This set is from the Art Deco era, 1920s and 1930s. The back plates are steel with a nickel plating. We see quite a bit of the nickel-plated treatment in the Art Deco period whereas, earlier, in the Victorian and Eastlake eras, hardware was predominately brass. The glass door knobs, however, remained popular, as they had for so many years.
This set consists of 7 pieces plus the spindle and screws. There are two matching knobs, two matching back plates, the mortise lock, key, and strike plate. There is also a spindle and set screws.
The 2-inch crystal knobs are the fluted style with nickel-plated necks. The Art Deco pattern back plates measure 6 inches long and 1 3/4 inches at the widest point. The Yale mortise lock is 3 1/2 inches by 3 1/8 inches. The face plate is 5 1/4 inches long and 15/16 inch wide. The strike plate fits with the lock and measures 3 5/8 inches long and 1 inch wide.
This is new-old-stock. The set has never been used. Everything works and is in good condition. It has sat for several years, waiting to be discovered. It could date to as late as the 1940s.