gemstone
Sapphire
Corundum (Al2O3) with traces of Iron and Titanium
Hardness: 9 on the Mohs scale. Color: Deep blue (cornflower to royal blue). Luster: Vitreous to sub-adamantine. Crystal structure: Hexagonal/Trigonal. Specific gravity: 3.95-4.03.
- Hardness
- 9 on the Mohs scale
- Color
- Deep blue (cornflower to royal blue)
- Luster
- Vitreous to sub-adamantine
Identified More gemstone →
Explore Sapphire in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 9 on the Mohs scale. Color: Deep blue (cornflower to royal blue). Luster: Vitreous to sub-adamantine. Crystal structure: Hexagonal/Trigonal. Specific gravity: 3.95-4.03.
Formation & geological history
Formed in igneous or metamorphic environments such as marble, basalt, or pegmatite. Frequently found in secondary alluvial (placer) deposits after weathering from primary host rock.
Uses & applications
Primarily used in high-end jewelry (rings, bracelets, necklaces). Industrial uses include watch crystals, high-durability windows, and abrasive tools due to its extreme hardness.
Geological facts
Sapphire is the birthstone for September. The most famous sapphires include the Star of India and the Logan Sapphire. While blue is most common, sapphires can occur in any color except red (which is classified as ruby).
Field identification & locations
Identified in the field by its high specific gravity, hexagonal crystal habit, and extreme hardness (scratching quartz or topaz). Major sources include Kashmir, Myanmar (Burma), Sri Lanka, Madagascar, and Thailand.
More like this
Other gemstone specimens
Ammolite
Ammolite (Biogenic Aragonite with trace elements; fossils of Placenticeras meeki and Placenticeras intercalare)
mineral
Red Jasper
Silicon Dioxide (SiO2) with Hematite inclusions
sedimentary
Amber
Succinite (Organic Gemstone)
mineral
Citrine
Silicon Dioxide (SiO2) with iron impurities
mineral
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)
mineral
Emerald
Beryl (Be₃Al₂Si₆Oထ₈) with Chromium/Vanadium impurities
gemstone