The carving of the present head, particularly of the sylised locks of hair framing the face, are reminiscent of a rock-crystal bust of a Roman Emperor in the Wallace Collection in London (Mann, loc. cit.). That bust, probably acquired by Sir Richard Wallace in the early 1870s is catalogued as German, late 17th century, and has been linked stylistically to another rock-crystal bust, of the Emperor Leopold I in the Kunsthistorisches Museum, Vienna, thought to date from around 1660 (private communication from Robert Wenley), illustrated in O. Schmitt ed., Reallaxiken zur Deutschen Kunstgeschichte, Stuttgart, II, 1948, fig. 24, p. 297. It is therefore probable that the head of the present bust orginates from the same artistic milieu as the two rock-crystal examples, but was set into the existing shoulders, with their lavish decoration, in the mid-19th century