gemstone

Polished citrine quartz (likely heat-treated amethyst)

Quartz, silicon dioxide (SiO₂)

AI-generated identification · may be incorrect

Hardness 7 Mohs; transparent to translucent honey-yellow, vitreous luster, trigonal crystal structure, and no cleavage with conchoidal fracture. The rounded, polished form obscures natural crystal faces; internal fractures and color zoning are visible.

Identified August 30, 2026More gemstone →

Explore Polished citrine quartz (likely heat-treated amethyst) in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Quartz crystallizes from silica-rich hydrothermal fluids in cavities of igneous rocks, commonly with amethyst; yellow citrine may form naturally or by heating amethyst. Quartz deposits range from Precambrian to recent, depending on host rock.

Uses & applications

Used as an ornamental gemstone in jewelry and carvings; polished pieces are inexpensive collector specimens. Quartz is also important industrially in glass, electronics, abrasives, and engineered stone.

Geological facts

Natural citrine is relatively uncommon, while much commercial citrine is heat-treated amethyst. Its yellow color is associated with iron impurities and irradiation or heating.

Field identification & locations

Common sources include Brazil, Uruguay, Madagascar, Zambia, and Spain. Confirm with a gemological test: quartz scratches glass, has refractive index about 1.544–1.553, and is not strongly birefringent; visual identification alone cannot prove citrine versus treated amethyst.