Emerald is the birthstone for May. A beautiful green colour, it also has a well known gemstone relative called Aquamarine. Emerald is rarely flawless, and often has inclusions which makes the gem so recognisable. A flawless Emerald therefore is a rare and valuable gem indeed. Often found in historical jewellery, Emeralds were also prized long ago by the Egyptians in the reign of Cleopatra.