gemstone

Blue Zircon

Zircon (Zirconium Silicate - ZrSiO4)

Hardness: 7.5 (Mohs scale), Color: Vivid blue (heated), Luster: Adamantine to vitreous, Crystal Structure: Tetragonal, Specific Gravity: 4.6-4.7, Cleavage: Indistinct

Hardness: 7

Identified July 9, 2026More gemstone →

Explore Blue Zircon in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 7.5 (Mohs scale), Color: Vivid blue (heated), Luster: Adamantine to vitreous, Crystal Structure: Tetragonal, Specific Gravity: 4.6-4.7, Cleavage: Indistinct

Formation & geological history

Formed as an igneous mineral in pegmatites and granitic rocks. Most blue zircon is produced by heat-treating brownish zircon found in alluvial deposits. Geological age can span billions of years, as zircon is the oldest mineral on Earth.

Uses & applications

Primarily used as a gemstone in jewelry; historically used as a diamond simulant due to high dispersion (fire).

Geological facts

Zircon is known for its high refractive index and double refraction, which can cause a 'doubling' effect of the back facets when viewed through the table. It is the birthstone for December.

Field identification & locations

Identify by its exceptional brilliance and doubling effect of facets. Blue zircon is mostly found in Cambodia, Myanmar, and Sri Lanka. For collectors, it is valued for its 'fire' or dispersion which rivals that of a diamond.