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Amethyst is an extremely sought-after gem which has been valued by many civilizations since antiquity. A variety of vitreous quartz, amethyst often forms dramatic prismatic crystals which are often formed into jewelry without being cut. Brazil and Uruguay are common sources of high quality amethyst. In the early Christian church, amethyst was believed to guard against intoxication, hence its derivation from the Greek "amethustos," meaning "not drunk." Authentic cow bone has been exquisitely carved, polished and hand finished to make this beautiful piece. Chalcedony is the general name for a variety of colored quartzes, many of which have a creamy appearance and luster. The gemstones given the name chalcedony are usually white to bright blue, while other colors have been given separate names--for instance, black onyx, green chrysoprase, and orange carnelian. Deep red garnet is derived from a number of minerals, including pyrope and almandine. Popularized in Bohemia in the Czech Republic, garnet has been used in decoration and jewelry across Europe for many years. Its color is generally a dark burgundy, sometimes with a hint of orange, pink, or purple. Opals form when silica gel hardens in the cracks of other rocks. Most of the world's precious opal comes from Australia, where opal is the national gem. A boulder opal is an opal that has been sliced together with its surrounding ironstone for a varied look. Fire opal from Mexico comes in shades of orange and Peruvian opal is an opaque blue-green stone. An opal doublet has polished precious opal on the top with an ironstone backing added for strength, making the slice of opal less prone to chipping. Tourmaline is a coveted stone that comes in a wide range of colors from black to pink, green and blue. Crystals which display more than one color together are common. A cross-section of a watermelon tourmaline crystal reveals green on the outside and pink within. Beautiful turquoise is a phosphate mineral popular all over the world. Mined since 5000 BC, it is one of the first gemstones known to be used by humans. Color variation from sky-blue to medium green is affected by differing amounts of copper and iron, more copper giving the stone a bluer color and more iron a greener one. Beautiful light blue turquoise is mined in Northern Iran and other varieties occur in Mexico, the United States and elsewhere.
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