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How does Joshua Jackson stand out in a room with former U.S. President Bill Clinton and European royal Prince Albert II of Monaco? With a grand romantic gesture, of course! During the auction section of the Nights in Monaco gala, held last night at Hôtel de Paris Monte-Carlo, the actor bid on this fancy “Boreal” necklace by Brazilian designer Carla Amorim, and won the design for his longtime love Diane Kruger with a $45,000 offer. “I’m flattered to have Diane, a beautiful, talented, professional, chic and generous woman wearing my designs,” Amorim told InStyle.com exclusively of the piece, which features 11.7 carats of white diamonds set in 18k rose gold. And it was all for a great cause—the evening raised over $750,000 for the Prince Albert II of Monaco Foundation and the William J. Clinton Foundation.

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Michelle Trachtenberg’s hair now has bright blue ends, and it’s all because of her new role as a psycho killer in the thriller The Scribbler, out next year. “It wasn’t even something they asked me to do, I just said ‘I think half my head should be blue,’” she told us at the Coach-hosted Childrens Defense Fund benefit party in Santa Monica last night. While producers denied a full head of blue hair, they compromised with just the tips, and Trachtenberg sought celebrity colorist Tracy Cunningham to dip-dye her strands. “We did it and it’s been so much fun,” she said. Of course, it took some getting used to. “It is super subtle though during the day it is a bright,” she said. “But after the first washing, I thought I killed one of the characters from Avatar!” Tell us: Do you like her look?

Plus, see more celebrity hair makeovers!

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— Kwala Mandel