Beautiful, reversible blue enamel pendant and choker, designed by Bjorn Sigurd Ostern for David Andersen. The pendant is reversible, and looks remarkably different when worn the different ways. It hangs very well, and is most striking when worn. The choker is original, and is also silver. Ostern was the chief designer for Andersen between 1961 and 1985. The pendant is clearly hallmarked, David-Andersen, Norway Sterling 925S, INV.B.S.O., and the choker is also hallmarked Andersen and 925S.