the silver-gilt crown has around 2,200 rose-cut and brilliant-cut diamonds, and originally contained the koh-i-noor diamond, as well as the cullinan iii and cullinan iv. in 1914, they were all replaced with crystal models, and the arches were made detachable so that it could be worn as a circlet or open crown. mary wore it like this after george v died in 1936.