A type of china with glaze that has been purposely crackled or covered with a network of fine crackle in the kiln. It is caused by the shrinking of the glaze as the vessel cooled after firing and was often the only ornament on the exquisite ware. The Chinese made many variations of this porcelain, some rare and valuable. In some examples there is engraved decoration under the glaze. The low-fired Ju stoneware is distinguished by a seemingly soft, milky glaze of pale blue or grayish green with hair-thin crackle. A variant with strongly marked crackle became known as ko ware as it was made by the elder brother (ko) of the director of the Lung-ch'üan factory.