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Winter 2003 Gems & Gemology Winter 2003 VOLUME 39, NO. 4 EDITORIAL _____________ 267 Tomorrow’s Challenge: CVD Synthetic Diamonds William E. Boyajian FEATURE ARTICLES _____________ 268 Gem-Quality Synthetic Diamonds Grown by a Chemical Vapor Deposition (CVD) Method Wuyi Wang, Thomas Moses, Robert C. Linares, James E. Shigley, Matthew Hall, and James E. Butler pg. 269 Description and identifying characteristics of Apollo Diamond Inc.’s facetable, single-crystal type IIa CVD-grown synthetic diamonds. 284 Pezzottaite from Ambatovita, Madagascar: A New Gem Mineral Brendan M. Laurs, William B. (Skip) Simmons, George R. Rossman, Elizabeth P. Quinn, Shane F. McClure, Adolf Peretti, Thomas Armbruster, Frank C. Hawthorne, Alexander U. Falster, Detlef Günther, Mark A. Cooper, and Bernard Grobéty A look at the history, geology, composition, and properties of this new cesium-rich member of the beryl group. 302 Red Beryl from Utah: A Review and Update James E. Shigley, Timothy J. Thompson, and Jeffrey D. Keith A report on the geology, history, and current status of the world’s only known occurrence of gem-quality red beryl. pg. 299 REGULAR FEATURES _____________________ 314 Lab Notes • Chrysocolla “owl” agate • Red coral • Coated diamonds • Natural emerald with nail-head spicules • Emerald with strong dichroism • High-R.I. glass imitation of tanzanite • Large clam “pearl” • Blue sapphires with unusual color zoning • Spinel with filled cavities 322 Gem News International • Comparison of three historic blue diamonds • Natural yellow diamond with nickel-related optical centers • Gem-quality afghanite • Blue beryl discovery in pg. 319 Canada • Gem-quality corundum from Colombia • Emeralds from Mada- gascar with strong blue/green dichroism • Peruvian blue opal • Interesting pearls from the North American West Coast • “Platinum quartz” from Brazil • Some rare faceted gem materials • Large scapolite from Tanzania • Update on tanzanite mining by AFGEM • Chatoyant glass cabochons from China • New synthetic opal varieties • Plastic imitations of a walrus tusk and a sperm whale tooth • Conference reports 348 Book Reviews 351 Gemological Abstracts 362 2003 Index pg. 332 ost gemologists know that Let us all remember that there is General Electric Co. created nothing inherently wrong with lab- the first industrial-quality oratory-grown products, provided synthetic diamonds in 1955. What they are properly disclosed at each many gemologists don’t know is that stage of the distribution pipeline. the production of polycrystalline thin Ultimately, though, the case for films of synthetic diamond actually synthetic diamonds will not be predates this, beginning in 1952. For played out in the trade per se, but decades, chemical vapor deposition rather in the marketplace and in (CVD) polycrystalline synthetic dia- the mind of the consumer. We all mond has been grown over sub- know that consumer confidence is strates and used in a variety of indus- the key to the success of the dia- trial products. mond industry. Anything that shakes that confidence will shake The lead article in this issue of the market and, inevitably, the Gems & Gemology describes the industry itself. creation of single-crystal synthetic diamonds grown by Apollo Diamond Inc. using a CVD The good news about synthetic diamonds is that, for the last process. At first glance, this doesn’t seem so alarming. After two decades, we have stayed well ahead of the learning all, gem-quality synthetic diamonds grown by the classic curve for identifying them, and I see no reason why this “belt” and BARS (high pressure/high temperature) tech- can’t continue. For much of this time, experts have debated niques have been around for decades, and have been whether diamonds grown synthetically would become com- available commercially (although in very small quantities mercially available in sizes, quantities, and prices that could and sizes and, for the most part, in yellow colors) since the fuel consumer demand for the product. The jury may still be mid-1980’s. Put simply, however, CVD-grown synthetic out on these issues. However, it is inevitable, given the diamond generally is a purer product than commercial syn- technology available today, that the right level of investment thetic diamonds created by high pressure/high temperature and the right long-term commitment to the product will techniques, and the CVD synthetics typically fall on the result in commercially viable gem synthetic diamonds. D-to-Z scale or are “brownies.” In addition, in most cases Indeed, the time for readiness appears to be now. sophisticated analytical equipment must be used to conclu- sively identify the material. After Apollo Diamond begins So what have we learned about synthetic diamonds over commercial production of CVD synthetic diamond in the past half century? We know that, while technology 2004, it will be vital for every practicing gemologist to will provide the innovation necessary to create new and understand the challenges that the material may pose to interesting products, this same technology will help fuel identification. the identification of these products as well. Gemological