He captioned the post, giving an eight-word verdict on his picture: “One frame. Pure elegance, forever held in time.”
Royal fans went wild when the pictures were originally released earlier in September and expressed their jubilation on social media.
One user wrote on Instagram: “Holy WOW [fire emojis] they look unbelievably gorgeous! And Catherine, she is ‘THE MOMENT!’ Like holy h*** she looks stunning.”
Another user added: “Omg I’m at lost for words. they both look so beautiful, but Princess Catherine, omg so beautiful, the dress omg so beautiful the tiara everything.”
A third one said: “Princess Kate represents the essence of grace and refinement.”
A fourth fan said: “Kate and William really nailed it at this state dinner. Both of the king’s sons wear formalwear so well and so effortlessly, and this gown was perfect on Kate.”
Kate was even praised by Mr Trump during his speech at the state banquet, saying that she is looking so “so radiant, so healthy.”
The US President said: “His Majesty has also raised a remarkable son in His Royal Highness, the Prince of Wales. Really amazing. We’ve gotten to know you and I think you’re going to have an unbelievable success in future. Melania and I are delighted to visit again with Prince William and to see Her Royal Highness, Princess Catherine, so radiant and so healthy; it’s so beautiful. It’s really a great honour, thank you.”