Emerald is one of the 4 stones thought of as precious stones for centuries, alongside Diamond, Ruby and Sapphire. Emerald is the green gem variety of the mineral Beryl. It gets its green colour from trace elements in the crystal such as Chromium or Vanadium (although Beryl coloured green by Vanadium is generally not regarded as a 'true' Emerald). It is the birthstone for the month of May, and for the sign of Cancer.The name Emerald derives from the Greek smaragdos, which means 'green stone', although it is probable that this name which was given to many green stones in ancient times that were thought to be Emerald were probably something else. They are very rarely transparent, and often full of inclusions, which are referred to as jardin, French for 'garden'. They are brittle and difficult to cut, and are often oiled to hide imperfections, and as such synthetic Emeralds are widely popular on the market.