COMPARE GUIDE
Synthetic Alexandrite (Flux / Hydrothermal)VSSynthetic Alexandrite (Pulled / Verneuil)
Side-by-side comparison of physical properties, fluorescence, and crystal system — to identify by observation.
| Property | A: Synthetic Alexandrite (Flux / Hydrothermal) | B: Synthetic Alexandrite (Pulled / Verneuil) | Verdict |
|---|---|---|---|
| Refractive index (RI) | 1.745–1.755 | 1.745–1.755 | Nearly equal |
| Specific gravity (SG) | 3.71–3.75 | 3.71–3.75 | Nearly equal |
| Mohs hardness | 8.5 | 8.5 | Nearly equal |
| Birefringence | 0.009 | 0.009 | Nearly equal |
| Dispersion | — | — | — |
| Property | A: Synthetic Alexandrite (Flux / Hydrothermal) | B: Synthetic Alexandrite (Pulled / Verneuil) |
|---|---|---|
| Crystal system | 斜方晶系 | 斜方晶系 |
| Pleochroism | 強（緑・赤紫・黄橙） | — |
| Chelsea filter | red | red |
| UV (long-wave) | strong (red) | strong (red) |
| UV (short-wave) | medium (red) | strong (red) |
◆Verneuil-grown 'synthetic alexandrite' is actually vanadium-doped corundum (Al₂O₃ : V) with RI 1.762–1.770, SG 4.00, Mohs 9, and a blue-purple color shift driven by vanadium d-d transitions — a fundamentally different species sold under a misleading trade name since 1909. Flux/hydrothermal synthetic alexandrite is genuine BeAl₂O₄ : Cr chrysoberyl with the proper green-red Ural-style color shift (RI 1.745–1.755, SG 3.71–3.75, Mohs 8.5). Refractometer and SG checks settle the species question in seconds.
Distinguishing tools
Tools that decide between Synthetic Alexandrite (Flux / Hydrothermal) and Synthetic Alexandrite (Pulled / Verneuil) 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.