01

What to look for

Under 10x loupe: solid, well-formed mineral crystals trapped inside the host gem. They may appear as bright, sharp-edged transparent or opaque solids.

02

What it means

The mineral species of the inclusion can indicate geographic origin or natural origin. Examples include pyrite in emerald, calcite in ruby, chromite in demantoid, and zircon with halos.

03

Expert move

Radiation halos around zircon inclusions strongly support natural origin. Check for dark halos around small bright crystals in tourmaline and corundum.