Tanzanite

Inside Tanzanite

Found in exactly one square mile on Earth — and nowhere else.

The story: Tanzanite is the blue-violet variety of zoisite, colored by trace vanadium and discovered only in 1967. Almost every other gem-forming mineral turns up in multiple countries around the world; tanzanite has only ever been found in one small stretch of hillside in northern Tanzania.

Why collectors chase it: That single-locality rarity, combined with strong pleochroism — the same crystal can flash blue, violet, or burgundy depending on the angle you view it from — makes it one of the more distinctive stones in any collection.

Care: Moderate hardness with real cleavage — avoid sharp knocks and skip the ultrasonic cleaner.