Thieves who stole items worth up to £1m from top auction house Christie's have still not been traced.
Jewellery, antiques, and valuable works of art including Fabergé pieces were taken from the London head office on the evening of 7 December.
No one has been arrested despite the burglary being captured on CCTV.
Scotland Yard informed the British Antique Dealers' Association to be alert if anyone approached them trying to sell the stolen items, according to The Mail on Sunday.
"Christie's is helping the Metropolitan Police to investigate a recent, isolated incident at its London offices," said a spokesperson for the auction house.
Scotland Yard did not confirm the name of the business but said: "We can confirm that officers from Westminster are currently investigating a burglary at business premises which is believed to have occurred between 6pm on Sunday, December 7 and 8am on Monday, December 8.
"A number of high value items were taken. Inquiries continue. No arrests have been made."
A dealer told the paper: "I'm absolutely shocked that it happened because the place is like Fort Knox."
Christie's is the world's leading art business which in the first half of this year had sales totalling £2,69bn ($4,2bn), making it the highest half year total in the company's history.