Tanzanite is the blue-violet variety of zoisite, found in only one place on Earth — near Mount Kilimanjaro in Tanzania. Its single source makes it rarer than diamond.
Tanzanite is graded on the richness of its blue-to-violet color, which intensifies with size.
A deep, saturated violetish-blue (trade grade "AAA"/"Exceptional") is the most valuable, often seen only in larger stones.
The classic balanced color seen in most jewelry; excellent value with lovely pleochroism.
Paler, more lavender stones — attractive and budget-friendly, common in smaller sizes.
Six main criteria determine the price per carat. It is their combination that sets the final value.
The key factor: a deep, vivid violetish-blue is most prized. Pleochroism means the stone shows blue and violet from different angles; cutters orient for the best face-up color.
Tanzanite comes from a single small area (Merelani, Tanzania), so "origin" is fixed — its rarity comes from this limited source.
Nearly all tanzanite is gently heated to turn brownish rough into blue-violet; this is standard, stable and expected.
Eye-clean is the norm and expected; visible inclusions lower value more than in included gems like emerald.
Color deepens with size, so large stones are both rarer and richer in color — and priced accordingly.
A report from a recognized lab (GIA, SSEF, Gübelin, GRS, AGL) confirms identity, origin and treatment, securing the valuation and resale.
The richest, most saturated violetish-blue stones top the market; pale stones are far cheaper.
Because color strengthens with size, the best color is usually found in larger tanzanites.
Found only near Kilimanjaro, tanzanite has a finite supply that some expect to be depleted within decades.
Standard gentle heating produces the blue-violet color and is fully accepted by the market.
Geographic origin can be a strong prestige marker that weighs on value.
The world's only source, near Mount Kilimanjaro.
Single sourceIllustrative price index (2010 = 100) for fine, certified stones.
Tanzanite's single, limited source underpins long-term interest, though it remains more affordable than the classic "big three".
Top vivid-blue stones in larger sizes are the most sought after.
Illustrative figures for fine, certified stones — not financial advice.
Orders of magnitude for a faceted tanzanite — top vivid-blue stones in large sizes sit at the upper end.
Indicative estimates — they do not replace a laboratory appraisal.
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