The diamonds total 85.62 carats altogether, with the largest a 25.75 carat diamond. They sold for a total purchase price of $40.3m (£30.1m) which was split equally between the two companies.
Both De Beers and Diacore are set to select “expert craftsmen” to study and work with the diamonds to “unlock their natural beauty” before they are presented to the public.
Paul Rowley, executive vice president of Diamond Trading at De Beers Group, said: “We are excited and humbled to have the opportunity to unlock the unparalleled beauty of these rare and extraordinary natural diamonds and share them with the world.
“Cullinan has produced some of the most beautiful diamonds the world has ever seen and these blue diamonds are no exception.”
Nir Livnat, executive chairman at Diacore, said: “I’m thrilled with the purchase of Cullinan’s rare blue diamond collection with De Beers, demonstrating our long-term vision and passion in creating one of-a-kind masterpieces.”