18-carat nibs on the 144 are not unusual, since they were produced for the French market and also turn up in Germany; they are not a sign of manipulation. The 144s from the 1950s consist of celluloid; later models of precious resin (Plexiglas); production ended around the year 2000. For polishing the precious resin, Wenol is used by Montblanc itself; alternatively Mellerud polish for acrylic and plastic or Displex, which slightly dissolves the topmost layer and fills scratches. The fittings are gold-plated or platinum-plated on brass; every polish removes material, which is why polishing should be done as rarely as possible. Real scratches in the gold plating cannot be polished out, since they are deeper than the coating; only tarnished surfaces can be refreshed.