Gems : Amethyst

One of the most beautiful of coloured gemstones, especially in its better qualities, amethyst is the clear purple, mauve or violet form of quartz. This means it’s related to citrine (the yellow form of quartz) and rock crystal (the colourless variety). Some quartz specimens can be different colours in different areas. Amethyst and citrine, for example, can both occur in the same stone and such stones are called ametrines.
As with other gemstones, the "best" colour can vary according to personal preference, and the quality of amethysts varies considerably. The most important attribute is an attractive colour. Rich, deep violet is generally the most popular and expensive, but a stone of medium colour intensity, with plenty of sparkle, can also be very attractive.
Amethyst is inexpensive compared with diamonds, rubies, emeralds or sapphires, particularly in lower qualities. And even at very high qualities, amethyst is still reasonable.