What an interesting side subject!
When I saw the Tiara at the exhibition in the Royal Mews that was one of the first thing I thought 'I've never noticed that before'
I'd always assumed that the pendants hung from the middle of the circles.
I personally don't think the ribbon can be removed anymore.
If you look at the picture of Queen Elizabeth wearing the tiara without either Pearls or Emeralds you can still see the ribbon at the back. Saying that maybe it looks a bit odd from a design point of view if you take out the ribbon.
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