M220101a
Top reads "ESCO", the writing in the half-circle reads "MADE IN GERMANY".
This is an unidentified mark which is sometimes incorrectly claimed to be either Edelstein or Gerold Porzellan, depending on who is trying to sell it. This type of mark arrangement is, of course, known from Villeroy & Boch. I assume the creator of this mark was trying to capitalise on Villeroy & Boch's reputation by using a mark that was different enough to avoid legal action, but similar enough to fool the casual observer.
M220101a
Top reads "ESCO", the writing in the half-circle reads "MADE IN GERMANY".