Found in just one place on earth, tanzanite is a relatively recent discovery. This blue variety of zoisite was named for Tanzania, the country where it was found, by Tiffany & Co. Because crystals show different colors depending on viewing direction, cutters can choose bluish purple or the more favored pure blue or violetish blue hue depending on how much weight they want to retain from the rough.
Tanzanite is the blue to violet to purple variety of the mineral zoisite. It is mined commercially only in one area of the world: the Merelani Hills of Tanzania, which is where it gets its name.
Tanzanite’s appearance is influenced greatly by its pleochroism, which is the ability of a gemstone to show different colors when viewed in different crystal directions. Tanzanite can be violetish blue—similar to a sapphire color—or much more purplish. Often, both the violetish blue and purplish colors are readily visible in a fashioned stone when it is gently rocked and tilted.
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 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.
D’Souza hoped that he’d been shown a new sapphire deposit. Instead, the deposit contained one of the newest of the world’s gems.
Within a short time, 90 more claims appeared in the same 20-square-mile area. No one was quite sure what the beautiful crystals were, but everyone wanted to lay claim to the profits they were certain to produce. The new gem would eventually be known as tanzanite, and it would, at times, rival the Big 3 in popularity.
Tiffany & Company recognized its potential as an international seller and made a deal to become its main distributor. Tiffany named the gem after the country it came from, and promoted it with a big publicity campaign in 1968. Almost overnight, tanzanite was popular with leading jewelry designers and other gem professionals, as well as with customers who had an eye for beautiful and unusual gems.
The instant popularity of this transparent blue to violet to purple gem was tied to its vivid color, high clarity, and potential for large cut stones.