“It now measures a little over three centimetres in length and width, 1.3 centimetres in depth and has a total of 66 facets.”

The Koh-i-Noor diamond has been worn in the crowns of several generations of royal women since the reign of Queen Victoria, so it will likely be worn by Camilla and then the Duchess of Cambridge when Prince William is King.

Claire Beatson, jewellery expert from the ethical jewellery brand Nightingale, told Express.co.uk: “In 1851 Queen Victoria and Prince Albert had the stone recut and polished to its current oval brilliant shape ‘in order for light to refract more brilliantly’.

“Victoria wore it as a brooch for many years, but the stone has been used in the crowns for the queen consorts since including Queen Alexandra and Queen Mary, until finally being placed in front of the Queen Mother’s crown.