from a private collection in Liguria

Typically found in Brazil (Rio Grande do Sul), Madagascar, and Russia (the Urals), it is the yellow-orange variety of quartz, colored by color centers associated with traces of Fe³⁺ in the crystal lattice. Natural citrine forms through hydrothermal crystallization in pegmatites and druses, often as the final stage in the color zoning of amethyst crystals subjected to mild natural geothermal heating; most of the citrine on the market, however, is produced by controlled heat treatment (approximately 400–500°C) of amethyst or smoky quartz, which thereby acquire a permanent yellow color. Trigonal system, hardness 7 on the Mohs scale, density 2.65 g/cm³, hexagonal prismatic habit.

A gemstone widely used in jewelry due to its warm color and lower cost compared to other yellow gemstones; prized by collectors when of natural origin (rarer and more valuable than heat-treated material); the traditional birthstone for November, symbolically associated with prosperity and positive energy.