Citrine is the yellow to orange variety of Quartz. Natural Citrine is not common; most Citrine on the gem market is produced by heat treating Amethyst and Smoky Quartz. It takes a relatively low temperature to change the color light to golden yellow, and heating to higher temperatures will give the stone a darker yellow to brownish-red color. The name Citrine is derived from the citron fruit, a yellow fruit similar to the lemon. (In fact, citron means “lemon” in several languages.)