COMPARE GUIDE
Imperial TopazVSYellow Topaz
Side-by-side comparison of physical properties, fluorescence, and crystal system — to identify by observation.
Physical propertiesPROPERTIES
| Property | A: Imperial Topaz | B: Yellow Topaz | Verdict |
|---|---|---|---|
| Refractive index (RI) | 1.629–1.638 | 1.629–1.638 | Nearly equal |
| Specific gravity (SG) | 3.50–3.57 | 3.50–3.57 | Nearly equal |
| Mohs hardness | 8.0 | 8.0 | Nearly equal |
| Birefringence | 0.010 | 0.010 | Nearly equal |
| Dispersion | — | — | — |
Optics & fluorescenceOPTICS & UV
| Property | A: Imperial Topaz | B: Yellow Topaz |
|---|---|---|
| Crystal system | 斜方晶系 | 斜方晶系 |
| Pleochroism | 強（黄・赤・ピンク） | 中（黄・無色） |
| Chelsea filter | inert | inert |
| UV (long-wave) | weak (yellow / orange) | weak (yellow / orange) |
| UV (short-wave) | inert | inert |
ObservationOBSERVATION
◆Pure yellow topaz lacks the pink/red component. Imperial is defined by warmer tones with red dominance.
Color categoriesCATEGORIES
A: Imperial Topaz
Yellow / orange
B: Yellow Topaz
Yellow / orange
DISTINGUISHING TOOLS · 3 ITEMS
Distinguishing tools
Tools that decide between Imperial Topaz and Yellow 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.