This is a fish copper red cup, xuede mark, possible mark and of the period, previous owner bought in saint. babara in 60s. from a banker's estate, I was told by many experts either it is xuande or kangxi. only 5 pieces in the world now, all in museum. This one is different with them, but same glaze with other xuande pieces. I have another 2 copies with it in kangxi period and late ming period sold with it.According to Chinese expert books, the only way to judge them is to compare their marks, whether it is deep into the body, and a lot of bubbles on the body. By these standards It shows this is a xuande piece.