The use of the blue color was associated with the Temple of Heaven, south of the palace, where the Emperor offered sacrifice at the winter solstice and also prayed for rain during the summer months.
Twelve-symbol blue robes are extremely rare and probably more rare than their yellow counterparts. Compare, however, a very similar kesi example, also dated to the early 19th century, illustrated by R.D. Jacobsen, Imperial Silks, Ch'ing Dynasty Textiles in The Minneapolis Institute of Arts, vol. I, Minneapolis, 2000, pp. 82-3., no. 12, which appears to be tailored and narrowed at the sides in a manner similar to the present robe. Another kesi example dated to the Daoguang or Xianfeng period is illustrated by H.E. Fernald, Chinese Court Costume, Royal Ontario Museum of Archaeology, Toronto, 1946, pl. IX, no. 7. Compare, also, the embroidered fragment of a twelve-symbol blue robe, in the A.E.D.T.A. Collection, dated to the mid-Qianlong period, illustrated by J.E. Vollmer, Chinese Costume and Accessories, Paris, 1999, pl. 14.