Gems & Gemology最新文献

{"title":"Inclusion and Trace Element Characteristics of Emeralds from Swat Valley, Pakistan","authors":"H. Guo, Xiaoyan Yu, Yuyu Zheng, Zhulin Sun, M. Ng","doi":"10.5741/GEMS.56.3.336","DOIUrl":"https://doi.org/10.5741/GEMS.56.3.336","url":null,"abstract":"","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"336-355"},"PeriodicalIF":2.6,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43332799","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":"Vietnam: Shell Nuclei, Pearl Hatcheries, and Pearl Farming","authors":"Nicholas Sturman, Kwanreun Lawanwong, Nuttapol Kitdee, Devchand Chodhry","doi":"10.5741/GEMS.56.3.402","DOIUrl":"https://doi.org/10.5741/GEMS.56.3.402","url":null,"abstract":"GEMS & GEMOLOGY FALL 2020 V is a land of great diversity and beauty. From the hustle and bustle of Ho Chi Minh City to the beauty of Hạ Long Bay and Hoi An (both UNESCO World Heritage Sites), there are innumerable places of interest. Economically, Vietnam is beginning to see significant investment from a wide range of businesses, domestic and foreign. While still dependent on agriculture, the country is emerging as a major player in the electronics and oil/gas industries, among others. These factors, together with a robust tourism industry, are resulting in an expanding population with greater prosperity than ever before. Jewelry, including pearl jewelry, ranks high on the list of luxury items, as there is a significant range of price points at which disposable wealth can be spent. From the costume jewelry sector to high-end offerings, there is something to suit all tastes. While cultured pearls, accounting for 99.9% of the market since the early 1900s, do not usually fall into the higher-end bracket, there remains a healthy demand from consumers (Shor, 2007; Heebner, 2015). The choice of bead cultured pearls in the marketplace is also diverse. Consumers may choose from the usual imported gray to black Tahitian bead cultured pearls, “golden” bead cultured pearls from the Philippines or Indonesia, and bead cultured pearls produced in China. Hạ Long Bay (figures 1 and 2) in northern Vietnam is where most pearl farms, producing predominantly “akoya” (Pinctada fucata martensii) pearls, may be found. These farms are a mix of independent operations and joint ventures with the Vietnamese government. A prime example of the latter is Spica, a Vietnamese-Japanese joint venture that has produced bead cultured pearls for more than a decade. Some farming activity is also found in the waters off southern Vietnam at Nha Trang, as will be seen later, and Phu Quoc (Strack, 2006). Vietnam has produced saltwater cultured pearls commercially since the 1990s. However, the first attempts reportedly began in the 1960s (Strack, 2006). Today, based on the 300–400 kg production from the two farms visited in this report, the country is estimated to produce approximately 2,000 kg per annum. The majority of the production is akoya, with a smaller quantity of Pinctada maxima, and much of the production is currently exported to China, Japan, India, and the United Sates. When the harvests are good, the quality tends to be higher, but the opposite also holds true.","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"402-415"},"PeriodicalIF":2.6,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41908068","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":"Separation of Natural Laboratory-Grown Diamond Using Time-Gated Luminescence Imaging","authors":"C. McGuiness, Amber M. Wassell, P. Lanigan, S. Lynch","doi":"10.5741/gems.56.2.220","DOIUrl":"https://doi.org/10.5741/gems.56.2.220","url":null,"abstract":"GEMS & GEMOLOGY SUMMER 2020 The task of identifying a diamond will typically fall to a diamond appraiser, grader, or gemologist while preparing a grading certificate or appraisal. Whether a diamond is natural or lab-grown is a key factor in its market value and is of paramount importance to the gemologist. Many characteristics can be used to distinguish between natural and synthetic dia mond, but the inherent variability in the properties of natural and synthetic diamond can make such a task difficult. A useful and proven characteristic is the emission of luminescence when a diamond is excited by a source of ultraviolet energy. Typically, a gemologist would utilize an ultraviolet lamp with excitation wavelengths of 365 nm (long-wave ultraviolet, LWUV) or 254 nm (short-wave ultraviolet, SWUV), which correspond to the emission lines of a low-pressure mercury-vapor lamp. In this application, “fluorescence” would be observed during ultraviolet excitation, while “phosphorescence” may be observed when the excitation is removed. The De Beers DiamondView instrument (Spear and Welbourn, 1994; Welbourn et al., 1996) was designed to authenticate natural diamonds and synthetic diamonds. It allows a more sophisticated observation to be made by way of a shorter wavelength excitation of <225 nm corresponding to the primary absorption edge and only exciting around 1-micron depth of material, such that observed luminescence","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"220-229"},"PeriodicalIF":2.6,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46934365","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":"Hydrogen