TANZANITE

Tanzanite is part of the zoisite mineral species and is only found in East Africa. Discovered in 1967 in the Umba Valley near the Usambara Mts. in Tanzania. Tanzanite may be colourless, yellow-green, brown, or blue to violet when found; the crystals are heat treated to enhance their colour.
Colour:Tanzanite is noted for its remarkably strong trichroism, appearing alternately sapphire blue, violet, and sage-green depending on crystal orientation. (Trichroism is the property possessed by certain minerals of exhibiting three different colours when viewed from three different directions under white lights. However, most tanzanite is subjected to artificial heat treatment to improve its colour and this significantly subdues its trichroism.
Hardness: 6.5
N.B: Tanzanite is a brittle stone and although it can be worn daily, care should be taken to protect it from knocks, pressure and extreme temperature changes. Do not use a home ultrasonic to clean jewellery with tanzanite