Tiffany - Schlumberger Tanzanite and Diamond Brooch. Photo Courtesy of Lang Antiques.

Tanzanite is a purplish blue variety of zoisite. Discovered in 1967 in Tanzania, it was introduced to the jewelry world in 1968 as Tanzanite by Tiffany & Co.

Gemological information

Gemological Information for Tanzanite
Color Blue, Violet, Bluish-Purple
Crystal Structure Orthorhombic
Refractive Index 1.691 to 1.700
Durability Fair to Poor
Hardness 6 to y
Similar Stones Benitoite, Amethyst
Treatments Heated to Produce Purplish-Blue from gray or brown
Country of Origin Tanzania
Tanzanite Care
Ultrasonic Cleaning Unsafe
Steam Cleaning Unsafe
Warm Soapy Water Save
Chemical Attack Attacket by Hydrofluoric and Hydrochloric Acids
Light Sensitivity Stable
Heat Sensitivity Fuses under a jeweler's torch


Gem Reference Guide, Los Angeles: Gemological Institute of America, 1988. Pp. 262-264.

Newman, Harold. An Illustrated Dictionary of Jewelry, New York: Thames and Hudson, 1981. Pp. 300.

Schumann, Walter. Gemstones of the World, New York: Sterling Publishing, Co., 1977. Pp. 160.