Burglars scaled a 10ft fence and smashed a ground-floor window to break into the Pumping Station on Penarth Road, Leckwith, Cardiff, on the afternoon of Wednesday, April 27.
As dealers at the Pumping Station examine their stock to establish what exactly has been stolen, detectives are urging antiques dealers to exercise vigilence.
While prices fell back last week, the high bullion price levels (that peaked the day before the theft at £30 an ounce for scrap silver) may have contributed to the timing of the crime.
PC Mike Brinkworth from Cardiff Bay Police Station said: "We are keen to get a message out to the community as soon as possible, particularly to any antique dealers who might be offered these items for sale." Generally high scrap metal prices have also been linked to the theft of bronze garden statuary and sculpture in recent years.
Anyone with information is asked to contact Cardiff Bay Police Station on 029 2052 7231.