The rim is often the first boundary a viewer notices on a turned dish. It defines the opening and creates a transition between the interior and the outer wall. Even a plain rim has a character, expressed through its width, angle and relationship with the rest of the profile.
A rounded edge can suggest softness, while a more defined edge can give a crisp outline. A broad rim may become the main feature of the object; a narrow one can allow the centre to dominate. These are visual choices rather than rules, and their effect depends on the size and shape of the whole piece.
Explore the idea by drawing a dish from above and from the side. Mark the rim in both views, then ask whether those drawings seem to describe the same object. This prevents the top view from becoming the only design consideration.
Use the archive photograph to identify where the edge begins and ends. Does your eye pause there, or move immediately into the centre? Discussing that response helps turn a small detail into a clear design decision. A well-considered rim can give a restrained piece a distinctive identity without requiring extensive decoration.