COMPARE GUIDE
Synthetic Red SpinelVSSynthetic Ruby
Side-by-side comparison of physical properties, fluorescence, and crystal system — to identify by observation.
- ◎ is higher in Synthetic Ruby, giving a numerical distinguishing point.
- ◎ is higher in Synthetic Ruby, giving a numerical distinguishing point.
- ◎ is higher in Synthetic Ruby, giving a numerical distinguishing point.
Note: properties whose numeric ranges do not overlap are auto-extracted. Both are measurable with a refractometer or heavy-liquid bath.
| Property | A: Synthetic Red Spinel | B: Synthetic Ruby | Verdict |
|---|---|---|---|
| Refractive index (RI) | 1.727–1.735 | 1.762–1.770 | B higher |
| Specific gravity (SG) | 3.62–3.66 | 3.98–4.05 | B higher |
| Mohs hardness | 8.0 | 9.0 | B higher |
| Birefringence | — | 0.008 | — |
| Dispersion | — | — | — |
| Property | A: Synthetic Red Spinel | B: Synthetic Ruby |
|---|---|---|
| Crystal system | 等軸晶系 | 六方晶系（三方晶系） |
| Pleochroism | — | 強（紫赤・黄赤） |
| Chelsea filter | red | red |
| UV (long-wave) | strong (red) | strong (red) |
| UV (short-wave) | medium (red) | strong (red) |
◆Synthetic ruby is Al₂O₃ : Cr (corundum, trigonal) — doubly refractive with weak , dichroic, RI 1.762–1.770, SG ~4.00, Mohs 9. Synthetic red spinel is MgAl₂O₄ : Cr (cubic) — singly refractive, no , RI 1.725–1.740, SG 3.60–3.64, Mohs 8. Single vs. double refraction at the refractometer is the immediate diagnostic.
Distinguishing tools
Tools that decide between Synthetic Red Spinel and Synthetic Ruby in practice.
Note: this page is auto-generated from published GIA / CGL reference values. Individual stones, treatments, and synthetics may fall outside these ranges. For a definitive identification, consult an accredited gem laboratory.