“There goes my mortgage!” exclaimed Cate Blanchett when one of her diamond Van Cleef & Arpels earrings fell to the red carpet Monday at MoMA before the premiere of Woody Allen’s “Blue Jasmine.” With the bauble safely back on, the actress explained that, despite heated speculation, her disgraced Park Avenue socialite character in the film isn’t directly based on Ruth Madoff. “Like everyone, I followed that phenomenal betrayal and transgression,” she said. “[The role is] informed by a lot of things . . . there are many women who have been affected, not only on the Upper East Side.” Press-shy Allen was away shooting his next film, but he sent along a note, joking: “I’m in the South of France so I can’t be there . . . I only wish I was in New York and couldn’t be there.” Guests mingling at a Harlow after-party included “The Sopranos” creator David Chase, Charlie Rose and Norah O’Donnell, Solange Knowles, CBS News’ Jeff Fager, Julie Taymor and Zosia Mamet. SK-II and Quintessentially sponsored the fete.