From 1926, when cast phenolic plastics were first used for making imitation-amber, I would guess there was a continuum of production, and that the material slightly changed over time. However, I could barely begin to characterize these changes.

I do recognize that by the 1990s the beads coming to us from W. Africa, that were then claimed to be "old amber" or "old copal," were a different sort of bead. And at that time I assumed these were newer/later fake amber beads, being passed-off as the "originals" (from the late 1920s and '30s..., 'til when?). However, I would not suggest that these late fakes are phenolic. I didn't test any of them; so they might or they might not be phenolic. To my eye, the material appeared softer. I am more inclined to suspect these are modern plastic beads from somewhere like China. They also come out of India (though the origin is unknown).

I'll try to show some of these.

Jamey