A gold ring with a ruby stone was stolen from an eldery woman's home during a burglary in Little Heath, Potters Bar.
It has the initials BK engraved on it and has sentimental value.
A ladies' watch with a silver strap, chinaware, clocks, hundreds of pounds and other pieces of jewellery were also stolen from the house, in Hawkhead Road, between 12pm and 2.50pm on Saturday, July 17.
Burglars entered through the unlocked front door while the eldery woman was out with a friend.
Jordan Carter, an civilian investigator from Hertfordshire Constabulary, said: "This is a callous offence by opportunistic burglars and we are keen to hear from anyone who can help us track down those responsible by contacting us with any information they might have."
Anyone with any information can call the non-emergency number 0845 33 00 222, citing crime reference B2/09/3052, or call Crimestoppers anonymously on 0800 555 111.
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