It's the only way I can describe this very interesting piece....HAT SHAPED INTERNAL DOME STRUCTURE. This anomaly looks like it has some carbon in it, but I think not...just the optical effect of this oddity. The insulator also has a few nice larger bubbles including one that's kidney shaped, a small area of white made up of minibubbling, and some interesting glass folds on the dome.

The flaws just include a shallow base flake, and a wear mark on the lower ridge from the tie wire.

This piece is a great one for those of you who collect oddities and junk in glass pieces.

I'm asking $45 plus shipping