It’s believed the frock was in store during the summer of 2016 and has since sold out worldwide.
This isn’t the first time the princes has championed the Spanish brand.
See Also: Kate Middleton Wears Plunging Marchesa Gown For Royal Dinner
Back in 2011, she wore a cornflower blue Zara dress to jet-off on her honeymoon with Prince William.
Related: Pippa Middleton Wears Stunning See-Through Lace Dress To Wimbledon
This article previously appeared on New Idea.