Re: colt single action army
Some Colt SAA's were nickel plated and are more valuable, all else being equal, than blue and c/h guns. The result is that quite a few have been plated in more recent years, so one needs some experience and a good eye to spot a fake. One thing to be suspicious of plating that is too good; any nickel plated gun that old that has had any use at all will not have a perfect finish.
If you can take pictures and post them, we can be of more help.