sensitivity of natural citrine further indicates that its color is not caused solely by trace elements.

Citrine is very rare in nature; most "citrine" on the market is actually heat-treated amethyst and is therefore not true citrine according the strict mineralogical definition. Amethyst loses its natural violet color when heated to above 200-300 C. Natural citrine tends to be pale in color, while heat-treated amethyst is typically a deeper yellow, orange, red, or even brown; the latter is sometimes