SPRING 2001 VOLUME 37, NO. 1 EDITORIAL 1 The Dr. Edward J. Gübelin Most Valuable Article Award Alice S. Keller FEATURE ARTICLES pg. 5 4 Ammolite: Iridescent Fossilized Ammonite from Southern Alberta, Canada Keith A. Mychaluk, Alfred A. Levinson, and Russell L. Hall pg. 27 A comprehensive report on the history, occurrence, and properties of this vividly iridescent gem material, which is mined from just one area in Canada. 26 Discovery and Mining of the Argyle Diamond Deposit, Australia James E. Shigley, John Chapman, and Robyn K. Ellison Learn about the development of Australia’s first major diamond mine, the world’s largest source of diamonds by volume. 42 Hydrothermal Synthetic Red Beryl from the Institute of Crystallography, Moscow James E. Shigley, Shane F. McClure, Jo Ellen Cole, John I. Koivula, Taijin Lu, Shane Elen, and Ludmila N. Demianets pg. 43 Grown to mimic the beautiful red beryl from Utah, this synthetic can be identified by its internal growth zoning, chemistry, and spectral features. REGULAR FEATURES 56 Gem Trade Lab Notes • Unusual andradite garnet • Synthetic apatite • Beryl-and-glass triplet imitating emerald • Diamond with hidden cloud • Diamond with pseudo- dichroism • Surface features of synthetic diamond • Musgravite • Five- strand natural pastel pearl necklace • Dyed quartzite imitation of jadeite 64 Gem News International • White House conference on “conflict” diamonds • Tucson 2000: GIA’s diamond cut research • California cultured abalone pearls • Benitoite mine sold • Emeralds from Laghman, Afghanistan • Emeralds from Piteiras, Brazil • Educational iolite • “Hte Long Sein” jadeite • Kunzite from Nigeria • “Rainbow” obsidian • New production of Indonesian opal • Australian prehnite • “Yosemite” topaz • Tourmaline from northern Pakistan • A 23.23 ct tsavorite • TGMS highlights • Vesuvianite from California • Opal imitations • Green flame-fusion synthetic sapphire • Platinum coating of drusy materials • Gem display • Micromosaics 79 2001 Gems & Gemology Challenge 81 Book Reviews 83 Gemological Abstracts pg. 74 The Dr. Edward J. Gübelin Most Valuable Article Award he ballots are in, and we are pleased to announce the winners of this year’s Dr. Edward J. Gübelin Most Valuable Article T Award. We extend our sincerest thanks to all the subscribers who participated in the voting. The first-place article, “Gemstone Enhancement and Detection in the 1990s” (Winter 2000), examined the prominent gem treat- ments of the last decade and discussed methods for their detection. Finishing in a close second place was “GE POL Diamonds: Before and After” (Fall 2000), which provided important clues to the identi- fication of type IIa diamonds that had undergone high pressure/high temperature (HPHT) processing by General Electric. Third place was awarded to “Gem Localities of the 1990s” (Winter 2000), a review of the decade’s new gemstone sources and its most important produc- ing localities. The authors of these three articles will share cash prizes of $1,000, $500, and $300, respectively. Following are photographs and brief biographies of the winning authors. Congratulations also to Ron Suddendorf of Darnestown, Maryland, whose ballot was drawn from the many entries to win a leather portfolio and a five-year subscription to Gems & Gemology. See some changes in this issue? With the new decade-century-mil- lennium, we’ve been updating the design of Gems & Gemology and have expanded the Gem News section to Gem News International. Please be assured that there has been no change in the quality of the information provided throughout. Just a more contemporary look for a publication—now 67 years young—that will continue to keep you on the leading edge of gemology as we enter this new era. Alice S. Keller, Editor [email protected] First Place Gemstone Enhancement and Detection in the 1990s Shane F. McClure and Christopher P. Smith Shane McClure, G.G., is director of West Coast Identification Services at the GIA Gem Trade Laboratory in Carlsbad. With over 20 years of laborato- ry experience, Mr. McClure is well known for his articles and lectures on gem identification. He is also an editor of the Gem Trade Lab Notes sec- tion. Chicago native Christopher Smith, G.G., is director of the Gübelin Gem Lab in Lucerne, Switzerland. A prolific author, Mr. Smith is a mem- ber of the Gems & Gemology Editorial Review Board. Shane McClure Christopher Smith MOST VALUABLE ARTICLE AWARD GEMS & GEMOLOGY SPRING 2001 1 Second Place GE POL Diamonds: Before and After Christopher P. Smith, George Bosshart, Johann Ponahlo, Vera M. F. Hammer, Helmut Klapper, and Karl Schmetzer Christopher Smith is profiled in the first-place entry. George Bosshart, George Bosshart Johann Ponahlo who holds a degree in mineralogy from the Swiss Federal Institute of Technology in Zürich, is chief gemologist at the Gübelin Gem Lab. He currently is involved in research on HPHT-enhanced diamonds. Johann Ponahlo has been an independent research associate at the Museum of Natural History in Vienna since 1990. A physicochemist with a degree from the Technical University of Vienna, Dr. Ponahlo