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JetVSOnyx
Side-by-side comparison of physical properties, fluorescence, and crystal system — to identify by observation.
- ◎ is higher in Jet, giving a numerical distinguishing point.
- ◎ is higher in Onyx, giving a numerical distinguishing point.
- ◎ is higher in Onyx, 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.
| Property | A: Jet | B: Onyx | Verdict |
|---|---|---|---|
| Refractive index (RI) | 1.640–1.680 | 1.530–1.540 | A higher |
| Specific gravity (SG) | 1.30–1.35 | 2.58–2.64 | B higher |
| Mohs hardness | 2.5–4.0 | 7.0 | B higher |
| Birefringence | — | 0.004 | — |
| Dispersion | — | — | — |
| Property | A: Jet | B: Onyx |
|---|---|---|
| Crystal system | 非晶質（炭素質） | 三方晶系（潜晶質） |
| Pleochroism | — | — |
| Chelsea filter | — | — |
| UV (long-wave) | — | — |
| UV (short-wave) | inert | inert |
◆Onyx is quartz (chalcedony) with Mohs 7, SG 2.58–2.64, and a white streak; jet is lignite with Mohs 2.5–4, SG 1.3–1.35, and a brown streak. Onyx is cool to the touch and inert to a hot pin; jet is warm to the touch and produces a coal-smoke smell under a hot pin. The hardness, density, and thermal-feel checks all separate the two on first handling.
Distinguishing tools
Tools that decide between Jet and Onyx 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.