One of the most valuable blue diamonds in existence will be auctioned by Sotheby’s in April. The De Beers Cullinan Blue was originally a type IIB 39.34 carat rough stone, unearthed from the Cullinan mine in April 2021. It was sold to De Beers and Diacore for US$40 million and was transformed into an internally flawless 15.10 carat step-cut fancy vivid blue diamond.
Only five blue diamonds weighing more than 10 carats have ever come to auction, and none of these ever exceeded 15 carats. De Beers now value this diamond at $48 million, although experts believe that the rarity of the gemstone could achieve a record price of up to US$4 million per carat.