gemstone
Ruby
Corundum (Al2O3)
Hardness: 9 on Mohs scale. Color: Red (due to chromium). Luster: Vitreous to sub-adamantine. Crystal structure: Trigonal. Cleavage: None. Specific gravity: 3.97-4.05.
- Hardness
- 9 on Mohs scale
- Color
- Red (due to chromium)
- Luster
- Vitreous to sub-adamantine
Identified More gemstone →
Explore Ruby in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 9 on Mohs scale. Color: Red (due to chromium). Luster: Vitreous to sub-adamantine. Crystal structure: Trigonal. Cleavage: None. Specific gravity: 3.97-4.05.
Formation & geological history
Forms in metamorphic rocks like marble or igneous rocks such as basalt. The red color is caused by trace amounts of chromium replacing aluminum in the crystal structure.
Uses & applications
Highly valued as a gemstone in jewelry. Historically used in the first lasers.
Geological facts
Ruby is one of the traditional cardinal gems. The name comes from 'ruber', Latin for red. The most valuable rubies have a color called 'pigeon blood'.
Field identification & locations
Identified by its high hardness (can scratch almost everything except diamond), red color, and trigonal crystal habit. Often exhibits fluorescence under UV light. Common locations include Myanmar, Mozambique, Sri Lanka, and Thailand.
More like this
Other gemstone specimens
Diamond and Gold Jewelry
Carbon (Diamond) / Au (Gold)
gemstone
Ammolite
Ammolite (Biogenic Aragonite with trace elements; fossils of Placenticeras meeki and Placenticeras intercalare)
mineral
Cubic Zirconia (simulant) or Diamond
ZrO2 (Cubic Zirconia) or C (Diamond)
gemstone
Black Opal Ring (Carved Opal)
Hydrated Silicon Dioxide (SiO2·nH2O)
gemstone
Red Jasper
Silicon Dioxide (SiO2) with Hematite inclusions
sedimentary
Cubic Zirconia (or possibly Diamond)
Zirconium dioxide (or Carbon)
gemstone