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Titanium rings are jewelry rings or bands which have been primarily constructed from titanium. The actual compositions of titanium can vary, such as "commercial pure" (99.2% titanium) or "aircraft grade" (primarily, 90% titanium, 6% aluminum, 4% vanadium), and titanium rings are often crafted in combination with other materials, such as gemstones and traditional jewelry metals. Even with these variations in composition and materials, titanium rings are commonly referred to as such if they contain any amount of titanium. Rings crafted from titanium are a modern phenomenon, becoming widely available on the market around the 1990s. Titanium rings offer several unique properties: they are biocompatible (hypoallergenic), lightweight, corrosion-resistant, and have the highest strength-to-weight ratio of any crystalline metal.〔Matthew J. Donachie, Jr. (1988). ''Titanium: A Technical Guide''. Metals Park, OH: ASM International. p. 11. ISBN 0-87170-309-2.〕 == History == Titanium was discovered in Cornwall, England, in 1791 by William Gregor. It was also discovered around the same time by Hungarian mineralogist Franz-Joseph Müller von Reichenstein, and later in 1795 by German chemist Martin Heinrich Klaproth – who gave titanium its name, a reference to the Titans of Greek mythology.〔Emsley, John (2001). "Titanium". ''Nature's Building Blocks: An A-Z Guide to the Elements''. Oxford, England, UK: Oxford University Press. pp. 451–452. ISBN 0-19-850340-7.〕 However, it was not until after 1932 that commercial use for titanium became possible, due to methods established by William Justin Kroll. Kroll devised ways of reducing titanium tetrachloride (TiCl4) into its metal form.〔Greenwood, N. N.; Earnshaw, A. (1997). ''Chemistry of the Elements'' (2nd ed.). Oxford: Butterworth-Heinemann. p. 955. ISBN 0-7506-3365-4.〕 His process is still used today for commercially-produced titanium.〔Lide, D. R., ed. (2005), ''CRC Handbook of Chemistry and Physics'' (86th ed.), Boca Raton (FL): CRC Press, ISBN 0-8493-0486-5〕 The cost of titanium rings can be very high. This is ostensibly because the process of extracting titanium from its various ores is laborious and costly.〔 Although it is indeed expensive as an engineering material, it is far less expensive than the jeweler's usual precious metals, even silver. At the start of 2014, no prices for pure titanium or its common commercial alloys exceeded US $10 per pound. The process of machining titanium rings is expensive and necessary since the metal is nearly impossible to craft by rolling or soldering in the way silver, gold and even platinum are formed. It is unknown who first crafted titanium into a ring or other jewelry piece. A titanium wedding-ring is used as a minor plot-point in the 1989 science fiction film and novel ''The Abyss''. Titanium started appearing on the open market in approximately the 1990s. Since 2000, availability of titanium rings has become large-scale, with most online and bricks-and-mortar jewelry stores likely to carry titanium-based rings as part of their inventory. Many outlets now specialize exclusively in the design and sale of titanium rings. 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「Titanium ring」の詳細全文を読む スポンサード リンク
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