COMPARE GUIDE
Natural Blue SapphireVSTanzanite
Side-by-side comparison of physical properties, fluorescence, and crystal system — to identify by observation.
Decisive distinctionsDECISIVE
- ◎ is higher in Natural Blue Sapphire, giving a numerical distinguishing point.
- ◎ is higher in Natural Blue Sapphire, giving a numerical distinguishing point.
- ◎ is higher in Natural Blue 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: Natural Blue 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: Natural Blue Sapphire | B: Tanzanite |
|---|---|---|
| Crystal system | 六方晶系（三方晶系） | 斜方晶系 |
| Pleochroism | 強（青・緑青） | 強（青・紫・黄） |
| Chelsea filter | inert | inert |
| UV (long-wave) | inert | inert |
| UV (short-wave) | inert | inert |
ObservationOBSERVATION
◆Sapphire is much harder (9 vs 6–7) and shows only two-color dichroism. RI is much higher.
Color categoriesCATEGORIES
A: Natural Blue Sapphire
Blue
B: Tanzanite
Purple / Blue
DISTINGUISHING TOOLS · 3 ITEMS
Distinguishing tools
Tools that decide between Natural Blue 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.