The term celadon is thought to derive from the name of the hero in a seventeenth-century French pastoral comedy. The color of the character Céladon's robe evoked, in the minds of Europeans, the distinctive green-glazed ceramics from China, where celadon originated. Some scholars object to such an arbitrary and romanticized Western nomenclature. Yet the ambiguity of the term celadon effectively captures the myriad hues of greens and blues of this ceramic type.
During the nearly five centuries of the Goryeo dynasty (918–1392), celadon constituted the main type of ceramics produced on the Korean peninsula. This exquisite ware typically appears gray-green in hue. The color of Goryeo celadon owes much to the raw materials—specifically, the presence of iron in the clay and of iron oxide, manganese oxide, and quartz particles in the glaze—as well as to the firing conditions inside the kiln. Temperatures were commonly around, or below, 1150ºC, and the level of oxygen within the kiln was dramatically reduced at some stage of the firing; this is known as a reducing, rather than an oxidizing, atmosphere. Goryeo celadon ranges from a plain, undecorated type to objects with incised, carved, mold-impressed, or inlaid designs, and to vessels embellished with colorful compounds like iron oxide (black or brown) and copper oxide (red), and also with gold.
Celadon represents a major technological and conceptual shift in the history of Korean ceramics. The high-fired gray stoneware of the preceding Unified Silla dynasty (668–935) and Three Kingdoms period (57 B.C.–668 A.D.) had set the stage for the manufacture of celadon, but the technology of the celadon glaze and of the kiln structure, adapted from China, was an important advance. Just as significant is the conceptual change. With the advent of celadon, particularly the highly refined pieces used by the royal court, there is a palpable aesthetic dynamic driving what ceramics should look like. Color becomes an important element in this transformation, as do interpretive designs in form and decoration.
Initially, Goryeo potters learned much of the technical expertise from the celadon traditions of Song-dynasty (960–1279) China, particularly of its southern coast. A Song envoy, Xu Jing (1091–1153), who visited the Goryeo capital, Gaeseong, in 1123, noted the resemblance of Goryeo ceramics to the celadons of China's Yue and Ru kilns. We see in early Goryeo examples a conscious emulation of certain stylistic features of Chinese wares—such as the shapes of bottles and bowls, and standard decorative motifs including lotuses, peonies, flying parrots, and scenes of waterfowl by the pond.
By the mid-twelfth century, Goryeo potters and patrons turned to articulating native tastes. This coincided with the consolidation of major celadon industries near the southwestern coast of the peninsula, in Jeolla Province—the Buan and Gangjin regions especially. The latter remains, today, the center of modern celadon production and of revivals of Goryeo traditions. The culmination of Goryeo celadon can be seen in inlaid (sanggam) celadon, a rarity in China. The delicate technique of sanggam involves etching the desired motifs on the dry clay body and filling in the carved space with black and/or white slip, after which the translucent glaze is applied and the vessel fired. The best of Goryeo inlaid celadon is breathtaking in its splendid presentation of clean form, vibrant design, and subtle yet alluring color combination of white, black, and green.