A thief grabbed a Rolex Daytona from a jewellers in West Street, Horsham, police say.
The man went into Whibleys Jewellers around 3.30pm yesterday (Thursday October 10) and asked to look at a watch.
When it was brought to him by the sales assistant to look at, he grabbed it and ran out of the shop into West Street and then headed into South Street.
Sussex Police say the Rolex Daytona was worth several thousands pounds.
The thief is described as white, of slim build, 5ft 10ins, with short mousey blonde hair and was wearing a navy blue zipped hooded top and dark blue jeans.
Police searched the area but could find no trace of him. They are appealing for witnesses to get in touch with them - call 101 quoting serial 0946 of 10/10 or email firstname.lastname@example.org