| Property | Alexandrite | Cordierite (Iolite) |
|---|---|---|
| Category | Semi-Precious Gems | Semi-Precious Gems |
| Primary Color | various | various |
| Mohs Hardness | 8.5 | 7.0–7.5 |
| Specific Gravity | 3.69 | 2.56 |
| Refractive Index | 1.739 | 1.542 |
| Crystal System | Orthorhombic | Orthorhombic |
| Luster | — | Vitreous,Greasy |
| Chemical Formula | — | — |
| Price Tier | Fine ($500-5,000/ct) | Moderate ($50-500/ct) |
| Daily Wear | Yes | Yes |