My take away way the way Luster disappeared in the fields, I thought it was there solid Luster, the photos didn't confirm it!
After you made your comment, I went back and studied it some more, and started getting drawn to the halos around the stars. I still think those are often an indication of contrast between the original surface (around the stars) and the surface that's been messed with (worn or tarnished and then dipped). But, like I said, not enough experience.