Things You'll Need
Instructions
Purchase or borrow a reference guide for Johnson Bros. china. This is necessary because the company has been continuously making patterns since 1883, and dating a single piece will be extremely difficult--if not impossible--without a guide.
Identify your pattern by using the reference guide. The guide is broken down into separate chapters based on shape or pattern. For example, the three major Johnson Bros. plate shapes are scalloped, coupe and smooth-rim. If you have a plate, and you can see the edges are scalloped (shell-shaped), then proceed to the chapter marked Scalloped Rim.
Read the information about your pattern shape once you have located it in the appropriate section chapter (you can identify your pattern by the several hundred illustrations of designs). The reference guide will include information such as the pattern name, pattern number, and history or production date in the relevant section.
Use the Internet to help you find and date your piece if you can't find it in the reference guide. Some pieces are extremely rare--even an expert cannot locate and detail all pieces manufactured by every factory. A good site to identify unidentified patterns is www.replacements.com (the world's largest retailer of china pattern replacements).