Summer 2001 VOLUME 37, NO. 2 EDITORIAL 95 The G&G Twenty Year Index: Two Decades of Evolution Alice S. Keller FEATURE ARTICLES 96 The Current Status of Chinese Freshwater Cultured Pearls Shigeru Akamatsu, Li Tajima Zansheng, Thomas M. Moses, and Kenneth Scarratt Based on recent visits to the pearl farms of Hanzhou Province, the authors report on the latest techniques being used to produce Chinese freshwater pg. 108 cultured pearls. 114 Spectral Reflectance and Fluorescence Characteristics of Natural- Color and Heat-Treated “Golden” South Sea Cultured Pearls Shane Elen UV-Vis reflectance spectra and fluorescence characteristics are useful in distinguishing undrilled natural- and treated-color yellow cultured pearls produced from the Pinctada maxima mollusk. NOTES AND NEW TECHNIQUES 124 A New Method for Imitating Asterism Shane F. McClure and John I. Koivula pg. 115 A new polishing process is being used to create the appearance of aster- ism in gems that have seldom if ever shown this phenomenon previously. REGULAR FEATURES 130 Gem Trade Lab Notes • “Banded” twinned diamond crystal • Diamonds with unusual inclu- sions • Feldspar with chrome diopside inclusions • Gibbsite dyed to imitate nephrite • Devitrified glass resembling jade • Early Japanese assembled cultured blister pearls • Dyed black faceted cultured pearls • New imitation: “Shell pearls” with a calcite bead 137 Thank You, Donors 138 Gem News International • Royal Asscher cut • Canadian diamonds • PDAC conference • A diamond table with trigons • “Burmite” • Cat’s-eye amethyst Brownish red to orange gems from Afghanistan/Pakistan • Clinohumite from Tanzania pg. 133 • An engraved emerald • Unusual rutilated quartz • Rubies and ruby deposits of eastern Madagascar • Ruby crystal with a mobile bubble • Green sapphire with pyrochlore inclusions • Vortex (Yogo Gulch) sap- phire mine update • “Canary” tourmaline from Malawi • Bismuth-bearing liddicoatite from Nigeria • “Jurassic Bugs” amber imitation • Assembled diamond imitations from Brazil • Enamel-backed quartz as a star sapphire imitation • Goldschmidt conference Moscow gemological conference • Harvard tourmaline exhibit 160 Book Reviews 163 Gemological Abstracts 171 Guidelines for Authors pg. 149 The G&G Twenty Year Index: Two Decades of Evolution t has been just over 20 years since Gems & Gemology pressure/high temperature (HPHT) presses are now syn- Iwas redesigned and the “new” format introduced. thesizing diamonds in virtually every color. Looking at the dozens of covers of these issues, which In other regions, names that were unknown to most of dominate the walls of my office, I think of the incredible us only five years ago are now part of the gemological par- effort that went into each one—the thousands of hours lance—Tunduru in Tanzania, Ilakaka in Madagascar, that our authors and staff invested in every issue to do Ekati in Canada. The availability of these significant new the research, write and refine the articles, and acquire the deposits of sapphires, rubies, and diamonds has shifted best illustrations. I also think of Harold and Erica Van the balance of supply and demand. At the same time, it Pelt, who photographed the vast majority of the cover has presented greater challenges to gemologists in identi- images, as well as the many individuals who loaned valu- fying sources and treatments. able gemstones and jewelry for them to capture on film. Scientific advances in the U.S. and elsewhere also What am I proudest of? The quality of the information have brought us synthetic moissanite, the first diamond and the depth of knowledge each issue simulant to match the thermal proper- represents. Today, 20 years after the ties of diamond. Whereas there was first issue of the redesigned G&G almost nothing written on diamond appeared, the articles in that issue—on treatments in the 1980s, articles on peridot from Zabargad, cubic zirconia, diamonds that have been fracture and the detection of diamond simu- filled or HPHT processed are promi- lants—are just as solid and useful as nent in the current index. Our first they were in April 1981. Certainly, index simply referred to “spec- since then there have been new peridot troscopy.” Today, there are entries for localities, changes in CZ, and more more than 10 different types of spec- diamond simulants, but these articles troscopy. Laser Raman microspec- continue to serve as a solid base for trometry—which we first reported on ongoing research on those topics. only three years ago—is now used rou- In the past two decades, we have tinely in major gem labs around the published over 5,500 pages of timely— world to identify inclusions and gem and timeless—articles, Lab Notes, materials, as well as to recognize Gem News entries, Book Reviews, and HPHT annealing in diamonds. Gemological Abstracts. This is truly a treasure chest of For this veteran of two decades of G&G, the Author information. But how do you access it? How do you find