[Ted]

I would say for WWI DWM and Erfurts look for bluing on the inside of the reciever and top of the frame. Look for the safety marking GESICHERT NOT to me painted in, look for bluing OVER pitting, try this with a Jewelers Loup you can see pitting that the reworker MIGHT not have gotten all of, but your eye cant see it. Look for full blue on high wear areas like the sideplate, sides of the barrel at the muzzle and ends of the frame rails on both side. A gun that is RARE or in VERY mint shape is always suspect in my view. Look at the muzzle, if the rework is poor the muzzle might be polished TOO high and the restrawed parts might be polished too high also. I usually either polish the heck out of the parts and muzzle or cut them to a matt to match the original types, in either instance I place my rework mark on the bottom of the stock lug. When bluing is placed over an old surface a lot of times the dip bluing appears ashen or matte black/gray or even parkerized. Most original guns will be a little shinier if dip or salt blued.

I have seen this on the import marked guns. Just my observations. Ted