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Message:: [QUOTE="Conder101, post: 1232039, member: 66"]When the dies are hardened they are heated then quickly quenched.  This leaves them with slightly roughened oxidized surface.  It is this oxidation (and a basining of the dies) that the initial polishing is to remove.  But the die lap does not get down into the design features so they still have a slightly roughened surface.  When the first coins are struck the polished fields supply the mirror fields to the coin while the rough surfaces in the devices makes a slightly rough surface on the devices of the coin that scatter light in all different directions.  This makes them appear white and frosty compared to the fileds which then to reflect the light all in one direction (and typically away from your eyes).  That provides the cameo contrast. As more coins are struck the movement of the planchet metal smooths those rough surfaces reducing the light scattering ability of the devices on the struck coins.  As more coins are struck the contrast continues reducing from the smoothing in the devices and roughening and flowlining of the fields.  You go from DCPL to CamPL to PL to just a frosty Unc.  If at some point the dies are repolished the devices may again show some contrast compared to the field, but not as much as when the die was new and possibly very little at all.  If the devices are well smoothed it would be possible to have a deep mirror prooflike with very little or even no cameo contrast.[/QUOTE]