JESSICA BIEL AND JUSTIN TIMBERLAKE

It's Old Hollywood come to life as Biel celebrates the silver screen siren in her slinky Ralph Lauren Collection silk charmeuse gown, accessorized with a clutch and heels from the designer with '20s Fred Leighton diamonds – and her dashing beau, Timberlake (in a William Rast tuxedo).

JESSICA ALBA

The star may be divine in her '30s-inspired Sophie Theallet for Gap dusty rose bias gown, a Ferragamo clutch and House of Lavande jewelry at the gala, but her dress is whisked off to auction tomorrow to benefit the Costume Institute, courtesy of co-chair Gap.

Katy perry light up dress