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In 1986, California named benitoite as its state gemstone, a form of the mineral barium titanium silicate that is unique to the Golden State and only found in gem quality in San Benito County. [ 80 ] ^ Colorado is the only state whose geological symbols reflect the national flag's colors: red (rhodochrosite), white (yule marble), and blue ...
Print/export Download as PDF; Printable version; In other projects ... Some rocks are used as gems, including: Anthracite; Anyolite; Bauxite; Concretions;
Gemstone. Group of precious and semiprecious stones—both uncut and faceted—including ( clockwise from top left) diamond, uncut synthetic sapphire, ruby, uncut emerald, and amethyst crystal cluster. A gemstone (also called a fine gem, jewel, precious stone, semiprecious stone, or simply gem) is a piece of mineral crystal which, when cut or ...
Jewelry applications of precious opal can be somewhat limited by opal's sensitivity to heat due primarily to its relatively high water content and predisposition to scratching. [11] Combined with modern techniques of polishing, a doublet opal can produce a similar effect to Natural black or boulder opal at a fraction of the price.
Diamond[ a] is a gemstone formed by cutting a raw diamond. Diamonds are one of the best-known and most sought-after gems, and they have been used as decorative items since ancient times. The hardness of diamond and its high dispersion of light —giving the diamond its characteristic "fire"—make it useful for industrial applications and ...
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Cut (gems) A decorative glass crystal about 4 cm (1.6 in) in diameter, having a facet cut often applied for gemstones. At some positions, coloured light (see rainbow colouring) can be regarded caused by the intended optical prism effect of the cut. A gemstone desired to be used in jewelry is cut depending on the size and shape of the rough ...
The first theme is using legendary luminous gems to illuminate buildings, for navigation lights on ships, or sometimes as guiding lights for lost persons (Ball 1938: 498–500). In India, the earliest country in which fine gemstones were known, belief in luminous gems dates back some twenty-five centuries.