An Important Exhibition of Seven Rare Gem Diamonds

King, John T.; Shigley, James E.

doi:10.5741/gems.39.2.136

Cited by 8 publications

(4 citation statements)

References 11 publications

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“…For example, in his description of several famous diamonds he encountered while in India, the French traveler and gem dealer Jean-Baptiste Tavernier (1676) mentioned seeing a 137.27 ct yellow diamond that he referred to variously as the "Florentine," the "Austrian Yellow," and the "Grand Duke of Tuscany." As with other colors, yellow diamonds have come to the public's attention through the interest generated by a number of special stones, such as the historical 128.54 ct Tiffany (figure 2; see Balfour, 2000) and 101.29 ct Allnat (see King and Shigley, 2003) diamonds, or the extraordinary 407.48 ct Incomparable (illustrated in King et al, 1994, p. 227). Indeed, the first reportedly authenticated diamond found in Africa, which was cut into the 10.73 ct Eureka, is a distinct yellow (Balfour, 2000; shown in Janse, 1995, p. 231).…”

Section: Introductionmentioning

confidence: 99%

Characterization and Grading of Natural-Color Yellow Diamonds

King¹,

Shigley²,

Gelb³

et al. 2005

Gems & Gemology

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oday, yellow diamonds are among the most widely encountered of the "fancy color" diamonds (figure 1). From 1998 to the present, GIA has issued grading reports on more than 100,000 yellow diamonds, by far the most common of the fancy-color diamonds submitted to our laboratory. In 2003, for example, 58% of the diamonds submitted for GIA Colored Diamond Grading Reports or Colored Diamond Identification and Origin of Color Reports were in the yellow hue. Nevertheless, these represented only 2.4% of all diamonds submitted for various grading reports that year. The dichotomy between being common among colored diamonds yet relatively rare overall has created a mix of information and sometimes erroneous assumptions about yellow diamonds. In addition, although information about their "origin of color" or unusual characteristics (see below) has been documented over the years, little has been published about their color appearance and its relationship to color grading (one exception being Hofer, 1998). This article presents data on more than 24,000 fancy-color yellow diamonds that were examined by the GIA Gem Laboratory during the years 1998 and 2003. While our main concern in this study was gathering information to characterize the gemological and spectroscopic properties of the entire population of samples, we were also interested in identifying any trends in size, color grade, or clarity grade among the yellow diamonds submitted to us that might be revealed over time. To that end, we selected a sample population from these two years separated by a five-year span. Following a brief review of the literature on the geographic sources, cause of color, and other physical properties of fancy-color yellow diamonds, this article will focus on expanding the published information about these diamonds by documenting and 88 YELLOW DIAMONDS GEMS & GEMOLOGY SUMMER 2005

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Section: Introductionmentioning

confidence: 99%

Characterization and Grading of Natural-Color Yellow Diamonds

King¹,

Shigley²,

Gelb³

et al. 2005

Gems & Gemology

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“…They are also recovered in the alluvium eroded from Cretaceous conglomerates of the Capacete formation (Read et al, 2004). Examples of large diamonds include the 27.09 ct vivid pink Queen Giacampos and the 13.90 ct Moussaieff Red, both found in the Abaeté River (King and Shigley, 2003). Other discoveries include the 0.59 The remarkable Bragança diamond-either 1,680 ct (Mawe, 1812) or 1,730 ct (Ferry, in Reis, 1959), depending on the source-was found in 1797 in the Abaeté region.…”

Section: Geologic Settingmentioning

confidence: 98%

Brazilian Diamonds: A Historical and Recent Perspective

Svisero¹,

Shigley²,

Weldon³

2017

G&G

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Brazil, which commanded global production in the 1700s and early 1800s, has remained a continuous source of diamonds for three centuries. Even though the country represented less than 1% of world production in 2015, a number of large famous diamonds, as well as fancy-color diamonds, have originated there. The sources are primarily alluvial, with diamonds transported by and deposited along a multitude of rivers. The diamonds are found mainly by independent miners (garim eiros) in riverbeds, in unconsolidated sediments, and in compacted sedimentary conglomerates. After a century of exploration for the primary sources, some economically viable kimberlite pipes have been discovered in recent years, with one occurrence now being developed for mining. This article traces the country's fascinating diamond history before focusing on the geologic setting of the diamond occurrences, as well as the challenges and future outlook for production. The locations of the secondary deposits, principally in the states of Minas Gerais and Mato Grosso, are presented.

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“…If green naturals are left on the finished stone, these can contribute to a green face-up color, but this layer is often mostly or completely removed during the faceting process. Natural diamonds with a saturated blue-to-green bodycolor are very rare, but they do exist; perhaps the best example is the famous 41-ct Dresden Green diamond (Kane et al, 1990; see also King and Shigley, 2003). Despite work over the past five decades, identifying origin of color in these cases remains very challenging for gemological researchers, and still it is not always possible for gem-testing laboratories to conclusively establish whether a green diamond is or is not laboratory irradiated unless it can be examined from the rough through the faceting process.…”

Section: Box B: the Irradiated Deepdenementioning

confidence: 99%

A History of Diamond Treatments

Overton

Shigley²

2008

The Global Diamond Industry

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been long periods, both ancient and modern, when diamond treatments were conducted in the relative open, and their practitioners were regarded by some as experts and even artists. Gem treatments, it must be recognized, are neither good nor bad in themselves-fraud comes about only when their presence is concealed, whether by intent or by negligence. This fact places a specific responsibility for full treatment disclosure on all those handling gem materials, and most especially on those selling diamonds, given their long and enduring value. That responsibility is one of knowing and understanding what happens as a result of treatment, having the expertise to recognize treated stones when they are encountered, and knowing when suspect stones should be examined by properly equipped gem-testing laboratories. This article is not intended to be a complete review of the history of diamond treatments, as such

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An Important Exhibition of Seven Rare Gem Diamonds

Cited by 8 publications

References 11 publications

Characterization and Grading of Natural-Color Yellow Diamonds

Characterization and Grading of Natural-Color Yellow Diamonds

Brazilian Diamonds: A Historical and Recent Perspective

A History of Diamond Treatments

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