look just below the label for a bead with whitish stuff on it. Rather than mold as in the growth in a damp climate, I think Lucien is referring to the mold used in making the beads. And I don't think this is it either. I have seen this effect before, but can only surmise it must result from some impurity in the glass that happens to be on the surface of the bead, and then due to the irregular surface, sediment of some material present in the finishing process?