I got out of modern pens, primarily because almost all of them over, say, £200 can be stunningly poor value for money, particularly in terms of their materials. It's also a world of bullshit. So:
'resin' = plastic
'precious resin' = plastic
no definition of the material = plastic
'plastic' = the cheapest plastic you've ever seen or felt
'gold' [carat unstated] = gold-plated
'gold highlights' = gold-plated
'metal' (type unstated) = monkey metal
celluloid = 'It may be celluloid, but don't bet on it'
Japanese celluloid = Chinese celluloid, folded (so you can see the lengthwise join if you look) and not drilled
'Italian celluloid'= Chinese celluloid (because the last Italian factory has burnt down)
'converter' = a cheap (i.e. pennies wholesale) plastic pump, made in China, that is common to many pen brands
'ebonite' = hard rubber
'b&p' = in a cheap plastic box with meaningless papers
'maki-e' = transfer/screen-printed to look like 'maki-e'
'urushi' = painted ... well, once or twice, anyway.
And so on.