Merelani tanzanite: single-source stones and crystals

Tanzanite is the blue-to-violet gem variety of zoisite associated commercially with the Merelani mining area near Mount Kilimanjaro. That geographic fact does not make every crystal equal. Colour, clarity, dimensions, weight, condition and expected yield remain parcel-specific.

Heat treatment is common in the tanzanite trade. Treatment status must be disclosed for the offered lot based on available evidence and, where required, an appointed gemological laboratory. We do not use an unsupported public label such as “investment grade.”