Instructions
Turn the plate over and check for a maker's mark. Early pottery and dish makers usually stamped a mark onto the bottom of their pieces. These marks can tell you who made the dish, and in what year it was made. For instance, handwritten marks are usually from before the 1800s, while marks that use the word "trademark" are from 1862 and later.
Take the dish to a local antique dealer or specialist and have her take a look at it. Often, antique dealers have inside information that can identify the dish as being old or as being a reproduction dish. You can also ask her what the dish might be worth.
Examine the glazing of the dish. If it is an old dish, the glazing should have some imperfections and cracking, due to the dish being hand made. A perfect glaze denotes machine-produced dishes.
Compare the pattern of the dish to other dishes. Does it look modern? You can bring your dish to the local library to find books about popular china and dish patterns, so that you can match your dish to popular patterns in the 19th and 20th centuries.
Look for signs of wear on the dish. The older a dish is, the more chance it has of showing wear and tear from years of use. Look for scratches, chops and cracks in the dish. While they may devalue the dish, they can denote that the dish is, in fact, old.