Definition
What is Ruby?
Ruby is the red gem variety of the mineral corundum. Its red color is principally associated with chromium incorporated into the crystal structure. Sapphire names corundum of other gem colors.
At a glance
Gemological properties
Values marked pending have not yet cleared the editorial source review.
| Gemstone name | Ruby | Mineral species | Corundum |
|---|---|---|---|
| Chemical formula | Al₂O₃ | Crystal system | Trigonal |
| Mohs hardness | 9 | Specific gravity | 3.95–4.05 |
| Refractive index | 1.762–1.77 | Birefringence | 0.008–0.01 |
| Primary color | Red | Optical character | Pending verification |
| Luster | Pending verification | Transparency | Pending verification |
Science & context
A layered reference
What is Ruby?
Ruby is the red gem variety of the mineral corundum. Its red color is principally associated with chromium incorporated into the crystal structure. Sapphire names corundum of other gem colors.
Evidence
References & further reading
- [1]Ruby Gemstone Overview
Gemological Institute of America
View source