Silver Cufflinks

by Alan
(London (UK))

I bought these silver cloured cufflinks with an enamel (?)decoration in a Belgian fleamarket a few weeks ago. There were dirty and tarnished and were sold as 1920s and 'sterling silver'. I had my doubts, but liked them and handed over Euro 12.50. They've cleaned up beautifully and are very pretty, but what are they? Wear on two edges seems to reveal a more gold coloured metal underneath - but I'm not sure. They are each marked 'U' or pehaps 'G' on the stem and there is pehaps a triangular (?) stamp on the other side.

To the naked eye they look finely made but under a jewellers glass they are clearly hand tooled or machined. They have a German design patent mark DRGM and are marked OSIDA.