Jewellery belonging to deceased relatives was stolen from a family in Frampton West during a sneak-in burglary on Saturday.
Lincolnshire Police said the incident happened between 2.30-3.30pm on Silvertoft Lane.
A police statement said: “While the family were in the garden preparing for a family barbecue, the offenders entered via the back door and stole phones, an iPad and a purse, together with a large amount of jewellery.
“Many of the jewellery pieces were legacies from deceased relatives and held an enormous amount of sentimental value.
Anyone with information shoulc call the police non-emergency number 101, quoting incident number 311 of June 17 or anonymously to Crimestoppers on 0800 555 111