Stoneware is a vitreous or semi-vitreous ceramic that is fired at a high temperature, is non-porous and so does not require glazing. Formulations for stoneware clay vary widely, and so the color can be a brownish or grayish white, which is why glazing is typical. Further, due to these variations, some collections are resistant to thermal shock and other are not. Unlike porcelain, it is more opaque and typically heavier in weight.
Most stoneware collections are dishwasher and microwave safe. Others are also oven safe, and even freezer safe. Refer to each manufacturer care instructions.