and Oxygen Stable Isotope Ratios of Dolomite-Related Nephrite: Relevance for its Geographic Origin and Geological Significance","authors":"Kong Gao, Ting Fang, Taijin Lu, Yan Lan, Yong Zhang, Yuanyuan Wang, Yayun Chang","doi":"10.5741/gems.56.2.266","DOIUrl":"https://doi.org/10.5741/gems.56.2.266","url":null,"abstract":"GEMS & GEMOLOGY SUMMER 2020 Nephrite is a near-monomineralic rock composed of tremolite-actinolite, Ca2(Mg,Fe)5Si8O22(OH)2. It occurs worldwide (figure 1) and is classified as dolomite-related or serpentine-related according to the different parent rocks and ore-hosting rocks, and both types form by metasomatism (Yui et al., 1988; Tang et al., 1994; Yang and Abduriyim, 1994; Harlow and Sorensen, 2005; Burtseva et al., 2015). The large and well-known dolomite-related nephrite deposits are distributed in the Xinjiang Uyghur Autonomous Region (hereafter abbreviated as Xinjiang) of China, Qinghai Province of China, Siberia in Russia, and Chuncheon in South Korea (figure 1). Data from smaller-scale deposits such as Val Malenco in Italy and Złoty Stok in Poland are also used in this study (figure 1). The rest of the data were collected from nephrites produced at multiple small-scale sources in China: Xiuyan, Tanghe, Dahua, and Luodian (figure 2). With nephrite jade, a premium is placed on geographic origin since the gem’s cultural significance differs by location. It is possible to have an opinion","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"266-280"},"PeriodicalIF":2.6,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47878477","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":"Naturally Colored Yellow and Orange Gem Diamonds: The Nitrogen Factor","authors":"C. Breeding, S. eaton-magaña, J. Shigley","doi":"10.5741/gems.56.2.194","DOIUrl":"https://doi.org/10.5741/gems.56.2.194","url":null,"abstract":"GEMS & GEMOLOGY SUMMER 2020 Among fancy-color diamonds, those with saturated blue, green, and red colors are the rarest and generally the most highly valued. Over the last decade, however, diamonds with pure hues in these colors have made up less than one-tenth of one percent of all diamonds examined at GIA, making them virtually unattainable in the marketplace. In recent issues of Gems & Gemology, we have documented the gemological and spectroscopic properties of the rarest of fancy-color diamonds ranging from pink-to-red, blue, and green to the more unusual white and black. This article will address the most common colored diamonds, those with yellow hues, while also examining their much rarer orange cousins (figure 1). This is the last of the fancy color groups in this series, and a brief summary of all the colored diamond groups is provided at the end of the article. Yellow and orange diamonds owe their color primarily to nitrogen impurities that are incorporated in the diamond lattice during growth deep in the earth. Nitrogen is the most common impurity in natural diamond due to the very similar atomic radii of nitrogen and carbon atoms (155 and 170 picometer Van der Waals radii, respectively) as well as the relative abundance of nitrogen in the growth environ-","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"194-219"},"PeriodicalIF":2.6,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47924416","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":"History of the Chivor Emerald Mine, Part II (1924-1970): Between Insolvency and Viability","authors":"K. Schmetzer, G. Martayan, A. Blake","doi":"10.5741/gems.56.2.230","DOIUrl":"https://doi.org/10.5741/gems.56.2.230","url":null,"abstract":"GEMS & GEMOLOGY SUMMER 2020 Many legends are told about the history of the Chivor emerald mine.1 The story begins with the sporadic working of the Colombian mine by indigenous people before being sought out by Spanish conquistadores in the first half of the sixteenth century. The property was exploited by the Spanish in the sixteenth and seventeenth centuries and then forgotten in the jungle for a period of more than two centuries after 1672. Schmetzer et al. (2020) chronicled the first part of the modern era commencing after the 200-year break, covering from 1880 to 1925. During that interval, Colombian miner Francisco Restrepo searched for and rediscovered the mine, and mining titles were granted to him and his associates in 1889. Through a series of transactions, the mining titles and land in the area came under the ownership of the Compañía de las Minas de Esmeraldas de Chivor, a Colombian entity in which Restrepo was involved. Only intermittent operational activities took place until 1912, when the German gem cutter and merchant Fritz Klein joined Restrepo with an increased focus on the operational side. Early mining by Restrepo and Klein yielded several finds promising enough for them to travel to Germany together in 1913 to seek investors (figure 1). Further work was curtailed one year later, however, when Restrepo died in 1914 and Klein, who had hoped to purchase the mine with German funding, was thwarted by the outbreak of World War I. When hostilities ended, Klein sought to recommence his efforts to buy the mine in 1919, but an American corporation, the Colombian