Black Porcelain Door Knob with Copper Plate and Lock - b48

This is a pair of black porcelain door knobs on a shank with 2 copper plates and a latch lock system. The knobs are 2 1/2'' in diameter. The lock plates are 1 1/2'' x 5 1/2''. They have a very Deco like design. They need a good clean and polish to be showpieces. I didn't know what needed to be done, so I did nothing. The key hole is a large skeleton type opening. I do not have the key.