Judith Crowe describes how gemstones are formed, how they are mined and the journey through which precious raw materials travel, how to assess the quality, rarity, classification, hardness and cut of minerals, how some gemstones are calibrated in carat and point and how to care for them, so that their color and transparency are preserved. A comprehensive glossary explains key terms of the technical terminology. Illustrations and color photos help identify the most common gemstones, from amethyst and diamond to tourmaline and quartz.