COMPARE GUIDE
Grossular GarnetVSPrehnite
Side-by-side comparison of physical properties, fluorescence, and crystal system — to identify by observation.
Decisive distinctionsDECISIVE
- ◎ is higher in Grossular Garnet, giving a numerical distinguishing point.
- ◎ is higher in Grossular 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.
Physical propertiesPROPERTIES
| Property | A: Grossular Garnet | B: Prehnite | Verdict |
|---|---|---|---|
| Refractive index (RI) | 1.734–1.759 | 1.611–1.669 | A higher |
| Specific gravity (SG) | 3.57–3.73 | 2.80–2.95 | A higher |
| Mohs hardness | 6.5–7.5 | 6.0–6.5 | Overlap |
| Birefringence | — | 0.022 | — |
| Dispersion | — | — | — |
Optics & fluorescenceOPTICS & UV
| Property | A: Grossular Garnet | B: Prehnite |
|---|---|---|
| Crystal system | 等軸晶系 | 斜方晶系 |
| Pleochroism | — | — |
| Chelsea filter | — | — |
| UV (long-wave) | — | — |
| UV (short-wave) | inert | inert |
ObservationOBSERVATION
◆Prehnite is semi-translucent with refractive index ~1.62 and lower SG (~2.9); grossular is transparent with RI ~1.74 and SG ~3.5.
Color categoriesCATEGORIES
A: Grossular Garnet
Green / Yellow / orange
B: Prehnite
Green
DISTINGUISHING TOOLS · 3 ITEMS
Distinguishing tools
Tools that decide between Grossular Garnet and Prehnite 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.