Duchess wore statement earrings belonging to her late Mother-in-Law Diana, Princess of Wales to BAFTA in February 2019.
Earrings were actually a combination of two different pairs. She was wearing the upper detachable part of Diana’s earrings with another pair of pearls Diana wore. It looks the pearls worn by Diana in picture shown below.
Telegraph described the earrings as,
Princess Diana left her jewellery to her sons, in order that their future wives may wear and enjoy it. And, true to her wishes, the Duchess of Cambridge attended the BAFTAs wearing a pair of diamond and pearl earrings from the collection of her husband’s late mother. The earrings feature a double curve of various cuts of diamonds, with a cluster of marquise-cut stones in the centre, from which hangs a single pearl. Princess Diana wore the earrings with sizeable, silver-toned South Sea pearl drops on several black-tie occasions.
She wore them with the Cambridge Lover’s Knot tiara, a piece the Duchess of Cambridge has also borrowed on several occasions, at a banquet for the Japanese Emperor Akihito in 1990, and again at a banquet in South Korea in 1992, when she paired them with the Spencer tiara she’d worn on her wedding day. The earrings appeared also during a visit to Pakistan in 1991, and at a gala at the Palace of Versailles in 1994.