The unique style of Ju porcelain glaze color is a slightly greenish blue hue with the slightest sparkle of rose pink luster, appearing quite different from the Yao-chou, Southern Sung Kuan (Official), and Lung-ch’üan celadons of the Sung dynasty. Starting in the period of the Ming and Ch'ing dynasty, Ju porcelains received particular attention among connoisseurs. Regardless of the terms they used to describe Ju wares, such as "sky-blue color", "blue sky after rain", or "light blue hue", they all were insufficient to capture the consummate skill and perfection of the color and luster of actual pieces. In addition, the grading of Ju porcelains, whether the surfaces of the glaze had crackle or were completely without any form of pattern, were considered in the view of connoisseurs to be in a class of their own and regarded as the paragon of celadons.