Summer 2018 Gems & Gemology
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SUMMER 2018 VOLUME LIV THE UARTERLY JOURNAL OF THE GEMOLOGICAL INSTITUTE OF AMERICA Characteristics of Natural-Color Blue Diamonds Black Diamonds from Zimbabwe Characterization of Yogo Sapphires Synthetic Diamonds Chart 2018 GIA SYMPOSIUM NEW CHALLENGES. CREATING OPPORTUNITIES. OCTOBER 7-9, 2018 • CARLSBAD, CA GIA RESEARCH TRACK Researchers and scientists respected across the industry and from around the world will present their latest findings. Topics include: Colored Stones and Pearls, Diamond Geology, Diamond Identification, Gem Characterization, Gem Localities and Formations, General Gemology and Jewelry, and New Technologies and Techniques. HARVARD BUSINESS TRACK Harvard Business School professors lead an exploration into Authentic Leadership, Customer Centricity and Disruptive Innovation utilizing the famed HBS case-study method. THE MUSIC PARADIGM An engaging and unforgettable learning experience that translates the unique insights of a symphony orchestra conductor into lessons on leadership and collaboration. FUTURESCAPE FORUM Symposium will close with Futurescape Forum – a landmark event that will change how you think about the industry’s trajectory. An interactive dialogue moderated by David Ager of Harvard Business School, industry leaders will deliberate their unfiltered predictions on the horizon for the gem and jewelry industry. Bruce Cleaver Gina Drosos Jason Goldberger Andy Johnson Rahul Kadakia Kent Wong De Beers Signet Jewelers Blue Nile Diamond Cellar Christie's Chow Tai Fook DON'T MISS OUT. REGISTER NOW AT SYMPOSIUM.GIA.EDU ADT180074_G&G Symposium Futurescape Forum_R6.indd 1 7/12/18 2:49 PM Summer 2018 VOLUME 54, No. 2 EDITORIAL 111 Summer Reading: Diamond Research, Yogo Sapphire, and Byzantine Garnet pg. 113 Duncan Pay FEATURE ARTICLES 112 Natural-Color Blue, Gray, and Violet Diamonds: Allure of the Deep Sally Eaton-Magaña, Christopher M. Breeding, and James E. Shigley Summarizes data collected on more than 15,000 natural blue/gray/violet diamonds examined by GIA during the last decade and examines the mechanisms that produce this color range. 132 Black Diamonds from Marange (Zimbabwe): pg. 134 A Result of Natural Irradiation and Graphite Inclusions Karen V. Smit, Elina Myagkaya, Stephanie Persaud, and Wuyi Wang Characterizes a suite of 40 natural brown to black diamonds from this deposit so that they can be distinguished from suspected treated black diamonds. 149 An Early Byzantine Engraved Almandine from the Garibpet Deposit, Telangana State, India: Evidence for Garnet Trade Along the Ancient Maritime Silk Road H. Albert Gilg, Karl Schmetzer, and Ulrich Schüssler Analyzes the chemical composition and inclusion characteristics of this ancient artifact. pg. 171 166 Cultured Pearls from Lake Kasumigaura: Production and Gemological Characteristics Ahmadjan Abduriyim Examines Japanese “Kasumiga” freshwater cultured pearls, which grow in a variety of colors. 184 Gemological Characterization of Sapphires from Yogo Gulch, Montana Nathan D. Renfro, Aaron C. Palke, and Richard B. Berg A look at the mining and distinguishing characteristics of this naturally vibrant blue sapphire. CHARTS 202 Features of Synthetic Diamonds Sally Eaton-Magaña and Christopher M. Breeding A guide to growth processes and characteristics of synthetic diamonds created by high- pressure, high-temperature (HPHT) and chemical vapor deposition (CVD) methods. pg. 185 REGULAR FEATURES 205 Thank You, Donors 206 Lab Notes Large faceted afghanite • Beryl/glass assemblage imitating emerald • Large HPHT-treated type IIb blue diamond • Natural melee found in synthetic diamond parcel • Repaired diamond • Cat’s-eye amphibole and jadeite • Two natural “horse conch” pearls • “Golden sheen” star sapphire • Cabochons from Crassostrea virginica shell • Irradiated CVD synthetic diamond • Large pinkish orange CVD • 15 ct HPHT synthetic diamond 220 Diamonds from the Deep Natural diamonds help solve the enigma of water in the earth’s deep mantle. pg. 231 224 G&G Micro-World Mushroom in copal • Gilalite altered to cuprite in quartz • Unusual color zoning in chame - leon diamond • Merelaniite inclusions in tanzanite • Microlite in topaz • Perettiite and tusionite inclusions in phenakite • Horse-shaped mica in sapphire host • Star spinel with four/six rays • Glass imi tation of horsetail inclusions in demantoid • Quarterly crystal: Wurtzite phantom in quartz 233 Gem News International Color-change Ethiopian grossular • Green-blue Maxixe beryl • Trapiche-like amethyst from Brazil • Twelve-rayed star sapphire from Thailand • Chemistry of golden sheen sapphire pg. 245 • Type IIa diamond with CaSiO walstromite inclusion • Sustainability projects • Etched 3 surfaces on HPHT synthetic diamonds • White nephrite imitating