Ge ware or Ko ware (Chinese: 哥窯; pinyin: Ge yao; Wade–Giles: Ko-yao) is a type of celadon or greenware in Chinese pottery. It was one of the Five Great Kilns of the Song dynasty recognised by later Chinese writers, but has remained rather mysterious to modern scholars, with much debate as to which surviving pieces, if any, actually are Ge ware, whether they actually come from the Song, and where they were made. In recognition of this, many sources call all actual pieces Ge-type ware.
It is clear that their distinguishing feature is deliberate crackle, or a network of cracks in the glaze; but this is not restricted to them, and in particular the related Guan ware uses very similar effects. Ge ware often shows "double crackle" or crackle of two types, and one view is that this is the defining characteristic of the type. A three-day conference at the Shanghai Museum in 1992 attempted to reach a clear definition of Ge ware, but could not reconcile all views.
"Ge" (Chinese: 哥) means "older brother" and the ware apparently takes its name from one of two potter Zhang brothers, from a story repeated in many sources from the Yuan onwards, with uncertain significance. They were both Longquan potters, perhaps in the Southern Song, though this is unclear. The elder brother developed a very special type of ware; the later sources say this was distinguished by crackled glaze, and Ge ware is supposed to be this type. The younger brother also developed a fine style of pottery, which is often taken to be the best quality early Longquan celadon.
Apparent pieces of Ge ware have been found in Yuan tombs, but not those from the Song, and increasingly the wares are regarded as a Yuan revival or replacement for Guan ware. Unlike Guan ware, it does not seem to have been produced for the court. There is a record of an incense-burner described as new being bought in 1355, close to the end of the Yuan, which compares it favourably to the "old" Guan ware. Production may well have continued into the early Ming dynasty.