mineral

White Sapphire

Corundum (Al2O3)

Hardness: 9.0 (Mohs scale); Color: Colorless (purest form); Luster: Adamantine to vitreous; Crystal system: Trigonal/Hexagonal; Cleavage: None (has parting); Specific gravity: 3.95–4.10

Hardness: 9
Color: Colorless (purest form)
Luster: Adamantine to vitreous

Identified March 11, 2026More mineral →

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Physical properties

Hardness: 9.0 (Mohs scale); Color: Colorless (purest form); Luster: Adamantine to vitreous; Crystal system: Trigonal/Hexagonal; Cleavage: None (has parting); Specific gravity: 3.95–4.10

Formation & geological history

Formed in aluminum-rich igneous rocks and regional metamorphic rocks such as mica schists and gneisses, as well as contact metamorphic crystalline limestones. They are often found in secondary alluvial (placer) deposits.

Uses & applications

Primary use is in high-end jewelry as a durable diamond alternative. Also used in industry for scratch-resistant watch crystals, optical components, and semiconductor substrates due to high thermal conductivity and hardness.

Geological facts

Sapphire is the second hardest natural gemstone after diamond. While sapphire is known for being blue, white sapphire is the purest form of the mineral corundum, containing no trace elements like iron, titanium, or chromium that produce color.

Field identification & locations

Identify in the field by its extreme hardness (will scratch almost everything but diamond) and high density. Found commonly in Sri Lanka, Madagascar, Australia, and parts of East Africa (Tanzania). Collectors should look for 'eye-clean' clarity and high-quality faceted cuts.