The Jewel of St. Hilary contains a fine cameo head in profile of the Emperor Augustus on a sardonyx. It is enclosed in a frame of silver gilt set with large rubies, sapphires, and pearls. The jewel was formerly employed as a pectoral or breast-ornament upon a silver reliquary bust of St. Hilary preserved in the Treasury of St. Denis. On the dispersal of the Treasury in 1791, the jewel was removed to the Bibliothèque Nationale. The framework dates from the twelfth century. It measures 3½ by 2½ inches.[47] The Cameo of Charles V of France, a sardonyx of three layers, dating from Imperial Roman times, represents a full length figure of Jupiter. It is mounted in the gold frame in which it was presented to the Treasury at Chartres by the King. Such prophylactic verses[48] as are found frequently side by side upon amulets and in cabalistic formulæ of the Middle Ages, are inscribed round its edge on a ground of blue and red enamel, together with the opening words of St. John's Gospel, which were supposed to serve as a protection, particularly against demons and thunder. The figure of Jupiter with the eagle probably passed for a representation of the evangelist. At the lower part is a crowned escutcheon bearing the arms of France, and on the crown is an inscription recording the presentation of the jewel by Charles V in the year 1367.[49] This beautiful example of French jewellery of the fourteenth century is 6 inches in length and 3 in width. [47] Babelon (E. C. F.), _Catalogue des camées de la Bib. Nat._, p. 107. [48] _St. Luke,_ IV. 30; and _St. John_, VIII. 2. [49] Babelon, _op. cit._, p. 1. Of slightly later date than the Jewel of St. Hilary, and of far more elaborate workmanship, though perhaps less well known on account of its somewhat remote situation, is the Schaffhausen Onyx. The stone, a fine sardonyx, is a Roman cameo of a female figure carrying a cornucopia and caduceus, and intended to represent Peace. Its setting, a superb specimen of mediæval goldwork, is mounted with figures of eagles and lions, chased in full relief and arranged in regular order between high bezels set with garnets, sapphires, pearls, and turquoises. The outside measurement of the jewel is 6 by 5 inches, and that of the stone 3½ by 3.[50] [50] For a full description of this jewel, see a monograph by J. J. Oeri, entitled _Der Onyx von Schaffhausen._ The large part played by superstition in the ornaments of the Middle Ages need not be further enlarged on. The virtues of charms were not only associated with gems and precious stones; for mystic letters, cabalistic inscriptions, and other devices were among the chief features of mediæval jewellery. Such devices lingered long after the Renaissance of learning had partially dispelled the mysticism of the Middle Ages; while similar superstitions in respect to precious stones are even now not entirely extinct, in spite of the assurances of modern science.