well, so that is even clearer an answer to my question
@CBH_TX , thank you
The policy is, as I would have thought, that any alteration, even if using an original part but installed by a third party, would immediately disqualify the watch as a " franken-rolex" and it would be no longer (for all intents and purposes) a Rolex to Rolex.
Which HAS to mean (I hope) that a Gree dial (in my case) or any other color on sale as a " pre-owned" Rolex by a AD HAS to be the Dial which comes with that particular watch (as per papers).
Because of this it would be highly beneficial (I don't know if that is the case) that the papers would mention, somewhere , that " this watch" has dial so and so and so on...
Lacking this mention on the papers, how could I know, when purchasing even from a known but not authorised dealer that the dial on the watch is absolutely kosher?
Again.
I am interested in a OP 41mm in green ( available at €1500 to €2000 more than new from a AD but secondhand) but if I purchase this from any other source , is there a way for me to tell that that is the proper dial ?