Tanzanite, first introduced to the world by American jeweller Tiffany & Co. in 1968, is a stunning blue variety of the mineral zoisite.
The only known deposit is Merelani Hills, northern Tanzania. At just two kilometres wide by eight kilometres long, it's not known for certain exactly how much tanzanite remains.
Unless otherwise specified, all tanzanite is assumed to have been heat-treated. This process, performed at relatively low temperatures, enhances the stone's colour and removes unwanted brown and yellow tints, which are common in raw stones.
When purchasing tanzanite, it’s important to buy from a reputable source because fake material is known to be in circulation. Furthermore, rough stones that have been heated are sometimes sold as unheated.
