Four men dressed entirely in black threatened the occupants of a Northampton home before stealing their jewellery.
On Saturday, December 22, between 5.45pm and 6.05pm, the men broke into a house in Shoal Creek, Collingtree Park.
Much of the jewellery they took was 'one-of-a-kind', a police spokeswoman said. Some of the items are pictured above.
Witnesses or anyone with information should call Northamptonshire Police on 101. Alternatively, they can call Crimestoppers anonymously on 0800 555111.