Then-Princess Elizabeth was given the breath-taking diamond upon her marriage to the Duke of Edinburgh in 1947.

Paul Hird, head of luxury auctions at John Pye Luxury, explained to Express.co.uk: “Whilst mining in the Williamson Mine in Tanzania, 1947, there was an incredible discovery containing one of the rarest flawless pink diamonds in the world.

“Upon the discovery of this stunning uncut gem, weighing an impressive total of 54.5 carats, the owner of the mine John Thoburn Williamson wanted to give the uncut diamond to Princess Elizabeth as a wedding gift that November.

“The then-Princess Elizabeth had this gem displayed in the palace before the royal wedding, and in 1948 Elizabeth had the diamond cut.