What Is Tanzanite? The Rare Blue-Purple Gemstone Explained

Quick Answer: Tanzanite is a rare blue-violet gemstone found only in one location on Earth — a small area near Mount Kilimanjaro in Tanzania. It displays a phenomenon called trichroism: it shows different colours (blue, violet, and burgundy-red) depending on the viewing angle. Tanzanite is considered a thousand times rarer than diamond and is one of the most sought-after coloured gemstones discovered in the 20th century.

In 1967, a Masai tribesman in Tanzania noticed some blue crystals in the earth. Tiffany & Co. identified the new mineral, named it after its country of origin, and launched it globally in 1968. In less than 60 years, tanzanite has gone from unknown to the world's most popular blue gemstone after sapphire. And there is only one mine. When it runs out, tanzanite is done.

Where Does Tanzanite Come From?

Tanzanite is found exclusively in a 4km² area in the Merelani Hills near Arusha, Tanzania. This remarkable geographical specificity makes it genuinely rare — not market-rare, but geologically singular. Geologists estimate the deposit will be exhausted within 20–30 years. Once it is mined out, there will be no more tanzanite. This has made tanzanite both a jewellery choice and an investment for some buyers.

What Makes Tanzanite Its Colour?

Tanzanite's blue-violet colour comes from vanadium impurities in a mineral called zoisite. In its raw form, tanzanite is often a brownish-red colour — the vivid blue-violet appears after heat treatment (usually around 600°C), which alters the oxidation state of vanadium. Almost all tanzanite on the market has been heat-treated; this is universally accepted and does not affect value.

Tanzanite Quality Grades

Like all coloured gemstones, tanzanite is graded on colour, clarity, cut, and carat. The most prized colour is a deep, saturated blue-violet with strong secondary violet tones — often described as AAA or AAAA grade. Lighter, paler stones are lower grades. The most valuable tanzanites are large (5 carats and above) with deep colour and high clarity. A fine 1-carat tanzanite can cost as much as a comparable ruby or sapphire.

Tanzanite in Jewellery

Tanzanite's hardness is 6.5–7 on the Mohs scale — softer than sapphire and somewhat vulnerable to scratching in rings. It is best set in protective bezel or partial bezel settings for rings, or used in earrings and pendants where it receives less abrasion. The colour works beautifully against both yellow gold (which warms the violet tones) and white gold or platinum (which emphasises the blue).

FAQ

Is tanzanite rarer than diamond?

Yes, significantly. Geologists estimate tanzanite is approximately 1000 times rarer than diamond, based on the size of the deposit versus diamond deposits globally. Unlike diamond, which is found on multiple continents, tanzanite has exactly one source on Earth.

Is tanzanite a good investment?

Tanzanite's value has generally appreciated over time due to its finite supply. Fine quality tanzanite (AAA, 5+ carats) has shown strong price appreciation. However, jewellery investment is complex — liquidity, provenance, and market conditions all matter. Buy tanzanite because you love it; treat any appreciation as a bonus.

Can tanzanite be worn daily?

With care, yes — particularly in earrings and pendants. Rings require more care due to daily abrasion. Avoid ultrasonic cleaners and steam cleaning; use only warm water and mild soap. Store separately from harder gemstones.

How can I tell if tanzanite is genuine?

Genuine tanzanite shows trichroism — looking through different axes of the stone gives different colours (blue, violet, burgundy). Synthetic tanzanite (very rare in the market) would not show this, nor would blue glass or cubic zirconia. For significant purchases, a GIA or AGL certificate confirms authenticity.

Tanzanite is one of the few gemstones where scarcity is not a marketing claim — it is geology. At KANSYA, we are drawn to materials with irreplaceable stories. Explore our gemstone jewellery collection.