Citrine is a variety of macrocrystalline quartz, which is defined by its somewhat yellowish hues that result from the presence of ferrous iron within the quartz structure. Chemically-speaking, citrine only differs from amethyst by way of its iron oxidation level, and can therefore be produced by heating its purple counterpart. As amethyst tends to be more commonly encountered in nature, most citrine in the marketplace is actually “burnt amethyst”.

While its varietal name is derived from the French for "lemon", citron, citrine is not to be confused with what we refer to by the trade-name of “lemon quartz”. This lesser-known gem variety differs from citrine by way of its pure yellow or slightly greenish hues, which contrast with citrine’s more orangish yellows. In addition, the coloration of lemon quartz is always produced artificially via irradiation and subsequent heating, while citrine is only merely heated in the way described above.