The Cameo Tiara!this is an "other" material tiara - not a diamond in sight.
The Cameo didn't run away with the victory, though. In fact, it had some pretty hefty competition from your top runner up:
The Chaumet Blue Enamel Kokoshnik. This is part of the Westminster collection, a design made to mimic traditional silk Russian kokoshniks but with blue enamel and a delicate diamond forget-me-not design on top. It was originally bought by a previous Duke of Westminster, and left the family before being purchased once again by the current Duke. It's an extraordinary piece of artwork, but sadly I don't think any depiction of it in use is publicly available.
3. The Midnight Tiara, Mary's "other" option.
4. The Cut Steel Tiara. Love it or hate it, it's become a favorite with the Swedish ladies, and it certainly is a different material.
5. Archduchess Isabella's Peridot and Diamond Tiara.
And here's the winner's circle so far:
Photos: AllOverPress/Geoffrey Munn/Scanpix/Getty Images