Handcrafted, unglazed and uncoloured, purple clay (zhisa) from Yixing, Jiangsu Province, China. These small cups are often called gongfu cups, which are ideal for oolong and puerh. They can be used with Yixing teapots. These cups are often used in Chinese tea ceremony.
For further info on Yixing teapots please see our blog: http://mateasse.com/blog/2014/04/24/yixing-purple-clay-teapots/