What an interesting discovery J-F! Congratulations! The brooch is so difficult to spot until images are enlarged that I am amazed at how you spotted it.

It is an unusual design. I wonder if it might have originally been meant to carry pendants?

If you have a date guide for any of the photos, I'll check to see if the media mentioned anything about her jewels -- although the chances are slim.

Congratulations again! What a charming way to start my day!