Amethyst occurs in primary hues from a light pinkish violet to a deep purple. Amethyst may exhibit one or both secondary hues, red and blue. This precious gem stone is a variety of the common stone quartz. Its typical purplish color is caused by a combination of mineral impurities and crystalline structure. The stone known as burnt amethyst is created by heating the gem, producing a yellowish tint.The ideal grade is called "Deep Siberian" and has a primary purple hue of around 75–80 percent, 15–20 percent blue and (depending on the light source) red secondary hues.
