Summer 2002 Gems & Gemology
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G EMS & G VOLUME XXXVIII SUMMER 2002 EMOLOGY S UMMER 2002 P AGES 123–204 Featuring: Characteristics and Grading of Pink Diamonds V OLUME 38 N O. 2 THE QUARTERLY JOURNAL OF THE GEMOLOGICAL INSTITUTE OF AMERICA Summer 2002 VOLUME 38, NO. 2 EDITORIAL 123 Remembering Gemology’s Renaissance Man John Sinkankas (1915–2002) Alice S. Keller 124 LETTERS FEATURE ARTICLES 128 Characterization and Grading of Natural-Color Pink Diamonds Carat Points John M. King, James E. Shigley, Scott S. Guhin, Thomas H. Gelb, and Matthew Hall Based on the largest sample of pink diamonds published to date, this report looks at differences between type I and type II pink diamonds and examines the color description terminology used for pink diamonds on GIA Gem Trade pg. 129 Laboratory grading reports. NOTES AND NEW TECHNIQUES 148 New Chromium- and Vanadium-Bearing Garnets from Tranoroa, Madagascar Karl Schmetzer, Thomas Hainschwang, Heinz-Jürgen Bernhardt, and Lore Kiefert A study of pyrope-spessartine garnets with unusual color behavior from Tranoroa, southern Madagascar. 156 Update on the Identification of Treated “Golden” South Sea Cultured Pearls Shane Elen pg. 157 On the basis of their fluorescence and atypical absorption features, 33 of 35 “golden” South Sea cultured pearls in a strand were identified as color treated. REGULAR FEATURES 161 Gem Trade Lab Notes • Aurichalcite cabochon • Another commercial U.S. facility offers HPHT annealing • Recognizing a color attribute’s effect on color grading fancy-color diamonds • Diamond “pearl” necklace • Internal laser drilling update • Unusual “pink” diamond • High-quality synthetic jadeite from General Electric • Cobalt-”diffused” sapphire • Schlossmacherite beads 170 Gem News International • Conference reports • New round cuts from Antwerp • Benitoite update • Cassiterite from Bolivia • Brazilian emerald with feldspar matrix • Sunstone feldspar from Tanzania • Update on Namibian demantoid garnet • Kyanite from Brazil • South Sea cultured pearls with broken beads • Developments in fresh- water cultured and “keshi” pearls • New sapphire locality in Afghanistan • Elbaite-liddicoatite tourmaline from Vietnam • Green zoisite reappears • Fuchsite imitations of emerald • Unusual synthetic rubies • Identification method for imitation asterism • Irradiated color-change fluorite 187 Thank You, Donors 188 Book Reviews 192 Gemological Abstracts pg. 165 203 Guidelines for Authors Remembering Gemology’s Renaissance Man John Sinkankas (1915–2002) ems & Gemology mourns the passing of associate editor 14,000-item library in 1988, it was the world’s finest private G John Sinkankas, who died in San Diego, California, on collection of gem and mineral literature. Now housed in the May 17 after a brief illness. John had celebrated his 87th Institute’s Richard T. Liddicoat Library and Information birthday just two days before. Center in Carlsbad, California, the Sinkankas collection John Sinkankas was the quintessential “Renaissance Man” includes thousands of rare and important books (see D. of gemology. He was a prolific author, a renowned lapidary, Dirlam et al., “The Sinkankas Library,” Spring 1989 G&G, the undisputed bibliophile in his field, a gem and mineral pp. 2–15). connoisseur, and a successful miner. He was also an accom- In 1982, John was awarded an honorary doctorate from plished artist in watercolor, and several of his paintings of William Paterson University. Two years later, a new peg- gems and minerals appeared in his books. Add to that his matitic phosphate mineral was named sinkankasite in recogni- more than two decades of contributions to G&G, and it is safe tion of his extraordinary contributions to the field. John to say that there will never be another John Sinkankas in received the Carnegie Mineralogical Award in 1988, and was gemology. named an Honorary Lifetime Member of the American Gem A native of Paterson, New Jersey, John began collecting Trade Association (AGTA) in 1992. minerals from the local quarries by the age of seven. After John’s contributions to Gems & Gemology were immeasur- graduating in 1936 from the New Jersey State Teachers able. A member of the editorial review board from 1981 to College (later William Paterson University), John started his 1983, and associate editor since 1984, he not only contributed 25-year career as a Navy pilot. He married his college sweet- numerous articles and book reviews, but he also diligently heart Marjorie Jane McMichael in 1940. John rose to the rank reviewed (and sometimes even rewrote) dozens of of captain before retiring in 1961, whereupon he and Marge manuscripts. settled in San Diego’s Pacific Beach community. This posi- As a friend of John’s for more than 25 years, I treasured his tioned him well for his many forays into the local gem peg- dry wit and unassuming personality. He was generous with matites. his encyclopedic knowledge and had a unique ability to take John’s childhood interest in gems