Tanzanite is the vibrant purplish blue to blue variety of the gem group Zoisite. Tanzanite is a high profile, popular gem only found in Tanzania with a hardness of 6.5 – 7 on Mohs scale. Tanzanite is the gem for 24th anniversaries and an alternative gem for the birthstone of December.
Colours of Tanzanite range from a less expensive light purple to a fine quality deep purplish blue. Tanzanite is doubly refractive with an RI of 1.692 -1.700 and displays intense trichroism. The specific gravity of Tanzanite is 3.15 – 3.58. Price can vary due to the often erratic availability. Tanzanite is brittle and must be treated with care. Do not clean it in an ultrasonic as it may fracture and avoid thermal shock.