COMPARE GUIDE
Natural AlexandriteVSColor-Change Garnet
Side-by-side comparison of physical properties, fluorescence, and crystal system — to identify by observation.
- ◎ is higher in Natural Alexandrite, 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: Natural Alexandrite | B: Color-Change Garnet | Verdict |
|---|---|---|---|
| Refractive index (RI) | 1.745–1.755 | 1.745–1.760 | Overlap |
| Specific gravity (SG) | 3.71–3.75 | 3.74–3.94 | Overlap |
| Mohs hardness | 8.5 | 7.0–7.5 | A higher |
| Birefringence | 0.009 | — | — |
| Dispersion | — | — | — |
| Property | A: Natural Alexandrite | B: Color-Change Garnet |
|---|---|---|
| Crystal system | 斜方晶系 | 等軸晶系 |
| Pleochroism | 強（緑・赤紫・黄橙） | — |
| Chelsea filter | red | red / pink |
| UV (long-wave) | weak (red) | inert |
| UV (short-wave) | weak (red) | inert |
◆Alexandrite's color change is vivid and unambiguous (green to red); color-change garnet's shift is muted and often called 'lazy.' Garnet is singly refractive (no , no dichroism) and runs higher in SG (3.8–4.0 vs 3.7), so a quick polariscope or SG check settles it.
Distinguishing tools
Tools that decide between Natural Alexandrite and Color-Change Garnet 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.