Aluminia "Tidemands" Marmelade Jar with lid from the Christmas of 1938. Diameter 12.5 cm. Height 8.5 cm. In the 1880s when production at the Royal Copenhagen factory was dropping to a dangerously low level they were taken over by Aluminia (founded 1863), successful makers of earthenware, and since that time the two ranges, earthenware and porcelain, have been running in tandem.