Stamps are perhaps the most reliable source of information for determining locale. Each factory or major production centre had its own logo, which generally identified the owner of the factory, stamped on the vessels’ bottoms. On occasion, the chief potter, not to be confused with the slaves who produced the vessels, would include his own stamp or signature. These insignias not only indicate locale, but also allow archaeologists to geographically mark the development of certain pottery styles by examining distribution patterns. Vessels that have not been stamped or signed are assessed by their appearance, as form, shape, and decoration are often regional expressions.  Another element that varies across the Mediterranean is the quality texture, and colour, of clay. Therefore, an examination of the fabric may also provide clues to a vessel’s origin. However, one must be judicious as these methods do have the ability to mislead.