gemstone
Blue Sapphire (likely lab-grown or treated)
Corundum (Aluminum Oxide, Al2O3)
Hardness: 9 on Mohs scale. Color: Deep royal blue. Luster: Vitreous (glass-like). Crystal structure: Trigonal/Hexagonal. Cleavage: None. Specific gravity: 3.98-4.06.
- Hardness
- 9 on Mohs scale
- Color
- Deep royal blue
- Luster
- Vitreous (glass-like)
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Physical properties
Hardness: 9 on Mohs scale. Color: Deep royal blue. Luster: Vitreous (glass-like). Crystal structure: Trigonal/Hexagonal. Cleavage: None. Specific gravity: 3.98-4.06.
Formation & geological history
Natural sapphires form in igneous or metamorphic rocks (marble, basalt, pegmatite) over millions of years; synthetic versions are created via the Verneuil flame-fusion or Czochralski process.
Uses & applications
Jewelry and adornment. Industrial sapphires are used for scratch-resistant watch crystals, optical components, and abrasives.
Geological facts
Sapphire is the second hardest natural substance on Earth after diamond. While blue is most famous, sapphires occur in every color except red (which is classified as ruby).
Field identification & locations
Identify by its high hardness (not scratched by quartz) and high refractive index. In jewelry settings like this, synthetic stones often show no bubbles or curved growth striae under magnification.
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