Gems & Gemology最新文献

{"title":"Technical Evolution and Identification of Resin-Filled Turquoise","authors":"Ling Liu, Ming-xing Yang, Yan Li, Jingru Di, Rukang Chen, Jia Liu, C. He","doi":"10.5741/GEMS.57.1.22","DOIUrl":"https://doi.org/10.5741/GEMS.57.1.22","url":null,"abstract":"","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"1 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41756344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How to Calculate Color from Spectra of Uniaxial Gemstones","authors":"Chen Shen, Aaron C. Palke, Ziyin Sun, M. Fairchild","doi":"10.5741/GEMS.57.1.36","DOIUrl":"https://doi.org/10.5741/GEMS.57.1.36","url":null,"abstract":"","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48205639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Micro-Features of Spinel","authors":"Nathan D. Renfro, John I. Koivula, S. McClure, Kevin Schumacher, J. Shigley","doi":"10.5741/GEMS.57.1.46","DOIUrl":"https://doi.org/10.5741/GEMS.57.1.46","url":null,"abstract":"","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46803915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Baroque-Era Rose Cuts of Colored Stones: Highlights from the Second Half of the Seventeenth Century","authors":"K. Schmetzer","doi":"10.5741/GEMS.56.4.458","DOIUrl":"https://doi.org/10.5741/GEMS.56.4.458","url":null,"abstract":"GEMS & GEMOLOGY WINTER 2020 Rose cuts encompass a variety of faceting arrangements, all of which lack a flat table (figure 1). In contrast to the considerable literature on the use of rose cuts in diamonds, there has been a dearth of information regarding their use in colored stones. The story of diamond fashioning started with the polishing and/or slight modification of the crystal faces of natural diamond octahedra, creating what is known as the point cut. Thereafter, simple table cuts were developed from the fifteenth century onward, becoming more complex over time (Lenzen, 1966; Falk, 1975; Tillander, 1995; Klein, 2005; Gilbertson, 2007; Ogden, 2018). Diamonds with rose cuts came later as a typical product of the sixteenth and seventeenth centuries, employing a cutting process that began with a rough cleavage fragment from a diamond octahedron. The standard appearance generally consisted of a flat base topped by a dome with six triangular facets at the center. Between the dome top and the base was an intervening layer with six, 12, or 18 additional facets (figure 2). Despite some inconsistency in terminology, these cuts are primarily denoted as Antwerp roses (6 + 6 facets), half-Dutch roses (6 + 12 facets), and full-Dutch roses (6 + 18 facets), respectively (Eppler and Eppler, 1934; Stranner, 1953). Visual evidence of the foregoing historical progression in diamond cuts is readily found in references depicting jewelry objects from bygone eras and in seventeenth-century sketchbooks of goldsmiths or jewelry designers such as T. Cletcher (1629) or G. Légaré (1663) (figure 3; see, e.g., Gans, 1961; Walgrave, 1993a,b; Scarisbrick, 1993). Political and economic circumstances related to the development of rose-cut diamonds are discussed by Kockelbergh et al. (1992) and De Bie (2014). In the decidedly less voluminous literature on colored stones cut without flat tables, the first appearance of such a faceted gemstone in art is found in a sixteenth-century painting by A. Bronzino (1542) portraying Venus, Cupid, Folly, and Time (an allegory of lust) (see Prim, 2018). The oval gemstone in that work shows a crown covered by multiple facets in the form of elongated rhombuses. Other isolated art and jewelry pieces from the second half of the sixteenth century and the seventeenth century likewise offer several examples (see, e.g., Prim, 2019). A notable influx of items displaying colored stones cut without flat tables then occurred with the 1912 discovery of the so-called Cheapside Hoard, dated before the Great Fire of London in 1666. Exemplars are contained in the catalog prepared for the 2014 exhibition BAROQUE-ERA ROSE CUTS OF COLORED STONES: HIGHLIGHTS FROM THE SECOND HALF OF THE SEVENTEENTH CENTURY","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42183747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mineral Inclusions in Sapphire from Basaltic Terranes in Southern Vietnam: Indicator of Formation Model","authors":"Doan Thi Anh Vu, A. Salam, Alongkot Fanka, E. Belousova, C. Sutthirat","doi":"10.5741/GEMS.56.4.498","DOIUrl":"https://doi.org/10.5741/GEMS.56.4.498","url":null,"abstract":"GEMS & GEMOLOGY WINTER 2020 Since the late 1980s, sapphire mines in southern Vietnam have supplied significant quantities of gem materials to the jewelry industry (figure 1). Commercial gem mines in southern Vietnam have been located in four main areas, including Dak Nong, Di Linh, Binh Thuan, and Krong Nang (figure 2) (Smith et al., 1995; Long et al., 2004; Garnier et al., 2005; Izokh et al., 2010; Vu, 2010, 2018). Specifically, the first discovery of abundant gem sapphires was in Dak Nong, followed by Di Linh, Binh Thuan, and Krong Nang, respectively. These sapphires accumulated in Upper-Pleistocene to Quaternary alluvial deposits. In 2017, we carried out field trips in southern Vietnam encompassing Binh Thuan Province, Di Linh (Lam Dong Province), Dak Nong Province, and Krong Nang (Dak Lak Province), where sapphire samples were collected directly from the mines (see figure 2). Gem mining activities in these areas are conducted by a few local miners. Pits are dug with basic tools before washing and hand picking along streams by artisanal miners (figure 3), and mines worked by machinery (figure 4) can also be found. Sapphires in this region usually range from dark blue to bluish green, yellowish green to green, with rare yellow sapphire. The natural intense blue sapphire is the best known and has been specifically recovered from the Dak Nong and Di Linh gem fields (figure 1, left). Other colors such as bluish green and yellowish green to green are common, particularly in the Binh Thuan and Krong Nang gem fields, respectively (figure 1, right). However, these sapphire varieties are generally heat treated for color enhancement. In addition, trapiche-type sapphires (figure 5) are sometimes found in these gem