mineral

Blue Sapphire (Ceylon)

Corundum (Al2O3) with traces of Iron and Titanium

Hardness: 9 on the Mohs scale. Color: Cornflower blue to deep velvet blue. Luster: Vitreous to sub-adamantine. Crystal structure: Hexagonal (Trigonal). Cleavage: None (has parting). Specific gravity: 3.95–4.03.

Hardness: 9 on the Mohs scale
Color: Cornflower blue to deep velvet blue
Luster: Vitreous to sub-adamantine

Identified March 26, 2026More mineral →

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Physical properties

Formation & geological history

Formed in metamorphic environments (marble or schist) or as primary crystals in igneous rocks (syenite, pegmatite). Frequently found in alluvial deposits. Ceylon sapphires from Sri Lanka come from geological formations over 500 million years old (Precambrian).

Uses & applications

Primarily used as a high-value gemstone for jewelry (rings, necklaces), and industrially for non-ornamental uses like high-durability watch crystals or scientific instruments due to extreme hardness.

Geological facts

Sri Lanka is known as the 'Gem Island' and has produced some of the world's most famous sapphires, including the 422-carat Logan Blue Sapphire. 'No heat' refers to stones that have not undergone thermal enhancement, making them much rarer.

Field identification & locations

Identify by its exceptional hardness (it can scratch almost anything except diamond) and high refractive index. In the field, look for water-worn hexagonal barrels in gravel pits or riverbeds. For collectors, check for specific inclusions like 'silk' (rutile), which can prove natural origin.

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