mutton-fat jade • DiamondView separation of glass-filled ruby • Wax-impregnated jade • Conference report Editorial Staff Editor-in-Chief Editors, Lab Notes Contributing Editors Duncan Pay Thomas M. Moses James E. Shigley gia.edu/gems-gemology [email protected] Shane F. McClure Andy Lucas Donna Beaton Subscriptions Managing Editor Editors, Micro-World Copies of the current issue may be purchased for Stuart D. Overlin Nathan Renfro Editor-in-Chief Emeritus $29.95 plus shipping. Subscriptions are $79.99 for one [email protected] Elise A. Skalwold Alice S. Keller year (4 issues) in the U.S. and $99.99 elsewhere. Cana- John I. Koivula dian subscribers should add GST. Discounts are avail- Editor Customer Service able for renewals, group subscriptions, GIA alumni, Jennifer-Lynn Archuleta Editors, Gem News Martha Erickson and current GIA students. To purchase print subscrip- [email protected] (760) 603-4502 tions, visit store.gia.edu or contact Customer Service. Emmanuel Fritsch For institutional rates, contact Customer Service. [email protected] Technical Editors Gagan Choudhary Tao Z. Hsu Christopher M. Breeding Database Coverage G&G is abstracted in Thomson Reuters products [email protected] Editorial Assistants (Current Contents: Physical, Chemical & Earth Sci- Jennifer Stone-Sundberg Brooke Goedert ences and Science Citation Index—Expanded, includ- [email protected] Erin Hogarth ing the Web of Knowledge) and other databases. For a complete list of sources abstracting G&G, go to gia.edu/gems-gemology, and click on “Publication Information.” Production Staff Creative Director Photographer Video Production Manuscript Submissions Gems & Gemology, a peer-reviewed journal, welcomes Faizah Bhatti Robert Weldon Larry Lavitt the submission of articles on all aspects of the field. Pedro Padua Please see the Author Guidelines at gia.edu/gems- Production and Photo/Video Producer Nancy Powers gemology or contact the Managing Editor. Letters Multimedia Specialist Kevin Schumacher Albert Salvato on articles published in G&G are also welcome. Juan Zanahuria Betsy Winans Please note that Field Reports, Lab Notes, Gem News International, Micro-World, and Charts are not peer- reviewed sections but do undergo technical and edito- Editorial Review Board rial review. Ahmadjan Abduriyim A.J.A. (Bram) Janse Benjamin Rondeau Copyright and Reprint Permission Tokyo, Japan Perth, Australia Nantes, France Abstracting is permitted with credit to the source. Timothy Adams E. Alan Jobbins George R. Rossman Libraries are permitted to photocopy beyond the lim- San Diego, California Caterham, UK Pasadena, California its of U.S. copyright law for private use of patrons. Instructors are permitted to reproduce isolated arti- Edward W. Boehm Mary L. Johnson Andy Shen cles and photographs/images owned by G&G for Chattanooga, Tennessee San Diego, California Wuhan, China noncommercial classroom use without fee. Use of James E. Butler Anthony R. Kampf Guanghai Shi photographs/images under copyright by external par- Washington, DC Los Angeles, California Beijing, China ties is prohibited without the express permission of the photographer or owner of the image, as listed in Alan T. Collins Robert E. Kane James E. Shigley the credits. For other copying, reprint, or republica- London, UK Helena, Montana Carlsbad, California tion permission, please contact the Managing Editor. John L. Emmett Stefanos Karampelas Elisabeth Strack Gems & Gemology is published quarterly by the Brush Prairie, Washington Manama, Bahrain Hamburg, Germany Gemological Institute of America, a nonprofit educa- tional organization for the gem and jewelry industry. Emmanuel Fritsch Lore Kiefert Nicholas Sturman Nantes, France Lucerne, Switzerland Bangkok, Thailand Postmaster: Return undeliverable copies of Gems & Gemology to GIA, The Robert Mouawad Campus, Eloïse Gaillou Ren Lu Fanus Viljoen 5345 Armada Drive, Carlsbad, CA 92008. Paris, France Wuhan, China Johannesburg, South Africa Our Canadian goods and service registration number Gaston Giuliani Thomas M. Moses Wuyi Wang is 126142892RT. Nancy, France New York, New York New York, New York Any opinions expressed in signed articles are under- Jaroslav Hyršl Aaron Palke Christopher M. Welbourn stood to be opinions of the authors and not of the Prague, Czech Republic Carlsbad, California Reading, UK publisher. Dorrit Jacob Nathan Renfro J.C. (Hanco) Zwaan Sydney, Australia Carlsbad, California Leiden, The Netherlands About the Cover For more than 120 years, Yogo Gulch in central Montana has been one of the world’s most illustrious sapphire sources. In this issue, Nathan Renfro, Aaron Palke, and Richard Berg offer a mining history and gemological charac- terization of Yogo sapphires. The cover photo shows a suite of rough Yogo sapphires atop samples of the ouachatite dike rock in which