Tanzanite

Tanzanite is a truly fascinating gemstone. It occurs in only one location worldwide, the East African state of Tanzania. Its colour is an intense blue, surrounded by a fine hint of purple.

Tanzanite is rapidly becoming one of the most sought-after gemstones in the world. It was discovered in 1967, and was soon being described as the 'gemstone of the 20th century'. It is amazing to think that such a beautiful gemstone had remained undiscovered for so long, and even more so in that apparently it was just by chance that Masai shepherds noticed some blue crystals sparkling in the sun and took some home with them

Tanzanite is a blue variety of the gemstone zoisite. Despite its beauty, the main drawback is that it is a relatively soft mineral, being about 6.5 on the Mohs scale. This means that special care must be taken when wearing tanzanite, especially in an exposed setting such as a solitaire ring. Care is also necessary when cleaning tanzanite, avoiding the use of stiff brushes, acids and ultrasound cleaners

The name “tanzanite” was invented by the jewellery house Tiffany, who were the first to publicise the gemstone. Perhaps they felt that the gemological name of “blue zoisite” didn't sound sufficiently marketable. Suffice it to say that it was undoubtedly a wise decision, as the name “Tanzanite” has now been universally adopted in the gem trade and by the gem-buying public.

Although cut tanzanite gemstones can display fabulous blue colours, ranging from deep ultramarine to pale violet, most raw crystals have a brownish hue which would be undesirable in a cut gemstone. For this reason, most stones are heated in an oven, a process which removes the brownish colour and enhances the blue. The heating of tanzanite is regarded as customary in the trade, unlike other gemstones where natural colour is more highly prized.

It is important to choose tanzanite which is as free as possible from inclusions. Apart from the obvious esthetic considerations, inclusions, especially in heated tanzanite, will render the stone more brittle and liable to fracture.

Although the larger cut tanzanite gemstones can be very sought-after and expensive, it is still possible to obtain smaller gems of extreme beauty for a relatively modest sum. The popularity of tanzanite has been much enhanced in recent years by the advent of online and television shopping channels, some of which are now devoted exclusively to the sale of coloured gemstone jewellery.