The "tarnish" may be surface soil, or treatment to make the bead look old. And, I feel, the color of the bead looks like 9-12K. Small pits and craters occur from casting.

We are each doing the best we can do to speculate based upon our personal areas of expertise. I have specialized in ojime, which are usually the same size and often made of metal, and fabricated or cast. Collectors gain advanced intuition through first hand experience -having invested money. Researchers gain knowledge by investing time. It takes one or the other or both to come closer to the truth.

A true bead researcher must see it in person. Or, at least, see results of a test for metal content. At the same time, Beadcollector.net participants are helping one another by revealing their logic -albeit in the dark.