This bottle represents the early Yangzhou style of enameling. It is possible that the blue glass bottle may have been sent down from the Palace Glassworks in Beijing, as, stripped of the enamels, the shape, color and quality of the glass bottle would all allow a Beijing attribution. Either the glass ground was originally intended to be enameled or the glass bottle was to stand alone, but was later enameled. For details of the various centers of enameling which produced wares for the Court in the mid-Qianlong period, see H. Moss, "Mysteries of the Ancient Moon", JICSBS, Spring 2006.
The style of the early Imperial orders from Yangzhou is drawn from Guyue Xuan wares produced at the Court, and several of the earliest are enameled on colored glass. For a Guyue Xuan enameled blue glass snuff bottle which was produced at the Palace Workshops, see the example, formerly from the J & J collection, sold in these rooms, 22 March 2007, lot 40. See also, Moss, Graham and Tsang, The Art of the Chinese Snuff Bottle. The J & J Collection, no. 198, for a yellow-glass example with an incised Qianlong mark. The group of colored-ground enameled glass bottles made at the Court, and represented by the two J & J examples, almost certainly inspired their Yangzhou equivalents.
As the workshops at Yangzhou flourished, they soon began to manufacture their own glass bottles, and the style of enameling evolved into a more painterly style of nature imagery, such as the birds and flowers of lot 213, and genre scenes. Enameled glass bottles produced at Yangzhou are usually marked either with a pale iron-red Qianlong reign mark in seal script, typical of distant production for the Court, or with an iron-red Guyue Xuan mark, also in seal script.