Comparison · Minerals
Diopside vs Heliodor
Diopside and Heliodor are easy to confuse because both are minerals. Diopside is harder (Mohs 5.5–6.5) than Heliodor (Mohs 5), so Diopside will scratch Heliodor 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 Diopside and Heliodor
- Diopside is harder (Mohs 5.5–6.5) than Heliodor (Mohs 5), so Diopside will scratch Heliodor and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
- Streak color differs: Diopside leaves a white streak on unglazed porcelain, Heliodor leaves white to light-colored.
- Diopside feels noticeably heavier for its size (specific gravity 3.2–3.3 versus 2.7 for Heliodor).
- Hold a thin edge to the light: Diopside is Transparent to translucent, Heliodor is opaque.
- They overlap in multicolored, but Diopside also comes in green, white, gray, blue, purple, and black.
Diopside vs Heliodor properties
| Property | Diopside | Heliodor |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 5.5–6.5 | 5 |
| Luster | Vitreous | vitreous |
| Streak | White | White to light-colored |
| Transparency | Transparent to translucent | opaque |
| Specific gravity | 3.2–3.3 | 2.7 |
| Crystal system | Monoclinic | varies |
| Common colors | Light to dark green, White, Gray, Blue-violet (violane), Black (chromian varieties) | Various |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $2–$150+ |
Which is more valuable?
Typical specimens of Diopside and Heliodor trade in a similar range, around $20.
About Diopside
Diopside is a calcium magnesium silicate pyroxene mineral, CaMgSi2O6, common in metamorphosed limestones and mafic to ultramafic igneous rocks. It typically forms stubby prismatic crystals with a nearly square cross-section, a hallmark of the pyroxene group's characteristic cleavage angles. Diopside's color ranges from colorless to deep green depending on iron and chromium content, and chromium-rich varieties are prized as gem material.
About Heliodor
Heliodor is gem-quality greenish-yellow variety of beryl.
Diopside vs Heliodor FAQ
Is Diopside the same as Heliodor?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Diopside is harder (Mohs 5.5–6.5) than Heliodor (Mohs 5), so Diopside will scratch Heliodor and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
How can you tell Diopside from Heliodor?
Diopside is harder (Mohs 5.5–6.5) than Heliodor (Mohs 5), so Diopside will scratch Heliodor and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Streak color differs: Diopside leaves a white streak on unglazed porcelain, Heliodor leaves white to light-colored. Diopside feels noticeably heavier for its size (specific gravity 3.2–3.3 versus 2.7 for Heliodor).
Which is harder, Diopside or Heliodor?
Diopside is harder: Mohs 5.5–6.5 against Mohs 5 for Heliodor.
Which is more valuable, Diopside or Heliodor?
Typical specimens of Diopside and Heliodor trade in a similar range, around $20.
