Citrien

Citrien, or citrine in English, is a yellow to brownish-orange variety of quartz (silicon dioxide). The name derives from the lemon-like color; in some languages the word is citrien. It is characterized by a vitreous luster and a transparent to translucent appearance. Its color results from trace amounts of iron and the effects of natural or artificial irradiation and heating.

Natural citrine forms when quartz crystals are subjected to heat in geological environments, or through irradiation that alters iron within the crystal. Because natural citrine is relatively rare, most stones sold as citrine are heat-treated variants of amethyst or smoky quartz to achieve a similar yellow color. Major current sources include Brazil (especially Minas Gerais), Madagascar, Spain, Russia, and the United States.

Citrine is a variety of quartz with chemical composition SiO2. It has a Mohs hardness of 7, a refractive index of about 1.54–1.55, and a conchoidal fracture. It lacks cleavage and is typically cut for faceted gems or cabochons.

Common methods produce citrine by heating amethyst or smoky quartz to around 450–520 °C, which converts the purple or brown color to yellow. There are natural and synthetic varieties; natural citrine remains paler, while amethyst-derived citrine is the most common commercial form. Ametrine is a natural variety that combines both amethyst and citrine within a single crystal. Madeira citrine refers to deeply colored stones from specific Brazilian sources.

Citrine is widely used in jewelry, often as faceted stones in rings, pendants, and earrings. It is relatively affordable compared with other colored gemstones. Clean with mild soap and warm water; avoid harsh chemicals. Prolonged exposure to high heat or strong sunlight typically has little effect on color.