The Welsh beauty was as elegant as ever in a chocolate jersey v-neck wrap dress and a crocodile skin clutch.
Had Catherine wanted colour it was there in spades in a collection that the New York designer described as "optimistic glamour".
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He tweeted followers that his vision was all about "graphic stripes, bold shades and geometric glamour... Bold shades of sun, palm and sky."
It certainly was eye-catching, featuring striped red and green bodysuits and a swimsuit with a gold zipper across the middle that the wearer could undo to make it into a bikini.
For sunset cocktails there were also luxe column dresses, with intriguing peekaboo cut outs teamed with silver cuffs.
The sunny palette reflected the upbeat atmosphere backstage where the designer had placed a handwritten note to inspire models.
It read: "Optimistic. Glamour. You are bold, confident and exude chic. Walk straight and strong, and remember you are the envy of everyone in the room. Have a great show!"