Joshua Jackson splashed out $45,000 on a necklace for girlfriend Diane Kruger.

The stunning couple are currently at the Cannes Film Festival in the South of France and last night (23.05.12) they went to nearby Monte Carlo, Monaco, to attend a 'Nights in Monaco' benefit dinner and auction.

While they were there, the 'Fringe' actor treated the stunning actress to a $45,000 Carla Amorim 'Boreal' necklace, featuring 11.7 carats of white diamonds set in 18 carat rose gold.

An onlooker told ''Diane was stunned and absolutely floored by the purchase. She kept kissing him the rest of the night because she was so shocked still! The necklace is out of this world and he definitely had his eye out for it.''

Although the couple have been together for over fives years, Diane, 35, recently revealed they have no plans to marry.

The blonde beauty - who was married once before - said: ''Without sounding pessimistic, I learned that I don't believe in marriage. I believe in a commitment that you make in your heart. There's no paper that will make you stay. A guy friend of mine said, and it made a lot of sense, that people should get married at the end of the road, not the beginning.''