Jessica Biel has a lot to smile about.

OK! NEWS: JESSICA BIEL AND JUSTIN TIMBERLAKE: NO WEDDING INVITE FOR CAMERON DIAZ

Not only is she in NYC preparing for her red carpet appearance at the 2012 Costume Institute Met Gala Ball tonight (the rumored theme: pink), she's also sporting a huge rock from fiancé Justin Timberlake.

OK! GALLERY: JESSICA BIEL CHECKS OUT JUSTIN TIMBERLAKE'S SWING

While the two haven't set a date for the wedding, Justin reportedly proposed over Christmas. The two have been on and off since 2007.