COMPARE GUIDE
Natural AmethystVSPurple Sapphire
Side-by-side comparison of physical properties, fluorescence, and crystal system — to identify by observation.
Decisive distinctionsDECISIVE
- ◎ is higher in Purple Sapphire, giving a numerical distinguishing point.
- ◎ is higher in Purple Sapphire, giving a numerical distinguishing point.
- ◎ is higher in Purple Sapphire, giving a numerical distinguishing point.
- ◎ is higher in Natural Amethyst, 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: Natural Amethyst | B: Purple Sapphire | Verdict |
|---|---|---|---|
| Refractive index (RI) | 1.544–1.553 | 1.762–1.770 | B higher |
| Specific gravity (SG) | 2.64–2.66 | 3.95–4.03 | B higher |
| Mohs hardness | 7.0 | 9.0 | B higher |
| Birefringence | 0.009 | 0.008 | A higher |
| Dispersion | — | — | — |
Optics & fluorescenceOPTICS & UV
| Property | A: Natural Amethyst | B: Purple Sapphire |
|---|---|---|
| Crystal system | 三方晶系 | 六方晶系（三方晶系） |
| Pleochroism | 弱（紫・赤紫） | 中〜強（紫・赤紫） |
| Chelsea filter | inert | pink |
| UV (long-wave) | inert | medium (red) |
| UV (short-wave) | inert | weak (red) |
ObservationOBSERVATION
◆Purple sapphire is harder (9 vs 7), has much higher RI/SG, and shows stronger dichroism.
Color categoriesCATEGORIES
A: Natural Amethyst
Purple
B: Purple Sapphire
Purple
DISTINGUISHING TOOLS · 3 ITEMS
Distinguishing tools
Tools that decide between Natural Amethyst and Purple Sapphire 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.