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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 ...
Website. www .gia .edu. The Gemological Institute of America ( GIA) is a nonprofit institute based in Carlsbad, California. It is dedicated to research and education in the field of gemology and the jewelry arts. [1] Founded in 1931, GIA's mission is to protect buyers and sellers of gemstones by setting and maintaining the standards used to ...
Beryl is a common mineral, and it is widely distributed in nature. It is found most commonly in granitic pegmatites, but also occurs in mica schists, such as those of the Ural Mountains, and in limestone in Colombia. [11] It is less common in ordinary granite and is only infrequently found in nepheline syenite.
Total carat weight (t.c.w.) is a phrase used to describe the total mass of diamonds or other gemstone in a piece of jewelry, when more than one gemstone is used. Diamond solitaire earrings, for example, are usually quoted in t.c.w. when placed for sale, indicating the mass of the diamonds in both earrings and not each individual diamond.
Present, dichroism or trichroism, depending on heat treatment. Tanzanite is the blue and violet variety of the mineral zoisite (a calcium aluminium hydroxyl sorosilicate ), caused by small amounts of vanadium. [3] Tanzanite belongs to the epidote mineral group. Tanzanite is only found in Simanjiro District of Manyara Region in Tanzania, in a ...
Gemology. Gemology or gemmology is the science dealing with natural and artificial gemstone materials. It is a geoscience and a branch of Stoneology and mineralogy. Some jewelers (and many non-jewelers) are academically trained gemologists and are qualified to identify and evaluate gems. [1] [2]