Meghan - who was with Prince Harry - wore Emilia Wickstead as she opened the ANZAC memorial in Sydney's Hyde Park.
"So fitting that Meghan wears a New Zealand designer Emilia Wickstead to honour the Anzacs," fashion expert Donny Galella told New Idea.
He estimated the dress to be worth more than $2500.
"Her elegant look was topped off with a chic pillbox style hat by the Queen's Milliner Philip Treacy," Donny added.
Emilia Wickstead is a New Zealand-born fashion designer based in London, England.
In 2014 she won the Red Carpet Designer of the Year Award at the Elle Style Awards, and her clients include Samantha Cameron, and the Duchess of Cambridge.
Philip Treacy is an award-winning Irish haute couture milliner, also based in London, who has been described by Vogue magazine, as "perhaps the greatest living milliner".