Fortunately they were historically some standards in place for jewelry hallmarks. These identifying marks tell the story about the piece and its maker. In a hallmark reference book you will find the array of images used by makers in their hallmarks, images such as birds, animals, insects, shapes numbers, letters and so on. As you continue your search knowing the image, you learn about the country and other clues such as approximate date, city and metal fineness. For more information, here is a good article on searching hallmarks.