From what period does the Montblanc Deskbase set 204 in green onyx version come, and is the model designation 204 also applicable to the fountain pen?

The Montblanc 204 desk pen and the matching base were produced between 1954 and 1959; remaining stock was on the part of Montblanc presumably still delivered until 1961. The time span named in the Rösler/Wallrafen book until 1969 counts as not consistent, since the wing-nib fountain pens were then succeeded by models with butterfly nibs (design Albrecht Graf Goertz) and correspondingly different sockets. The fountain pen officially also bore the number 204. The rolled-gold version counts as higher-quality than today's electrolytic gildings, since it requires more craft skill. The component plugged into the pen receptacle is called a socket.