Just some guesses. The engraving is probably too nice to be factory. Its a deeper relief than you usually see from them. The grips look like factory exotics, if only because of the small diameter inset gold medallions (but those can be harvested and reused.) Normally the jeweling isn't factory, either.
Jeweling is an old processes. If you pull the sideplates from old hand ejectors, you sometimes see a pattern milled onto it. The jeweling we see here is just a series of overlapping circles. You can do that at home with a drill press and a pencil with a good eraser, and some automotive rubbing compound. Its pretty hard to do freehand. But using a vice and a straightedge clamped to force in-line movement, you can manage.