I think you're asking how can I tell if a chip is clay or plastic, because clay chips are expensive to reproduce and I can't think of any modern clay reproductions (although there are "tributes" made on CPC molds, they are usually not Paulsons).
Plastics can be identified by sound, feel and/or the obvious injection nipple mark. There are China clays that use Paulsons H&C mold...that might be the closest you'll come to a modern reproduction. But sounds and feel should be a dead giveaway.
Also, check the chip guide.