Agateware

Pottery made with colored clays swirled together in a marble-like pattern, or covered with colored slips that are swirled together to achieve a similar effect.

The Japanese techniques of neriage and nerikomi for clay, and mokume-gane for metal; and the glassmaking technique of millefiore (now also used with polymer clay) offer additional inspiration.

A piece by Robin Hopper

Below is a piece by Taras Telyatinskiy, showing a common method of marbling. Taras inserted a few strips of red clay into a ball of white clay, then threw the vessel on the wheel. The spinning action of the wheel twisted the red clay into spirals as Taras pulled the clay up.

To see a method of using colored slips to marble a platter, see this Ceramics Arts Daily article featuring the work of Michelle Erickson, shown below.