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The Hope Diamond, also known as ''Le Bijou du Roi'' ("the King's Jewel"), ''Le bleu de France'' ("the Blue of France"), and the Tavernier Blue, is a large, ,()〔 deep-blue diamond, and now housed in the National Gem and Mineral collection at the National Natural History Museum in Washington, D.C. It is blue to the naked eye because of trace amounts of boron within its crystal structure, and exhibits red phosphorescence after exposure to ultraviolet light.〔Schmid, Randolph E. The diamond glows only after the light has been switched off. The glow can last for anything up to 2 minutes. "(UV Light Makes Hope Diamond Glow Red )". ''ABC News''. January 7, 2008.〕〔Hatelberg, John Nels. "(The Hope Diamond phosphoresces a fiery red color when exposed to ultraviolet light )". Smithsonian Institution.〕 It is classified as a Type IIb diamond, and is notorious for supposedly being cursed. It has a long recorded history, with few gaps, in which it changed hands numerous times on its way from India to France to Britain and eventually to the United States, where it has been regularly on public display since. It has been described as the "most famous diamond in the world". ==Physical properties== * Weight. In December 1988, the Gemological Institute of America's Gem Trade Lab determined that the diamond weighed .〔 * Size and shape. The diamond has been compared in size and shape to a pigeon egg,〔 walnut,〔 a "good sized horse chestnut"〔 which is "pear shaped."〔 The dimensions in terms of length, width, and depth are 25.60 mm × 21.78 mm × 12.00 mm (1 in × 7/8 in × 15/32 in).〔 * Color. It has been described as being "fancy dark greyish-blue"〔 as well as being "dark blue in color"〔 or having a "steely-blue" color.〔 As colored-diamond expert Stephen Hofer points out, blue diamonds similar to the Hope can be shown by colorimetric measurements to be grayer (lower in saturation) than blue sapphires.〔Hofer, Stephen, Collecting and Classifying Colored Diamonds, p.414〕 In 1996, the Gemological Institute of America's Gem Trade Lab examined the diamond and, using their proprietary scale, graded it ''fancy deep grayish blue''.〔King,et al., "(Characterizing Natural-color Type IIb Blue Diamonds )", Gems & Gemology, Vol. 34, #01, p.249〕 Visually, the gray modifier (mask) is so dark (indigo) that it produces an "inky" effect appearing almost blackish-blue in incandescent light.〔 Current photographs of the Hope Diamond use high-intensity light sources that tend to maximize the brilliance of gemstones.〔Wise, ibid. p.29-30〕 In popular literature, many superlatives have been used to describe the Hope Diamond as a "superfine deep blue", often comparing it to the color of a fine sapphire, "blue of the most beautiful blue sapphire" (Deulafait), and describing its color as "a sapphire blue".〔Wise, Richard W., ''Secrets of the Gem Trade, The Connoisseur's Guide to Precious Gemstones'', Ch. 38, p.235. ISBN 0-9728223-8-0.〕〔Note: Other references include Mawe (1823), Ball (1835), Bruton (1978), Tolansky (1962). However, these descriptions are somewhat wide of the mark.〕 Tavernier had described it as a "beautiful violet".〔 * Emits a red glow. The stone exhibits an unusually intense and strongly colored type of luminescence: after exposure to short-wave ultraviolet light, the diamond produces a brilliant red phosphorescence ('glow-in-the-dark' effect) that persists for some time after the light source has been switched off, and this strange quality may have helped fuel "its reputation of being cursed."〔 The red glow helps scientists "fingerprint" blue diamonds, allowing them to "tell the real ones from the artificial."〔 The red glow indicates that a different mix of boron and nitrogen is within the stone, according to Jeffrey Post in the journal ''Geology''. * Clarity. The clarity was determined to be VS1, with whitish graining present.〔 * Cut. The cut was described as being "cushion antique brilliant with a faceted girdle and extra facets on the pavilion."〔 * Chemical composition. In 2010, the diamond was removed from its setting in order to measure its chemical composition; after boring a hole one nanometre (four-billionths of an inch) deep, preliminary results detected the presence of boron, hydrogen and possibly nitrogen; the boron concentration varies from zero to eight parts per million. According to Smithsonian curator Dr. Jeffrey Post, the boron may be responsible for causing the blue color of the stones after tests using infrared light measured a spectrum of the gems.〔 * Touch and feel. When Associated Press reporter Ron Edmonds was allowed by Smithsonian officials to hold the gem in his hand in 2003, he wrote that the first thought that had come into his mind was: "Wow!" It was described as "cool to the touch."〔 He wrote: * Hardness. Diamonds in general, including the Hope Diamond, are considered to be the hardest natural mineral on the Earth, but because of diamond's crystalline structure, there are weak planes in the bonds which permit jewelers to slice a diamond and, in so doing, to cause it to sparkle by refracting light in different ways. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hope Diamond」の詳細全文を読む スポンサード リンク
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