It is known as ‘The Premier Blue’ – a rare 7.59-carat fancy vivid blue diamond. On October 7, ‘The Premier Blue’ will go to auction in Hong Kong, with the expected sale price to be in excess of $19 million. At that price, it would set a world record for the highest price paid for any diamond, per carat.

‘The Premier Blue’ is unique in so many ways.

First is the size. The 7.59-carat diamond is about the size of a shirt button. Second, blue diamonds are seldom sold on the open market. They have coveted by royals and collectors for centuries. Finally, ‘The Premier Blue’ is a round cut – rarely used in colored stones because of the high wastage.

The most famous example of a blue diamond is the famed ‘Hope Diamond’, which was bought by King Louis XIV of France in the 17th Century.