The Ocean Tiara(Monaco) can also be worn as a necklace, as seen here on Princess Charlene. She is also shown here with matching earings...
Princess Charlene of Monaco, the necklace, with converts into a tiara, has a wave motif that celebrates her love of swimming
Tatiana, Princesse de Grèce. | On the day of her wedding to Prince Nicolas of Greece, Tatiana wore a tiara loaned by her stepmother, the former Queen Anne-Marie of Greece, which she herself had received for her son's (the groom's) 18th birthday "Antique Corsage Tiara"
A rarely seen photo of Princess Grace wearing what appears to be a turquoise tiara and necklace, though these pieces may have been borrowed as they don't appear in any of the exhibitions of Monaco's royal jewels.
HRH Caroline, Princess of Hanover, Hereditary Princess of Monaco wearing the Hanover floral tiara.
Some of Princess Grace's jewels on display in Monaco