Ruyao/汝窑 features simple glossy design. The set is made with ice-cracking techniques (冰裂汝窑）. 

Tea cups are double wall, giving a steady, heavy and thick feeling at hand, as qualities. The double also preventing the outer wall from getting too hot for your hands to grab, while hot tea is in the cup.

For more details, please google ice-cracking technique, Ruyao tea set( 冰裂汝窑）.