Picked this up just for spare parts but was wondering what it would have looked like originally. In Richter's book, page 71, there are some close reference numbers so it looks like it was originally a moon phase version. The Felsa 693 movement is in poor shape and I doubt will ever run again. Size is 35mm and it's marked 20 micron gold plated between the lugs. Looks like more of a rose gold color. Serial number dates it to 1950. For $8 I just had to rescue it.
