What's That Rock?Tanzanite
A blue-violet variety of zoisite found only near Mount Kilimanjaro in Tanzania. Nearly all of it is heat-treated.
How to identify Tanzanite
- Shifts between blue and purple depending on angle
- Moderately hard but can chip
- Pleochroic: different colors in different directions
Often confused with
- Sapphire
- Iolite
- Blue-violet glass
- Synthetic corundum
Real or fake?
- Almost all tanzanite is heat-treated to get its color
Is Tanzanite valuable?
Moderate to high.
Typical retail prices
Cut gemstone$100–700per carat
Prices rise quickly for deep color and for stones over three carats.
Typical retail ranges in US dollars, compiled from public dealer and marketplace listings in October 2026. Real prices vary widely with quality, size and origin. This is general information, not an appraisal.
What changes the price
- Color: strong, deep blue-violet is the top grade; pale or brownish stones cost less
- Clarity and size: eye-clean stones over 3 carats are scarce and expensive
- Treatment: nearly all tanzanite is heated to get its color, which is routine
- Single source: it comes only from the Merelani Hills, Tanzania; imitations are common
Uses
- Jewelry
Care
Chips easily at edges. Avoid hard knocks and sudden temperature changes.
Identifying a stone from a description or a photo is an estimate. Many stones look alike. Ask an expert or a gem lab before you buy, sell or rely on an identification.
Updated October 2026