The Stewart Sapphire, which had been owned by the Royal House of Scotland for centuries, was given to George III. The original owner of the sapphire was reputed to have been King Alexander II of Scotland, who had it set in the crown for his coronation in
The Angouleme Emerald Tiara worn by Marie Antoinette and made by Evrard and Frederic Bapst for the French crown jewels in There are 1031 diamonds and 40 emeralds in the setting. When sold in an observer remarked that anyone who had not seen it
Edwards Crown - Anne Boleyn is the only consort, before or since, to have been crowned with the St Edward crown, which is reserved for the actual monarch. I know she was crowned as a regent would have been.
The Cullinan I white diamond, cut from the largest gem quality diamond ever found. It was set in the British royal scepter and is currently in the London Tower with the other jewels of the British crown.