RocksdayPyrope vs Ruby
How to tell them apart
Blood-red magnesium garnet formed deep in the mantle and carried up by volcanic eruptions.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
Red corundum, colored by chromium. After diamond it's the hardest natural gemstone.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
Quick tests
- Hardness: Ruby is clearly harder: Mohs 9 versus 7–7.5.
Key differences
- Ruby is harder and forms hexagonal crystals.
Side by side
| Property | Pyrope | Ruby |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 7–7.5 | 9 |
| Luster | Vitreous | Adamantine to vitreous |
| Streak | White | White |
| Colors | Red | Red, Pink |
| Crystal system | Cubic | Trigonal |
| Specific gravity | 3.58–3.65 | 3.97–4.05 |
| Formula | Mg₃Al₂(SiO₄)₃ | Al₂O₃ (with chromium) |
| Found in | Bohemia, Czech Republic; Garnet Ridge, Arizona | Mogok, Myanmar; Montepuez, Mozambique |
Properties that are the same for both are grayed out.
How to identify pyrope
- Fiery blood red, often as small rounded grains.
- Hardness 7–7.5.
- Commonly loose grains in volcanic or kimberlite ground.
Crystal system: Cubic
Full Pyrope guide →How to identify ruby
- Red to pinkish red, often in six-sided barrel crystals.
- Hardness 9 — scratches topaz and quartz.
- Glows red under a UV light.
Crystal system: Trigonal
Full Ruby guide →More comparisons
Could you tell them apart from a blurry close-up?
Play today's Rocksday