Photographed from the GIA Collection for the CIBJO project. Collection# 30881, 26.63 ct round brilliant cut vivid blue tanzanite, cut in Idar Oberstein; Collection# 35079, 3.71 ct round brilliant light blue tanzanite from the Dr. Eduard J. Gubelin collection; Collection# 35038, 11.18 ct cushion cut blue tanzanite from the Dr. Eduard J. Gubelin collection, and Collection# 35078, 3.41 ct pale lavender oval cut tanzanite from the Dr. Eduard J. Gubelin collection.

Found in just one place on earth, tanzanite is a relatively recent discovery. Tiffany & Co named this blue-violet variety of zoisite in honor of Tanzania, where it was first unearthed in 1967. Because the crystals show different colors depending on the viewing direction, cutters can fashion gems with a range of color from violetish blue to bluish violet depending on how much weight they want to retain from the rough.

Tanzanite is relatively new to the colored stone galaxy. As the most common story of the tanzanite mining boom goes, in 1967 a Masai tribesman stumbled upon a cluster of highly transparent, intense violet-to-blue crystals weathering out of the earth in Merelani, an area of northern Tanzania. He alerted a local fortune hunter named Manuel d’Souza, who quickly registered four mining claims.

Facts about Tanzanite

Mineral: Zoisite
Chemistry: Ca2Al3(SiO4)3(OH)
Color: Violet blue to bluish violet to violet purple
Refractive Index: 1.691 to 1.700
Birefringence: 0.008 to 0.013
Specific Gravity: 3.35
Mohs Hardness: 6 to 7