Hmmm it would be a novelty for sure. Clay products are still fairly limited in scope-blocks, pots, jugs, statues, and hives I think. Artifact statues are always nice- they go wonderfully in dining rooms or noble rooms, however we can't actually place pots or jugs. Having indestructable pots and jugs aren't that great either. It would only serve to "fluff" your created wealth.
So an artifact Porcelain statue decorated with diamonds and spikes of platinum should have a value through the roof and boost small dining halls to legendary (or get your king to STFU about how his dining rooms isn't as good as the Duke's), however it could just as easily be a porcelain JUG. *sigh* If anything, I don't see why clay can't be used to make tables or cabinets. Our dwarves can build entire towers out of porcelain (blocks) and heavy statues many times the size of themselves, but they don't consider clay worthy of making tables and chairs out of? Earthenware has a value of 3 (equal to obsidian/triple normal stone) and stoneware has a value of 4. Porcelain is at 10. This is similar to the spread of glass production (green/clear/crystal 2/5/10). Why we can make mid-value furniture out of GLASS but not clay is beyond me. A full suit of tin-glazed porcelain rooms should make any lower noble shit kittens. With good decorations should be able to easily appease higher nobles too.