In the Roman world entire rings of yellow amber were sometimes formed, and in a few instances figures or heads have been engraved in relief upon the chaton. Their execution need not have presented any greater difficulty than did the carving of the many small amber figures which have come down to us from ancient times. A carved amber ring in the Franks Bequest of the British Museum is beautifully formed with full-relief figures of Venus and of Cupid on either side. It is cut out of a single piece of amber, and is considered to be the finest example extant of Roman carving in that material,[171] but unfortunately is considerably damaged. Pliny declares that in his time amber ornaments were almost exclusively for women’s wear; indeed, a few years later, Artemidorus, in his “Oneirocritica,” an interpretation of dreams, after saying that amber and ivory rings were only appropriate for women, proceeds to assert that this was true of all kinds of rings.[172] There are but a very few ivory rings in the British Museum, although the collection includes several bone rings, probably for wear on the thumb. The relief-carving of masks has been thought to make it likely that they were actors’ rings.[173] Not only have entire emerald and ruby rings been formed, but even the intractable diamond has lately been cut in this form. An entire diamond ring, the work of the diamond-cutter Antoine, of Antwerp, was shown in the exposition held in Antwerp in 1894.[174] Another such ring has since been executed by Bart Brouwer of Amsterdam. In this latter ring the facets are all triangular. The unrivalled Heber R. Bishop Collection of Jades, now in the Metropolitan Museum of Art, New York City, contains an ancient thumb-ring (_pan chih_), entirely of jade, from the time of the Han Dynasty (206 B.C.-220 A.D.). Its major and minor diameters are 1.16 inches and 1.03 inches, respectively, and it weighs .809 ounce. The material is the nephrite variety of jade, the color being clouded gray with very dark brown veinings. The rings of this type were worn on the thumb of the left hand to protect it from injury by the bowstring after the discharge of the arrow. The dark veining results from the filling of the fissures in the material with some brownish-black substance; it is an excellent example of the amphibolic alteration of jadeite, which is shown by chemical analysis to be present here to the amount of 4.15 per cent. (No. 330 of the collection).