These factors lower the value of these stones. Heat treatment can lighten the color of very dark amethyst. Lower-quality light-colored amethyst and even light-colored quartz have been dyed to impart a ...

These factors lower the value of these stones. Heat treatment can lighten the color of very dark amethyst. Lower-quality light-colored amethyst and even light-colored quartz have been dyed to impart a ...

A variety of crystallized quartz, of a purple or bluish violet color, of different shades. It is much used as a jewelers stone. Amethyst is an English word that is used in many sentences in different ...