I have a set of 6 double-handled cups that I am told are boullion cups. I don't know much about them other than they are marked Paul Mueller Selb Bavaria. The mark dates to the 1920's, but I am trying to find out more about this pattern. There doesn't seem to be much out there about Paul Mueller, only that they became part of Hutschenreuther around 1917. This mark seems to be the one used for this line 1922 or so until 1928. Seems to be correct as the design is very art deco.
I also have a coffee pot, sugar bowl, creamer and 4 cups and saucers marked Retsch Wunseidel. In 2003 they became part of the GPK Group, and when I contacted them they said they had no records for any of the patterns prior to that by the Retsch company. It is a lovely set, probably not very old, but in great shape.
I collect things for their beauty, not their value.