gemstone
Blue Sapphire (Faceted)
Corundum (Al2O3)
Hardness: 9 on Mohs scale; Color: Deep royal blue; Luster: Adamantine to vitreous; Crystal structure: Trigonal; Specific gravity: 3.98-4.06
- Hardness
- 9 on Mohs scale
- Color
- Deep royal blue
- Luster
- Adamantine to vitreous
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Physical properties
Hardness: 9 on Mohs scale; Color: Deep royal blue; Luster: Adamantine to vitreous; Crystal structure: Trigonal; Specific gravity: 3.98-4.06
Formation & geological history
Formed in sapphire-bearing metamorphic rocks (schist, gneiss) or igneous rocks (alkaline basalts, syenites) through high pressure and temperature over millions of years.
Uses & applications
Primarily used in high-end jewelry (rings, pendants, brooches) and historically in industrial applications like watch crystals and high-durability sensors.
Geological facts
Sapphire is the birthstone for September and represents wisdom and royalty. It is the second hardest natural mineral after diamond.
Field identification & locations
Identified by its high hardness, intense blue color (caused by iron and titanium), and high refractive index. Large faceted stones are commonly found in Sri Lanka, Madagascar, and Myanmar.
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