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. Porcelain. Microwave and dishwasher safe. Do not overheat in a microwave or heat without water. Do not use abrasive cleansers or steel wool. Product size and shape varies in each item due to manufacturing process.