| Property | Almandine | Black Opal |
|---|---|---|
| Category | Semi-Precious Gems | Semi-Precious Gems |
| Primary Color | various | white |
| Mohs Hardness | 7.0–7.5 | 6.0–6.5 |
| Specific Gravity | 3.95 | 1.97 |
| Refractive Index | 1.77 | 1.37 |
| Crystal System | Isometric | Amorphous |
| Luster | Vitreous | Vitreous |
| Chemical Formula | — | — |
| Price Tier | Moderate ($50-500/ct) | Moderate ($50-500/ct) |
| Daily Wear | ใช่ | ไม่ใช่ |