Tanzanite

History
Tanzanite is a new stone on the gem market, discovered in Tanzania in 1967.

Features
Tanzanite is a beautiful purplish-blue variety of zoisite. It shows both blue and violet colors as the stone is turned. Frequently found in completely flawless specimens, it is softer than amethyst, but with equally rich color. It has perfect cleavage in one direction so it should be treated gently.

Treatments
Most tanzanite available commercial is heat treated. Tanzanite naturally shows three colors - blue, violet and red, however the red color is considered "undesirable" and heat treatment drives this third color off, leaving the more coveted blue and violet behind.

Principal Deposits
Tanzanite is found only in Tanzania, even though other varieties of zoisite are found in Norway, Western Australia and North Carolina in the US.

Rarity 
Flawless tanzanite of good color is less rare than a flawless ruby, however obtaining untreated stones is very rare indeed, as most of the buying public is unaware of the heating process used to rid tanzanite of the reddish undertone.