Mr Graff said he was delighted to have beaten the three other bidders competing for the diamond.
He said: “It is the most fabulous diamond I’ve seen in the history of my career.”
It is not the first time he has paid such a high price for a jewel. In 2008 he spent £15 million on a blue 35.56-carat “Wittelsbach-Graff” diamond
Mr Graff, the UK’s number one diamond dealer, is the 36th richest man in the country, according to the 2009 Sunday Times Rich List.
In what experts called the biggest jewel heist in British history, last year armed robbers stole £40 million worth of gems from Graff jewellers in Mayfair.
