1980, pp. 71-78. Mason of J. C. Keppie Co. The impact on the diamond's worth is a ltey issue. On the one hand, lasering often Mr. Tiffany briefly outlines several of history's most improves the clarity of a stone, increasing its value famous diamonds, and compares them with some ob- hundreds of dollars while the lasering itself costs only scure yet noteworthy stones. Citing diamonds from $25 to $35; on the other hand, the fact that a diamond such places as Iran, the Soviet Union, and India, Tiffany has been lasered could make the stone undesirable to suggests that many of these "unltnowns" have been some and in most cases reduces its value about 10% hidden away in private collections or discovered too from that of a similar stone that hasn't been lasered. recently to gain public notoriety. Sixteen pictures of Is it ethical not to tell the buyer a stone has been la- stones from the lranian Crown Jewels and the Soviet sered? The controversy over this issue will continue. Diamond Fund are included together with descriptions of their color and weight. NPK RlS Editor's Note: The December 1980 issue of ICK reported that the jeweler's Vigilance Committee has A visit to a diamond mine, I and 11. H. Hurst, Modern reversed its position, and now recommends that laser- leweler, Vol. 79, No. 9, 1980, pp. 10-59 and No. ing be disclosed. 10, 1980, pp. 16-48. For those who have never visited an actual diamond The diamond market: a new concentration of power. mine, this brief but interesting "tour" in Kimberley, M. Gilbert, lewelers' Circular-Keystone, Vol. 151, South Africa, malzes enjoyable reading. The color pho- NO. 9, 1980, pp. 79-90. tos included in the article give one a glimpse of the Industry Projects Editor Mitchell Gilbert describes in modern technology now used in these operations, detail new efforts by DeBeers to concentrate power in somewhat resembling the mining of coal, copper, or the diamond marlzet. Every member of the jewelry limestone. Hurst also describes the Pan Plant, where trade will be affected by the dramatic changes occur- the crushed blueground is processed. It is noteworthy ring at all levels, from sales and distribution to mining. that X-ray sorters, which use the natural fluorescence A review of the reasons why the cost of rough dia- of diamonds, are part of the recovery. We are reminded monds is escalating gives insight into the five ways of the mystique, wonders, and hopes of diamond min- DeBeers obtains 85% of the world's rough production. ing by the story of how the finder of a 616-carat dia- Three ltey considerations are upgrading living stan- mond received $20,000 plus a new house from DeBeers dards for its black African worlters, prolonging the life as a reward and incentive to find more like that one- of its mines, and establishing policies that enable it to it should happen to all of us! GR

Gemological Abstracts GEMS & GEMOLOGY Spring 198 1 5 1 GEM INSTRUMENTS AND TECHNIQUES sen to program in tables of selected gemstones by as- cending refractive indices, by alphabetical listings, and Application of multi-purpose spectrophotometer and by individual "gem profiles" which list major identi- X-ray fluorescence analysis to distinguish natural fying characteristics of the gemstone. When informa- and synthetic alexandrites (in Japanese). N. Hori- tion on an unknown is put in, all possibilities in the uchi, lournal of the Gemmological Society of la- computer's memory within a given range are suggested. pan, Vol. 6, No. 3, 1979, pp. 77-80. The author also discusses other types of programs lnviting reader comments and contribution to his con- that can be modified to suit a particular need. These tinuing research, author Nobuo Horiuchi of the Central programs appear to be very easy to read and implement. Gem Laboratory, Ueno, Taito-la, Tokyo, contends that Stating that the programs were initially used as teach- with the emergence of sophisticated synthetics and ing aides, Read also suggests that this computer can be new natural gem sources, the multipurpose spectro- a valuable sales tool for retailers. NPK photometer together with X-ray fluorescence analysis can offer a new means of distinguishing alexandrite Etude par spectroscopie raman d'inclusions dans les (chrysoberyl) originating in different localities (Many- diamants, saphirs et emeraudesll (Study of inclu- ara, Tanzania; Bahia, Brazil; Tokowaya, Russia) from sions in diamonds, sapphires, and emeralds by Ra- its synthctic counterparts (flux alexandrite from both man spectroscopy-part 1). M. L. Dele-Dubois, P. Kyoto Ceramic Co. and Creative Crystal Co.) Horiuchi Dhamelincourt, and H. J. Schubnel, Revue de does not comment extensivelv on K. Nassau's Czo- Gemmologie a.f.g., No. 63, 1980, pp. 11-14. chralski alexandrite, although its properties are pre- This is the first of a two-part article on the use of Ka- sented in chart form along with those of the stones man spectroscopy, which permits the simultaneous listed above. The author details the physical and opti- identification of both the host material and its inclu- cal properties of the natural and the synthetic