COMPARE GUIDE
Purple SapphireVSTanzanite
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 Tanzanite, 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: Purple Sapphire | B: Tanzanite | Verdict |
|---|---|---|---|
| Refractive index (RI) | 1.762–1.770 | 1.690–1.700 | A higher |
| Specific gravity (SG) | 3.95–4.03 | 3.30–3.38 | A higher |
| Mohs hardness | 9.0 | 6.0–7.0 | A higher |
| Birefringence | 0.008 | 0.009 | B higher |
| Dispersion | — | — | — |
Optics & fluorescenceOPTICS & UV
| Property | A: Purple Sapphire | B: Tanzanite |
|---|---|---|
| Crystal system | 六方晶系（三方晶系） | 斜方晶系 |
| Pleochroism | 中〜強（紫・赤紫） | 強（青・紫・黄） |
| Chelsea filter | pink | inert |
| UV (long-wave) | medium (red) | inert |
| UV (short-wave) | weak (red) | inert |
ObservationOBSERVATION
◆Tanzanite has RI 1.69–1.70 and SG 3.35 with strong trichroism (blue/purple/yellow-brown); purple sapphire has RI 1.76+ and SG 4.0 with dichroism only.
Color categoriesCATEGORIES
A: Purple Sapphire
Purple
B: Tanzanite
Purple / Blue
DISTINGUISHING TOOLS · 3 ITEMS
Distinguishing tools
Tools that decide between Purple Sapphire and Tanzanite 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.