We’ve all heard of the one that got away, the fishy tale in the pub, the publisher who turned down Harry Potter or the record label who thought the Beatles a rubbish band. They all had happy endings, a friendly pint in the pub, a rich and famous author or the greatest band in the world. But the story of the discovery of tanzanite is rather different.
The received wisdom is that it was discovered by a tailor from Goa, living near the Merelani mines in Arusha, in the foothills of Mt Kilimanjaro, Tanzania, one Manuel D’Souza.
Enter Ndugu Jumanne Ngoma (Swahili for playing music on Tuesday) a gypsum miner. On his way through the bush to visit relatives he saw some pretty crystals, some of them very large ( a feature of Tanzanite) and collected about 5 kilos. As no-one in Arusha was interested, he borrowed some money for his fare and travelled 300 Km to Nairobi. A company dealing in precious stones there couldn’t identify the mineral, but would investigate and let him know. They gave him his return bus fare, for which he left them his 5Kg bag of crystals and went home.
In 2004, some 33 years later, he still had not heard from them.
He sent some more of the crystals to a German firm who verified them as a variety of zoisite. Zoisite is found in many places and comes in pinks, yellows and browns, but this blue version was new and only found in the Merelani mines. This German company had no interest in the crystals, saying there was no current market.
A year or so later, Mr. Ngoma heard of Manuel D’Souza claiming to have
discovered tanzanite. He then began the long and arduous journey of claiming the discovery himself. After seventeen years, the Tanzanian Government’s mining ministry recognized Mr. Ngoma’s claim and certified him as the discoverer of tanzanite. However, by this time, the state-owned Tanzania Gemstones Industry had monopolized 10 square miles around the mines and permitted no–one else to mine.
And Mr. Ngoma? Still mining gypsum.
Tanzanite is a transparent gemstone, available in the less costly pale lavender colours through to the very costly saturated deep vivid ultramarines and sapphire blues, shot through with pinks and purples, (pleochrosim) It is not a terribly hard gemstone, 6.5 – 7 in hardness (talc = 1, diamond = 10) so care should be taken with ring-set stones. Cutting is difficult as the stone has perfect one-direction cleavage; think of wood cut with grain and splitting, and you’ll have some idea. In the rough, tanzanite crystals can have a brown-yellow tint, and this is corrected by heating the stone to around the 500 degree C mark to give it it’s trademark beautiful colours. Nearly all tanzanites have been heat treated.
NEVER EVER clean tanzanite in an ultrasonic bath. I know of a most beautiful, voluptuous even, 50 ct tanzanite, worth squillions, sent to a respected London company for setting. After setting it was handed to an un-supervised work experience person for cleaning. Thinking it was a sapphire, (at 50 carats???) he put it in a hot ultrasonic bath, quenched it cold water, and……..it shattered. I know this is true, it was my stone.
Tanzanite has to be my favorite gem, second only to diamond. The combination of a vivid tanzanite accented with diamonds and set in either platinum or palladium has to be the most glorious combination and I have made many bespoke pieces like this. Please see StrawberryWood’s website for more beautiful pieces that can be created for you.Back to last page All articles/FAQ