Tanzanite is a precious stone belonging to the zoisite mineral family. Its colour ranges from deep blue to intense violet. It displays remarkable optical properties, revealing three distinct hues depending on the viewing angle. Manuel d'Souza, a Portuguese prospector, discovered the first tanzanite in 1967. Tiffany & Co gave it its current commercial name.

Tanzanite comes from a single deposit in the entire world. This zone is located in the Merelani region, in north-eastern Tanzania. The slopes of Kilimanjaro are home to this exceptional geological source. No other tanzanite deposit has been discovered to date. This geological uniqueness makes it one of the rarest stones on earth.

The price of a tanzanite varies according to colour saturation and carat weight. Expect to pay €300 to €800 per carat for a good-quality tanzanite of around 1 carat. For 2–3 carats of equivalent quality, prices range from €800 to €2,000 per carat. Exceptional tanzanites with a deep, saturated blue-violet can reach €3,000 to €5,000 per carat. The ideal colour combines a rich deep blue with vivid violet reflections.

Tanzanite comes from a single deposit in the world, at Merelani in Tanzania. This zone measures just 7 km². Geological reserves have been gradually declining since the 1990s. Experts estimate that only 20 to 30 years of mining remain. At this rate, tanzanite could become an unobtainable collector's stone by around 2055. This finite supply continues to drive growing interest among investors.

Yes, the vast majority of tanzanites on the market undergo low-temperature heating (around 500°C). In its rough state, the stone displays an unattractive brownish-yellow colour. Heating reveals tanzanite's characteristic blue-violet. This treatment is universally accepted and stable over time. Naturally blue tanzanites that have not been heated remain extremely rare and costly.

Tanzanite can be suitable for an engagement ring, with a few precautions. Its hardness of 6.5 to 7 on the Mohs scale makes it more delicate than sapphires or rubies. A protective setting is recommended to limit the risk of impact. The stone is better suited to occasion rings than to intensive daily wear. For an everyday ring, a blue sapphire remains the stronger technical choice.

Tanzanite is associated with transformation, wisdom and intuition. Its blue-violet colour evokes meditative states and spirituality. In 2002, it became the official birthstone for the month of December. This designation by the American Gem Trade Association gives it a strong symbolic standing. Tanzanite is also traditionally given to celebrate a new beginning or a personal milestone.

Tanzanite requires a degree of care owing to its moderate hardness. Avoid impacts, extreme temperatures and harsh chemicals. Clean the stone with lukewarm soapy water and a soft brush. Ultrasonic cleaners and steam baths must be avoided. Remove your jewellery for sport, housework and swimming.