RocksdayChrysoberyl vs Diaspore
How to tell them apart
A very hard beryllium aluminum oxide. Its varieties include color-changing alexandrite and cat's eye.
Photo: Matteo Chinellato, CC BY-SA 3.0
An aluminum hydroxide; gem crystals from Turkey change color from green-yellow to pinkish with the lighting.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
Quick tests
- Hardness: Chrysoberyl is clearly harder: Mohs 8.5 versus 6.5–7.
Key differences
- Chrysoberyl (alexandrite) is harder and shows a stronger green-to-red change.
Side by side
| Property | Chrysoberyl | Diaspore |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 8.5 | 6.5–7 |
| Luster | Vitreous | Vitreous to pearly |
| Streak | White | White |
| Colors | Yellow, Green, Brown | Yellow, Green, Brown, White |
| Crystal system | Orthorhombic | Orthorhombic |
| Specific gravity | 3.7–3.8 | 3.3–3.4 |
| Formula | BeAl₂O₄ | AlO(OH) |
| Found in | Sri Lanka; Minas Gerais, Brazil | Milas, Turkey; Ural Mountains, Russia |
Properties that are the same for both are grayed out.
How to identify chrysoberyl
- Hardness 8.5 — harder than topaz.
- Yellow-green, often in heart-shaped or six-pointed twinned crystals.
- Alexandrite looks green in daylight and red under incandescent light.
Crystal system: Orthorhombic
Full Chrysoberyl guide →How to identify diaspore
- Bladed or platy crystals with a perfect cleavage.
- Color shifts between daylight and warm light in gems.
- Hardness about 7.
Crystal system: Orthorhombic
Full Diaspore guide →More comparisons
Could you tell them apart from a blurry close-up?
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