research laboratories are making every The producer has stated that, initially, 5,000–10,000 carats of effort to keep up with this technology, faceted CVD synthetic diamond will be available. Most of challenging as it may be, and to do every- these goods will be quarters and thirds, but by the end of thing they can to protect the public by 2004, stones as large as a full carat may be on the market. properly identifying and disclosing gem- While larger sizes typically will be identified in a qualified quality synthetic diamonds. laboratory, the fact that most diamonds under a carat are not sold with grading reports is cause for concern. The producers are unequivocal about their insistence on proper disclosure, and all indications to GIA certainly support that premise. But could these goods later be “salted” into parcels of natural dia- monds by unscrupulous hands, fully intending to deceive William E. Boyajian, President their customers? Undoubtedly. Gemological Institute of America EDITORIAL GEMS & GEMOLOGY WINTER 2003 267 GEM-QUALITY SYNTHETIC DIAMONDS GROWN BY A CHEMICAL VAPOR DEPOSITION (CVD) METHOD Wuyi Wang, Thomas Moses, Robert C. Linares, James E. Shigley, Matthew Hall, and James E. Butler Brown-to-gray and near-colorless single-crystal type IIa synthetic diamonds grown using a chemi- cal vapor deposition (CVD) technique by Apollo Diamond Inc. have gemological properties that are distinct from those of both natural diamonds and HPHT-grown synthetic gem diamonds. The tabular crystals typically range up to 1 ct or more and a few millimeters thick, and consist of an overgrowth on a natural or synthetic diamond substrate. Faceted CVD synthetic diamond usually cannot be separated from natural diamond with standard gemological techniques; although when portions of the substrate are still present, an experienced gemologist may be able to recognize dif- ferences in luminescence or color between the overgrowth and substrate. In all cases, however, the CVD synthetic diamonds examined to date could be identified in a gemological laboratory by the combination of a strong orangy red fluorescence seen with the De Beers DiamondView deep- ultraviolet imaging system, a characteristic anomalous birefringence (strain) pattern, and distinctive features in their infrared absorption spectra (e.g., at 3123 cm-1) and photoluminescence spectra (strong 575 and 637 nm emissions, a doublet at 596 and 597 nm, and a line at 737 nm). pollo Diamond Inc. of Boston, Massa- IIa brown diamonds, which can be decolorized at chusetts, has succeeded in growing facetable, high pressure and high temperature (see box A). Asingle-crystal type IIa synthetic diamonds Preliminary notes on GIA’s examination of some of using a patented chemical vapor deposition (CVD) these Apollo samples were published by Wang et al. technique (Linares and Doering, 1999, 2003). For (2003) and appeared in the August 8, 2003 issue of characterization of this material, the company has the GIA Insider (GIA’s electronic newsletter: provided a number of brown-to-gray and near-color- http://www.gia.edu/newsroom/issue/2798/1842/ less gem-quality crystals and faceted samples, which insider_newsletter_details.cfm#3). Spectroscopic represent what is intended to become a commercial analysis of an Apollo CVD synthetic diamond also product for use in high-technology applications as was performed recently by other researchers well as for jewelry purposes (figure 1). Because of the (Deljanin et al., 2003). The purpose of the present growth conditions and mechanisms used, the gemo- article is to provide a more complete description of logical properties of these CVD-produced synthetic this material and its identifying features. diamonds differ from those of both natural diamonds and synthetic diamonds grown at high pressures and temperatures. For the same reasons, the brown col- See end of article for About the Authors and Acknowledgments. oration of CVD synthetic diamonds may not react in GEMS & GEMOLOGY, Vol. 39, No. 4, pp. 268–283. the same way, or as efficiently, as most natural type © 2003 Gemological Institute of America 268 CVD SYNTHETIC DIAMONDS GEMS & GEMOLOGY WINTER 2003 Figure 1. This jewelry is set with CVD synthetic dia- monds from Apollo Diamond Inc. The pendant contains an HPHT-annealed 0.2 ct CVD synthetic diamond with a color equivalent to “K” on the GIA diamond grading scale (sample no. 57687). The 0.31 ct sample (no. 56924) in the ring on the left is equiva- lent to Fancy Dark brown in color. The Fancy Light brown 0.45 ct CVD synthetic dia- mond (no. 57688) in the ring on the right was HPHT annealed, but no change in color was observed (see box A). Composite of photos by Elizabeth Schrader. BACKGROUND • Is resistant to heat, acids, and radiation Synthetic diamonds have been produced by the high • Is a good electrical insulator, but can be doped pressure/high temperature (HPHT) technique since to act as a semiconductor 1955, with the growth of crystals of a size and quality • Is transparent to visible and almost all infrared suitable for jewelry first announced in 1970 radiation (Crowningshield, 1971; Burns and Davies, 1992).
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