Sophie, Duchess of Edinburgh turns the milestone age of 60 on Jan. 20. Here, fashion insiders, including designers of some of the royal's favorite brands, reveal the secrets of her style evolution.

The picture of a relaxed looking Sophie was taken by fashion photographer Christina Ebenezer.

The Duchess of Edinburgh is said to be celebrating her birthday privately with husband Prince Edward Sophie, the Duchess of Edinburgh is marking a milestone birthday! She turned 60 on Jan. 20, and friends and former colleagues have been honoring her contribution to the royal family – amid the release of the duchess' stunning new portrait.

The royal family Instagram account is getting ahead of the festivities and just shared Duchess Sophie's portrait before her birthday on Monday. However, there's one tiny detail that I almost missed—and it has nothing to do with her photos.

Sophie, the Duchess of Edinburgh is turning 60 in style. The royal—who marked her milestone birthday on Monday, January 20—released a trio of stunning portraits to commemorate the special occasion over the weekend that seemingly included a subtle sartorial nod to her grand new title.

Photographer Christina Ebenezer also shared her favorite part of the photo shoot Sophie, the Duchess of Edinburgh is starring in a new portrait for her 60th birthday, and the photographer behind the camera is sharing an unseen snap from the photo session.