Characteristically reddish brown, but can be white or plum-blue, moonstone occurs in the Coimbatore district of Tamil Nadu. Material from the Kangayam district in southern India includes both cat’s eye and star varieties.
SG = 2.582.59. RI(1.520-1.525): DR 0.005 Moonstone from the Karur–Kangayam belt shows various hues including pearly white, grey, bamboo-green, light brownish pink and black. The gem varieties are characterized by a milky white sheen that moves across the crystal when rotated against the light, and is identical to the chatoyancy observed in cat’s eye chrysoberyls from southern Kerala. Green Indian moonstone has been reported. ‘Royal blue’ sheen high calcium moonstone (probably labradorite cf ’rainbow moonstone’) is reported from Patna, Bihar. The best material is 1 ct or less.