The Duchess of Cambridge picked palest baby blue for her appearance at the Wildlife Photographer of the Year awards - her third engagement in three days. But as Kate is around twelve weeks into her second pregnancy it's probably too soon to know the sex of her next baby so this brand new evening dress isn't a clue to the newest member of the Royal Family.
Queen Margrethe of Denmark chose powder blue for the first outfit on her State Visit to Croatia before changing into midnight blue for the State Dinner held in her honour that evening.
The Queen was in darkest blue when she greeted the President of Singapore as he and his wife began their State Visit to the UK.
And it was turquoise blue for her now legendary appearance at the Science Musuem where she made royal history by sending her first tweet.
The week ended with Queen Letizia choosing dark blue and black for her gala outfit at the Prince of Asturias Awards in Oviedo.