The rim of a cup meets the person more closely than its decoration does.

What touches the body matters more than what faces the room. A cup is judged in the mouth long before it is judged on a shelf, and a rim that is too thick or slightly rough will undo any amount of beautiful glaze on the outside. Decoration is for the observer. The rim is for the person actually drinking, which is to say the person the object was supposedly for.

Wherever you are making or choosing something, find its rim, the part that meets a hand or a mouth or an ear. Get that right first and let the visible part follow.