By InStyle Staff
Updated Mar 26, 2012 @ 1:30 pm
Amy Smart, Keira Knightley, Diana Ross
Credit: Tony DiMaio/startraksphoto; Ian West/PA Wire/AbacaUSA; Jeff Vespa/WireImage

It's a big day for Hollywood birthdays! Amy Smart celebrated her 36th today, Keira Knightley turned 27, and Diana Ross blew out 68 candles. Congratulations, ladies! To celebrate, we're taking a look back at Keira Knightley's beauty transformation, from breakout Bend It Like Beckham star to glamorous red carpet regular. Click through the gallery to see her best beauty moments.