Amethyst is, by definition, purple quartz (crystalline silicon dioxide). The purple color ranges from fairly light, called “Rose de France." To a deep violet purple, the best of which has some flashes of blue and red (Siberian Amethyst). Typically with amethyst, the labor that goes into faceting the stone is going to represent the bulk of the price of the cut gemstone. For some price context, faceted amethyst gemstones from India may sell for as little as $2 per carat where some of the material with better color from brazil will sell for $5-10/caret.