Kate Middleton and Camilla Parker Bowles wore blue and meaningful brooches for the Commonwealth Day celebration at Westminster Abbey.

Middleton wore a vintage-inspired peplum jacket and midi skirt from Erdem's pre-fall 2023 collection.

Middleton pinned a Prince of Wales feather pin on her blazer that has ties to a long line of princesses.

The pin was gifted to Princess Alexandra of Denmark in 1863 and includes blue sapphires, white diamonds, rubies, and emeralds.

The pin was worn by subsequent Princesses of Wales, including Princess Diana and Camilla.

Camilla accessorized with sapphire-and-diamond flower earrings that once belonged to Princess Diana.

Middleton carried her favorite Emmy London suede clutch in navy and wore coordinating Gianvito Rossi heels and a blue hat.

The pin is estimated to be worth $400,000.

The lining of Middleton's skirt revealed a reverse print of the fabric.