A robber stole diamond rings and other jewellery items after threatening staff with a handgun in a raid at a jewellers in Hertfordshire.
The items were taken in the robbery at Baker Brothers on Leys Avenue in Letchworth on Friday afternoon.
Police said the suspect was a white man of medium build and height, who was clean shaven and aged about 30 to 40.
He was wearing a reddish-brown wig, dark clothing and had a sports bag, which he filled with the stolen goods.
Det Sgt Pete Clavey said: "This was a nasty and unusual incident for Letchworth, although fortunately no one was injured.
"The robbery happened at a busy time in the town centre, when many people would have been out and about for lunch, and so may have seen something.
"I would like to appeal to anyone who saw a man matching the suspect description before or after the incident, or has any information about it, to get in touch.
"In particular, we believe the offender sat outside the shop for a period of time before going in to commit the robbery."