Identification marks, usually found on the bottom of pottery, can tell you many things. A mark may identify the artist, the company that made the piece, the pattern, the country of origin or the date of manufacture. The marks may be applied in a number of ways; they can be impressed, painted or stamped into the clay.
Review a reference book to get familiar with the field. Helpful titles include "Kovels' New Dictionary of Marks: Pottery and Porcelain," "Miller's Pottery and Porcelain Marks," "Pictorial Guide to Pottery & Porcelain Marks" and "A Dictionary of Marks." Make sure the book you choose has clear illustrations and explanations.
Get familiar with guidelines that help date stamps. For instance, the use of colors became more common after 1850, and the name of the country of origin was introduced after 1891.
Identify the manufacturer on a stamp. The manufacturer's name may be spelled out or marked by an initial or a symbol. If it's not spelled out, compare the image or initial to images in books and online (see Resources).
Identify the stamp's pattern. The pattern may include a name or number. If there's only a number, find the pattern name associated with the number in a reference book.
If you can't identify the stamp on your own, turn to a pro. Replacement companies, appraisers and antique-store owners have a wide range of knowledge, and extensive resources at their fingertips.