“Grades” were generally used as a classification system to indicate the quality, level of finish, and characteristics of a movement. Some companies adhered to stricter classification, such as Elgin, where each “grade” was (typically) a specific size, model, finish, orientation, setting type, jewel count, and adjustment level. Other companies, such as Illinois and Waltham, were more relaxed with their classifications, and a particular grade might have been available in a variety of sizes, models, orientations, jewel counts, etc.
Grades should not be confused with models. Model designations were generally used to distinguish plate designs manufactured at the factory. Models can typically be identified by the cut and profile of the plates while the grade determines the finishing traits. Each model was usually produced in a variety of grades.