Getting dressed to play the super-rich — and super-stylish — Serena Van der Woodsen on the CW’s hit Gossip Girl, is “like playing dress up,” star Blake Lively tells PEOPLE. “It’s not like having a costume designer, its like having the best stylist out there!” So naturally when she had to choose an outfit for Tiffany & Co.’s Blue Book 2008 launch gala on Saturday, Lively turned to her costumer for a quick Alberta Ferretti loaner. Even, as it turns out, if she did already wear it once before. “I wore this on the show,” she admitted with a laugh. “But the scene got cut!” If only we could all get dressed from the cutting room floor!