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Natural Kyanite Cabochon

Refraction Index: 1.71 - 1.75
Hardness: varies from 4 to 5 and from 6.5 to 7.0, depending on the direction of the cleavage planes
Specific Gravity: 3.58+
Species: Silicate
Treatment: None
Care: Wash with soapy water. Avoid harsh detergents. Never clean ultrasonically or steam clean.

Kyanites name comes from Greek word  "kyanos" which means deep blue.