Dimitrios Kambouris/WireImage, Gilbert Carrasquillo/FilmMagic

Fergie and Mary-Kate Olsen each debuted a new, eye-catching look this week— though their choice of color and style couldn't be more different.

Pictured here at the 34th Annual March Of Dimes Beauty Ball, Fergie appears to have darkened her (normally blonde) tresses and opted for a pin-straight style. It's a more refined, sophisticated look for the songstress, and one that I adore.

Mary-Kate, on the other hand, chose to lighten her locks for last night's Anniversary Gala at the Metropolitan Opera. It may not be an everyday look, but I'm loving her tousled texture and dramatic side part. It's youthful, and adds an edge to her elegant ensemble.

All in all, two very different but equally appealing styles, in my opinion.