Gemstones of the World is truly the single volume that every hobbyist, jeweler, jewelry maker, and rockhound needs: it's the cornerstone of the field. And this updated edition contains a host of new findings on "Gemstones for Collectors," additional gems in the "Table of Constants," and the "double fraction" figures that experts have long wanted--a very special new feature. All the gemstones are treated in their many variations: more than 1,500 full-color...