Karl Lagerfeld’s arrival at Le Maison du Caviar caused a stir, as it always does. But he had nothing on Katy Perry, who turned up at the dinner Hogan was hosting last night to celebrate Lagerfeld’s fourth collection for the label in a skin-tight dress and blue hair. “It’s either Las Vegas showgirl hooker or it’s Balmain,” the pop star said. “It’s actually my first time wearing [the French label]; I’m moving up.”

Perry sat across from Hogan’s Diego Della Valle at the head table and spent most of the evening showing off her ring to jewelry freaks like Daphne Guinness and Lady Amanda Harlech. Shaped like a diamond pavé syringe and filled with tiny rubies, it was made by her date for the night, Markus Molinari, who designs under the name J. Molinari. Lagerfeld favorite Saskia de Brauw and the new Bond girl Bérénice Marlohe were the dinner’s other big attractions.

—Nicole Phelps