alexan- sions. Because it is noninvasive and not destructive, drites to facilitate comparison and to emphasize the this technique is well suited for studying gems with need for a spectrophotometer and X-ray fluorescence the exception of materials that are opaque to the wave- analysis in identification. lengths of the excited photons. With the multipurpose spectrophotometer, pat- With this technique, a stream of laser-generated terns between 400 and 700 nm are the same for the photons penetrates the specimen, and a study of the natural (Bahia and Manyara) alexandrite and the syn- Raman spectrum locates and identifies the different thetics produced by Kyoto Ceramics and Creative atomic constituents present therein. The beam is se- Crystals. A graph illustrates the unique differences lected according to the inclusion in order to excite as below 400 nm, however. Kyocera alexandrite has little fluorescence as possible. considerable absorption in this area, while Creative al- Examination of some South African diamonds iden- exandrite reaches a small peal< at 385 nm; 355 nm is tified inclusions of chrome spinel, peridot, , its actual peak marked by a sharp decline. This absorp- graphite, and pyrope. A violet sapphire from Colombia tion pattern, similar to that found in the natural stone, contained a calcite crystal and a zircon with a tiny results from the material's iron content. The unique apatite crystal. The text is clearly illustrated with graphs absorption (at 685 nm, with a dale at 420 nm) in Ky- of the spectra and some inclusion photographs. An ex- ocera alexandrite is due to its chrome content and the cellent list of references follows the article. CKG absence of iron. In the X-ray fluorescence analysis, the stones on the A phosphoroscope. R. M. Yu and D. Healey, lournal of chart were tested for chrome, iron, gallium, germa- Gemmology, Vol. 17, No. 4, 1980, pp. 250-258. nium, and platinum. Chrome was found in natural al- In this article, the authors explain the use of ultraviolet exandrite but not in large amounts in the synthetics. absorption in gem identification. The phosphoroscope Iron was found in all but the Kyocera alexandrite. In allows direct observation without need of film, al- the Creative Crystal stone, iron had a very high peak, though film can be used if a permanent record is desired. approximately 1.5 times higher than in the natural. The specimen is placed in a simple wooden box atop Platinum was found in the Kyocera product because of a black cloth covering phosphorescent paper. An ultra- the crucible used in its creation. The procedures de- violet light (short wave) is directed on the stone and a tected gallium only in the naturals and germanium mirror below the paper allows one to view the results only in the Russian natural material. A LS through a port. In the section on observations, a rigid mathematical presentation is given to explain the cause Computer-aided gem identification. P. Read, Journal of of the dark rim seen around the edges of the stone. The Gemmology, Vol. 17, No. 4, 1980, pp. 239-249. type of film recommended and its use are briefly Peter Read has designed table-top computer programs described. for a CRT (TV-type) read-out to aid in gem identifica- Three figures are used to compare the results of test- tion. To facilitate use of this time-saver, Read has cho- ing synthetic and natural rubies, sapphires, and emer-

52 Gemological Abstracts GEMS & GEMOLOGY Spring 1981 alds. The absorptive effect of iron in each material is aquamarine deposits, the supply of which has de- discussed. Chzlck Fryer creased in recent years. While the Bahia region, north of Itabira, has recorded emerald finds, no one ever an- GEM LOCALITIES ticipated an emerald occurrence in Minas Gerais. The search began in 1978, with the first significant discov- The Cruzeiro mine: past and present. J. P. Cassedanne, ery made in 1979. J. 0. Cassedanne, and D. A. Sauer, Mineralogical According to Shono, who visited the mine, the Record, Vol. 11, No. 6, 1980, pp. 363-370. quality of the Itabira emeralds is not inferior to the The Cruzeiro pegmatite mine, located northwest of Colombian stones and is far superior to those found in Governador Valadares in Minas Gerais, Brazil, is one Bahia. Both the color and tone are good; crystals as of the most famous gem pegmatite mines in the world. large as one kilo have been uncovered. Compared to First worked for strategic mica during World War 11, it the Bahia stones, the Itabira crystals have few craclts. has since become famous for its outstanding gem tour- Tubular inclusions are characteristic. malines, which are usually pink or green and may be Manual mining is being conducted on 200-250 m' quite large. This article is the most comprehensive to sections that are further broken down into 10 m2areas date on the Cruzeiro mine. The authors present a de- to which five to eight miners and one supervisor are tailed description of the local geology and assigned. Profits from the weekly sale of emeralds are of the deposit, with photographs and geologic maps. allocated on a 20180 ratio between