The missing item is a gold pair cased pocket watch by Daniel Quare with a signed gold champleve dial and verge escapement and is hallmarked for London 1698.
It was purchased at auction in Denmark and shipped to the UK. However, it went missing on its journey.
The shipper of the item has launched an investigation.
Owner Peter Hall said: “Due to the new customs regulations the parcel had to be labelled with the contents and value.
“With some delay it was delivered to me and appeared to be intact. But it was in fact empty, and on examination it was clear that the bottom of the package had been slit open and retaped with a different tape as used by the shipper.
“I believe that with delays awaiting customs clearance, and labels advertising the contents, this is likely to become a lot more common with the new EU Customs situation.”
Anyone with information on this incident should call 101 quoting the Dorset Police reference number 18-402 with crime number 55210043333 or call Crimestoppers anonymously on 0800 555 111.