She described selecting the piece at Buckingham Palace in the run-up to her wedding to Prince Harry in May, on which she gained the title Duchess of Sussex and formally joined the royal family.
Prince Harry also commented on the selection day, which he came along to even though, in his words, "I shouldn't have really even been there".
She chose a platinum tiara inlaid with ten diamonds. The tiara was made in the 1930s for Queen Mary, the grandmother of Queen Elizabeth, and is known as the Queen Mary Bandeau.
She discussed the day she chose the item in a newly-released audio to accompany an exhibition of her wedding outfit at Windsor Castle, which opened Friday.
In the recording, cited by MailOnline, Meghan says:
She praised the tiara for being "so clean and simple", which she said was the ideal complement for her Givenchy wedding dress.
Harry also spoke on the recording, describing the Queen Mary tiara as "the one that suited the best, the one that looked the best on you without question."
He added: "I shouldn't have really even been there, but such an incredible loan by my grandmother, it was very sweet."
The exhibition at Windsor Castle opened while Meghan and Harry were on the other side of the world, attending the Invictus Games athletics event for wounded soldiers in Sydney, Australia.
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