Alexander I: A Porcelain Cabinet Cup with Sulphide Glass Bottom, 1820s. The cup with raised birdmaskhandle, decorated with knight's helmets en grisaille with ciselé gilt band against a green ground, the base of the cup set with a glass plaque with an encased biscuit profile portrait of Emperor Alexander I wearing a laurel wreath, the edges of the glass faceted, the cameo inscribed on the reverse "Desprez, Rue des Récolets No. 2 à Paris," mildly obscured by abrasion. Height: 2 3/4 in. (7 cm).In 1792 Barthélemy Desprez, formerly a sculptor at Sèvres, established his own workshop on Paris's rue des Récollets (although spelled with a single 'l' on the firm's plaques). Biscuit profile portraits of notable contemporary figures of the day encased in glass became a well-known and successful product of his workshop and production continued when his son Nicolas inherited the business in 1813. The image of the emperor is based on the 1814 cast by Bertrand Andrieu in honor of Alexander's triumphal entry into Paris that year. For a comparable cup, see Sotheby's New York, April 21, 2010, lot 260. The sulphide cameos were also sold on their own and could be displayed in simple frames. For an example, see Paul Jokelson,Sulphides: The Art of Cameo Inscrustation, 1968, fig. 44, page 34.