You have accidently set up a false dichomomy—because plenolic plastic IS "resin." It happens to be artificial resin, but still is resinous.

So, the issue is not on telling "plastic from resin." The object should be to identify the material, whether it be natural or artificial resin, recent, semi-fossil, or fossil resin; and wheher it is justified, or not to charactrerize the material as "amber."

Your beads appear to be phenolic plastic beads, post-dating 1926. Perhaps some ten years ago, new phenolic plastic beads (imitating amber) were still being made—and those from West Africa were sold as "old amber." Since that time, most of the new amber-like beads I've seen tend to be from thermolabile plastics (soft easily-melted materials), and may or may not be made from preformed constructions (such as canes)—since some appear to be injection-molded, or the like. China now makes a LOT of plastic imitations; and I see beads that appear to be new versions of "African" beads (the beads we came to associate with West Africa in the ealry 1970s, though originally from Germany and/or Central Europe)—but these new beads are from (out of) India.

The Amber Forum I moderate is very useful for sorting out amber issues.

Jamey