Diamond: look-alikes and how to tell
Short answer
Diamond is commonly confused with moissanite, cubic zirconia, white sapphire, paste (glass), laboratory-grown diamond.
Whether it is diamond, whether natural or laboratory-grown, its weight, colour or clarity. No photo tells and no app measures it.
Look-alikes
- moissanite
- cubic zirconia
- white sapphire
- paste (glass)
- laboratory-grown diamond
What to look at
The cut and its period, wear on facet edges (glass and cubic zirconia abrade; diamond does not), the setting, and whether the mount deserves a good stone.
What settles it
- Jeweller’s thermal tester: separates diamond from glass and cubic zirconia, but NOT from moissanite.
- Electrical conductivity tester: usually separates moissanite, but is not conclusive (it fails with poor contact or coated stones).
- Natural or laboratory-grown: only a gemmological laboratory (GIA, IGI, HRD) with spectroscopy.
Frequently asked
What can diamond be mistaken for?
moissanite; cubic zirconia; white sapphire; paste (glass); laboratory-grown diamond.
How can I tell diamond from its look-alikes?
Jeweller’s thermal tester: separates diamond from glass and cubic zirconia, but NOT from moissanite. Electrical conductivity tester: usually separates moissanite, but is not conclusive (it fails with poor contact or coated stones). Natural or laboratory-grown: only a gemmological laboratory (GIA, IGI, HRD) with spectroscopy.