Ming Cup

If You are wondering ,Rust spots are helpful to collectors since they require centuries to develop and their presence can be an indicator of age. They are easiest to see on Porcelain since the base material is usually white.

Rust spots seem more common on 'Blue and White' Porcelain of the Ming era since these older pieces have been around long enough for rust spotting to develop. As well, there seems to have been more impurities in the clay used during that ancient time.