Zircon is one of the birthstones of December is derived from the Arabic words 'zar' and 'gun', meaning 'gold' and 'colour', zircon is found in a wide range of colours such as: blue, yellow, orange, brown, green, colourless, and red (the most prized colour). For many years colourless zircon was used to imitate diamonds. The oldest rock ever discovered was a zircon found in Australia that is 4.4 billion years old. Zircon is one of the few coloured stones that might show visible dispersion. It was thought to induce sound sleep.