specializes in the study of cathodoluminescence in gems, particularly diamonds and jade. Vera M. F. Hammer has been the curatorial assistant for the mineral and gem collection of the Federal Gem Institute at the Museum of Natural Vera Hammer Helmut Klapper History in Vienna since 1992. Dr. Hammer studied mineralogy and crys- tallography at the University of Vienna. Her research specialties are X- ray diffraction analysis, the gemology of colored diamonds, and UV-Vis- IR-spectroscopy of colored gemstones. Helmut Klapper received his doc- torate in crystallography from the University of Cologne. Since 1990, he has been professor of mineralogy and crystallography and head of the crystal growth laboratory of the University of Bonn. Dr. Klapper’s main research fields are crystal physics, crystal growth, and the characteriza- tion of crystal defects by X-ray diffraction topography. Karl Schmetzer, who obtained his doctorate in mineralogy and crystallography from Karl Schmetzer Heidelberg University, is a research scientist residing in Petershausen, near Munich, Germany. Dr. Schmetzer has written numerous articles on natural and synthetic gems, and is also a member of the G&G Editorial Review Board. Third Place Gem Localities of the 1990s James E. Shigley, Dona M. Dirlam, Brendan M. Laurs, Edward W. Boehm, George Bosshart, and William F. Larson James Shigley Dona Dirlam James Shigley is director of GIA Research in Carlsbad. Dr. Shigley, who received his Ph.D. in geology from Stanford University, has published a number of articles on natural, treated, and synthetic gems. He is also a member of the G&G Editorial Review Board. Dona Dirlam, G.G., is direc- tor of the Richard T. Liddicoat Library and Information Center at GIA in Carlsbad. She has a B.Sc. from the University of Minnesota and an M.Sc. in geology and geophysics from the University of Wisconsin, Madison. Brendan Laurs, G.G., is senior editor of Gems & Gemology. He obtained a B.Sc. in geology from the University of California at Santa Barbara and an Brendan Laurs Edward Boehm M.Sc. in geology from Oregon State University. Prior to joining GIA, Mr. Laurs gained experience as an exploration geologist specializing in colored gems. Edward Boehm, G.G., is a gem dealer and gemological consultant. President of JOEB Enterprises in Solana Beach, California, Mr. Boehm has a degree in geology and German from the University of North Carolina in Chapel Hill. George Bosshart is profiled in the second-place entry. William Larson is president of Pala International (Fallbrook, California), a company that has been involved with gem-mining projects worldwide. Mr. Larson holds a degree in geological engineering from the Colorado School of Mines. He has traveled extensively to gem deposits, including 135 trips William Larson into the Far East and more than 40 visits to Africa. 2 MOST VALUABLE ARTICLE AWARD GEMS & GEMOLOGY SPRING 2001 AMMOLITE:IRIDESCENT FOSSILIZED AMMONITE FROM SOUTHERN ALBERTA, CANADA By Keith A. Mychaluk, Alfred A. Levinson, and Russell L. Hall A relative newcomer to the world gem market (since the 1960s), Ammolite is a form of aragonite that is obtained from vivid iridescent fossilized ammonite shells mined in Alberta, Canada. The gem material, from the extinct species Placenticeras meeki and P. intercalare, is found only in certain horizons of the Bearpaw Formation of Late Cretaceous age (about 70 –75 million years old). Because the iridescent layer is generally thin and fragile, most Ammolite is fashioned into assembled stones. This article describes the history of Ammolite as a gem material and the geologic setting of the main producing mines; offers an explanation for the formation of Ammolite and the origin of its color (i.e., iridescence caused by an interfer- ence phenomenon); presents production data, gemological properties, and a grading classification; and describes the manufacturing process. mmolite is one of the few new natural gem mines at Bleiberg, Austria (Niedermayr, 1994). materials to enter the marketplace in the However, any similarities between Ammolite and A last 50 years (figure 1). Like tanzanite and other iridescent shell materials are superficial. sugilite—which were introduced to the trade in Although the iridescence of lumachelle is associated 1967 and 1980, respectively—Ammolite occurs in with an ammonite, specifically Carnites floridus, sufficient quantities to be economically significant. this species is significantly older (Late Triassic in Ammolite is a trade name for the iridescent, nacre- age) than those that give rise to Ammolite, and the ous layer of the shell of specific fossil ammonites two materials have different geologic occurrences. (figure 2) found in the Bearpaw Formation of Late Further, lumachelle differs from Ammolite in Cretaceous age (figure 3). Commercial quantities of appearance (e.g., most Ammolite has a characteristic gem-quality Ammolite have been reported only fracture pattern). The former has been used primari- from southern Alberta and only from the two ly for nonjewelry purposes (i.e., as an ornamental ammonite species Placenticeras meeki and P.