Izumiyama porcelain from Arita started the porcelain industry in Japan 400 years ago. It is rarely used now, because it is hard to work with and lacks the whiteness of other porcelain deposits discovered later. It is also very expensive.
But it has beautiful texture when carved soft and great color in the wood kiln. These pieces are all still unfired. Fluting is a common decoration method for porcelain because porcelain is HEAVY. Also, it is extremely difficult to throw thin, so fluting is a good way to lighten it up.
This last pic is of a 400 year old porcelain fluted cup with gold repairs.