Korean celadon glazes remained relatively constant in visual appearance and technology throughout the Koryo dynasty (A.D. 918-1392), the result of a conservative craft workshop tradition that supplied jadelike translucent green-glazed wares for the court. Although some of the more labor-intensive practices were modified, the basic technology changed little during the final phase of production in the early Choson dynasty (15th and 16th centuries A.D.) when the chief market for these wares changed. This technological consistency is contrasted with the diversity in visual appearance and ceramic technology found in Chinese celadons, and the potential interactions of these traditions are explored. The Korean celadons are more akin technologically to the southern tradition of celadon manufacture, which encompasses such wares as Longquan celadon, Yue and Guan. Koryo Dynasty celadons (ch'ongja) in their early phase in the 11th century A.D. could not be made to replicate the appearance of Chinese Yue and Yaozhou wares for technological reasons - constraints of raw materials and kilns. Although the glaze compositions are very similar to those of Yue and Guan, differences in the technical parameters are responsible for the variations in appearance. A glaze layer with partly dissolved quartz, various black particles, bubbles, and only a minute amount of anorthite at the glaze-body interface are responsible for the unctuous, translucent textural depth. With the advent of inlay (sanggam) in the mid-12th century A.D., a distinctive Korean technology developed to produce an outstanding green-glazed ware. These wares were capable of retaining a hard-edged precision necessary to render complex inlaid patterns. The white inlay is composed of a porous mixture of crushed quartz rock and minor amount of clay, which promoted the intentional control of crazing as a design element. The technology of white inlay is different from areas of black, grey or brown inlay where there is usually no crazing and the inlay was probably prepared by a sintering and grinding operation prior to application on pottery. In the 15th century A.D. white porcelain was introduced as the major new court ware, and a slip-decorated ware with greenish glaze, known as punch'ong, became mostly a popular ware. Clay was used for the white decoration, as is used in modern replications. Other technical parameters are reported which are responsible for the variations in visual appearance within this conservative technological tradition.