Creamware, pearlware and whiteware evolved over time. In addition, there were over 100 Staffordshire potters using many different formulas for the bodies and glazes on these wares. Pinning these variations down to specific wares of a specific time period or potter is not possible from just looking at a sherd. The difference between creamware and pearlware is often limited to a small amount of cobalt added to the glaze. China glaze, however, is defined as a combination of ware and decoration. It is an imitation of Chinese porcelain, i.e. the glaze is tinted blue for the correct look, the patterns are in a Chinese style, and the footrings on plates are often undercut in a Chinese style (Miller and Hunter 2001). Shell-edged plates with Chinese-style painted centers should be called China glaze; these date from c.1775 to c. 1810. If the plate has a blue tint, but no Chinese-style decoration, it can be classified as pearlware. Keep in mind that the important thing is that it is a table ware and should be studied in conjunction with other table wares.
The line between pearlware and whiteware is even fuzzier than that between creamware and pearlware. When the Staffordshire potters began to copy bone china, which is very white, they did this in a couple of different ways. One was to cut back on the amount of cobalt tint, so that the ware looked much whiter. However, these vessels still often show a faint blue tint in areas where the glaze is thicker, such as near footrings. One is left with trying to interpret the intent of the potter. Another way was to produce a whiter body and a colorless glaze. Keep in mind that there were many potters, and not all of them were masters of their materials (Miller and Earls 2008:91-92).