This tiara is owned by the Spanish Royal Family.
It was made by the French jewellers Maison Mellerio was exhibited in an International Fair in Paris in 1867. It was then bought by Queen Isabel II of Spain as a wedding gift for her oldest daughter, the Infanta Isabel.
The Infanta died without children, so the tiara passed to her nephew King Alfonso XIII. When the Spanish monarchy fell in 1931, much of their jewelry was confiscated, but this tiara was smuggled out, making it the oldest tiara in their collection.
It's designed to look like a seashell and has eighteen briolette shaped diamonds and seven large pearls, dangling from it which move when the wearer moves.