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name:
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Imperial Topaz
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| gemstone variety:
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Topaz
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| trade name 1:
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Imperial Topaz
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| trade name 2:
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Pink Topaz
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| trade name 3:
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Blue Topaz
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| basic colour:
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orange
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|
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Colour :
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yellow to cognac-orange to red, pink, blue and
colourless
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Quality :
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the best colour is an intense orange-red or a strong
pink. Yellow is less desirable. Facetted Topaz should be
eyeclean. Usually facetted Topazes have a perfect brilliancy
and lustre when they are cut into the right proportions.
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History :
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The origin of the word "topaz" is not clear. Some
people derive it from the Sanskrit word 'tapas'= fire. The
Romans associated Topaz with Jupiter, the god of the sun.
Imperial Topaz has nothing to do with yellow quartz
(Citrine), which in former times was also designated topaz.
The biggest gem quality cut topaz with more than 1660 carats
is the Braganca of the Portuguese Crown.
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Curiosities / Saga :
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Countrys of Origin :
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Brazil, the region of Ouro Preto in the south of Minas
Gerais, produces the finest cognac colours. Topaz from Sri
Lanka, Pakistan and Russia is colourless or of a not
attractive gray-brown. Colourless rough can be irradiated to
produce blue stones
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Birthstone :
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November - Topaz
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Hardness :
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8
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Treatment :
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orange,red=none; pink=heated; blue=irradiated
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Size :
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normally between 0.50 and 10.00 carats, anything above
10.00 carats in fine peach colour is extremely rare
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Specific gravity :
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3.52 - 3.58
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Chemical Composition Formula :
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Al2 ((F,OH)2 SiO4)
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Chemical Composition Name :
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fluosilicate of aluminium
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Crystal system :
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rhombic
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Light refraction :
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1.605 - 1.640
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Double refraction :
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0.008 - 0.010
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