To my knowledge, the grip straps and trigger guards on this Pietta model, are nickel plated. Not silver. I know one person who has owned a pair of these 1851's for just over a year, now. No problems, to date. The plating on the revolvers seems pretty durable and holds up well. However, nickel plating can thin, flake or chip. So, those areas which see hard use, abuse, or wear ie: edges....could eventually suffer some damage. But, as revolver frame parts don't normally endure the same stresses as say: nickel plated brass cases...the expectation is that service life should be good.
That being said, my pal(cowboy action competitor) shoots his guns a LOT. But has not reported seeing any sign of finish deterioration. Should this occur though, Pietta grip straps/trigger guards, are interchangeable and easily swapped out. They are ###y-looking cap 'n ball guns, though. Especially when fitted with a pair of faux ivory grips. Hope this helps.
Al