owner and miners, The deposit consists of three elongated, subparallel respectively. In the near future, mechanized mining pegmatite lenses, frequently only a few meters in width. techniques will be used. A LS The main wallroclz is a white-to-light buff, medium- Opal in Piaui State, Brazil. E. A. Jobbins, Zeitschrift der grained quartzite. The gem pockets appear to be local- Deutschen Gemmologischen Gesellschaft, Vol. 29, ized where the pegmatites widen and are most differ- No. 1 and 2, 1980, pp. 40-54. entiated. These widenings are frequently controlled by Geologist Jobbins describes three opal-bearing areas in local arches in the hanging wall. the northern half of Piaui State, pinpointing sites pre- Currently, the mining operations are supported by viously ltnown but unsubstantiated. Four types of opal independent miners working on the mica in leased deposits, each with unique mining operations, occur in areas of the deposit. However, the search for gem tour- the Pedro 11, Castelo do Piaui, and Varzea Grande lo- maline continues. Peter Iceller calities, but only Pedro I1 is economically significant. First Discovery of Ruby in Australia. D. H. McColl and Jobbins focuses on the Pedro I1 area, describing first its R. G. Warren, Mineralogical Record, Vol. 1 1, No. 6, geology and then the individual occurrences of precious 1980, pp. 371-375. opal and how they are mined. These are located on a The first significant discovery of commercial ruby was map that includes the rivers, a major agent in the dis- made in the Harts Range of the Northern Territory of tribution of alluvial , as well as the quartz-dolerite Australia in 1978. The ruby occurs as well-formed, dykes that functioned as feeders for quartz-dolerite hexagonal tabular crystals up to 5 cm in diameter and sills. The author suggests that the decomposition of 1 cm thick in a distinctive layer of greenish gneiss these sills, in providing the necessary silica, is one of within the Riddock amphibolite. It is thought that the five factors that may be involved in precious-opal for- amphibolite formed from a terra rossa soil profile on mation at Pedro 11. He also notes that while the phys- a limestone contaminated with pyroclastics and inter- ical characteristics of the precious opal differ consid- laminated with lavas and tuffs. erably from one deposit to the next in the Pedro I1 area, To date, very little material of faceting quality has the overall quality is such that there is great similarity been found. The Australian rubies do, however, cut with some of the Australian opals. pleasing cabochons. No asteriated material has been In contrast, there are no reports of precious opal in noted. The deposit appears to be extensive, with pros- the Varzea Grande or Castelo do Piaui areas, although pects good for more ruby from the Harts Range common opal ranging in color from clear to milky to area. Peter Keller reddish orange has been found. These areas could be New emerald mine in Itabira (in Japanese). Y. Shono, explored further, but Jobbins concludes that the Boi Gemmological Review, Vol. 2, No. 2, 1980, pp. 8- Morto region of Pedro I1 is most favorable for locating 10. new deposits. DMD With a map, some photographs, and a text based on JEWELRY ARTS personal observations, Yoshihiro Shono, a gemstone importer-exporter, introduces the reader to the first Gold as art. B. Cartlidget Aurz7mJ Val. 80, No. 3, 1980, significant commercial-quality emerald source in the pp. 4-7. Minas Gerais region of Brazil. The new emerald site, The author, a jewelry designer and freeman of the Wor- Itabira, historically has received recognition for its shipful Company of Goldsmiths, begins by summariz-

Gemological Abstracts GEMS & GEMOLOGY Spring 198 1 53 ing what an extraordinary metal gold is and how its ing, and sales techniques. The author shows himself unique qualities have affected events throughout his- to be a practical gemologist by suggesting ways to tory. The imagery and symbolism surrounding the avoid sales-ltilling expressions such as "flaw," "cheap," metal itself permeate language and transcend culture. and "cheaper." He discusses the term semi-precious, Its stability as a metal lends toward hoarding, wor- advising that it be discarded. This article also covers shipping, and the passing of personal objects from gen- such topics as display, lighting, birthstones, slzillful eration to generation. price tagging, and other sales techniques. Throughout Gold is fashioned by means of a great variety of the article, Mr. Sabbagh instructs gemologists to use techniques and is combined with various metals to their gemological ltnowledge to achieve sales priorities. produce a broad range of colored alloys. The experience ET of working with gold can be frustrating to all but the SYNTHETICS AND SIMULANTS most dedicated artist. Once mastered, though, it offers access to a very personal form of expression. The au- Nuevas tecnicas de observacion de la luminiscencia en thor lists well-linown artists from around the world diamantes y en algunos de sus substitutos (New and describes the techniques and styles