Friday, April 27, 2012

Gemstone of the Week: Moonstone

Moonstone is a very interesting gem.  It has an unusual sheen known as 'adularescence' which is described as "a floating, shifting light effect caused by the structural unevenness of moonstone" (quote from Renee Newman's book "Gemstone Buying Guide").  Moonstone belongs to the Feldspar  group of minerals and can occur in Olgioclase Feldspar, Orthoclase Feldspar, Sanidine (an Alkali Feldspar), and Anorthoclase Fledspar.  The effect found in Moonstone results from the layering of two different types of Feldspar (often Albite and Orthoclase) and causes the light to scatter giving it it's unusual optical effect.   Moonstone can be white, colourless, light grayish-blue, gray, yellow, orange, brown, blue, or green.  Moonstone is found all over the world, but some of the major sources are Sri Lanka, Burma, and India.  Moonstone can be anywhere from $5-$100 per carat depending on how transparent or opaque the stone is, as well as, the colour (near transparent blue is generally the most valuable).

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