Simoon,
Looking at the photo of the top of the gun, the end of the center toggle retaining pin (which can be seen at the top of the left toggle grip) and the 200-meter number platen are both unblued. These are solid indicators that this Luger retains its original finish.
If you have gone through Tom Armstrong's excellent post on authenticating Imperial Navy Lugers and everything is proper, you have a really excellent original Commercial Navy Luger.
--Dwight
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