Tanzanite

Description

The name refers to the more or less intense blue-violet variety of zoisite (hydrated sorosilicate of calcium and aluminum that crystallizes in the rhombic system). All the raw crystals of Tanzanite have a certain percentage of yellow or greenish color that is quite unpleasant for which they are subjected to a slight heating (about 500 degrees) to improve their color.

General physical properties: hardness from 6 to 7 - density from 3.16 to 3.36 g / cm ^{3 - refractive indices 1.696-1.700 and 1.702-1.718 with birefringence from 0.006 to 0.018}

Weight 1.91 Kt

Size 8.75x6.65x4.20 mm

Cut: mixed of oval shape

Color: very uniform violet blue with accentuated luster

Purity: pure 

Treatments: heating

Origin: Arusha - Tanzania