Index offered a distinct pleasure as I was reminded of what you need? those who have contributed so much to the journal. We are pleased to provide a solution: our Twenty “Godfathers” of gemological research such as Robert Year Index (1981–2000). We have revised and updated Crowningshield, Edward Gübelin, Richard T. Liddicoat, the subject and author listings from our first 15 years, and Kurt Nassau were joined by an impressive group of and added the annual indexes for the last five. new researchers such as Emmanuel Fritsch, Henry Hänni, In the course of preparing this Index, we were all Bob Kammerling, Bob Kane, John Koivula, Shane struck by the changes that were necessary since our McClure, Tom Moses, Ken Scarratt, Karl Schmetzer, and first index was published in Winter 1981—changes not James Shigley, among many others. only in gemology, but also in geography and technolo- We hope that you too will enjoy using the index and gy, many of them interrelated. find it a valuable reference tool. Explore the thousands For example, the most significant change to the geopo- of entries to learn what you need to know to stay litical landscape since the Spring 1981 issue has been the abreast of the rapidly evolving world of gemology. breakup of the Soviet Union. For our industry, however, this change has been more profound than the simple replacement of names on a map. With the new socioeco- nomic climate in this region has come an influx of natu- ral gem materials onto the world market—most notably Alice S. Keller from the release of diamonds that were in the government Editor stockpile, but also from renewed mining activity for such [email protected] classic gems as demantoid garnets. There also has been an unprecedented impact on the availability of synthetic Note: See the ad on page 159 of this issue to purchase a printed gem materials—new synthetic rubies, sapphires, emer- copy of the Gems & Gemology Twenty Year Index, or access it alds, and quartz varieties, to name but a few. Russian high free of charge by visiting us online at www.gia.edu/gandg. EDITORIAL GEMS &GEMOLOGY SUMMER 2001 95 THE CURRENT STATUS OF CHINESE FRESHWATER CULTURED PEARLS By Shigeru Akamatsu, Li Tajima Zansheng, Thomas M. Moses, and Kenneth Scarratt Chinese freshwater cultured pearls (FWCPs) are assuming a growing role at major gem and jewelry fairs, and in the market at large. Yet, it is difficult to obtain hard information on such topics as quantities produced, in what qualities, and the culturing techniques used because pearl culturing in China covers such a broad area, with thousands of individual farms, and a variety of culturing techniques are used. This article reports on recent visits by two of the authors (SA and LTZ) to Chinese pearl farms in Hanzhou Province to investigate the latest pearl-culturing techniques being used there, both in tissue nucleation and, much less commonly, bead (typically shell but also wax) nucleation. With improved techniques, using younger Hyriopsis Cumingi mussels, pearl culturers are producing freshwater cultured pearls in a variety of attractive colors that are larg- er, rounder, and with better luster. Tissue-nucleated FWCPs can be separated from natural and bead-nucle- ated cultured pearls with X-radiography. he popularity of Chinese freshwater cul- demand for information, two of the authors (SA tured pearls (FWCPs) has risen dramatically and LTZ) visited six FWCP farms and one nucleus Tin the world’s markets. The unique charac- manufacturer in China’s Zhejiang district; they teristics of the Chinese FWCP—in terms of size, also examined hundreds of Chinese FWCPs. The shape, and color—have been key to this popularity trip was made from July 25 to 29, 2000; informa- (figure 1). Chinese FWCPs are available in sizes tion in this article has been confirmed and updat- ranging from 2 mm to over 10 mm; in an interest- ed since then based on the second author’s ing variety of shapes such as round, oval, drop, monthly trips to the pearl-farming areas to visit button, and baroque; and in rich colors such as his pearl factory in Zhuji City, as well as to pur- orange and purple, often with a metallic luster. chase freshwater cultured pearls for export. In The vast majority of these Chinese FWCPs are addition, the first author has visited Chinese nucleated by mantle tissue only, although some freshwater pearl-culturing areas several times dur- nucleation with spherical beads has taken place ing the past two years. This article reports on the (Bosshart et al., 1993; “China producing nucleated current status of the Chinese freshwater cultured rounds,” 1995; Matlins, 1999; “China starts...,” pearl, both the various culturing techniques used 2000; Scarratt et al., 2000). This makes them dis- and the cultured pearls themselves, updating (and tinct from the overwhelming majority of cultured superseding) the pearl-culturing information in pearls from other localities, which are bead nucle- Scarratt et al.