Unfortunately, only the BRF knows the truth right now be we will eventually know as well. We do believe that the Tiara she wore is the real deal. Remember, the Royal Family often changes jewelry, and has it turned into something else. It is quite possible that Queen Mary’s Bandeau was altered over the past few decades and that is why it looks different from when Queen Mary wore it. But if we hear anything different we will definitely let you know!
Thank you Anon!