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name:
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Paraiba Tourmaline
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| gemstone variety:
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Tourmaline
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| trade name 1:
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Paraiba Tourmaline
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| trade name 2:
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Tourmaline
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| trade name 3:
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| basic colour:
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blue
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Colour :
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turquoise-blue to neon-blue to neon-green to
emerald-green
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Quality :
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the best colour is a vivid neon-blue or an emerald
green. Even heavy inclusions are accepted, as there are
hardly any flawless Paraiba Tourmalines of good colour.
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History :
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In 1987, after 5 years of unsuccessful search in the
Brazilian garimpo, Mr. Hector Barbosa found the first stone
of this totally new Tourmaline near the village Sao
José da Batalha in the federal state of Paraiba. The
original mine is not bigger than a house and is basically
exhausted since 1993! For that reason, gems in good quality
are becoming more and more expensive. The surprisingly "new"
Tourmaline colours are due to a small amount of copper but
also a little bit of gold! Dealers all over the world are
competing for the new Paraiba Tourmaline, which means that
it can command retail prices over U$ 20,000 per carat for
the finest specimens. Although this is more than other
colour of Tourmaline, it is very little when you consider
how rare these gemstones are. Diamonds are quite common in
comparison.
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Curiosities / Saga :
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Countrys of Origin :
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In the centre of the federal state of Paraiba in the
Northeast of Brazil
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Birthstone :
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October - Tourmaline
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Hardness :
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7.5
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Treatment :
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sometime heat-treated
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Size :
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mostly small sizes between 0.10 and 0.50 carat. Fine
colour Paraiba Tourmaline above 1.00 carats are extremely
rare.
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Specific gravity :
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3.10 - 3.26
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Chemical Composition Formula :
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Na(Li,Al,Cu,Mn)3 Al6 (BO3)3 Si6018 (OH)3 F
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Chemical Composition Name :
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Hydrous and fluor- bearing sodium- lithium- aluminium-
copper- manganese- boronsilicate
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Crystal system :
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trigonal
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Light refraction :
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1.610 - 1.650
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Double refraction :
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0.016 - 0.022
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