fields.","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"498-515"},"PeriodicalIF":2.6,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42462734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluorescence Characteristics of Blue Amber from the Dominican Republic","authors":"Zhiqing Zhang, Jiang Xinran, Wang Yamei, Fanli Kong, A. Shen","doi":"10.5741/GEMS.56.4.484","DOIUrl":"https://doi.org/10.5741/GEMS.56.4.484","url":null,"abstract":"GEMS & GEMOLOGY WINTER 2020 Amber is widely distributed around the world. It is of interest not merely as an important natural fossil resin witnessing the history of the earth and providing direct evidence for paleobiologists, but also as a widely loved organic gemstone. Transparent yellow amber from the Dominican Republic, Mexico, and Myanmar displaying a blue or greenish blue glow when viewed on a black background in normal sunlight is called “blue amber” in the Chinese gem trade. This paper focuses on amber displaying this characteristic and will refer to this material as blue amber. In the Guangzhou and Shenzhen amber trading centers, Dominican blue amber can be sold for up to thousands of Chinese RMB (around several hundred U.S. dollars) per gram, while Mexican material fetches only several hundred RMB (around several tens of U.S. dollars) per gram—even though they have a similar appearance. Bellani et al. (2005) first described blue amber and studied the fluorescence emission, excitation, and optical absorption spectra of Dominican blue and non-blue (including yellow and red varieties) amber. They found that multiple emission fluorescence peaks at 449 nm, 476 nm, and 505 nm occurred in this blue amber, while only a broad fluorescence band was observed in non-blue amber. They further","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"484-496"},"PeriodicalIF":2.6,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49464682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Low-Temperature Heat Treatment of Pink Sapphires from Ilakaka, Madagascar","authors":"Sudarat Saeseaw, Charuwan Khowpong, W. Vertriest","doi":"10.5741/GEMS.56.4.448","DOIUrl":"https://doi.org/10.5741/GEMS.56.4.448","url":null,"abstract":"GEMS & GEMOLOGY WINTER 2020 Heat treatment has been used to improve the color and/or clarity of corundum for more than a thousand years. Various parameters such as temperature, heating and cooling time, and oxidizing or reducing atmosphere will affect the final color (Emmett and Douthit, 1993; Emmett et al., 2003; Hughes et al., 2017). The border between highand low-temperature heat treatment has been defined by Emmett (in Hughes et al., 2017) as the temperature needed to dissolve second-phase microcrystals, which is somewhere between 1200° and 1350°C. Heating at high temperatures will damage most inclusions in ruby and sapphire and is often detectable by trained gemologists. In contrast, heating corundum at low temperatures, sometimes below 700°C, will only subtly affect their internal inclusions, making the treatment much more challenging to detect without advanced instrumentation (figure 1). Previous studies on the effect of low-temperature heat treatment on inclusions have focused on rubies from Mozambique (Pardieu et al., 2015; Sripoonjan et","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"448-457"},"PeriodicalIF":2.6,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45719201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Natural-Color D-to-Z Diamonds: A Crystal-Clear Perspective","authors":"S. eaton-magaña, T. Ardon, C. Breeding, J. Shigley","doi":"10.5741/GEMS.56.3.335","DOIUrl":"https://doi.org/10.5741/GEMS.56.3.335","url":null,"abstract":"GEMS & GEMOLOGY FALL 2020 When people hear the word diamond, colorless diamonds generally come to mind— not the more exotic colors discussed earlier in this article series. In purchasing a diamond, they are likely to choose one that is colorless to nearcolorless. When one thinks of perfection in a diamond, a D-Flawless stone is usually the benchmark. The lack of color, which so inhibits the consumer appeal of many other gemstones, is instead considered a measure of stature for diamonds. Therefore, we finish this series (Breeding et al., 2018, 2020; Eaton-Magaña et al., 2018a, 2018b, 2019) by examining diamonds with very little to no color at all—those on the D-to-Z grading scale. Although they make up by far the largest proportion of stones submitted to GIA, detailed statistics of D-to-Z diamonds have never been presented before. In each of our previous colored diamond articles, we presented data on stones submitted to GIA from 2008 to 2016. For example, GIA examined more than 15,000 naturally colored blue/gray/violet diamonds in that period (Eaton-Magaña et al., 2018a). During those same years, GIA received millions of D-to-Z diamonds (e.g., figure 1). For this study, we examined all D-to-Z diamonds submitted for grading reports or dossier reports to any of GIA’s laboratories during much of 2017. From our analysis of submissions over the last decade, those from 2017 and used in this study are representative of GIA’s current and historical intake. Any diamonds submitted on multiple occasions during this period were identified, and only the most recent data for each stone are included in this study.","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"318-335"},"PeriodicalIF":2.6,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45001323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A History of European Royal Jewel Sales, Including Sotheby's 2018 Auction of Marie Antoinette's Jewels","authors":"R. Shor","doi":"10.5741/GEMS.56.3.356","DOIUrl":"https://doi.org/10.5741/GEMS.56.3.356","url":null,"abstract":"","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"356-379"},"PeriodicalIF":2.6,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41474683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unique Raindrop Pattern of Turquoise from Hubei, China","authors":"Ling Liu, Ming-xing Yang, Yan Li","doi":"10.5741/GEMS.56.3.380","DOIUrl":"https://doi.org/10.5741/GEMS.56.3.380","url":null,"abstract":"","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"380-400"},"PeriodicalIF":2.6,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43640788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}