COMPARE GUIDE
GGG (Gadolinium Gallium Garnet)VSYAG (Yttrium Aluminum Garnet)
Side-by-side comparison of physical properties, fluorescence, and crystal system — to identify by observation.
- ◎ is higher in GGG (Gadolinium Gallium Garnet), giving a numerical distinguishing point.
- ◎ is higher in GGG (Gadolinium Gallium Garnet), giving a numerical distinguishing point.
- ◎ is higher in YAG (Yttrium Aluminum Garnet), giving a numerical distinguishing point.
- ◎ is higher in GGG (Gadolinium Gallium Garnet), 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: GGG (Gadolinium Gallium Garnet) | B: YAG (Yttrium Aluminum Garnet) | Verdict |
|---|---|---|---|
| Refractive index (RI) | 1.970–1.980 | 1.830–1.836 | A higher |
| Specific gravity (SG) | 6.95–7.05 | 4.55–4.65 | A higher |
| Mohs hardness | 6.5–7.0 | 8.3 | B higher |
| Birefringence | — | — | — |
| Dispersion | 0.045 | 0.028 | A higher |
| Property | A: GGG (Gadolinium Gallium Garnet) | B: YAG (Yttrium Aluminum Garnet) |
|---|---|---|
| Crystal system | 等軸晶系 | 等軸晶系 |
| Pleochroism | — | — |
| Chelsea filter | inert | inert |
| UV (long-wave) | inert | inert |
| UV (short-wave) | weak (orange) | weak (orange) |
◆YAG (Y₃Al₅O₁₂, RI 1.83, SG 4.55–4.65, Mohs 8.25) is dramatically lighter than GGG (SG 7.02) — hand-heft test gives immediate diagnostic at any size above 0.5 ct. YAG also typically shows only weak pink UV where GGG shows strong orange. Both are singly refractive cubic garnets — the SG and UV differences are the clean diagnostics.
Distinguishing tools
Tools that decide between GGG (Gadolinium Gallium Garnet) and YAG (Yttrium Aluminum 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.