It is very unusual when a recently discovered gemstone has a huge impact on the world gemstone market. It happened with paraiba tourmaline in the 1990’s. But the case of tanzanite in the 1960’s is even more intriguing.

Tanzanite, a rare violet-blue form of the mineral zoisite, was first discovered in 1967 in Tanzania. East Africa remains the only source for tanzanite and the supply is extremely limited. The limited supply, combined with soaring demand, has resulting in rising prices.

The immense popularity of tanzanite is surprising. Originally the gem was known by the more pedestrian name, “blue zoisite.” But even that name was a bit of a stretch, since tanzanite is rarely blue in nature. In its natural state, it is a rather uninspiring brown, and the violet blue is produced through heat treatment. It is not a particularly hard-wearing gem either. At 6.5 on the Mohs hardness scale and with delicate cleavage, it is less durable than common quartz. How did such a gem come to sell for prices up to $1000 a carat?

The answer is marketing. Tanzanite got its first big push into the market with the help of Tiffany & Co., who gave it the new name “tanzanite” and mounted a major advertising campaign in 1969. Tiffany showed little restraint in hyping tanzanite. Henry Platt, the grandson of Louis Comfort Tiffany, described tanzanite as “the most beautiful blue stone to be discovered in over 2000 years.”

Though tanzanite is a very pretty stone, it is fair to say that it has suffered from marketing excess more than any other gem. Effusive ad copy informs us that tanzanite was “formed more than 585 million years ago.” But of course all minerals are millions of years old. Tanzanite, we are told, is 1000 times rarer than diamond. But since diamond is hardly rare, we could say the same about tsavorite garnet and zircon and a number of other gems.

The successful marketing of tanzanite combined with limited supply to create astonishing prices for the gem in the market. For those who love colored gemstones, fine tanzanite certainly has its place. Predictions are that the mines in northern Tanzania will be worked out within 15 years, so it is certainly worth buying if you can find it a reasonable price. But buy tanzanite on its own merits and ignore the marketing hype.