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Fire OpalVSImperial Topaz
Side-by-side comparison of physical properties, fluorescence, and crystal system — to identify by observation.
Decisive distinctionsDECISIVE
- ◎ is higher in Imperial Topaz, giving a numerical distinguishing point.
- ◎ is higher in Imperial Topaz, giving a numerical distinguishing point.
- ◎ is higher in Imperial Topaz, 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: Fire Opal | B: Imperial Topaz | Verdict |
|---|---|---|---|
| Refractive index (RI) | 1.430–1.460 | 1.629–1.638 | B higher |
| Specific gravity (SG) | 2.00–2.20 | 3.50–3.57 | B higher |
| Mohs hardness | 5.5–6.5 | 8.0 | B higher |
| Birefringence | — | 0.010 | — |
| Dispersion | — | — | — |
Optics & fluorescenceOPTICS & UV
| Property | A: Fire Opal | B: Imperial Topaz |
|---|---|---|
| Crystal system | 非晶質（含水シリカ） | 斜方晶系 |
| Pleochroism | — | 強（黄・赤・ピンク） |
| Chelsea filter | inert | inert |
| UV (long-wave) | weak (green) | weak (yellow / orange) |
| UV (short-wave) | weak (green) | inert |
ObservationOBSERVATION
◆Imperial topaz has dramatically higher SG (~3.5) and is much harder (Mohs 8); it feels noticeably heavy at equal size and shows stronger dichroism.
Color categoriesCATEGORIES
A: Fire Opal
Opal / Yellow / orange
B: Imperial Topaz
Yellow / orange
DISTINGUISHING TOOLS · 3 ITEMS
Distinguishing tools
Tools that decide between Fire Opal and Imperial 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.