Mary-Kate Olsen Dyes Her Hair Brown!

Mary-Kate Olsen Kevin Mazur/Getty Images for jcpenney; Jamie McCarthy/Getty Images

New beau, new hair!

At the CFDA Awards in NYC on Monday, Mary-Kate Olsen was the center of attention for two reasons; one of them being her new dark hair color!

The natural blonde embraced her fraternal twin bond with her sister Ashley Olsen and debuted a set of rich brunette locks on the evening's red carpet. Dressed in an all-black design from her and Ashley's own label, The Row, the 25-year-old fashion designer also wore Sidney Garber jewelry and Louis Vuitton shoes.

At the ceremony, the sisters were presented with the Womenswear Designer of the Year Award, beating out popular designers like Marc Jacobs and Proenza Schouler.

Mary-Kate's hair change comes just days after it was confirmed that she is dating former French president Nicolas Sarkozy's younger brother, Olivier Sarkozy.

"It's true, they're dating, and she's definitely interested in him," the Olsen insider tells Us Weekly about her new romance with the 42-year-old Frenchman. Though Olsen and Sarkozy are 17 years apart, the source says their age differences suits her just fine.

"MK is constantly complaining about boys not being mature enough for her," the source explains. "She got the kids out of her system. Now being a businesswoman dominates her time, and she is rarely impressed with guys."

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