of a few. In- techniques for observing luminescence in dia- dustrial processes have made gold jewelry more avail- monds and in some of their substitutes). J. M. able to more people but commercial production has not Bosch Figueroa, L. M. Roberdeau, Gemologia, Vol. lzept pace with contemporary design. This is due par- 11, No. 43 and 44, 1979, pp. 7- 12. tially to the trends that commercial designers follow To compare and contrast diamonds and their substi- and partly to the concerns of manufacturers. This ar- tutes, the writers devised an apparatus to expose stones ticle offers much to the salesperson and artist alilze. to long-wave fluorescence (3650 A) and recorded the R SS results. The specimens selected were cut stones that exhibited -Cape diamonds, brown Inlay techniques used in netsuke. F. Yano, Arts of Asia, diamonds, and colorless gem materials used as dia- Vol. 10, No. 5, 1980, p. 155. mond substitutes. The diamond substitutes emitted This article defines and describes inlay techniques phospl~orescencestrong enough to expose photographic used in netsulte, beginning with the origin of inlay in plates. The stones were exposed to the fluorescence for netsulte and some of the schools that have used this three minutes, first at 20"250Cr then at 300°C. technique. While some authorities believe inlay de- Of the Cape-series diamonds, those with sharp blue veloped as early as the 16th century, others think it phosphorescence showed more intense color at the originated in the 18th century. Mr. Yano defines inlay higher temperature; those that showed blue with whit- as "the technique of combining or filling in different ish opalescence became yellowish at 20"-25°C and in- materials to express one's art." tensely blue as the temperature approached 300". The The article features a photograph of Alzihide brown-series stones showed indefinite yellow and were Kawahara, who is described as the only living artist in lightly opalescent at 20"-25" C, with the color more Japan who has mastered both inlay and carving tech- intense at 300°. Corundum and synthetic spinels were niques. There are also six photographs showing the dark red at the lower temperatures, becoming orangey development and finished version of his lzappa (water red as the temperature increased. YAG and GGG were imp) netsulte, which is made of wood inlaid with tor- orangish at 20"-25", turning reddish with increased toise shell. temperature. In discussing the evaluation of inlay techniques, the The findings lay the groundworlt for the application author explains that the joining of the two materials of ultraviolet light to the further study of colored dia- is most important: there should be no space between monds, natural and treated, as well as other gemstones. them. Even if the inlay fits perfectly at the sides, there SLD may still be a space at the bottom. Older Japanese cleal- ers detect this by tapping the work with an ivory chop- The optical constants of G.G.G. K. Nassau, journal o/ stick; if it sounds hollow, they know there is a gap at Gemmology, Vol. 17, No. 3, 1980, p. 148. the bottom. The quality of the fit not only dctermines In this short article, Dr. Nassau gives refractive index the value of the netsuke but also affects the durability (1.970) and dispersion (0.045) values for G.G.G. based of the piece. ET on recent precision measurements by Dr. D. L. Wood of the Bell Telephone Laboratories. ET RETAILING Synthesis of emerald and other colour-varieties of beryl Promoting and merchandising coloured stones. J. Sab- minerals (in Japanese).I. Yagi and N. Adachi, 10~1.- bagh, Iournal of Gemmology, Vol. 17, No. 3, 1980, nal of the Gemmological Society of lopon, Vol. 6, pp. 165- 180. NO. 3, 1979, pp. 67-72. Mr. Sabbagh discusses the merchandising of colored Different from both the flux and hydrothermal meth- stones and covers inventory, point-of-sale merchandis- ods of emerald synthesis, the newly developed gas-

54 Gemological Abstracts GEMS & GEMOLOGY Spring 1981 solid reaction method described by authors Isao Yagi a structural inclusion which produces the amethyst and Naosulte Adachi produces crystals that closely ap- color when irradiated. The smoky coloring, which de- proximate their natural counterparts in both physical valuates the stones, can be held to a minimum by us- and optical properties. ing charge quartz of high purity or adding oxidizers The explanation of the process is purposely brief such as lithium nitrite. Crystals grown by this method and vague because the patent is pending. Oxygen and usually have a flattish shape with hillocks composed fluorine gas react with crystalline or amorphous Be0 of Brazilian twins on the positive rhombohedra1 faces (beryllium oxide), A1,0, (aluminum oxide), SiO, (sili- and dophinean (sic) twins on the negative rhombo- con dioxide), and chemicals in a platinum tube hedral faces. at very high temperatures. Then, at lower temperatures, The second method of growing synthetic amethyst crystallization occurs on seed crystals of natural beryl. crystals also used the hydrothermal process but with To form a 1-cm crystal, this