Tourmaline vs Opal
Tourmaline is harder (Mohs 7–7.5) than Opal (Mohs 5.5–6.5), so it resists scratching better; Opal is softer than quartz dust (7) and needs more care in everyday rings.
Tourmaline has the higher refractive index (1.624–1.644 vs 1.450), which a refractometer can use to separate them.
Tourmaline is denser (SG 3.06 vs 2.15); a tourmaline of the same size weighs about 42% more.
Advertisement
Ad space (in-content)
| Property | Tourmaline | Opal |
|---|---|---|
| Species / material | Tourmaline | Opal (hydrated silica) |
| Mohs hardness | 7–7.5 | 5.5–6.5 |
| Refractive index | 1.624–1.644 | 1.450 |
| Specific gravity | 3.06 | 2.15 |
| Crystal system | Trigonal | Amorphous |
| Birefringence | 0.014–0.021 | None |
Values are typical ranges from standard gemmological references; individual stones can vary.
Test it yourself
More comparisons
Diamond vs TourmalineDiamond vs OpalRuby vs TourmalineRuby vs OpalSapphire vs TourmalineSapphire vs OpalEmerald vs TourmalineEmerald vs OpalAquamarine vs TourmalineAquamarine vs OpalMorganite vs TourmalineMorganite vs OpalAlexandrite vs TourmalineAlexandrite vs OpalSpinel vs TourmalineSpinel vs Opal