O.P.CO. Syracuse China White Heavy Diner Style Coffee Mug 3-R Rare Pattern

This O. P. CO., Syracuse China Coffee Mug is in exceptionally clean and in very good vintage condition. I see no flaws or imperfections, no chips, cracks, crazing. It features a "No Tip Hourglass" shape. It has a green stamp on the bottom that reads: O.P.CO., Syracuse, China, 3-R (which is the date code manufactured-March 1937). The cup holds 8 oz. full and weighs 1 lb. 3 oz! It's a solid and heavy cup! The cup is a glossy white with a pattern that is black and gray, a green circle around the cup and on the handle.