What is the biggest jewel on the crown?

The biggest jewel on the British Crown Jewels is the Cullinan Diamond, which weighs an impressive 3,106 carats. It was discovered in South Africa in 1905 and was later cut into several gems, with the largest two, Cullinan I and Cullinan II, being set into the Sovereign's Star and the Imperial State Crown, respectively. Cullinan I, also known as the Great Star of Africa, is the largest clear cut diamond in the world.