Nice color ,BUT, from the pictures (#3 and # 5) it appears to have been reblued, over polished and the plum just may be the "effect" of an improper bluing process, low temp or not left in the salts long enough....this happens all too often in many shops that are "In a hurry"?? fast turn over?? used to be a common sign in guns ,such as 'nickel steel Winchesters, they will turn plum when reblued, there are tricks to help avoid this, far too much to try and explain in a post reply...having been in the rebluing business for many years, had three companies over the past 49 years our first shop was 'Cleveland Bluing Co. on the east side of Cleveland ,Ohio, then later on in Eastlake ,OH we ran into this all too often, folks coming in with stuff that was done at "other" bluing shops, many out of town......... yes Ruger folks like and think its "pretty" but when in fact it is a bluing ( finish) error,,,either through process or in the case of Rugers the materials used in the steel casting batch ( the mix)....try and sell an old Winchester with those "pretty" colors.......
BUT yes, it is neat looking, still have pictures ofthe late 'flatgates' (Carl L) old 22 that was "plum" as can be........