Hey Rosanna, When you heated the Phenolic Amber beads did you ever cross section them to see if the darkened color went all the way through VS surface? As well- the beads heated in Africa that were darkened by heating? I don't recall reading that, but I'm betting you did.

The fact of phenolic amber beads changing color because of oxidative chemical reactions over short and long time periods is a great help in understanding what is causing variations in appearance of some beads. As well as, of course the fact of originally dyed beads, and beads intentionally manipulated in Africa by heat, and reshaping, drilling, etc. I suppose the cracked beads with dark veining are the result of "off gassing" / air introduction as the dark veining appears to follow the cracks.
Thanks, Anne