I seem to remember that at one time Colt owned Sile, who made grips in Italy.
Some Python Colt Custom Shop Target grips were made of Rosewood in Italy for Colt.
Sile made fairly exact replicas of Colt grips as replacements even after Colt no longer owned the company.
These were often made of a hardwood with walnut stain and some were walnut, possibly European walnut.
I have no idea what the "R" was for but Sile would make grips for other companies and probably would fit them with medallions they chose.
It's at least possible some owner refitted a set of Sile grips with his own medallion.