Comparison · Minerals vs Precious Stones
Dioptase vs Emerald
Dioptase and Emerald are easy to confuse. Emerald is harder (Mohs 7.5) than Dioptase (Mohs 5), so Emerald will scratch Dioptase and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Dioptase and Emerald
- Emerald is harder (Mohs 7.5) than Dioptase (Mohs 5), so Emerald will scratch Dioptase and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
- Streak color differs: Dioptase leaves a green streak on unglazed porcelain, Emerald leaves white.
- Dioptase feels noticeably heavier for its size (specific gravity 3.28–3.35 versus 2.76 for Emerald).
- Hold a thin edge to the light: Dioptase is Transparent to translucent, Emerald is transparent.
- They overlap in green, but Emerald also comes in yellow.
- Well-formed crystals give it away: Dioptase is Trigonal, Emerald is hexagonal.
Dioptase vs Emerald properties
| Property | Dioptase | Emerald |
|---|---|---|
| Type | Minerals | Precious Stones |
| Mohs hardness | 5 | 7.5 |
| Luster | Vitreous | vitreous |
| Streak | Green | White |
| Transparency | Transparent to translucent | transparent |
| Specific gravity | 3.28–3.35 | 2.76 |
| Crystal system | Trigonal | hexagonal |
| Common colors | Emerald green, Bluish green | Green, Bluish Green, Yellowish Green |
| Rarity | common | legendary |
| Typical specimen value | $2–$150+ | $500–$50000+ |
Which is more valuable?
Emerald is usually the more valuable of the two: a typical collector specimen runs about $3000 against $20 for Dioptase, and premium Emerald can reach $50000 or more.
About Dioptase
Dioptase is a copper cyclosilicate mineral, Cu6Si6O18·6H2O, prized for an intense emerald-green color that rivals fine emerald despite being a completely different mineral species. It forms in the oxidized zones of copper ore deposits under arid conditions, typically as small but brilliantly lustrous crystals. Dioptase is too soft and brittle to be widely used as a gemstone, so its value lies almost entirely with mineral collectors.
About Emerald
Emerald is a green variety of beryl, colored by trace amounts of chromium and vanadium. It's one of the four precious gemstones.
Dioptase vs Emerald FAQ
Is Dioptase the same as Emerald?
No. Dioptase is a mineral while Emerald is a precious stone. Emerald is harder (Mohs 7.5) than Dioptase (Mohs 5), so Emerald will scratch Dioptase and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
How can you tell Dioptase from Emerald?
Emerald is harder (Mohs 7.5) than Dioptase (Mohs 5), so Emerald will scratch Dioptase and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Streak color differs: Dioptase leaves a green streak on unglazed porcelain, Emerald leaves white. Dioptase feels noticeably heavier for its size (specific gravity 3.28–3.35 versus 2.76 for Emerald).
Which is harder, Dioptase or Emerald?
Emerald is harder: Mohs 7.5 against Mohs 5 for Dioptase.
Which is more valuable, Dioptase or Emerald?
Emerald is usually the more valuable of the two: a typical collector specimen runs about $3000 against $20 for Dioptase, and premium Emerald can reach $50000 or more.
