Tanzanite may be blue, purple or slate gray. Tanzanite is rarer than diamonds with only one mine source in the world. It was discovered in northern Tanzania in 1967 and is a variety of the mineral zoisite. A synthetic version of tanzanite is called tanzanique. Tanzanite is often heat treated to improve its color and clarity. Tanzanite can easily be scratched or chipped. Clean your Tanzanite with warm, soapy water and a soft bristle brush. Avoid using ultrasonic cleaning.