Burglars stole a diamond ring worth £1,000 from a farm in Trimdon Grange.
Sometime between 11pm on Thursday, 28th January and 6am the next day the burglar(s) walked across a muddy field to gain access through a rear door to a farmhouse.
They escaped with the jewellery and several hundred pounds cash from the kitchen and sitting room before leaving through the rear door.
The ring is described as very distinctive and has been with the owner more than 50 years.
It is a cross over ring, set with three larger diamonds surrounded by a number of smaller stones - total diamond weight around .44 metric carat.
The band is yellow gold, stamped 18 carat.
Anyone with information is asked to contact Det Con Alan Meehan in Durham CID via 101 or ring Crimestoppers, 0800 555111.