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Stones / Misunderstood / Tanzanite

Tanzanite

Zoisite — trichroic blue-violet

Found in one place on Earth. Supply declining. The opportunity window is closing.

Tanzanite exists in a single deposit near Mount Kilimanjaro in Northern Tanzania — roughly 7km by 2km of mineralised rock. When that deposit is exhausted, there will be no more. Trichroic — showing blue, violet, and burgundy at different viewing angles — it is one of the most optically complex gems in existence.

6.5–7
Mohs Hardness
1.691–1.704
Refractive Index
Trichroic
Optical Phenomenon
Tanzania only
Origin
Increasingly Rare
Availability

The History

Tanzanite was unknown until 1967, when a Maasai tribesman named Ali Juuyawatu stumbled upon a cluster of transparent blue-violet crystals near the village of Merelani. Tiffany & Co. acquired the rights and named the stone after its country of origin — a masterstroke of commercial positioning. Henry Platt of Tiffany described it as the most beautiful blue stone discovered in 2000 years. Within a decade it had become one of the world's most commercially significant gems.

"Tanzanite is trichroic: depending on the viewing angle, it shows blue, violet, and a deep burgundy-red. Cutters must choose which face to present at the table — a decision that defines the stone's character entirely."

Why I Love Working With It

Tanzanite's trichroism creates design opportunities that single-colour stones can't offer. A stone cut to show blue from the top catches violet through the pavilion — a colour shift that becomes visible as the wearer moves. I design settings to exploit this: open galleries, lightly obstructing halos, prong placement that reveals rather than conceals. The stone does the work; the setting enables it.

What to Look For

The finest tanzanites show deep, vivid blue-violet with strong colour saturation and excellent trichroism. Avoid stones with grey, brown, or green undertones. Larger stones (above 5 carats) show colour more dramatically. Almost all commercial tanzanite is heated to remove brown overtones — this is standard and accepted. Unheated tanzanite with good colour is exceptionally rare.

Pieces Featuring Tanzanite

From the Métamorphism collection

Explore Related Stones

Tanzanite sits between sapphire and amethyst in the colour spectrum

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