I recently bought a digital microscope that could magnify objects up to 1600x (maybe not well, but it does work). One of the first things I looked at was a BU Morgan with a light wiping on the obverse. This first image was taken at about 800x. You can see the flow lines expanding radially from right to left. You can also see the hairlines going from top left to bottom right. Note how they go over the E; that's how you can tell that they are not die polish. Same magnification, just a different area. The flow lines are a bit clearer. This image was taken at 1600x in the same location as the above image. You can clearly see the ridges that were etched into the die. These ridges reflect the light on one side, which is what causes the cartwheel luster. Also note how the cleaning hairlines disrupt these ridges. That is why an abrasive cleaning will destroy luster. This image was also taken at 1600x, but 180 degrees from the previous image. There was no cleaning on this part of the coin. The ridges are very clear in this image, and you can clearly see how the light is reflected off of only one side. I'm sure all of this is already well-published, but I had fun shooting the images so I thought I'd share.