The Japanese word for ceramics is “yakimono,” which is used to refer to all aspects of ceramics and pottery. Some pottery schools in Japan date back to the 12th century, and there are six primary regions, or “kilns,” of pottery schools in Japan:Bizen, Shigaraki, Seto, Echizen, Tamba and Tokoname. The six main schools are referred to as “rokkouyo” and each school has a distinctive style and appearance, due in part to the clay composition in the area. Most schools mark their pottery. There are a few ways to help identify Japanese pottery marks, which are called “kamajirushi.”
Turn the pottery piece over to view the maker’s mark. Marks may also be found on the side or the lip of the piece. Almost all Japanese pottery items bear an incision or mark made by the craftsman, although some makers did not mark the item so that the pottery itself was their signature. Non-marked pieces are called “non-kamajirushi.”
Look at online references of maker’s marks by rokkouyo or style. For example, images of marks from the six primary pottery schools can be found at Yakimono.net. (See References)
Find listings of Japanese trading company marks online at websites like GotTheBorg.com, as some pottery items do not bear the manufacturer’s mark if the company used independent factories to create items. The trading company mark was also occasionally placed on a sticker instead of inscribed onto the pottery item. One example of a trading company that marked its items is Noritake, which used close to 400 different factories to make pottery pieces. (See Resources)
Find reference books with detailed photographs and information about Japanese pottery marks. Examples of reference books include “Japanese Marks & Seals (Kegan Paul Japan Library)” by James Lord Bowes and “1100 Marks on Foreign Pottery & Porcelain” by L.W. Publishing.
Locate the country of origin mark, which was required by the U.S. Congress beginning in 1891. Originally, most pieces from Japan were marked “Nippon” until 1921, when Congress requested that customs change the marked name to “Japan.” As such, pottery pieces that are marked “Nippon” are likely pre-1921.