Generally the hallmark and maker’s mark reference materials are organized by time period. Further, hallmarks use country origin and time period within the country. It becomes complicated when a maker’s mark spans several design periods.
Learning more about basic jewelry era parameters helps narrow the investigation and search. Solving the puzzle on interpreting a mark stamped on a piece of jewelry requires a good deal of sleuth work and knowledge building. Here is a good article on jewelry marks that takes you step by step in peeling apart the jewelry mark.