The Portland Tiara for a duchess to wear at a glittering and hugely important royal occasion, has been stolen in UK, Mirror reported. 

Richard Edgcumbe, Curator of Jewellery at the Victoria and Albert Museum in London, said: "The Portland Tiara is one of the great historic tiaras of Great Britain."

"The Portland Tiara is one of the great historic tiaras of Great Britain. Since its creation by Cartier in 1902, using diamonds from the historic collections of the Dukes of Portland, it has been recognised as a jewel of supreme importance, a superb design magnificently executed,” he said.

The centre-piece of the tiara is the Portland Diamond, which is flanked by two diamond drops and other pendant diamonds, all set in gold and silver.

He was reportedly pinched along with a diamond brooch from the Portland Collection Gallery.

A silver Audi S5 suspected to have been involved in the offence.

"We particularly want to hear from anyone who has any information about a silver Audi S5 which is suspected to have been involved in this offence. This vehicle was found abandoned and burnt out in Cross Lane, Blidworth, about half-an-hour after the incident,” Detective Inspector Neil Humphris said.