“The gemstone of the 20^th Century”

Its unique and vibrant blue-lavender color has made the gemstone tanzanite a welcome recent (in gemstone terms) addition to the gemstone family. First discovered in northern Tanzania in 1967, tanzanite has still only been discovered at this five mile square source in the Merelani Hills at Mererani.

Tanzanite is the gem variety of the mineral zoisite, and when it is first mined the stone actually possess a green hue. Heat treatment generates the blue-lavender color, and nearly all tanzanite is treated in this way.

Since its discovery (and promotion as the “gemstone of the 20^th Century” by experts) tanzanite has rapidly increased in reputation and popularity. The only slight drawback with the stone is the single direction of its cleavage. In gemstone terms, cleavage is the ‘tendency of the stone breaking cleanly along certain planes to produce smooth surfaces’, and the single direction of the cleavage in tanzanite is an issue because it can limit the color maximization processes available to the gem cutter. Fortunately, tanzanite is one of the few stones that already has a strong enough color, so this is does not become as big an issue as it could be.

Pleochroism - the property of some gemstones to display different colors when viewed from different angles and under different light sources - is excellent in tanzanite, and dark-blue, red-purple and green-yellow shades can all be seen when viewing the stone.

The rise in popularity of tanzanite meant that in December 2002 the American Gem Trade Association (AGTA) declared that the gemstone was the latest to become an official birthstone for the month of December, becoming an alternative to zircon and turquoise.