Fall 2000 Gems & Gemology - Gemfrance

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Pearl Nucleation Misquote? It is difficult to correlate the statements in the Editor’s Summer 2000 editorial about the value of peer review with the errors I found in the article by K. Scarratt et al. on nuclei in Chinese freshwater cultured pearls (FWCPs), which appeared in that same issue [pp. 98–109]. I have been misquoted twice in that article. First, in referencing my article in the April 2000 issue of Lapidary Journal, the authors state (p. 98), “Most recently, articles in the trade press (see, e.g., Matlins, 1999–2000a and b, 2000; Ward, 2000) have claimed that the vast majority of large FWCPs currently being described as “non-nucleated” are bead nucleated, with the largest sizes obtained by multiple insertions and reinsertions of nuclei formed from . . . freshwater cultured pearls.” I did not say that “the vast majority” of the large round FWCPs are pearlbead nucleated, because I know that statement is untrue. This error is repeated on page 107, with the statement: “The recent reports in the trade literature that tissuenucleated freshwater cultured pearls are being used as ‘nuclei’ to produce most of the recent large round Chinese FWCPs appear to be based on growth structures observed in pearls that have been cut in half (see, e.g., Matlins, 1999–2000a, 2000; Roskin, 2000; Ward, 2000).” Again, I have never said—or written—that “most” of the large Chinese FWCPs are pearl-bead nucleated because I know that statement is untrue. On page 29 of my referenced Lapidary Journal article I state very clearly, “I came to believe that at least some of the new pearls were being nucleated with old freshwater pearls that may have been tumbled or ground to round.” At no time does that sentence say or suggest that I think “the vast majority” or “most” of FWCPs are bead-nucleated. IN MEMORIAM John Latendresse (1925–2000) John Robert Latendresse, one of the world’s leading authorities on pearls and the creator of the cultured pearl industry in the United States, died on July 23 at his home in Camden, Tennessee, following a battle with lung cancer. He would have been 75 years of age on July 26. Born in Beresford, South Dakota, Mr. Latendresse settled in Tennessee in the 1950s. In 1954, he founded Tennessee Shell Company, which soon became the world’s primary supplier of the shell used to create the mother-of-pearl beads for cultured pearls. Convinced that local mollusks could be used to produce cultured pearls, he founded American Pearl Company, the first pearling company in the United States, in 1961. Over the next 20 years, he painstakingly tested over 300 bodies of water Just the opposite is true. I wrote that I believe “at least some of the new pearls” are bead nucleated. Fred Ward Gem Book Publishers In reply The authors and I appreciate this opportunity to clarify the use of Mr. Ward’s article as a reference for the two sentences cited above. Indeed, Mr. Ward does state in his article only that he believes “some” of the large Chinese FWCPs are bead nucleated. However, the citation of his article in conjunction with these two statements was not intended to indicate that they were quotations from Mr. Ward. Rather, as is stated in our Guidelines for Authors, “References should be used . . . to refer the reader to other sources for additional information on a particular subject.” In his Lapidary Journal article, Mr. Ward provides a number of quotes from others that were interpreted to be in support of the argument that bead-nucleated FWCPs are primarily responsible for the large Chinese FWCPs that have recently entered the market. For example, he quotes one pearl dealer (Fuji Voll, p. 29) to the effect that “I agree with you that nucleation with other pearls is the most likely explanation for today’s big rounds” and the late John Latendresse (p. 30) “Like you, I have no doubt they are nucleating with other pearls to get the big rounds.” We apologize if our intent was misconstrued, as the desire was not to put words in Mr. Ward’s mouth but rather to lead the reader to the extensive information he had gathered from trade representatives, some of which appeared to support the statements indicated. Certainly, Mr. Ward’s article provided useful commentary on this topic. Alice S. Keller Editor, Gems & Gemology before determining that the Tennessee River was ideal for culturing freshwater pearls. Today American Pearl Company produces freshwater cultured pearls in distinctive shapes and colors. Mr. Latendresse was always eager to share his vast knowledge of pearls, and he actively supported research and education efforts. With James L. Sweaney he co-authored “Freshwater Pearls of North America,” which appeared in the Fall 1984 issue of Gems & Gemology and won the G&G Most Valuable Article Award for that year. John Latendresse is survived by his wife, Chessy, five children, seven grandchildren, and seven great-grandchildren. Always the consummate gentleman and an enthusiastic advocate for strong standards in the pearl industry, he will be greatly missed. Fortunately, the pearl industry will benefit from his legacy for many years to come. Letters GEMS & GEMOLOGY Fall 2000 191
GE POL DIAMONDS: BEFORE AND AFTER By Christopher P. Smith, George Bosshart, Johann Ponahlo, Vera M. F. Hammer, Helmut Klapper, and Karl Schmetzer This study of type IIa GE POL diamonds before and after HPHT annealing by GE significantly expands on their characterization. The color change was dramatic: from the N–O range through Fancy Light brown before, to D–H after. However, there was little change to the inclusions, graining, and strain as a result of HPHT exposure. Photoluminescence (PL) studies—conducted at liquid helium, liquid nitrogen, and room temperatures in the 245–700 nm range—identified a significant reconfiguration of the lattice involving substitutional impurities, vacancies, and interstitials. Key regions of PL activity included the areas of the N3, H3, and N-V centers. X-ray topography identified the extent of lattice distortion. Cathodoluminescence may help establish that a diamond is not HPHT annealed. A distinction between nonenhanced and color-enhanced type IIa diamonds can be made through a combination of observations and features. ABOUT