Grace Kelly's engagement ring is one of the most expensive rings in history.
It was a 10.48-carat emerald cut diamond flanked by two bagette cut side stones, set into a platinum band. It was designed especially for her by Cartier and cost $4 million in 1956. It's reputed to be worth $38 million now. (By contrast Princess Diana's sapphire ring cost £100,000 in 1981 and is worth £500,000 now).
After her engagement, she shot the movie High Society before sailing to Monaco to get married, and she wore her ring in the movie - naturally the cinematographers shooting the movie gave it prominance as she was making history, so it's now part of Hollywood legend too.
