In Monday night's Gossip Girl Season 5 premiere, Blair Waldorf (Leighton Meester) nearly had a fit when she learned that despite landing a spread in French Vogue, she'd be wearing the gown belonging to her future mother-in-law, Princess Sophie Grimaldi (Joanne Whalley).

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But luckily for the stylish and opinionated Upper East Sider, the gown, which had been passed down for generations in the royal French family, was actually quite stunning.

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The Gossip Girl costume department (headed by stylist Eric Daman) chose this chantilly lace THEIA bridal gown, which retails for $2,495 and features pearl buttons down the sleeves, a scooped neckline and a crystal-encrusted waistline.

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"The gown was originally designed prior to the Duke and Duchess of Cambridge's royal wedding," a representative for the brand tells Us Weekly. "It's the look that THEIA Creative Director Don O'Neill had envisioned Kate Middleton wearing down the aisle."

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Celeb fans of THEIA include Taylor Swift, Carrie Underwood and Emmy Rossum.

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