process, which takes 20- aqueous solutions of ammonium fluoride as the sol- 40 days, is repeated two or three times at temperatures vent. With this solvent, the aluminum-alkaline cen- of 800"-1000°C and gas pressure of one atmosphere. ters of smoky coloring are eliminated. For crystals of The rate of crystallization depends on the doping the best color throughout the growth layer, alkaline agent used. By taking advantage of the differing rates metal ions such as those of lithium are added. This of formation under controlled conditions, crystal grow- protects the amethyst color centers from thermal de- ers can create beautiful multicolored beryl, including struction while in the autoclave. The external mor- a watermelon variety. phology differs from that of the material produced by produced by the gas-solid reaction method the first method in that it has growth pyramids instead may be used to simulate a wide variety of gemstones, of twins on the crystal surfaces. including morganite, aquamarine, garnet, The spectra of the synthetic amethysts have the blue spinel, amethyst, , peridot, , ama- same approximate absorption bands as natural amc- zonite, rubellite, rose quartz, and others. The ASIC thyst, although the alkaline-produced stones match (synthetic) emerald closely resembles the'natural in the spectra of the natural material more closely than appearance and properties and is discussed most com- do the fluoride-produced stones. As helpful as the text, pletely in the article. nine figures, and bibliography are, the reader is advised In addition to photographs, the authors provide that the article has been roughly translated and will charts of optical and physical properties for various require extra effort to read. GSH doping materials. The exact doping agents for the ASIC emerald are not given, but its characteristics are as fol- MISCELLANEOUS lows: color, green; Munsell color standard, 5G Jh; di- Les joyaux de la couronne de France a la veille de la chroism, strong blue green to yellow green; spectrum, revolution (The French crown jewels on the eve of absorption above 7000 A and at 6900 A, weak at 5900 the revolution). B. Morel, Revue de Gemmologie a and below 4200 A; fluorescence, light red under both a.f.g., No. 63, 1980, pp. 2-8. long- and short-wave ultraviolet lightj average refrac- The author bcgins with an account of how the jewels tive index, 1.570; specific gravity, 2.67. X-ray diffrac- belonging to the French royalty were inventoried and tion Datterns are also noted for the ASIC emerald and appraisals made according to decrees of the National for other doping agents. Assembly in May and June 1791, on the eve of the While the authors claim success, they also ac- French Revolution. He explains how diamonds were knowledge the need to improve the technique, espe- cially with respect to speed and the transparency of the evaluated during that period, and points out the dif- end product. A LS ferences between the old carat (0.205 g) and the metric carat (0.200 g) as well as interpreting currency equiv- Synthetic amethyst: its history, methods of growing, alents in modern francs. morphology and peculiar features. V. S. Balitsky, The historic detail may be of interest, since some Zeitschrift der Deutschen Gemmologischen Ge- well-ltnown stones are mentioned. However, the arti- sellschaft, Vol. 29, No. 1 and 2, 1980, pp. 5-15. cle is primarily a catalog of all the royal jewels: not Balitsltv discusses the evolution of the basic methods only diamonds, but also unmounted pearls, rubies, to- of growing synthetic amethyst while highlighting their pazes, and emeralds. It includes six well-captioned, characteristics and their differences. The first method black-and-white photographs and sketches and a short used the hydrothermal .process with a strong alltali- bibliography citing several catalog and historical aqueous solution as a solvent. Iron is incorporated as references. CKG

Ge~nologicalAbstracts GEMS & GEMOLOGY Spring 198 1 55 Stephanie Dillon, Editor

AFGHANISTAN SITUATION addition, there are more than 1,500 registered exporters. Reports from a neutral observer -are that Afghanistan's Obtaining sufficient rough has been a problem: India's gem-yielding districts, in mountainous terrain, have sole mining operation at Panna supplies only 0.001% not fallen to the Russians. of the 18 million carats used annually, and the amount Sar-El-Sang, in the province of Badalzhshan, is the purchased from De Beers is less than satisfactory. prime source of , and the Nurestan pegma- Expanding domestic production to 100,000 carats a tite district produces beryls, , and Izunzite. year is an industry goal. Also in process are plans to Prior to the Russian incursion, about a ton of lapis was purchase rough directly from Ghana, the world's fifth exported per year. Although mining has virtually halted, largest diamond producer. it appears that material continues to leave the country, thanks to the considerable reserves existing at the time China. Last September, a year-long Sino-German trade of the invasion. agreement, whereby German training and