Features reported for this material
Tanzanite
Striated prismatic crystals, often well formed with wedge-shaped terminations.
orthorhombic
Brown to khaki in the ground; the blue-violet appears on heating. Strongly trichroic — blue, violet and burgundy from three directions.
The drawing is a wedge-shaped, flattened. Flattened into a wedge or a triangle rather than a column. Compare it with what is in your hand as a prompt for better photographs, not as an identification. Waterwear, damage and incomplete growth can remove the expected form.
Editorial status: specialist review pending
Evidence record for this page
The links are editorial source targets, not certificates for a submitted stone. The page remains noindex until a named specialist checks the entry claim by claim.
- Handbook of Mineralogy, Mineralogical Society of America — mineral identity, crystal system, habit, physical properties, recorded localities.
- GIA Gem Encyclopedia and Gems & Gemology research — gem-variety terminology, trade context, reported sources, treatment context.
- GIA introduction to gem treatments — treatment categories, limits of visual treatment assessment, disclosure context.
- CIBJO Coloured Stone Commission, Official Gemstone Book — accepted nomenclature, artificial-product terminology, treatment disclosure terminology.
Author: pending · Specialist reviewer: pending · Review date: pending · Next review: pending
What it gets mistaken for
Tanzanite is reported as being confused with iolite, sapphire, purple spinel and synthetic forsterite. Photographs cannot resolve many of those alternatives. If you are not certain, say so and preserve the name you were originally given as a seller claim.
Also traded as: blue zoisite.
Where it comes from
Reported producing localities in this working reference include Tanzania. This is not proof that a stone came from one of them, and it does not mean an approved purchase route exists there.
Treatment
HEATING IS ALL BUT UNIVERSAL and expected; unheated brown rough is the normal state.
Tell us what has been done to it, if you know, and distinguish what you know first-hand from what somebody told you. Media cannot establish treatment. Any acceptance policy and laboratory requirement is decided for the case.
How to photograph it
Daylight, on a plain white surface, and, only if the material is safe to wet, photograph the same material dry and briefly wet. This can reveal different apparent surface and internal features without proving identity, quality or value. Put a ruler or another clearly identified scale reference in the frame. The full guide is here.