A thief ran off with a £25,000 diamond ring after posing as a customer at a jewellery shop in Leeds city centre.
The man walked into Rox, in the Trinity Leeds shopping centre, and pretended to be interested in the 2.72-carat diamond ring.
He asked to take a closer look and grabbed the ring from the member of staff’s hands before running from the store.
Security staff chased him but lost him on Mill Hill.
The ring, which had a platinum band, had two trapezoid-cut diamonds and one emerald-cut stone.
Police have released a CCTV image of a man they want to find.
PC Matt Thirkill, of the City Neighbourhood Policing Team, said: “As well as the loss of such a high value ring, this was a very distressing experience for the member of staff involved and we urgently need to identify this man.
“Although his face is not clear on the CCTV images, his clothing is distinctive and we would like to hear from anyone who thinks they know who it might be.
”The ring itself is also very distinctive and we would like to hear from anyone who has been offered such a ring for sale.”
The thief was described as white with brown hair. He was wearing a black or navy hooded top, a cow-patterned t-shirt, jeans, and a navy baseball cap.
The incident happened at about 4.15pm on Monday, May 11.
Anyone with any information should contact PC Thirkill at Leeds central police station via 101 or call Crimestoppers, anonymously, on 0800 555111.