Leighton Meester
Credit: Jackson Lee / Splash News, Courtesy Monique Lhuillier

Gossip Girl filmed the Blair Waldorf–Prince Louis of Monaco wedding in New York last night! Photographers caught Waldorf (played by Leighton Meester) on set, tearfully running out of the ceremony in her elaborate gown and diamond tiara. OK, so she may not marry the Prince—we won't know for sure until the episode airs in January—but she did get to wear the dress! "It's phenomenal," the show's stylist Eric Daman told of the look at the launch of his DKNY hosiery collection last month. "It has that kind of bravado and gorgeousness and is also subtle and beautiful." And he gave us a few hints: First, "She is with child, so I doubt that it's going to be white," he said. Second, "It's a bridal designer who also designs ready-to-wear." After pouring over images of wedding gowns with his clues in mind, we're thinking Monique Lhuillier is behind the strapless lace and tulle gown with a sweetheart neckline and side bow. Waldorf's look is similar to the "Emma" style the designer created for her fall 2012 collection, with a few tweaks, like the ivory hue and a fuller skirt. Tell us: What do you think of Blair's wedding dress?

Plus, see more from Monique Lhuillier's latest bridal collection in the gallery!