and minerals continued complex concepts, such as crystallography, and put them in throughout his naval career. After World War II, he enrolled terms that a layperson could understand. His influence was in correspondence courses from GIA and the American Gem global, especially in the lapidary arts, where many who never Society (AGS). A self-taught lapidary, John began cutting even met John spoke of him as their mentor. gems in 1947. Today two of his most important gem carv- John Sinkankas is survived by his wife, Marjorie; daugh- ings, a 7,478 ct quartz egg and the world’s largest faceted ters, Sharon J. Tooley of San Diego and Marjorie E. Coates of golden beryl (2,054 ct), are on permanent display at the Virginia; sons, John W. Sinkankas of Los Angeles and Smithsonian Institution in Washington, DC. George M. Sinkankas of Tennessee; nine grandchildren; and Inspired to light the way for others, he began writing an six great-grandchildren. amateur lapidary column for Rocks & Minerals magazine in At the request of the Sinkankas family, GIA has estab- 1951. His first book, Gem Cutting—A Lapidary’s Manual, was lished the John Sinkankas Library Fund. If you would like to published in 1955. More than a dozen books followed, contribute to the fund, please send your donation to: Dona including Emerald and Other Beryls (1981), Gemology: An Dirlam, Liddicoat Gemological Library and Information Annotated Bibliography (1993), and the three-volume series Center, 5345 Armada Drive, Carlsbad, California 92008 Gemstones of North America (1959, 1976, and 1997). ([email protected]). John once described his approach to writing: “It’s really quite a thrill when you find little bits of information that you didn’t know, that you’ve never seen before. And you have a great deal of satisfaction in putting it down in black and white so everybody else can share that information.” As John’s writing projects expanded, so did his and Alice S. Keller, Editor Marge’s private library. At the time GIA purchased their [email protected] EDITORIAL GEMS &GEMOLOGY SUMMER 2002 123 LETTERSLETTERS color emissions (fire) for each of these 16 viewing posi- COMMENTS ON THE GIA tions for a variety of diamond proportions would more ANALYSIS OF DIAMOND “FIRE” closely represent the real-world observation of diamonds. This article from GIA’s study of the impact of proportions on the appearance of a round brilliant cut diamond The GIA Study Is a Huge First Step. This first step (Reinitz et al., Fall 2001, pp. 174–197) is a work of includes the ability to measure and compare the number, admirable dedication, intelligence, and technology and color distributions, and intensity of rays entering and represents a huge commitment of resources. emerging from diamonds of differing proportions. It is unfortunate that this huge effort has two major Although not included in the GIA articles (see also T. S. gaps. First, it confines the study of entering rays to the ver- Hemphill et al., “Modeling the appearance of the round tical, ignoring the vast majority of rays that enter the dia- brilliant cut diamond: An analysis of brilliance,” Fall mond from directions other than the perpendicular, and 1998 Gems & Gemology, pp. 158–183), it seems reason- therefore result in very different emerging light patterns. able and important to combine the diverse brilliance and Second, the “fire” (dispersion) calculations are taken fire measurements into a single “metric.” from the total of emitted rays impacting on a virtual Table 2 of the Fall 2001 article (p. 179), which compares hemisphere that encloses all of the diamond above the “Proportions and Calculated Metric Values for 28 girdle. In the real world, diamonds are viewed from indi- Diamonds” from the study, is the only place where the fire vidual points of view, so that the “fire” of the diamond metric is examined in actual (as opposed to virtual) dia- can be judged only from those points. Thus, the study monds. Note that within this group of 28 diamonds, five of uses only one illumination direction, where in actuality the eight that most closely adhere to both the American diamonds are illuminated from an infinity of positions. Ideal Cut (AGS “0”) and the Tolkowsky cut* show DCLR Conversely, simultaneous viewing from an infinity of (dispersed colored light return, the metric for fire) of over positions over an entire hemisphere could never occur, as 3.75 and a combined WLR (weighted light return, the met- diamonds can be seen from only one location at a time. ric for brilliance) and DCLR of over 4.03. Thus, the two fundamental bases for this study do not Those stones are: reflect what actually happens when diamonds are illumi- nated or viewed. If we were to add three other entering beams of light— No. Crown Pavilion Table WLR DCLR Combined angle angle WLR and DCLR say, at 20°, 40°, and 60° from the vertical—the light emis- sions resulting from these new sources would likely be very different from the purely vertical rays used in the 1 34.3° 40.6° 54% 0.283 3.97 4.25 study.