Uma Thurman's big engagement

Jun 27, 2008, 9:40 GMT

Uma Thurman (L) arrives with Arpad Busson at a dinner held on the occassion of Nelson Mandela\'s 90th birthday in Hyde Park Central London 25th June 2008. \'A\' list celebrities and dignitaries from all over the world have gathered for the legendary African leader\'s party that will be followed by a large concert at the same location on 27th June. EPA/STR

Uma Thurman is reportedly engaged to Arpad Busson.

The 'Kill Bill' actress - who has been dating Swiss financier Arpad, who is nicknamed Arki, since last year - showed off a diamond ring so big "so can't fit it through the sleeve of her coat" at Elton John's 10th White Tie and Tiara benefit in Windsor, England, last night (26.06.08).

An onlooker told the New York Daily News newspaper: "All the ladies were wide-eyed because the ring was so massive! It was so huge that she can't fit it through the sleeve of her coat."

Uma - who has two children with ex-husband Ethan Hawke - was shocked when Arpad presented her with the ring during their UK trip, which will also see them celebrate former South African president Nelson Mandela's 90th birthday.

A friend of the actress said: "It was a really old-fashioned romantic gesture. It's a done deal. They're already planning the wedding."

The 38-year-old actress recently appeared in a court case against Jack Jordan, a man who was found guilty of stalking her.

The friend added: "Everyone is so happy for Uma after what she went through with that stalker. Arki is a guy who can take care of her.

"Uma is hoping this time, it's really love. Everyone wants the best for her. And Arki is a really sweet guy."

Uma was previously married to actor Gary Oldman, while Arpad has two children with Australian supermodel Elle Macpherson.