If you compare it to the later 1917 Navy that is for sale
here, you'll see that the barrel serial number on the one you are looking at doesn't have the s/n halos you'd expect to find on a rust blued pistol. Also the sections inside the frame are not in the white. The straw looks like new.
So... it's very possible that the one you're looking at has been refinished. The work looks very well done.
Marc
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Igitur si vis pacem, para bellum -
- Therefore if you want peace, prepare for war.