Grace Kelly & Prince Rainier III engagement ring

The Oscar winner's engagement ring is almost as well-known as she is. After meeting at the Cannes Film Festival the same year, Prince Ranier III of Monaco proposed to Grace Kelly during the Christmas season of 1955.

After a year of romance, Prince Rainier III, Prince of Monaco, proposed to Grace Kelly in 1956. Prince Rainier proposed with a ring made from two family heirlooms, which formed interweaving diamond and ruby circlets. Prince Rainier also handed Kelly a second engagement ring, which she may wear out, because this ring was part of Monaco's sovereign jewels. Cartier created the engagement ring, which contained a 10.47-carat emerald cut perfect diamond. Grace Kelly & Prince Rainier III's engagement ring was said to have cost over $4 million at the time.

Kelly has been a longstanding admirer of Cartier jewelry since filmmaker Alfred Hitchcock introduced her to the brand.

Estimated Cost: $4.06 million