Tanzanite: The Rarest Gemstone Guide
TL;DR: Tanzanite is a blue-violet gemstone discovered in 1967 and found in only one place on Earth — a small area near Mount Kilimanjaro in Tanzania. At 6–7 on the Mohs hardness scale it's softer than sapphire, so it suits occasional wear or a protective setting better than daily-wear rings.
A Genuinely Rare Gemstone
Tanzanite is found in a single mining area roughly 8 kilometres by 2 kilometres near Mount Kilimanjaro — nowhere else on Earth has produced gem-quality tanzanite in commercial quantity. It was discovered in 1967 and named by Tiffany & Co, who recognised its potential and marketed it under a name referencing its country of origin rather than its mineral name, zoisite.
Colour and Trichroism
Tanzanite displays trichroism — showing different colours (typically blue, violet, and burgundy) depending on the angle it's viewed from. Cutters orient the rough stone specifically to maximise the blue-violet colour most associated with tanzanite, since this is the most commercially desired combination. Heat treatment, standard and widely accepted in the trade, enhances this blue-violet colour in the vast majority of tanzanite sold today.
Durability Considerations
At 6–7 on the Mohs scale, tanzanite is considerably softer than sapphire or diamond, and more prone to chipping along its cleavage planes than its hardness rating alone suggests. It suits occasional wear, a protective setting such as a bezel, or pieces other than a daily-wear ring — pendants and earrings put less strain on the stone than a ring subjected to constant hand contact.
Why It's Becoming More Scarce
Because tanzanite comes from a single, finite geographic source with no alternative deposits found anywhere else, known reserves are genuinely limited in a way that doesn't apply to most gemstones. This has driven sustained long-term price appreciation and growing collector interest — a similar dynamic to alexandrite, another rare colour-driven collector's stone.
Tanzanite at À Vie Diamonds
We can source certified tanzanite for pendants, earrings, and rings designed with appropriate protective settings. Get in touch to discuss a commission.
Related Reading
- Moonstone: A Complete Guide — another stone that suits protective settings over daily-wear rings
- Opal: Beauty, Fragility, and Whether It Suits Daily Wear
Frequently Asked Questions
Where does tanzanite come from? A single small mining area near Mount Kilimanjaro in Tanzania — nowhere else on Earth produces gem-quality tanzanite commercially.
Is tanzanite durable enough for an engagement ring? At 6–7 on the Mohs scale, it's softer than sapphire and more prone to chipping, so it suits a protective setting or occasional wear better than an everyday ring.
Is heat-treated tanzanite less valuable? No — heat treatment is standard, widely accepted trade practice for tanzanite and does not carry the stigma some treatments do in other gemstones.
Last reviewed: July 2026 · À Vie Diamonds