Tanzanite: A Single-Source Gem and What Scarcity Means for Value

Tanzanite was identified in 1967 in the Merelani Hills of northern Tanzania and has never been found in commercial quantity anywhere else. The deposit covers roughly seven square kilometres, split into blocks worked by a mix of large-scale and small-scale miners.

Why the supply is finite

Geologists broadly agree that the conditions which formed tanzanite — a specific mix of vanadium-bearing zoisite under unusual metamorphic pressure — occurred once, in one place. Estimates of remaining reserves vary, but every published study points the same way: production will decline within a generation.

What that does to prices

• Fine, deep blue-violet tanzanite above five carats has risen steadily as depth and difficulty of mining increase.
• Commercial-grade material remains accessible, which keeps the gem visible in jewellery worldwide.
• Untreated blue stones are rare — most tanzanite is gently heated to remove brown tones, and this is accepted practice when disclosed.

Buying well

Look for saturated colour with a strong violet flash, good clarity (tanzanite is usually eye-clean), and a cut that faces up evenly. Because tanzanite has a Mohs hardness of 6–7, it is best set in pendants and earrings or in protective ring settings.

SOMSTONE sources tanzanite directly from licensed Merelani operators, and every stone is presented with its inspection record.