gemstone
Ruby
Corundum (Al2O3)
Hardness: 9 on Mohs scale; Color: bright red; Luster: adamantine to vitreous; Crystal structure: hexagonal/trigonal; Specific gravity: 3.97-4.05.
- Hardness
- 9 on Mohs scale
- Color
- bright red
- Luster
- adamantine to vitreous
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Physical properties
Hardness: 9 on Mohs scale; Color: bright red; Luster: adamantine to vitreous; Crystal structure: hexagonal/trigonal; Specific gravity: 3.97-4.05.
Formation & geological history
Formed via contact metamorphism in marble or in igneous rocks like basalt. Natural gems take millions of years to form; synthetic versions are created via flame fusion or hydrothermal processes.
Uses & applications
Primarily used in high-end jewelry (rings and pendants) and historically used in early laser technologies.
Geological facts
The red color is caused by trace amounts of chromium. Ruby is the birthstone for July and is the hardest natural gemstone after diamond.
Field identification & locations
Identified by its high hardness, intense red fluorescence under UV light, and characteristic internal inclusions (silk).
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