Cat's eye diaspore, sometimes marketed under the name Zultanite, is a color change gem from Turkey recently introduced to the international market. Diaspore is a hydrated aluminum oxide colored by manganese. It was first faceted as a gemstone in the 1980s, but has never been mined commercially until recently. With reasonably good hardness (6.5 to 7 on the Mohs scale) and good brilliance, diaspore has been attracting considerable attention in the gem world.
Cat's eye diaspore gems are fairly rare. The chatoyancy or cat's eye effect is caused by the alignment of rutile needles.
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