The reality star took to Instagram today (13 March) to show off a teeny glimpse of the beauty, and we were desperate to see more.
Her close-up selfie gave us a look at the top of the dress, which featured a detailed embellished neckline, teal ruffles and a tweed front.
Captioning the snap, Rosie wrote: "The neckline of this @matthewwilliamson dress is unreal #dressofdreams #ohmw"
We did a little bit of research and managed to find the item in its full glory, yay!
As well as a stunning neckline, this Matthew Williamson frock features a matching embellished nipped-in waist of dainty blue beads. While the rest of the dress consists of a indigo tweed pattern. Amazing.
Unfortunately, no matter how much we love this incredible piece, it costs a whopping £1,795. Eek!
Rosie didn't reveal where she was heading in her fancy frock, but no doubt it was somewhere pretty special.
She finished off the get-up with soft, loose waves and a dainty "love" necklace.
And it's not the only thing that Rosie has been making us jealous over. Earlier this week, the Chelsea girl showed off a bespoke Edie Parker clutch and teeny tiny "R" necklace.
We really need to go shopping with this girl. Pronto!
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