My collection rules are simple. If any pearl handled revolver turns out to be an after-market alteration, I buy a set of black hard rubber stocks. I now have lots of pearl stocks in a plastic bag in the back of the safe, but all my guns are as they left the factory. That rule is important to me in all my firearms collecting ventures. Besides most pearl stocks are thin and slippery, not what you want at the shooting range.
Many nickel guns show up with pearls, apparently original owners thought they looked better than hard rubber, so bought a set over time. A couple years ago I ran the question by SWCA Forum members, showing Model 1896 revolvers with both after-market pearls and hard rubber stocks. Results were 3 to 1 in favor of black hard rubber. I guess there are a lot of lunatics on this Forum.