|The Victoria & Albert Museum|
Here, we see a gilt metal clock-watch with a mother-of-pearl medallion set with onyx cameos of the Emperors Augustus and Vespasian, and a gold bust of the goddess Minerva with a crown of rose-cut diamonds. The whole of the piece is luxuriously set with stones
Made in Germany by Johann Salomon Mayer, the piece is dated 1738. The medallions of mother-of-pearl are mounted on a gilded copper into which the agate cameos of the Roman Emperors are set. The bust of Minerva with her helmet is modeled from carnelian and her armor is gold, set with diamonds (mostly brilliant and table-cut), almandine and hessonite garnets, and emeralds. Enameling adds further color and dimension.
Though the case was made in Germany, the watch movement was probably made in London in about 1690. This movement was used in another watch before being set into this piece. The top plate of the movement bears the name of Du Thuillay of Halle.