Thanks to all for the comments.
I always thought a tazza was more of the type with a raised rim, to hold sweets and the like. Well, you learn every day. And yes, the idea really is to provide a platter for fruit or cheese or whatever, that is raised from the table and therefore provides more space on the table itself.
I usually tend to strive for simplicity of form. As many of you probably know, the simple forms are the most difficult, because they have to be perfect, and the balance is easily upset.
Pete, when you say these sell quite well, what kind of money are we talking about?