A collection of vintage coins, some dating back 200 years, were stolen during a burglary in Bovingdon last month.
The break-in occurred in Shantock Lane between 7am on Monday, February 19, and 11am on Thursday, February 22.
The offender entered the rear garden before using a rock to smash a patio door.
They then entered the property and carried out a search before taking a large collection of collectible coins from a display cabinet.
These included a King George IV sovereign from 1826, a William IV 1831-37 gold sovereign, a George III 1817 sovereign, a George IV Sovereign 1st type (1821-1825), and a 2010 Sir Winston Churchill gold double sovereign.
Detective Constable Peter Spiers said: “I am keen to speak to anyone who may have been offered these distinctive coins for sale.
“Perhaps you work in an antique shop or a pawnbroker, or you may have seen something similar for sale on eBay.
“Many of these items are of great sentimental value to the victim and I am doing my best to reunite them with their possessions.”
If you witnessed what happened, or have any further information that could assist the investigation, email email@example.com, report information online at www.herts.police.uk/report, or call 101, quoting crime reference number D1/18/1683.
Alternatively you can contact the independent crimefighting charity Crimestoppers, anonymously, on 0800 555 111 or online at www.crimestoppers-uk.org