W. Gadomski

 producer/manufacturer
 Pewterer

What we know at this moment is that W. Gadomski was operating in Sankt Johann, part of the city of Saarbrücken, probably around the beginning and first quarter of the 20th century. It was possibly a pewterer, however I have also seen a porcelain cup-and-saucer stamped with a W. Gadomski mark.
Pictured is the marking inside the pewter lid of a pressed glass stein, and the lid itself.