Why solid gold? It would be way too ductile, heavy, and conduct far too much heat. Diamond might actually be better: low surface energy means a low coefficient

Why solid gold? It would be way too ductile, heavy, and conduct far too much heat. Diamond might actually be better: low surface energy means a low coefficient of friction, so it would be much easier to clean. It would still suck the heat right out of your cheeks, though. Realistically, porcelain or other ceramics are probably the ideal material.