Gorgeous, these look like real white pearl grips at a fraction of the cost, we used to sell the real ones decades ago, we have a reference.  Superior to other imitation pearl, these really look like pearl, these are carved from solid stock, hand polished, not cast or poured.  Come with a screw and brass escutcheons.

If you're not sure if you have a J, K or N frame, just flip out the cylinder and it should be stamped on the inside of the frame. For additional Smith and Wesson model to frame information, see the list picture below.