A Norwegian silver thimble, maker Hans Christian Ostrem (1842 – 1912). He used the OXO mark for many of his silver designs. It is of Norwegian 830 silver grade. It is smaller than most English thimbles so maybe for a child. It is 3/4″ high including the domed top and 5/8″ or (47mm) diameter measured at the base. All beautifully engraved with a border of triangles and radiating lines within each triangle. Hallmarks clearly OXO and OS. With a few minute dings due to age.