If Stella McCartney is on a red carpet, you’d better believe it’s a spectacular one. At a party — co-hosted by her friend Liv Tyler — to celebrate the opening of the designer’s boutique at Saks Fifth Avenue, we asked her whether the royal wedding or the Costume Institute gala had the most eye-popping red carpet. The self-assured McCartney responded, coolly, “The Met ball, definitely, because I was involved in the Met.” The daughter of Paul McCartney served as a Met ball chairperson and hosted the after-party at Crown. Later, she added, “They were very different, so I don’t think you can compare the two. They were like polar-opposite situations.”