Burglars broke into a property in Eccleston, stealing a haul of expensive jewellery and thrashing the house.
Officers were called to the address on Wedgewood Gardens on Monday after the owner returned home to find crooks had forced their way in via the back of the property.
A Rolex watch and Omega watch, as well as two yellow metal engagement rings plus a diamond and yellow metal wedding ring with diamonds and ruby stones were taken.
A significant amount of cash was also stolen.
Officers have carried out a forensic examination of the scene and conducted out house to house enquiries.
Det Con Roy Waller said: “The items of jewellery are of great sentimental value to the victim and would be almost impossible to replace.
“I’d like to appeal to the consciences of the offenders and ask them to put themselves in the victims’ position and think how they’d feel if this happened to them. I would ask them to do the right thing and find a way to get the stolen items back to their rightful owner.
“Clearly it has been extremely distressing for the victim to return home to find offenders have not only taken their precious belongings, but violated their privacy.
“We would appeal to anyone who might have witnessed anyone acting suspiciously on or around the Wedgewood Gardens area of St Helens sometime between 8.30am and 12.25pm on Monday, 6 July to contact us.
“I’d also ask members of the public to be on the lookout in case they are, or have been, offered items of jewellery as a gift or for sale either on the street, in pawnbrokers or in pubs or have seen any of the items for sale on the internet.”
Anyone who has any information is asked to call St Helens CID on 0151 777 6013 or Crimestoppers, anonymously, on 0800 555 111.