COMPARE GUIDE
Blue Spinel (Natural)VSBlue Topaz
Side-by-side comparison of physical properties, fluorescence, and crystal system — to identify by observation.
Decisive distinctionsDECISIVE
- ◎ is higher in Blue Spinel (Natural), giving a numerical distinguishing point.
- ◎ is higher in Blue Spinel (Natural), 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: Blue Spinel (Natural) | B: Blue Topaz | Verdict |
|---|---|---|---|
| Refractive index (RI) | 1.712–1.736 | 1.610–1.620 | A higher |
| Specific gravity (SG) | 3.58–3.61 | 3.50–3.57 | A higher |
| Mohs hardness | 8.0 | 8.0 | Nearly equal |
| Birefringence | — | 0.010 | — |
| Dispersion | — | — | — |
Optics & fluorescenceOPTICS & UV
| Property | A: Blue Spinel (Natural) | B: Blue Topaz |
|---|---|---|
| Crystal system | 等軸晶系 | 斜方晶系 |
| Pleochroism | — | 中（青・無色） |
| Chelsea filter | inert | inert |
| UV (long-wave) | inert | inert |
| UV (short-wave) | inert | inert |
ObservationOBSERVATION
◆Blue topaz is doubly refractive with refractive index 1.61–1.64 and SG 3.5, and shows perfect basal ; blue spinel is singly refractive with RI 1.71+ and SG 3.6, with no .
Color categoriesCATEGORIES
A: Blue Spinel (Natural)
Blue
B: Blue Topaz
Blue
DISTINGUISHING TOOLS · 3 ITEMS
Distinguishing tools
Tools that decide between Blue Spinel (Natural) and Blue Topaz 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.