Quartz has the most semiprecious gemstones of all
minerals. Pure quartz is clear, so any impurity will allow the gem to
have that color. Amethyst, is prized for itís deep purple color. The
color caused by traces of ferric iron, determines the price of amethyst,
the more intense and pure the color is the higher the price. However,
some pale lilac, which was once considered low grade, has been recently
marketed as "Rose de France." With its unusual cuts, it is
gaining popularity and hence value.