Everybody please, look at the title of the original question and the photographs of the markings. That's why I repeately state that we need to know the complete and correct markings.
The original question asked about guns with the DIAMOND name and the photographs show
the BLUE DIAMOND STEEL Completely different names, different makers and different sellers.
Guns with the name Blue Diamond Steel name were made by the Tobin Arms Company and were sold by the Norvell-Shapleigh Hardware Company of St. Louis,MO from 1903 to 1915. Guns with the name Diamond or Diamond Arms Co were made by the Stevens Arms Company, Iver Johnson's Arms & Cycle Works or Harrington & Richardson and were sold by the Shapleigh Hardware Company of St. Louis,MO. One must give the complete and correct information to get a complete and correct answer to ones questions.