The ink-view windows of the 1950s models like 342 or 042 were made at the factory of transparent blue plastic; a blue tone is therefore normal. Whether an allegedly "never filled" pen really is ink-free is difficult to ascertain externally; colour deviations at the transition to the grip section can indicate ink residues. When buying such pieces, scepticism towards seller statements is therefore in order. Especially from eBay providers in Singapore and neighbouring regions, due to frequent negative experiences, is advised against.