Identify a stone by criteria

Identifying a stone without a photo

Lapidem's AI identification works from a photograph — but sometimes you don't have one to hand, or you simply want to cross-check your own observations. This identification by criteria tool follows the mineralogist's approach: start from what you can see and narrow the field. Three criteria are often enough to go from hundreds of minerals down to a serious shortlist.

The three criteria that do the sorting

Dominant colour is the most natural starting point — and also the most treacherous, because a single mineral can occur in every shade: fluorite is purple, green, yellow or blue; quartz is colourless, purple, yellow, pink or brown. That is why colour alone is never enough.

Transparency narrows things considerably: a stone that is transparent (you can see through it), translucent (light passes but shapes do not) or frankly opaque belongs to very different families. A transparent green stone suggests emerald or peridot; a green opaque one points instead to malachite, serpentine or jade.

Hardness is the most discriminating criterion — and the most objective, since it does not depend on your perception. Our tool offers bands based on the scratch test: scratched by a fingernail (under 2.5), by a copper coin (2.5–3.5), by a knife (3.5–5.5), slightly scratching glass (5.5–7), or scratching glass effortlessly (7 and above). See our interactive Mohs scale for the full method.

Cross-referencing clues, like a detective

The tool's database covers 45 of the most common collection stones. The principle is that of an investigation: each criterion eliminates suspects. “Green, opaque, scratched by a knife” leaves only a handful of candidates — and you will then know what to check next. To go further, two powerful complementary tests: the streak colour on porcelain, and the reaction under a UV lamp.