This unusual shaped vessel appears, to the best of our knowledge, to be one of the rarest guang example known. A Guang-shaped vessel with cover from the Qing Court Collection although smaller and of a less refine decoration and less elaborated shape is illustrated in The Complete Collection of Treasures of the Palce Museum, Metal-bodied Enamel Ware, Hong Kong 2002, pl.118.
The inspiration for both shape and decoration comes from ancient bronzes of the Shang and Zhou dynasties and is part of the fashion for archaism in the Qianlong reign. The shape can be clearly identify as a guan vessel, these rare wine vessels from the Shang Dynasty. The enamel decoration follows the tradition of the gui vessels, with a large taotie mask adorning the front part on both sides of the central divide, and with the motif of confronted gui dragons. The gilt-bronze crenellated flanges enhance these archaistic features.
For Qianlong vessels inspired from the ancient shapes and decorations, see the zun vase also from the Qing Court Collection, illustrated in Op. Cit., pl.115 ; or the you vessel illustrated in Enamel Ware in the Ming and Ch'ing Dynasties, National Palace Museum, Taipei 1999, p.146, pl.62.