More than ten thousand diamonds will be on display at Buckingham Palace this year during it's annual summer opening.
They're set into works acquired by British monarchs over the course of three centuries.
Among the works in the exhibition is the Delhi Durbar Tiara, which is on display to the public for the first time.
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The ComRes survey for ITV News and LBC showed the Labour candidate increasing his overall lead over Conservative rival Zac Goldsmith.
The latest poll for ITV London and LBC shows Sadiq Khan leads Zac Goldsmith by 45% to 36% on first preference votes.
Corbyn was unveiling a poster less than a mile away as Khan gave his final campaign speech to party supporters in London.