Said to have belonged to Count Stephen Keglevich [1740-1793], Vienna. Said to have belonged to the duke of Marlborough, Blenheim Palace. (Duveen, New York); purchased 3 February 1923 by Joseph E. Widener, Elkins Park, Pennsylvania, probably as Italian, sixteenth century; inheritance from the Estate of Peter A. B. Widener by gift through power of appointment of Joseph E. Widener, after purchase by funds of the Estate, 1942.
- Inventory of the Objects d'Art at Lynnewood Hall, Elkins Park, Pennsylvania, The Estate of the Late P.A.B. Widener. Philadelphia, 1935: 46.
- Works of Art from the Widener Collection. Foreword by David Finley and John Walker. National Gallery of Art, Washington, 1942: 11, as Italian 16th Century.
- Steingräber, Erich. Alter Schmuck. Munich, 1956: 113, fig. 185; English ed. 1957: 112, fig. 185.
- Hackenbroch, Yvonne. Renaissance Jewellery. London and Munich: 1979: 41, no. 76, color pl. 4.
- Newman, Harold. An Illustrated Dictionary of Jewellery. London, 1981: 198, 199.
- Wilson, Carolyn C. Renaissance Small Bronze Sculpture and Associated Decorative Arts at the National Gallery of Art. Washington, 1983: 165-166.
- Distelberger, Rudolf, Alison Luchs, Philippe Verdier, and Timonthy H. Wilson. Western Decorative Arts, Part I: Medieval, Renaissance, and Historicizing Styles including Metalwork, Enamels, and Ceramics. The Collections of the National Gallery of Art Systematic Catalogue. Washington, D.C., 1993: 291-294, color repro. 292.
Table-cut stones are in rectangular box settings. The enamel does not always fill the cavities provided. There has been some loss of enamel. The chalcedony is drilled through both vertically and horizontally. Four pin hinges connect the black enameled flange on the reverse side. The flange is worked separately so that the gem can be put into the mounting. The stone under the suspension loop could be quartz. The diamonds are of inferior quality.