Citrine is a type of quartz that is named after the French "citron" or lemon, because citrines often have a rich yellow to golden tone. In ancient times, people who believed gems had a metaphysical quality used citrine as shield against the evil thoughts of others. Most of the citrine found today is from Brazil. It often starts out as amethyst that is heat treated, which brings out a golden color that is stable. Citrine is considered, along with topaz, one of November's birthstones.