Police said the suspect was dressed all in black, wearing tracksuit bottoms, a hooded top, and a face covering, and was riding a black mountain bike.
PC Kevin Doherty said: “This was a brazen daylight robbery and we would appeal to anyone who may have witnessed the incident or seen the suspect in the area to come forward.
“We are also releasing images of the stolen items in the hope that someone may have seen them or been offered them for sale. We would particularly urge owners of second hand jewellery stores or pawn shops to check for these items.”
Mr Doherty said the stolen items were valuable, but also held “significant sentimental value” for the victim, who was “desperate” to get them back.