Ruby vs Garnet (almandine)
Ruby is harder (Mohs 9) than Garnet (almandine) (Mohs 7–7.5), so it resists scratching better.
Garnet (almandine) has the higher refractive index (1.790 vs 1.762–1.770), which a refractometer can use to separate them.
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| Property | Ruby | Garnet (almandine) |
|---|---|---|
| Species / material | Corundum | Garnet |
| Mohs hardness | 9 | 7–7.5 |
| Refractive index | 1.762–1.770 | 1.790 |
| Specific gravity | 4 | 4.05 |
| Crystal system | Trigonal | Cubic |
| Birefringence | 0.008–0.010 | None (isotropic) |
Values are typical ranges from standard gemmological references; individual stones can vary.