Chinese Girl by Vladimir Tretchikoff

Mr Graff, chairman of Graff Diamonds International, owns the Delaire Graff Estate near Stellenbosch, South Africa, where the picture will go on public display with the rest of his art collection.

The work by Siberian-born artist Vladimir Tretchikoff was part of a sale of South African art at Bonhams auction house.

Millions of reproductions of the picture, also known as the Green Lady because of the unusual blue-green skin tone of the subject, have been sold since it was painted in the 1950s.

A Bonhams spokesman said: "It's very exciting. Suddenly the market has decided they like what they can see with Tretchikoff."

The sum is the highest ever paid for a work by Tretchikoff, who was born in Russia in 1913 but emigrated to South Africa after the Second World War, working for a period as a propaganda artist for the British Ministry of Information.

The familiar image of the woman, with her dark hair and bright red lips, has featured on T-shirts, mugs and posters.

The picture, which has been described as one of the most important pop culture images in Britain, was inspired by Monika Sing-Lee, who modelled for Tretchikoff after he spotted her at work in her uncle's launderette in Cape Town, South Africa.