A term that is used frequently regarding Satsuma or Japanese pottery and ceramics is "Gosu Blue".
Gosu Blue refers to the use of certain natural minerals and elements such as Cobalt or Asbolite to be used as the base for an under glaze or over glaze of the piece of pottery. Satsuma Pottery that has been decorated using the Gosu Blue techniques has a certain bluish hue to the images that are hand painted onto the surface of the pottery.
If Gosu Blue is used as an over glaze, the images become brighter and more vivid.
Gosu Blue Satsuma Pottery is possibly the most popular type to own and therefore commands a higher price than other types of Japanese ceramics. Pottery that was produced using this method was seldom made and was made during the mid 19th century in Kyoto, Japan.