1) Identifying devices 2) Symbols of high quality 3) What monty earned 
The Maker's or Sponsor's Mark, introduced 1363, identifies the silversmith, originally by means of a symbol suggestive of his name, his products or location. From the 17thC, initials or the first two letters of the craftsman's name were more common. The Duty Mark or Sovereign's Head occurs on silverware 1784-1890, when a new silver tax was imposed; …...
a group of distinctive marks applied to wrought silver to describe standard, maker, date and origin. Hallmarks vary according to country and place of assay.