You have what appears to be an original pre-1899 Colt with pearl grips. That makes it a collector's gun. The engraving can increase the value. Trying to wire wheel or sand the surface will radically lower the value and destroy any collector interest. A Colt archives letter may show if the pearl grips were original, who, and where it was shipped to. Certain ship-to locations add value. If it was shipped to a specific person, that helps as well, especially if it was someone of historic importance.