Celadon, iron-glazed porcellanous stoneware produced in China, Korea, Japan, and Thailand.

Celadon glaze is transparent and iron-pigmented, fired in a reducing kiln and usually producing grey, pale,blue or green, borwnish-olive, or white pieces. its popularity in East Asia  was due partly to the superstition that it would break or change colour if poison was poured into it, and because of its resemblance to jade.

The classification of some of the finest celadons as true porcelain is problematic, because of the high firing temperatures used to vitrify true porcelain;
however, there is general consensus that classic celadon wares were some of the greatest ceramic works ever made.

The first celadon-glazed stonewares appeared in China during the Six Dynasties period (ad 220-589): called Yue (or green) ware, they marked the liberation of Chinese pottery from the influence of bronze casting, manifested in simpler, more elegant shapes.

The Tang dynasty saw further refinement of celadon, with better firing technology producing more porcellanous wares and further refinement of the designs, usually bowls and vases with blue-green glazes.

The height of Chinese ceramic art was reached after the 10th century under the Song dynasty, when various regional kiln sites produced wares of unparalleled beauty. The great early celadons of the Northern Song were Run ware, thickly glazed in blue or lavender with reddish-purple splash decoration, Ru, a coarser, slightly crackled ware produced especially for the imperial family, glazed light
bluish-grey (and now very rare).

The more robust and less exclusive Cizhou wares had transparent glazes and brown or black slip painting or graffito, as well as carved, incised, moulded, or enamelled decoration; other wares were grey, olive green, or olive brown.

Under the Southern Song, Guan ware was adopted as the imperial celadon, a heavily crackled ware thickly glazed in colours from blue to grey or green and often imitating ancient bronze forms. Longquan celadons were thin and highly porcellanous, elegantly undecorated and lightly glazed in blue-green, imitating jade: its forms were highly varied, sometimes inspired by Middle Eastern ware, in other instances copying ancient jades. Jun ware, dark-bodied with a blue-black speckled blackish-brown glaze called “hare's fur”, became a very popular in japan.

The great tradition of Chinese celadons largely ended with the Mongol conquest and the Yuan dynasty: production continued, but designs gradually became coarser and decoration heavier. Korean celadons became distinguished after the 10th century under the Koryo dynasty, normally with a thick bluish-green or
greyish-brown glaze finely decorated with inlaid floral designs highlighted with black and white slip, and represent the best successors to the Chinese tradition.

From the 13th century Japanese potters copied imported Yue ware and Korean celadons, producing black or olive green celadon wares at Seto which were so popular that they gave the Japanese language a modern generic term for ceramics, Setomono. Later fine celadons were produced at Arita.

Thai celadons had translucent glaze in grey or green, often crackled, with fluted designs or floral motifs. Production of celadons has continued into the 20th century throughout East Asia, in some cases being extensively revived. The finest Chinese celadons are very rare (only some thirty pieces of Ru ware survive) and immensely valuable.