Can you show a picture of the pen?
It will be a Modern Skyline and the currently available demonstrators have metal palladium plated caps indeed. But I think that there once was also a full demonstrator in that collection.
Best is to contact the Eversharp company owner Syd Saperstein who is by the way also the moderator of this forum:
It appears that the full demonstrator was from the 1990s when the Eversharp company was owned by Emmanuel Caltagirone who produced the pens in France, Europe.
Check these two threads for the full story on how Eversharp survived, really interesting:
Edited by joss, 03 September 2017 - 20:23.