Natural Tanzanite Gemstones

Natural Tanzanite Gemstones

Tanzanite is the blue to violet variety of zoisite (Ca2Al3(SiO4)(Si2O7)O(OH)), found in only one place on Earth: the Merelani Hills of northern Tanzania. Its most distinctive trait is strong trichroism, blue, violet and burgundy in different directions. With a Mohs hardness of 6 to 7 it is softer than sapphire and best suited to pendants, earrings and carefully worn rings.

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Gemstone guide

Natural Tanzanite Gemstones

About tanzanite

Tanzanite was discovered in 1967 and named by Tiffany & Co., which introduced it to the world. It became a modern birthstone for December in 2002. Almost all tanzanite is heated: rough from the mine is often brownish or greenish, and gentle heating removes those tones to leave the familiar blue-violet. The treatment is permanent and accepted throughout the trade.

What you'll find in this collection

All our tanzanite comes from Tanzania and is heated, as is standard. You'll find small faceted rounds, ovals and pears from about 0.2 to 0.85 carats, in blue to violet tones, well suited to earrings, accent stones and small pendants.

How to recognise tanzanite

Turn a tanzanite and you will see its color shift between blue and violet, and in some directions a reddish purple; cutters orient the stone to show the strongest blue. Tanzanite is usually very clean. It is lighter than sapphire, about 3.35 against 4.0, and softer, while iolite, another violet-blue gem, is much lighter and shows a grey to yellowish color in one direction.

Caring for tanzanite

Tanzanite has one perfect cleavage and is sensitive to knocks and sudden temperature changes. Choose protective settings, clean it only with lukewarm soapy water and a soft brush, and never use ultrasonic or steam cleaners.

Every stone is natural, and each listing gives its weight, size, origin and treatment, with photos of the actual stone.