Ruby
red · Corundum family
| Also known as | Corundum (Corundum family) |
|---|---|
| Colour | Red |
| Mohs hardness | 9.0 |
| Lustre | Subadamantine, vitreous, pearly (on partings) |
| Streak | White |
| Crystal system | Trigonal |
| Transparency | Transparent, translucent |
| Cleavage | No true cleavage |
| Fracture | Conchoidal, splintery |
| Chemical formula | Aluminum oxide with chromium, AlO:Cr |
| Specific gravity | 3.97–4.05 |
What is Ruby?
Ruby is a pinkish-red to blood-red-colored gemstone, a variety of the mineral corundum, consisting of aluminium oxide (α-Al2O3). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called sapphires, and rubies are also sometimes referred to as "red sapphires".
How to identify Ruby
- Lustre: Subadamantine, vitreous, pearly (on partings).
- Hardness: Mohs 9.0 — hard enough to scratch glass.
- Streak: White.
- Habit: Trigonal crystal system.
Ruby value
Ruby is a fine gemstone priced per carat by quality — colour, clarity, cut, carat and origin — not by weight in grams. Typical market ranges:
| Quality | Price per carat |
|---|---|
| Commercial | $100–$3,000 / ct |
| Good | $1,500–$12,000 / ct |
| Fine | $5,000–$45,000 / ct |
| Top | $20,000–$150,000+ / ct |
Ranges cross-validated across two independent research passes against gemstone price guides, 2026-06 — sources: gia.edu, gemsociety.org, thenaturalrubycompany.com. Colour saturation, clarity, cut and origin move the price enormously, and treatments or lab-grown stones sell for a fraction — so this is a guide, not an appraisal. Have anything valuable checked by a certified gemmologist. See the full crystal & gemstone value guide.