technology are combined with Chinese labor and diamonds, cul- minated in the opening of Pelting's first diamond-cut- DIAMONDS ting factory. The Pelting branch of China's Australia. Since 1978, exploration in Western Aus- National Arts and Crafts and lndustrial Products Com- tralia's Kimberley region has been pursued by numerous pany received the lzey to the factory from V.K. Nara- groups on over 5,700 claims of 120 hectares (296.4 simhan, of Frankfurt. The same day, the diamond- acres) each. Samples from one of 28 lzimberlite pipes cutting school, established by the German company for in Ellendale Province have yielded approximately one 50 students in January of 1980, was donated to the carat per 22% tons of material, with close to 18,000 Chinese authorities. stones taken thus far from the region. The largest piece More diamond-cutting schools and factories are to of rough was 6.47 carats; the average weight was 10 be cstablished. China reportedly plans to employ points. It is thought that these sources will produce a 300,000 people in the cutting of diamonds by 1985. high percentage of gem-quality stones. Diamonds are mined in Hunan province both from More excitement has been generated over primarily a huge source discovered in the 1960s and from a pipe industrial-quality finds near Lalze Argyle, close to the recently found in Liaoning. Estimates are that 1.8 to Northern Territory border. Eight hundred carats of dia- 2.8 million carats are being produced, with some Amer- monds per 100 tons of associated alluvial gravels have ican advisers assisting in the renovation of the mines. been recovered as far as 20 miles from the pipe itself. The Chinese plan to market their diamond exports The pipe covers 1 11 acres at the surface, making it one through Frankfurt rather than De Beers. of the world's largest. More than 5,000 carats have been produced, with the largest stone weighing 7.03 carats. U.S.A.The Wyoming Geological Survey is extending to The treatment plant has been relocated here from a second year the completion of its report on diamond Ellendale. It will have the capacity to process up to deposits in kimberlitic pipes and placer traps in the 3,000,000 carats per year from the upper alluvial Laramie and Snowy ranges. Undertaken by the Mining deposits. and Mineral Resources Institute of the University of Wyoming for the U.S. Department of the Interior, the India. A countrywide exploration project was announced study has turned up two new lzimberlites as a result of last April, following the geologic find of potentially the stream-sediment samples collected last summer. worlzable deposits. India's diamond-cutting shops number around U.S.S.R.-Record Stone. In December, the discovery of 20,000 and employ 300,000 cutters and polishers. In the largest diamond yet found in the Soviet Union was

56 Gem News GEMS & GEMOLOGY Spring 1981 reported. According to Tass, the Soviet news agency, stones and imported diamonds, colored stones, gold, it is egg-shaped, lemon-yellow, transparent, and weighs and silver, which will be marketed chiefly in Japan, 342.5 carats, 110 more than the previous record-holder, North America, and Europe. the Star of Yakutia. It was also found in the Yakutia region of northeastern Russia. TUCSON GEM AND MINERAL SHOW ACTIVITY RUBY - Aquamarine. Aquamarine from mountainous Boise While much of the material from Kenya is brownish County, Idaho, attracted considerable interest. Aquas and suitable only for cabochons, the gemstone belt have been mined in the area for about two years. Each from the Taiti Hills to the Tanzania border has been pocket produces approximately a half-kilo of crystals. found to contain deposits of fine, Burmese-color rubies The rough has yielded cut stones of up to seven carats of up to one carat. No real mining activity has occurred of excellent, medium color. as yet. A large ruby field in Australia's Harts Rangc, north- east of Alice Springs in the Northern Territory, has Red Beryl. From a total production over the last year yielded approximately 40,000 carats in cut stones in of 1,000 carats of red beryl from the Wah-Wah Moun- the past year and a half. Since most of the material is tains of Utah, about 500 carats were on display in not of high quality, the find does not affect the current Tucson. The majority of the yield has been stones of shortage of finer stones. from 10 points to one-half carat, the largest fine-quality A recently discovered ruby deposit in Mysore state, stones weighing about one and one-half carats. southern India, has produced stones of fine color but suitable only for spheres and cabochons. Synthetic Red Beryl. While its emeralds are showing The Hunza Valley of northeastern Pakistan is a 30- fine color, Regency Created Emeralds Company, in its square-mile area containing deposits of various gems, attempt to produce red beryl through the hydrothermal but it is particularly rich in ruby. From July 1977 to process using manganese as a coloring agent, has so far June 1978,42.2 million carats of rubies were recovered produced only pink beryl. there. A government corporation