In the early days "Grade" had a lot to do with the quality and fineness of the Twist/Laminated/Damascus tubes the barrels were made from. The amount/quality of the engraving, the quality of the wood, the fineness/intricacy of the checkering and the fit/finish of the internal parts all sprung from the quality of the tubes being used. Many decades ago "Babe" Delgrego showed me Parker Bros. set of tumblers showing the increasingly fine polish as the grades went up.