The hall mark, Caixiu tang zhi (Made for the Hall of Brilliant Elegance), is a Qianlong period hall mark.
The poem inscribed on these bowls, Sanqing cha (Three Purity Tea), was one of the Qianlong Emperor's favorites, and described the tea made from plum blossoms, finger citron and pine nut kernels, and further describes the virtues of tea making. Each New Year the emperor would hold a tea-drinking banquet in the Forbidden City and his guests were invited to write poetry.
Bowls of this type are usually painted entirely in iron red, rather than the combination of iron-red and lime-green enamel seen on the present bowls. Other related bowls of the former type with Qianlong iron-red seal marks, rather than hall marks, include one in the National Palace Museum, Taiwan, illustrated in Emperor Qianlong's Grand Cultural Enterprise, Taipei, 2002, no. 51, and another in the Palace Museum, Beijing, illustrated in The Life of the Emperor Qianlong, Macao Museum of Art, Macao, 2002, no. 79. Three other bowls of this design, in carved red lacquer, the more usual iron red, and underglaze blue, are illustrated and discussed by P. Lam in "Tang Yin (1682-1756): The Imperial Factory Superintendent at Jingdezhen", T.O.C.S., vol. 63, London, 1998-99, p. 69, fig. 4. (Fig. 1) See, also, the pair of bowls and covers with the four-character hall marks, Xiqing tang zhi (made for the Xiqing Hall), in iron red, sold in these rooms, 26 March 2010, lot 1437.