[Setec Astronomy]

Wait a minnit...you say it is a machined finish with a clear coat, then you say the paint color matches...is it clear or colored? The way you describe the dark spots getting bigger as you sand indicates layers of something being removed, is the wheel painted silver/gray and you have sanded through that down to the primer and/or metal?

I damaged one of my high polished cleared wheel lips, and my problem when I was sanding the metal is I got it shinier than the rest of the wheel, so it didn't really match...that could also be what you are seeing. The appearance may be different between the original cleared aluminum, your sanded aluminum, and your repaired (sanded/cleared) area. After I was done sanding/polishing, the repaired area looked very different from the rest of the wheel, but after the new clear it looked less different. It still looked pretty crappy under the glaring bench light but on the car you don't notice it.