This shape of this delicately potted cup is quite unusual. The majority of Yongzheng cups of this type have more rounded form and the diameter of their foot rings is smaller in proportion to their mouth rims. An example of this latter type can be seen in the turquoise-glazed cup in the Baur Collection (illustrated by John Ayers in The Baur Collection - Chinese Ceramics, vol. 3, Geneva, 1972, no. A478). However a white-glazed Yongzheng cup in the same collection is much closer in its proportions to the current turquoise vessel. The Baur white cup is illustrated ibid., no. A412. A red-glazed Yongzheng cup in the collection of the National Palace Museum, Taipei is similar in proportion to the current cup, but has slightly more rounded sides (illustrated in Catalogue of a Special Exhibition of Ch'ing Dynasty Monochrome Porcelains in the National Palace Museum, Taipei, 1981, p. 47, no. 11). A turquoise-glazed cup from the Richard Kan Collection (illustrated in Shimmering Colours, monochromes of the Yuan to Qing periods, The Zhuyuetang Collection, Art Museum, The Chinese University of Hong Kong, 2005, p. 179, no. 106) is similar, but has slightly more rounded sides.