COMPARE GUIDE
White MoonstoneVSWhite Opal
Side-by-side comparison of physical properties, fluorescence, and crystal system — to identify by observation.
Decisive distinctionsDECISIVE
- ◎ is higher in White Moonstone, giving a numerical distinguishing point.
- ◎ is higher in White Moonstone, 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: White Moonstone | B: White Opal | Verdict |
|---|---|---|---|
| Refractive index (RI) | 1.518–1.526 | 1.430–1.470 | A higher |
| Specific gravity (SG) | 2.55–2.61 | 1.98–2.20 | A higher |
| Mohs hardness | 6.0–6.5 | 5.5–6.5 | Overlap |
| Birefringence | 0.005 | — | — |
| Dispersion | — | — | — |
Optics & fluorescenceOPTICS & UV
| Property | A: White Moonstone | B: White Opal |
|---|---|---|
| Crystal system | 単斜晶系 | 非晶質（含水シリカ） |
| Pleochroism | — | — |
| Chelsea filter | — | inert |
| UV (long-wave) | — | weak (white / blue / green) |
| UV (short-wave) | weak (orange) | weak (white) |
ObservationOBSERVATION
◆Opal shows broken play-of-color in discrete patches rather than a continuous billowing sheen, and is much lighter (SG ~2.1).
Color categoriesCATEGORIES
A: White Moonstone
Colorless
B: White Opal
Opal
DISTINGUISHING TOOLS · 2 ITEMS
Distinguishing tools
Tools that decide between White Moonstone and White Opal 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.