Also not trained in the fine metallurgical sciences, but the tools that I have
owned which were nickel plated only had red or brown rust where the plating was
flaked off or worn through. Anywhere there was nickel, red/brown was absent. My
45 plane being a good example.

Years ago I acquired a 71 router plane which had a large amount of nickel loss
everywhere and the bottoms was rough from pitting. I lapped the bottom smooth
and took it to a local plating shop that did nickel plating and had it redone.
Not for aesthetics so much as for protection from future rust and to prevent
damaging the workpiece.  Interestingly the gentleman who was helping me had been
doing plating a good long while and advised me there would be a color difference
between the new nickel and the original nickel due to contemporary changes in
the alloy makeup of nickel plate. The original has just the slightest yellow to
it and the modern nickel plate is a "whiter" nickel color. This plane had great
pear handles on it and I picked it up for a song. The plating was relatively
inexpensive at the time; I think I paid $25 to have it done. It sure was shiny
and pretty. A good thing about the modern nickel color is that it can't be
easily passed off as a pristine mint plane. The color difference is that
noticeable. I won't ever sell this plane so no danger of it being misrepresented
in my lifetime.

Sent from my iPhone
Brent Kinsey