The Duke and Duchess of Cambridge joined the Queen and members of the Royal Family on the first day of Royal Ascot.
The top appears to be a customised piece with added sheer sleeves, based on Elie Saab's Resort 2019 collection.
Kate completed her race day look with her Kiki McDonough topaz earrings and a pair of silver heels.
Royal fans on Twitter gushed over Kate's outfit, calling it 'perfect' and 'stunning'.
It's believed to be the first time the duchess has worn Lebanese fashion designer Elie Saab.
His designs have been worn by other notable royals, which include Queen Rania of Jordan, Victoria, Crown Princess of Sweden and Princess Madeleine of Sweden.
Saab's creations have also been worn by Beyonce, Angelina Jolie, Priyanka Chopra, Helen Miller and Taylor Swift.
first look of the Duchess of Cambridge 🖤- 👑Catherine_thegreat_duchess👑 (@duchesskatemid) 18 June 2019
She looks wonderful pic.twitter.com/TID1q4MHMp
Don't they look dashing 💙- Crown Pandora 👑 (@CrownPandora) 18 June 2019
The Duchesses dress is by Ellie Saab hat by Philip Treacy & blue topaz earrings by @kikimcdonough.
It's a winner, I love every element, it's very elegant & classic Catherine look ! https://t.co/b6KT0bxFCN
But did the Duchess of Cambridge break the strict dress code at Ascot?
Strapless and sheer dresses and tops are not permitted in the Village Enclosure - Kate's sheer sleeves might be deemed to be against the rules.
Fortunately, the duchess is standing in the Royal Enclosure and the guidelines for that area don't mention that sheer dresses and tops are not allowed.
Similarly, Queen Maxima, 48, also wore a dress with semi-sheer sleeves.
The Cambridges were joined in the carriage by the Prince of Wales and Duchess of Cornwall, who wore a pale pink outfit.
The Queen, 93, wearing a cornflower blue ensemble led the procession, was accompanied by the Duke of York and King Willem-Alexander and Queen Maxima of the Netherlands.
Blue appeared to be the theme of the day, as sisters Princess Beatrice, 30, and Princess Eugenie, 29, both wore dresses in complementary shades.
- This article first appeared on Yahoo