Emerald Syndicate, Ltd., had in the interim obtained an option to purchase the mine. That option was exercised, and the mine was sold in December 1919 to two key representatives of the American group, Wilson E. Griffiths and Carl K. MacFadden. On behalf of the Colombian Emerald Syndicate, mining operations HISTORY OF THE CHIVOR EMERALD MINE, PART II (1924–1970): BETWEEN INSOLVENCY AND VIABILITY","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"230-257"},"PeriodicalIF":2.6,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48850206","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":"Optical Whitening and Brightening of Pearls: A Fluorescence Spectroscopy Study","authors":"Chunhui Zhoi, T. Tsai, Nicholas Sturman, Nanthaporn Nilpetploy, Areeya Manustrong, Kwanreun Lawanwong","doi":"10.5741/gems.56.2.258","DOIUrl":"https://doi.org/10.5741/gems.56.2.258","url":null,"abstract":"GEMS & GEMOLOGY SUMMER 2020 Optical brightening agents (OBAs) are chemical compounds that can absorb light in the ultraviolet and violet region of the electromagnetic spectrum and emit light in the blue region as fluorescence, due to their extended conjugation and/or aromaticity. They are sometimes called fluorescent brightening agents or fluorescent whitening agents, and have been frequently used to enhance the appearance of fabric and paper (Lanter, 1966; Leaver and Milligan, 1984; Esteves et al., 2004; Bajpai, 2018). While many types of brighteners are listed in the Colour Index (https://colour-index.com), only a handful are commercially important. Some examples are shown in figure 1. Photoluminescence is light emission from any form of matter after the absorption of photons. Fluorescence is a type of photoluminescence in which a molecule dissipates its absorbed energy through the rapid emission of a photon, while phosphorescence is the emission of radiation in a similar manner to fluorescence but on a longer timescale, so that emission continues after excitation ceases. Fluorescence can be generated by exciting the substance via a range of energy sources. The molecule in the substance absorbs the source energy and once excited moves from a lower electronic state to a higher one. Immediately after absorbing energy, it loses the energy by emitting a photon; this process of photon emission is called luminescence. Typically, fluores-","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"258-265"},"PeriodicalIF":2.6,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42447808","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":"The Evolution of Chinese Jade Carving Craftmanship","authors":"Mingying Wang, Guang-Yi Shi","doi":"10.5741/gems.56.1.30","DOIUrl":"https://doi.org/10.5741/gems.56.1.30","url":null,"abstract":"","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"30-53"},"PeriodicalIF":2.6,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47180284","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":"History of the Chivor Emerald Mine, Part 1 (1880-1925): From Rediscovery to Early Production","authors":"K. Schmetzer, G. Martayan, Jose Guillermo Ortiz","doi":"10.5741/gems.56.1.66","DOIUrl":"https://doi.org/10.5741/gems.56.1.66","url":null,"abstract":"GEMS & GEMOLOGY SPRING 2020 The foregoing outline of the story, as presently known, has been drawn largely from three books authored by individuals who led the mining activities at Chivor during different eras: German gem merchant Fritz Klein, South African mining engineer Peter W. Rainier, and American gem hunter and buyer Russell W. Anderton. All three men wrote in a style to highlight the adventurous nature of the work. Klein’s memoir covered the period from approximately 1911 to 1923 and was initially published in 1941, with a slightly updated version released in 1951. Rainier’s narrative chronicled from the second half of the 1920s to the early 1930s and was printed in 1942. Anderton’s work, coming to press in 1953 in the United States and 1954 in the United Kingdom, recounted activities of the late 1940s and early 1950s. The events presented in the three books have, since their respective publications, found their way in numerous variations into historical articles or descriptions as well as gemological, mineralogical, or geological papers.1 The rediscovery of Chivor by Francisco Restrepo (figure 1) and the clues that motivated his search have been a particularly popular topic. In general, the events described by Klein, Rainier, or Anderton have been accepted as facts in the literature, and only Klein’s description and dating of the rediscovery","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"66-109"},"PeriodicalIF":2.6,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41755148","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":"Rhodonite-Pyroxmangite from Tanatz Alp, Switzerland","authors":"F. Caucia, L. Marinoni, M. Riccardi, O. Bartoli, Maurizio Scacchetti","doi":"10.5741/gems.56.1.110","DOIUrl":"https://doi.org/10.5741/gems.56.1.110","url":null,"abstract":"","PeriodicalId":12600,"journal":{"name":"Gems & Gemology","volume":"56 1","pages":"110-123"},"PeriodicalIF":2.6,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46048054","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}