Emerald derives its beautiful green color from the presence of chromium and vanadium. Emeralds are rarely flawless, so stones are often oiled to fill disguise cracks, hide flaws, and enhance color. To minimize the loss of materials, step cut (or "emerald-cut", as it is known) is commonly used, but ancient engravings are known, and cameos, intaglios, and beads can make the best of a flawed stone.

Found in granites, pegmatites and schist's, as well as alluvial deposits, the finest emeralds are forming Colombia. Other sources are Austria, India, Australia, Brazil, South Africa, Egypt, the USA, Norway, Pakistan, and Zimbabwe.

Most emerald used in historical jewellery would have been from Cleopatra's mines in Egypt's, which now yield only poor-quality emeralds.