Hi
We normally test it by rubbing in our Palm. Then phenolic resin makes smell like burned wood. And also as Rosanna mentioned you can use hot needle which in result phenolic becomes dark red . Even if you bring fire close to that becomes red . Although this might not be scientific I Saw this way for 20 years. If we don't want to damage bead , always smelling gives answer.
Lovely beads Nishedha
Best wishes

Ali