Mr Schröck said: “Not only is Princess Diana’s engagement ring one of the most recognisable pieces of jewellery in history, but it is also steeped in so much history and controversy, which makes it without a doubt the most iconic engagement ring in the Royal Family.

“Made up of an 18-carat white gold band and 14 solitaire diamonds surrounding a gorgeous, royal blue 12-carat sapphire, the style of this ring was unusual for its time.

“Believed to have taken inspiration from a brooch Prince Albert gifted Queen Victoria as a wedding gift in 1840, Diana’s ring is a stunning representation of something old, something new and also something blue.

“There was a lot of controversy surrounding this ring, due to it being picked straight out of a jewellery catalogue rather than custom made, which was tradition in the Royal Family.