This exceptionally skillfully painted box is an impressive example of the ability of the ceramic decorators in the Qing dynasty to imitate a range of different materials using enamel colors on porcelain. A new array of glaze and enamel colors was developed in the imperial workshops during the Kangxi and Yongzheng reign periods, and thus by the Qianlong period the craftsmen had a vastly enlarged palette with which to create new designs and effects on porcelain. The 18th century fascination with imitating other materials through the use of glazes and enamels on porcelain can clearly be seen in a set of seven thumb rings in the collection of the National Palace Museum, Taipei, each of which imitates a different material, including pudding stone, wood, bamboo, marble, inlaid bronze, malachite and turquoise; see Emperor Ch'ien-lung's Grand Cultural Enterprise, National Palace Museum, Taipei, p. 199, no. V-36. The Qianlong emperor appears to have had a great desire for novelty and exotic products, and thus the greatest number of porcelains decorated to imitate other materials was made during his reign.
'Pudding stone' is a generic term applied to any conglomerate sedimentary rock that is characterised by colorful inclusions. The conglomerate is composed of pebbles that have been worn smooth by water and have been cemented together by a finer mineral deposit. This finer mineral deposit fills in the spaces between the pebbles and forms a solid rock. The particular pudding stone that was admired in China was formed from pebbles of jasper cemented together with quartz, and it is this that the ceramic decorator of the current box has so successfully recreated on porcelain.
Amongst the new enamel colors developed at the imperial workshops during the Yongzheng and Qianlong reigns, two particularly facilitated the imitation of various natural materials. These were two orangey reds, both created using iron oxide. Iron-red enamels had a long history on Chinese ceramics, but in the 18th century the craftsmen discovered that if they replaced some of the lead oxide used as a flux in the original iron-red enamel recipe with potassium nitrate they could achieve an orangey red that was good for imitating lacquer, the grain in certain woods, and 'pudding stone'. The craftsmen also discovered an orangey red glaze that could be fired at high temperatures, which was probably produced using a highly feldspathic low-lime porcelain glaze with a low iron oxide content, and which could be applied thinly, fired in reduction and cooled in oxidation. The wide range of colors available, including an extremely subtle range of browns and orangey reds have allowed the ceramic decorator to create the very realistic composite stone seen on the current box.
A Qianlong circular box decorated to look like 'pudding stone' in the collection of the Palace Museum, Beijing is illustrated in Kangxi. Yongzheng. Qianlong - Qing Porcelain from the Palace Museum Collection, Beijing, 1989, p. 424, no. 106. This box has a circular famille rose panel depicting Europeans on the top of the cover. The Beijing Palace Museum also has a Qianlong tripod censer enameled in imitation of 'pudding stone' in its collection illustrated ibid., p. 423, no. 105; and a Qianlong double-lozenge brush pot decorated to imitate 'pudding stone' is illustrated in The Prime Cultural Relics Collected by Shenyang Imperial Palace Museum, Chinaware, Part II, Shenyang, 2008, p. 199, no. 9.