mineral

Ruby

Corundum (Aluminum Oxide with Chromium), Al2O3:Cr

Hardness: 9.0 on Mohs scale. Color: Pinkish-red to blood-red. Luster: Vitreous (glassy). Crystal Structure: Trigonal/Hexagonal. Cleavage: None. Specific Gravity: 3.97-4.05.

Hardness: 9
Color: Pinkish-red to blood-red
Luster: Vitreous (glassy)

Identified May 29, 2026More mineral →

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Physical properties

Hardness: 9.0 on Mohs scale. Color: Pinkish-red to blood-red. Luster: Vitreous (glassy). Crystal Structure: Trigonal/Hexagonal. Cleavage: None. Specific Gravity: 3.97-4.05.

Formation & geological history

Formed in metamorphic rocks seperti marble or granulite, and occasionally in igneous rocks. They are created under high pressure and intense heat in the Earth's crust. Most rubies are found in Tertiary or older deposits.

Uses & applications

Primarily used as a gemstone in high-end jewelry. Also used in industrial applications such as lasers (ruby lasers), watch bearings, and precision instruments due to its extreme hardness.

Geological facts

The most valuable color is known as 'pigeon's blood' red. Ruby is the birthstone for July. Synthetic rubies were first created in 1902 by the Verneuil process and are difficult to distinguish from natural ones without magnification.

Field identification & locations

Identify by its extreme hardness (cannot be scratched by steel or quartz) and its characteristic red color. Commonly found in Myanmar (Burma), Thailand, Sri Lanka, and Madagascar. Look for the 'silk' (rutile inclusions) under a jeweler's loupe in natural specimens.

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