mines, cuts, polishes, and markets the stones. While much of the material is considered excessively flawed, some specimens that Sugilite-A New Gem Material. "Royal lavulite," have appeared in the U.S. indicate that stones of excel- referring to the sugilite accidentally discovered in last lent quality may be forthcoming. year's roof collapse of a South African manganese mine, was prominent in Tucson. Of the probable three tons in the deposit, 360 kg are suitable for jewelry, about 18 SAPPHIRES kg of which show extraordinary color-blue-purple to Kashmir, India, sapphire production, halted in recent red-purple to magenta. years, may be resumed on the recommendation of the board of directors of state-owned Jammu and Kashmir Pink Fluorite. Of special interest to mineral collectors Minerals Ltd. The plan to lease out the Paddar Sapphire were samples of pink fluorite from a December find in Mines was made by thc state in 1977. The leasehold of Huanzala, Peru. About 500 matrix pieces with octa- JKM is due to expire in 1982; a new lease order must hedral crystals were discovered. be approved by the Indian government. Four firms are The color does not fade in sunlight, but rather bidding for a 20-year lease, offering plans for mine intensifies after several days' exposure. The crystals, development and establishment of a state gem-cutting unusual for their color as well as for their sharply and polishing industry. octahedral shape (most fluorite is cubic), are up to 40 A sapphire deposit in North Queensland, Australia, mm in size, some clear enough for faceting. The crys- has yielded stones of up to 10 carats. tals show a rich pink color in daylight, with green cen- ters; under fluorescence and incandescence, the colors SRI LANKA LAPIDARY become dim. The Greater Colombo Economic Commission of Sri Lanka has signed an agreement with a Monte Carlo Topaz. Topaz was another stone in great abundance at gem and jewelry dealer to establish a gem-cutting the show. However, the recent closing of two Ouro enterprise in the coastal town of Kalutara, 16 miles Preto mines, combined with the approach of the rainy south of Colombo. About 400 people will be employed season (when mine activity generally slows or halts), on the five-acre site to work with locally available gem- may soon be reflected in a topaz shortage.

Gem News GEMS & GEMOLOGY Spring 1981 57 Carnegie Institute's Museum of Lizzadro Museum of Lapidary Art- Natural History-4400 Forbes Ave., 220 Cottage Hill, Wilder Park, Elm- Pittsburgh, PA 15213. Telephone: hurst, IL 60126. Telephone: (312) (412)622-3269. 833-1616. The Hillman Hall of Gems opened The Lizzadro is a public museum in September 1980, and contains a displaying gems, minerals, and art collection of over 2500 gems and objects made of gem materials; there minerals. is a large collection of carved and numerous mineral specimens. Denver Museum of Natural His- Earth science lectures are presented tory-City Park, Denver, CO 80205. each Saturday afternoon at 2:OO. On Telephone: (303) 575-3923. Sundays, there are gem-cutting A gem hall is under construction to demonstrations via closed circuit be opened this fall. It will occupy an television. alcove off the museum's new min- eral hall and will present all new Los Angeles County Museum of donations and exhibits from the Natural History-900 Exposition museum's collection. There will be Blvd., Los Angeles, CA 90007. Tel- about ten displays of gems from ephone: 744-3328. around the world, including a 10,599- "Sweat of the Sun, Tears of the carat Brazilian topaz that was part Moon" is the largest exhibit of Co- of an artistic project created by Sal- lombian gold artifacts and rough and vador Dali. A special collection of cut emeralds ever to be exhibited Colorado gemstones will include outside of the Republic of Colum- approximately 30 specimens. bia. Opens July 4 and continues through September 6, 198 1.

The Adele Steacy Memorial Schol- At a meeting held February 12 in arship is offered annually and is open Tucson, Arizona, formation of a new to a resident of Brockville, Ontario, organization, the American Gem needing aid to study gemology. The Trade Association, Inc., was an- scholarship provides up to $2,500 nounced. The object of AGTA is for the recipient, who will seek em- to promote the interests of colored ployment in the Canadian jewelry stone dealers while establishing a industry upon the completion of his code of ethics for the industry. In- studies, to attend G1A or its equiv- formation can be obtained from alent in Canada. Should no appli- Treasurer David Nassini, of Ameri- cation be made by a Brocltville res- can-Ariana Trading Company, 2 ident, other residents of Ontario will West 46th St., New York, NY 10036. be considered. Applications may be submitted to the Assistant Registrar Gems eS Gemology welcomes news (Student Awards), Queen's Univer- of exhibits and events of a gemolog- sity, Kingston, Ontario K7L 3N6, ical nature. Please contact Ste- prior to July 1. phanie Dillon, Gemological Insti- tute of America, 1660 Stewart St., Santa Monica, 90404. Telephone: (213) 829-2991.

