mineral

Synthetic Sapphire and Ion-X Glass

Single-crystal Alumina (Al2O3) and Ion-strengthened Aluminosilicate Glass

Hardness: 9 (Mohs scale) for sapphire, ~7 for Ion-X; Color: Transparent; Luster: Vitreous; Crystal structure: Trigonal/Hexagonal; Specific gravity: 3.98 g/cm3 for sapphire.

Hardness: 9 (Mohs scale) for sapphire, ~7 for Ion-X
Color: Transparent
Luster: Vitreous

Identified March 9, 2026More mineral →

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Physical properties

Hardness: 9 (Mohs scale) for sapphire, ~7 for Ion-X; Color: Transparent; Luster: Vitreous; Crystal structure: Trigonal/Hexagonal; Specific gravity: 3.98 g/cm3 for sapphire.

Formation & geological history

Laboratory-created via the Verneuil process or Kyropoulos method. These materials are modern industrial synthetics used in high-precision electronics.

Uses & applications

Used for protective screens and optical sensors in smartwatches and smartphones due to high scratch resistance and optical clarity.

Geological facts

Sapphire is the second hardest natural substance on Earth after diamond. In smartwatches, it is used on the heart rate sensor (back) and sometimes the front crystal face.

Field identification & locations

Identify by their extraordinary resistance to scratches and clarity under bright light. Usually found in consumer electronics manufacturing hubs like China and South Korea.

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