Emeralds were formed millions of years ago and, due to the unique set of circumstances required, are incredibly rare. Emeralds belong to the mineral family known as beryl: several different varieties of the mineral exist, including aquamarine, morganite and heliodor, but the green emerald is the most prized and valuable.
An emerald’s colour – varying from bluish green to pure green with vivid colour saturation – is determined by the levels of chromium, vanadium and iron present in the gemstone.