The markings on the bottom of antique plates exist to identify the manufacturer, country of origin and other details pertaining to the plate's origin. These marks are distinct to each individual manufacturer so that plates and other china, and ceramic and porcelain antiques are traceable back to the companies that made them. Identifying the markings on the bottom of your old plate may take some research, but the results will tell you a lot about your china.
Examine the entire plate bottom looking for any markings. Magnify the markings if necessary to see every detail. The information provided by each marking can be quite telling in identifying details on the plate's origin. Take note of all details on the bottom of the plate, including what the markings say, distinct artwork or logos and even the color of each mark.
Determine if there is a marking indicating the country of origin using the phrase "Made in." Not only does this narrow down manufacturers based on origin country, it will also tell you that the plate was manufactured after 1890, which is when the United States began to require that all imported goods bear a marking with their country of origin.
Narrow down your options based on specific clues that these "back stamps" or plate markings provide. For example, according to "Figurines-Sculptures," printed marks that utilize the British Royal Arms were manufactured following the 19th century. The term "bone china" also indicates a 20th century piece. On the other hand, plates bearing a Staffordshire knot would have a manufacture date between 1845 and 1890.
Reference an antiques and collectibles website or book using the clues you have to determine the manufacturer of your plate markings. Many of these guides are organized by country of origin or specific characteristics of the markings for easy browsing and identification. Although every manufacturer has a distinct mark, some can appear similar.