Features reported for this material
Corundum
Barrel-shaped or bipyramidal hexagonal prisms; Sri Lankan gravels yield waterworn pebbles with the habit softened away.
trigonal
Frequently milky, silky or colour-zoned in rough. Dry material reads grey — the difference between wet and dry on blue sapphire rough is larger than on almost anything else.
The drawing is a barrel-shaped hexagonal prism. Wider at the middle than at the ends, with a flat termination at each end. 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
Blue sapphire is reported as being confused with iolite, tanzanite, spinel, benitoite and synthetic corundum. 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: corundum.
Where it comes from
Reported producing localities in this working reference include Sri Lanka, Madagascar, Australia, Tanzania, Nigeria, Thailand, China, United States. 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 routine and expected. Diffusion and beryllium treatment excluded.
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.