Well, Prosser beads are mass-produced not flame-worked, and only a kiln (or furnace) could attain the bright red heat.
I was actually describing what I know from enamelling, where you get smutty pits and bubbles if any scraps of organic matter have fallen into the work before it is fired.
Essentially I suppose this is what makes real volcanic lava bubbly!
I am certain that it would not be possible to add the bubbles and bumps to prosser beads already made.
Stefany