gemstone
Blue Sapphire
Corundum (Al2O3)
AI-generated identification · may be incorrectHardness of 9 on the Mohs scale, deep blue color, subadamantine to vitreous luster, trigonal crystal system, and no true cleavage.
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Physical properties
Hardness of 9 on the Mohs scale, deep blue color, subadamantine to vitreous luster, trigonal crystal system, and no true cleavage.
Formation & geological history
Forms in aluminum-rich metamorphic or igneous rocks like pegmatites and marbles under high pressure and temperature over millions of years.
Uses & applications
Extensively used in fine jewelry, luxury watches, and industrial applications such as scratch-resistant watch crystals and scientific instruments.
Geological facts
Sapphire is the precious gemstone variety of corundum, with red varieties classified as ruby. It is the birthstone for September.
Field identification & locations
Identified by its exceptional hardness, lack of cleavage, and characteristic hexagonal barrel crystal habit when raw. Found globally in alluvial gravel deposits.
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