THE AUTHORS Mr. Smith is director, and Mr. Bosshart is chief gemologist, at the Gübelin Gem Lab, Lucerne, Switzerland. Dr. Ponahlo is senior research scientist, and Dr. Hammer is research scientist, in the mineralogy and petrography department at the Museum of Natural History, Vienna, Austria. Prof. Klapper is the head of the crystal growth research group at the Mineralogisch-Petrographisches Institut, University of Bonn, Germany. Dr. Schmetzer is a research scientist residing in Petershausen, near Munich, Germany. Please see acknowledgments at the end of the article. Gems & Gemology, Vol. 36, No. 3, pp. 192–215 © 2000 Gemological Institute of America M arch 1, 1999 is a watershed date in the gem and jewelry trade. This is when General Electric (GE) and Lazare Kaplan International (LKI) unveiled their latest contribution to the diamond and jewelry industry: diamonds that had undergone a new GE process “designed to improve their color, brilliance, and brightness” (Rapnet, 1999). Colloquially, these diamonds became known as “GE POL” or “Pegasus” diamonds, because they were being marketed through LKI subsidiary Pegasus Overseas Ltd. (POL). At the July 2000 Jewelers of America trade show in New York, however, the brand name Bellataire was officially launched. The first gemological description of GE POL diamonds appeared in fall 1999, when GIA published an overview of the macroscopic and microscopic features observed in 858 GE POL diamonds they had examined up to August 1999 (Moses et al., 1999). Subsequent articles by the SSEF Swiss Gemmological Institute and De Beers provided more analytical details on GE POL diamonds and suggested spectroscopic methods of identification (Chalain et al., 1999, 2000; Fisher and Spits, 2000). The Gübelin Gem Lab (GGL) has had an ongoing cooperation with GE, LKI, and POCL (Pegasus Overseas Company Ltd.) to investigate the gemological and analytical characteristics of GE POL diamonds, in order to help develop identification criteria. Because of this collaboration, staff members at GGL were given the opportunity to document a selection of diamonds taken from current GE production, both prior and subsequent to high pressure/high temperature (HPHT) processing (figure 1). This study represents the first independent investigation of actual GE POL diamonds both before and after processing by General Electric. Such an investigation is crucial to understanding the mechanisms behind the color alteration and thus to providing greater insight into potential methods of identification. The present report not only addresses the alterations in color, inclusions, graining, and strain produced by the GE process, but it also considerably expands the 192 GE POL Diamonds GEMS & GEMOLOGY Fall 2000
Page 2 and 3: pg. 237 pg. 217 pg. 247 REGULAR FEA
Page 6 and 7: Figure 1. These two illustrations s
Page 8 and 9: When a type IIa diamond is exposed
Page 10 and 11: GE5 GGL1 2.72 ct 0.61 ct Before Aft
Page 12 and 13: after processing revealed little ch
Page 14 and 15: Figure 7. These UV/Vis/NIR absorpti
Page 16 and 17: A couple of samples also revealed p
Page 18 and 19: Figure 10. Because of the greater s
Page 20 and 21: Figure 11. The CL color of the GE P
Page 22 and 23: ditions, as described by Fisher and
Page 24 and 25: al., 1999). As described above, mos
Page 26 and 27: BOX C: RUSSIAN HPHT-PROCESSED DIAMO
Page 28 and 29: Collins A.T., Kanda H., Kitawaki H.
Page 30 and 31: island, approximately 90 km northea
Page 32 and 33: Quaternary. The 35-km-wide stratovo
Page 34 and 35: BOX A: SAPPHIRE PRODUCTION FROM THE
Page 36 and 37: parent without causing them to beco
Page 38 and 39: Figure 13. When viewed perpendicula
Page 40 and 41: Figure 20. In a view almost paralle
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Page 44 and 45: As shown in the correlation diagram
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Page 48 and 49: (Nicholson, 1993). The sites are lo
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Page 52 and 53: TABLE 1. Saladoid gem and ornamenta
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Figure 11. Note that there are two
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Baik, 1983; Cody, 1990; Rodríguez,
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occur on Antigua. These were found
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pathoids; figure 2). It has been re
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Figure 4. The haüyne samples exami
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tures sometimes showed orange to pi
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REFERENCES Arem J.E. (1987) Color E
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Figure 2. The laboratory recently e
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Figure 5. These round brilliants (t
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Figure 9. This 2.34 ct heated rough
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De Beers’s newly stated direction
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Aquamarine from southeast India. Fi
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Figure 9. This 0.69 ct fresnoite wa
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Natural History, New York) and S. S
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& Gemology, pp. 78-89). The massive
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fluorescent light; for this sample,
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groups found in organic matter such
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particular carat weight would be fo
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Gemological ABSTRACTS EDITOR A. A.
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and high-wavenumber (~3800-2800 cm
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chain is found in the highly public
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Tertiary-age diamondiferous fluvial
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JEWELRY RETAILING Mistakes jewelers
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Irradiation at doses of 7.6-187 kGy
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Fall 2000 Gems & Gemology - Gemfrance

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