Emerald is a valuable Beryl that owes its colour to chromium or vanadium, which make it bright green. Emeralds can have many flaws and, therefore, can be brittle and liable to break. The value of an emerald depends on cut, colour, clarity and carat. Clear stones with vibrant colour command the highest prices. It is found in Brazil, Pakistan, Russia, East Africa, India, Madagascar and Columbia. Source: Encyclopedia of gemstones and minerals.