COMPARE GUIDE
Gray SapphireVSLabradorite
Side-by-side comparison of physical properties, fluorescence, and crystal system — to identify by observation.
Decisive distinctionsDECISIVE
- ◎ is higher in Gray Sapphire, giving a numerical distinguishing point.
- ◎ is higher in Gray Sapphire, giving a numerical distinguishing point.
- ◎ is higher in Gray Sapphire, 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.
Physical propertiesPROPERTIES
| Property | A: Gray Sapphire | B: Labradorite | Verdict |
|---|---|---|---|
| Refractive index (RI) | 1.762–1.770 | 1.559–1.573 | A higher |
| Specific gravity (SG) | 3.95–4.03 | 2.65–2.75 | A higher |
| Mohs hardness | 9.0 | 6.0–6.5 | A higher |
| Birefringence | 0.008 | 0.008 | Nearly equal |
| Dispersion | — | — | — |
Optics & fluorescenceOPTICS & UV
| Property | A: Gray Sapphire | B: Labradorite |
|---|---|---|
| Crystal system | 六方晶系（三方晶系） | 三斜晶系 |
| Pleochroism | 弱（灰・淡灰） | — |
| Chelsea filter | — | — |
| UV (long-wave) | — | — |
| UV (short-wave) | inert | inert |
ObservationOBSERVATION
◆Labradorite shows strong (a metallic blue-violet ); gray sapphire is uniform and shows no optical phenomena.
Color categoriesCATEGORIES
A: Gray Sapphire
Black / gray
B: Labradorite
Black / gray
DISTINGUISHING TOOLS · 2 ITEMS
Distinguishing tools
Tools that decide between Gray Sapphire 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.