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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 ...
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 ...
Category. Commons. Diamond clarity is the quality of diamonds that relates to the existence and visual appearance of internal characteristics of a diamond called inclusions, and surface defects, called blemishes. Clarity is one of the four Cs of diamond grading, the others being carat, color, and cut . Inclusions are solids, liquids, or gases ...
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Jet (gemstone) Jet is a type of lignite, [ 1] the lowest rank of coal, and is a gemstone. Unlike many gemstones, jet is not a mineral, but is rather a mineraloid. [ 2] It is derived from wood that has changed under extreme pressure. The English noun jet derives from the French word for the same material, jaiet (modern French jais ), ultimately ...
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.