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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 ...
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Pleochroism. 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 ...
Main opal producing countries Opal is a hydrated amorphous form of silica (SiO 2 · n H 2 O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to its amorphous property, it is classified as a mineraloid , unlike crystalline forms of silica, which are considered minerals .
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 ...
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 evaluate gemstone quality.
Sri Lanka ’s gem industry has a very long and colorful history. Sri Lanka was affectionately known as Ratna-Dweepa which means Gem Island. The name is a reflection of its natural wealth. Marco Polo wrote that the island had the best sapphires, topazes, amethysts, and other gems in the world. [ 1] Ptolemy, the 2nd century astronomer recorded ...
New York City. , New York. , United States. Website. www .gemscience .net. Gemological Science International, or GSI, is an independent gemological organization that is one of the largest gemological entities in the world, with offices in four continents. [1] [2] [3]