Corundum · Mohs 9
Ruby: Identification, Meaning & Care
Ruby is red corundum colored by chromium. Treatment is common, so valuable stones benefit from a laboratory report.
Ruby properties
- Formula
- Al₂O₃
- Mineral group
- Corundum
- Mohs hardness
- 9
- Color
- Red to purplish red
- Transparency
- Transparent to opaque
- Luster
- Vitreous to subadamantine
- Cleavage / fracture
- None; parting may occur
How to identify Ruby
- Very high hardness gives well-polished surfaces good durability.
- Silk-like rutile inclusions may occur in natural stones.
- Color and inclusions alone cannot prove natural origin.
Ruby care
Water
Warm soapy water is usually safe for untreated material; filled stones need specialist care.
Light & heat
Generally stable in normal conditions.
Storage
Store separately from harder materials and cushion sharp edges, points, or cleavage-prone faces.
Traditional meaning
Historically linked with devotion, rank, vitality, and protection.
Traditional symbolism is presented as cultural history or personal practice, not as a scientific or medical claim.
Sources & further checking
- Mindat mineral database
- GIA Gem Encyclopedia
- RRUFF mineral database
- International Mineralogical Association
See our full methodology.