Dig into the world of geology with the Rock On! series! Groovy Gems introduces readers to what gems are and how they form, including mineral gems and organic gems. Chapters discuss crystal systems, imitation and synthetic gems, cultured pearls, how gems are used, and their importance throughout history. Sidebars introduce birthstones, precious metals, and conflict diamonds. Full-color photographs of brilliant diamonds, pearls, geodes, star sapphires,...