58 Gem News GEMS & GEMOLOGY Spring 1981 AMBER: most mineralogical applications. THE GOLDEN GEM Additional information provided in- OF THE AGES cludes atomic structure, chemical By Patty C. Rice, 289 pp., illus., Van composition, physical properties, BOOK crystal form, and occurrence. Illus- Nostrand Reinhold Co., New York, 1980. $26.95 trations, where appropriate, show the atomic structure, the orientation of As Dr. Rice indicates in her preface, REVIEWS optical directions relative to crystal the intent of this book is to en- John I. Koivula, Editor 1 habit, the variation of optical prop- lighten people on all aspects of am- erties with composition, and the ber, including its history, lore, sci- appearance of the mineral in thin ence, and modern sources. After an section. Of particular value to re- introduction [part 1) that touches on the casual reader as well as for the searchers is the list of references that amber both as a gemstone and as a gemologist interested in refining his follows each description. fossil resin, the human aspects of or her knowledge of amber. Part 11 consists of 267 pages in amber are presented in part 2, be- which the optical and physical DONA M. DIRLAM properties of all nonopaque min- ginning with its earliest occur- Santo Monica, California rences in the archaeological record. erals, including those described in part I, are summarized. The min- Of particular interest to some will OPTICAL MINERALOGY be the description of the early trade erals are grouped according to opti- routes in Europe as derived from The Nonopaque Minerals cal character and are listed in order finds of amber artifacts. Within this By Wm.Revel1 Phillips and Dona T. of increasing refractive index. This section, the organization of the am- Griffen, 677 pp., illus., W. H. Free- method of arrangement facilitates ber guilds and the historical meth- man d Co., Sun Francisco, CA, optical identification. It is part I1 ods of collecting amber are de- 1981. $39.95 that gives this boolt its singular im- scribed, as are the amber centers of Wm. Revell Phillips's earlier work, portance, for nowhere else does such the USSR and Europe. Finally, no Mineral : Principles and an up-to-date compilation exist. boolt on amber would be complete Techniques, has become a popular In its planning, arrangement, without the chapter on lore that college-level text covering the basic content, editing, and printing, this follows. principles of optical mineralogy. is a first-class publication. It is not Part 3 comprises the largest sec- Missing from that book, however, without minor errors (i.e., mineral- tion of the book, with four chapters are the tables of optical constailts ogy is misspelled in the first line of on the more scientific aspects of the and mineral descriptions that are the preface), but these are easily dis- golden gem, from its physical prop- generally included in such texts. regarded. This work should quicltly erties through the geologic theories Phillips, together with Dana T. be accepted as a standard reference of its origin and finally to a descrip- Griffen, conceived Optical Miner- by mineralogists and petrologists. tion of the other natural resins that alogy: The Nonopaqr~eMinerols as As such, it is well worth its price of are similar to amber. The final sec- a companion volume to provide the $39.95; however, this price may dis- tion, "Commercial Aspects," in- important optical data. From this courage its use as a supplementary cludes a chapter on amber imita- original concept, however, grew college text. tions and how to distinguish them; their ambitious attempt to compile The book's value as a gemolog- the chart of their characteristics will "a truly comprehensive summary of ical reference must be considered be helpful to the gemologist. the optical properties of minerals." somewhat limited. Not all of the A major asset of this book is the In this attempt they have been re- diagnostic optical properties used by use of so much information from markably successful. Their work gemologists are included [i.e., ab- Eastern Europe and the Soviet ably rcplaces earlier, out-of-date sorption spectra, fluorescence), im- Union. There are also references at standard references in the field. Al- portant gem varieties are not the end of every chapter and an ex- though the book is intended pri- stressed and in some cases are not tensive bibliography at the conclu- marily for mineralogists and pe- even mentioned, and the terminol- sion of the work. Many unusual trologists, worlters in related fields, ogy and explanations are not gem- specimens and jewelry pieces are including gemology, are likely to ologically oriented. Nevertheless, included in the photographs, but one find it of value. for gemologists with mineralogy wishes that more care had been The book is divided into two backgrounds, those working with talten to show their uniqueness. An- parts. The first 398 pages contain unusual gemstones or rough gem other suggestion for subsequent edi- detailed descriptions of 159 of the materials, and those using miner- tions of the book would be to in- more common rock-forming min- alogical techniques, this reference clude a table of illustrations. erals or mineral series. The descrip- will prove particularly useful. Amber: The Golden Gem of the tions are clear and concise. The op- ANTHONY R. KAMPF Ages will be enjoyable and useful for tical data provided are complete for Los Angeles, California

Boolc Reviews GEMS & GEMOLOGY Spring 1981 59