CHICAGO (CBS) — A $25,000 reward is being offered for the safe return of an antique clock stolen last month from an antique show at the Merchandise Mart.

About 3:45 p.m. on May 21, three people approached an exhibit at the Chicago Antiques + Art + Design Show on the seventh floor of the Mart in the 200 block of West Merchandise Mart Plaza, according to Chicago Police.

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As a male and female distracted employees, another female stole the clock, police said. The suspects got away with the clock, which is encrusted with diamonds and mother of pearl, and valued at nearly half a million dollars. 

“It was unfortunate that this theft happened during what was otherwise a wonderful and successful show for M.S. Rau Antiques from New Orleans,” a statement from the CMO of Rau Antiques, Lori Paige, said.

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“Though there was security throughout the Chicago Antiques, Art + Design Show, the thieves were able to steal an incredibly rare Asprey & Co. mystery clock that is valued at $425,000,” she said.

M.S. Rau Antiques announced Tuesday that a $25,000 reward is being offered for the safe return of the clock. To receive the reward, the clock must be returned in pristine condition and in working order.

Anyone with information should call Detective Li or Detective Nickeas at the Chicago Police Department at (312) 742-7456, and reference the M.S. Rau Antiques case. Any leads sent directly to M.S. Rau Antiques will not be forwarded.

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(Source: Sun-Times Media Wire © Chicago Sun-Times 2017. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)