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).

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.

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.

"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."

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