gemstone

Blue topaz (likely treated)

Topaz, Al₂SiO₄(F,OH)₂

AI-generated identification · may be incorrect

Mohs hardness 8; typically vivid blue, transparent, and vitreous with strong faceting and birefringence. It has orthorhombic crystals, perfect basal cleavage, and specific gravity about 3.5–3.6; the intense blue is commonly irradiation- and heat-induced.

Identified August 10, 2026More gemstone →

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Physical properties

Formation & geological history

Topaz crystallizes from fluorine-rich late-stage igneous fluids, especially granite and rhyolite pegmatites, commonly forming millions to hundreds of millions of years ago. Major sources include Brazil, Nigeria, Pakistan, Russia, Sri Lanka, and the United States.

Uses & applications

Used primarily as an ornamental gemstone in rings, pendants, and display pieces; large clean faceted stones are affordable alternatives to sapphire. Industrial use is limited, though topaz is collected for its crystals.

Geological facts

Natural blue topaz is uncommon; most commercial blue material is treated colorless topaz. Cleavage makes it vulnerable to sharp impacts despite its high scratch resistance.

Field identification & locations

Identify by its blue color, glassy luster, high hardness, dense feel, and cleavage; confirm with gemological refractive-index and specific-gravity testing. The pictured precision-cut rectangular stone appears consistent with blue topaz, though image-only identification is not definitive.