Citrine
Citrine is a variation of quarts, with a color range from pale yellow to brown due to ferric impurities. Natural Citrines are extremely rare and most citrines are heat-treated amethysts or smoky quartz. There is a way of telling heat-treated citrine from natural though. The heat-treated citrine will have small lines in the crystal as opposed to having a cloudy or smokey appearance inside the crystal.
