Tanzanite: Tanzania’s Eponymous Gem

Written by Thomson Safaris
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Zoïsite (Tanzanite)” by Didier Descouens – Own work. Licensed under CC BY 3.0 via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:Zo%C3%AFsite_(Tanzanite).jpg#mediaviewer/File:Zo%C3%AFsite_(Tanzanite).jpg

There’s no “best” way to remember a trip to Tanzania, but there is a sparkliest: tanzanite, a beautiful blue-violet gemstone named after the country where it was first discovered in 1967.

That’s pretty recent as far as gemstones go; classics like diamonds, pearls, and rubies have been studding the foreheads of royalty for centuries, after all. That likely has a lot to do with the way in which tanzanite was discovered. Emmanuel Merishiek Mollel, a Maasai tribesman living near Arusha (where he worked as a tailor), reportedly came across the remains of a lightning fire. Nestled in the charred earth were sparkling blue stones he’d never seen before. At first, he thought the stone must be peridot, but soon realized it couldn’t be.

After consulting with a gemologist based in Nairobi, Kenya, who consulted with scientists in the United States as well as the Gemological Institute of America, they finally determined that this was a new gem entirely, which formed when a known mineral, zoisite (an opaque, orangey-brown material), was exposed to high heat.

Naturally-formed tanzanite is still found only in the Manyara region of Tanzania, meaning that high-quality stones from the region can fetch as much as $1000/carat. Unlike some stones, however, tanzanite can be “made to order,” at least to some degree.

Heating zoisite, either naturally (through lightning or forest fires) or in a furnace, causes it to change from orange to a crystalline blue and violet stone (if you hold a piece of tanzanite under different types of light, different colors become more prominent; fluorescent light brings out the blue, whereas incandescent light makes the violet more prominent). The way the stone is cut can also affect the dominant hue. Stones cut on a shorter axis will appear bluer, but this results in more waste during the cutting process; because of this, strongly blue (as opposed to blue-violet) stones are especially costly.

So who do we have to thank for this stunning stone?

Who else: Tiffany’s.

As mentioned, zoisite was already a known element at the time of tanzanite’s discovery, in 1967, and the treatment applied may change its appearance, but it doesn’t change the elemental material involved. Scientifically, the gem was and is known as “blue zoisite.”

But Tiffany’s didn’t think such an awkward name would help sell the stone. Hoping to capitalize on the gem’s rarity (since it could, and can, only be found in northern Tanzania) and its novelty, they renamed it after its country of origin, running a series of ads that emphasized that the stone now existed in only two places worldwide: Tanzania and Tiffany’s.

Don’t worry; these days you don’t need a robin’s-egg blue box to hold your violet-blue stones; tanzanite, though still rare, can be found at jewelers worldwide.