Royal style watchers were quick to notice that the dress Kate was wearing had once been worn by Prince Harry's girlfriend, Meghan Markle.
Kate, who is four months pregnant with her third child, dazzled in the Diane von Furstenberg Zarita lace outfit at the charity bash at Kensington Gardens orangery.
Meghan also stepped out in a shorter version of the same dress in February 2012 at the Pacific Design Center in West Hollywood, California, to an event encouraging tolerance and acceptance.
Interest in Meghan's fashion has already grown since her relationship with Harry went public just over a year ago.
There are several Twitter accounts dedicated to the actresses style. But the 36-year-old Suits actress has closed down her own lifestyle blog The Tig and limited her red carpet appearances since her relationship with Harry became serious.
We think both ladies look stunning in the lace number!