The glaze on this dish is exceptionally fine. The color is a clear sky blue, while the texture of the glaze has been well controlled to produce a cloudy opalescence. Control of both temperature and duration of firing was crucial to both the color and texture of Jun glazes, and had to be finely judged by the kiln master. The dish is also set apart from many other Jun wares, by the fact that its foot and base are fully glazed and the base bears five, relatively neat, round spur marks. A number of vessels with similar fine blue glaze and spur marks on the base excavated from the kiln site at Juntai, Yuzhou, Henan province in 1974 are illustrated in Ceramic Finds from Henan, University Museum and Art Gallery, University of Hong Kong, 1977, p. 87, no. 58. Neat round spur marks can also be seen on several other Jun wares of particularly high quality preserved in museums. Two such vessels are the small blue-glazed, eight-lobed dishes included in the Illustrated Catalogue of Ru, Guan, Jun, Guangdong and Yixing Wares in the Percival David Foundation of Chinese Art, London, rev. ed., 1999, p. 35, no. A4. Three Jun ware pieces in the collection of the National Palace Museum also have spur marks on their bases. One is a shallow bowl with straight rim, which has five spurs on its glazed base, illustrated in Porcelain of the National Palace Museum - Chün Ware of the Sung Dynasty, Hong Kong, 1961, p. 72, pls. 29a and 29b. The other two are bowls with thumb-rests and small handles, which have three round spur marks on their glazed bases, ibid., pp. 70-1, pls. 27a, 27b, 28a and 28b.
Two Jun dishes of similar size and shape to the Barron example, but with splashed copper decoration in the Palace Museum, Beijing are illustrated in Zhongguo taoci quanji 12 Junyao, Shanghai, 1983, nos. 11 and 16. The Percival David Foundation also has two dishes of the same shape and size as the Barron example. The most famous of these has a similar glaze color to that seen on the Barron dish, but with splashed copper decoration. See R. Scott, Imperial Taste - Chinese Ceramics from the Percival David Foundation, San Francisco, 1989, p. 39, no. 15. The other dish is of slightly paler color with extensive copper splashes as can be seen in Masterpieces of Chinese Ceramics from the Percival David Collection, Osaka, 1998, p. 51, no. 21. This dish has three spur marks on its base, but they are larger and less neat than those on the Barron dish.
The Asian Art Museum of San Francisco has a Jun ware dish of similar size and shape to the current piece, but the San Francisco dish has dark red copper splashes. See He Li, Chinese Ceramics, London, 1996, p. 152, no. 241. Like the current dish, the San Francisco dish has round spur marks on its glazed base, but while the Barron dish has five spur marks, the San Francisco dish has only three. A dish of similar size and shape to the current vessel in the Baur Collection, Geneva, see M. Tregear, Song Ceramics, London, 1982, p. 135, no. 169, has additional copper suffusions, but, like the Barron dish, has five spur marks on its glazed base.