COMPARE GUIDE
Gray SpinelVSLabradorite
Side-by-side comparison of physical properties, fluorescence, and crystal system — to identify by observation.
- ◎ is higher in Gray Spinel, giving a numerical distinguishing point.
- ◎ is higher in Gray Spinel, giving a numerical distinguishing point.
- ◎ is higher in Gray Spinel, 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: Gray Spinel | B: Labradorite | Verdict |
|---|---|---|---|
| Refractive index (RI) | 1.712–1.736 | 1.559–1.573 | A higher |
| Specific gravity (SG) | 3.58–3.61 | 2.65–2.75 | A higher |
| Mohs hardness | 8.0 | 6.0–6.5 | A higher |
| Birefringence | — | 0.008 | — |
| Dispersion | — | — | — |
| Property | A: Gray Spinel | B: Labradorite |
|---|---|---|
| Crystal system | 等軸晶系 | 三斜晶系 |
| Pleochroism | — | — |
| Chelsea filter | — | — |
| UV (long-wave) | — | — |
| UV (short-wave) | inert | inert |
◆Labradorite (plagioclase feldspar Ca(Al₂Si₂O₈)·Na(AlSi₃O₈), Mohs 6–6.5, SG 2.69–2.72, RI 1.560–1.572, doubly refractive biaxial, characteristic spectral chiller' from internal albite-anorthite lamellae, typically translucent grey body) versus grey spinel (Mohs 8, SG 3.58–3.61, RI 1.712–1.736, singly refractive, no , transparent). The test (spectral colour flashes from internal lamellar diffraction) is diagnostic of labradorite; grey spinel shows no comparable optical effect. The specific-gravity difference (2.69–2.72 versus 3.58–3.61) and refractive-index difference (1.560–1.572 versus 1.712–1.736) are diagnostic.
Distinguishing tools
Tools that decide between Gray Spinel and Labradorite 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.