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Untreated tanzanite is a trichroic gemstone, meaning that light that enters this anisotropic crystal gets refracted on different paths, with different colour absorption on each of the three optical axes. As a result of this phenomenon, a multitude of colors have been observed in various specimens: shades of purple, violet, indigo, blue, cyan ...
TanzaniteOne Mining Ltd was founded by Richland Resources, a gemstone development and mining company who were listed on the London Stock Exchanges AIM market (AIM:RLD) in 1994 . In 2014 TanzaniteOne was sold to a private company, Sky Associates , who are now the current owners.
Richland Resources Ltd is a gemstone mining, development and exploration company who are listed on the London Stock Exchanges AIM market. [1] ( AIM:RLD) Richlands developed and operated TanzaniteOne Mining Ltd – the world's largest tanzanite gemstone mining company, based in Merelani, Tanzania from August 2004 until March 2015.
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
Rare or unusual gemstones, generally understood to include those gemstones which occur so infrequently in gem quality that they are scarcely known except to connoisseurs, include andalusite, axinite, cassiterite, clinohumite, painite and red beryl. [27] Gemstone pricing and value are governed by factors and characteristics in the quality of the ...
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The carat (ct) is a unit of mass equal to 200 mg (0.00705 oz; 0.00643 ozt), which is used for measuring gemstones and pearls. The current definition, sometimes known as the metric carat , was adopted in 1907 at the Fourth General Conference on Weights and Measures , [ 1 ] [ 2 ] and soon afterwards in many countries around the world.
Fordite in Dearborn, Michigan, 2019. Fordite, also known as Detroit agate, Motor City agate, [1] paint rock, or paint slag, [2] is a lapidarist term for polished pieces of finely layered paint masses from automobile factories.