Porcelain Microwave and dishwasher safe Made in Japan Do not overheat in the microwave or heat without water. Wash with care. Do not use abrasive cleansers or steel wool. Product shape and capacity vary in each item due to the nature of the manufacturing process. Appearance of color glaze unevenness varies in each item. Some products may take on scorched-like texture on the surface. It is an unique glaze effect called "yo-hen", unintended color transformation show on the ceramic and porcelain after firing.