Tanzanite - Three Kinds !

True Blues: While in Tanzania last summer, gemologist Chris Smith, discovered that many Tanzanites come from nature already blued. Because every Tanzanite that is mined is sent for heating, it is assumed by almost everyone that all of these Zoisites need oven time to be baked to this gem’s distinctive violet-blue coloration. But during a visit last fall to Tanzanite One, the De Beers-like mining and marketing organization for most of the world’s tanzanite, gemologist Chris Smith, found that a significant number of mine-run Zoisites had already been blued in the ground. “I was quite surprised to see that quite a number of stones were coming from the ground with a natural blue color," said Chris. So Chris started a project to determine a means of identifying natural-color tanzanite. As part of the study, he found there were three kinds of stones being mined.

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Natural Brown Tanzanite: The first and by far the most predominant are those with the root-beer bottle brown that need heating to be converted to blue; Natural Blue Tanzanite: the second have been partially naturally annealed by heat or lightning, so display an overall blue appearance but show brown in one direction; Annealed Blue Tanzanite: the third are stones that have been fully annealed and no longer possess any brown coloration.

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Does this mean that there could be what Smith calls “a new niche market” for natural-color, as opposed to heated Tanzanite—similar to that for sapphire? Smith believes so, but is quick to say that the applications of his findings are better left to marketers rather than gemologists. And lately since Tanzanite is actually a Zoisite relative, green colored "Tanzanian" stones are starting to appear on the market.

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Thanks to Chris and Colored Stone Magazine for the updated pictures.

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