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2. List of U.S. state minerals, rocks, stones and gemstones

   en.wikipedia.org/wiki/List_of_U.S._state...

   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 ...

3. Gemological Institute of America - Wikipedia

   en.wikipedia.org/wiki/Gemological_Institute_of...

   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.

4. List of gemstones by species - Wikipedia

   en.wikipedia.org/wiki/List_of_gemstones_by_species

   Gemstones of the World revised 5th edition, 2013 by Walter Schumann ISBN 978-1454909538 Smithsonian Handbook: Gemstones by Cally Hall, 2nd ed. 2002 ISBN 978-0789489852 v

5. Opal - Wikipedia

   en.wikipedia.org/wiki/Opal

   The term first appears in Roman references around 250 BC, at a time when the opal was valued above all other gems. The opals were supplied by traders from the Bosporus, who claimed the gems were being supplied from India. Before this, the stone was referred to by a variety of names, but these fell from use after 250 BC.

6. Tanzanite - Wikipedia

   en.wikipedia.org/wiki/Tanzanite

   Tanzanite is only found in Simanjiro District of Manyara Region in Tanzania, in a very small mining area approximately 7 km (4.3 mi) long and 2 km (1.2 mi) wide [4] near the Mererani Hills. [ 5 ] Tanzanite is noted for its remarkably strong trichroism , appearing alternately blue, violet and burgundy depending on crystal orientation. [ 6 ]

7. Jet (gemstone) - Wikipedia

   en.wikipedia.org/wiki/Jet_(gemstone)

   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 ...

8. Gemstone - Wikipedia

   en.wikipedia.org/wiki/Gemstone

   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 ...

9. Diamond (gemstone) - Wikipedia

   en.wikipedia.org/wiki/Diamond_(gemstone)

   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 ...