Is heated tanzanite a 'lower' grade?

No. Heating tanzanite is universal commercial practice and is not a quality indicator. The treatment is stable, residue-free, and lab-disclosed. Heated tanzanite is the only commercial tier of meaningful supply. The price differentiators within tanzanite are colour saturation, clarity, size, and cut — not treatment status.

Does untreated tanzanite exist?

Geologically yes, commercially very rarely. Tanzanite rough naturally shows trichroism with blue, violet, and brownish-yellow visible from different crystal axes. Most rough is brownish without heat. Stones that emerge naturally blue without treatment are uncommon and often smaller. Authentic GIA 'no indications of heating' tanzanite is a thin collector category.

Why is tanzanite found only in Tanzania?

The Merelani Hills deposit in northern Tanzania is the only commercially producing tanzanite source globally. The variety formed under highly specific metamorphic conditions that have not been replicated elsewhere. Production volumes have decreased over the past decade as the deposit ages.

Does Skyjems carry untreated tanzanite?

Currently no. Skyjems' tanzanite inventory is heated material — the standard commercial tier — with treatment disclosed on every product page. Untreated tanzanite sourcing is possible on documented request through the curator's network. Contact +1-416-366-3335 or [request a private viewing](https://skyjems.ca/pages/schedule-a-private-viewing).

ENCYCLOPEDIA · DAVID SAAD · SKYJEMS

Untreated Tanzanite — Lab-Certified

Name: Skyjems
Address: 27 Queen St East, Suite 1011, Toronto, ON, M5C 2M6, CA
Telephone: +1-416-366-3335
Price range: $$$$

Key concepts: tanzanite, untreated tanzanite, merelani tanzanite, blue zoisite, heated tanzanite

Tanzanite is a blue-violet zoisite found exclusively in the Merelani Hills of northern Tanzania. The variety was discovered in 1967 and is now one of the most-traded blue stones globally. Effectively all commercial tanzanite is heat-treated — the standard heating dissolves brown undertones from the rough and produces the saturated blue-to-violet colour collectors recognise. Untreated tanzanite is structurally rare and not represented in Skyjems' primary inventory — natural-colour rough is uncommon and most material that could be sold "untreated" is brown or yellowish-tinted.

Why nearly all tanzanite is heated

Tanzanite rough emerges from the Merelani deposits in three colour states (trichroism): blue, violet, and brownish-yellow visible from different crystal axes. Standard heating at 380–500°C dissolves the brown axis and pushes the colour toward saturated blue-to-violet. The treatment is stable, residue-free, and is industry-standard practice. GIA and Lotus disclose treatment as "indications of heating" on the lab letter — but this is so universal in tanzanite that the designation is rarely a price differentiator within the variety.

What "untreated tanzanite" requires

Tanzanite that is naturally blue (not brownish) without heat treatment is geologically unusual. Such stones do exist but are rare, often smaller, and show colour saturation below what heated material achieves. Most "untreated" tanzanite on the market is mislabelled or the lab letter has not been updated. Authentic GIA "no indications of heating" tanzanite is a thin collector category.

Skyjems inventory snapshot

Skyjems' tanzanite inventory at /collections/tanzanite is heated material — the standard commercial tier — with treatment disclosed on every product page. Untreated tanzanite is not currently held in primary inventory; sourcing on documented request is possible through the curator's network.

Private viewings and bespoke

Contact +1-416-366-3335 or request a private viewing.