Signet rings were very popular in the latter part of the eighteenth century and into the nineteenth century. Then, later on, they were revived in the latter part of the nineteenth century, this revival continuing into the twentieth century. In the earlier period it was customary to engrave the crest and motto, or the full arms and motto, on the ring stone, which was generally bloodstone or carnelian, occasionally white chalcedony, more rarely lapis lazuli, in contradistinction to the large seal fobs, in which the favorite stones were amethyst, rock crystal, smoky topaz (quartz variety), pale chalcedony or some lighter colored material. Many signet rings were engraved upon gold, the sides of the rings being also engraved, as a general rule. Since the year 1900, great interest has been aroused in seal rings, many of the designs of which are incised in gold or in platinum, the entire ring being of gold or platinum, or having a platinum disk set in a gold hoop. The entire variety of fancy stones is used: pale amethyst, ruby, beryl, aquamarine, zircon, garnet, sard which has been stained brown, carnelian (rarely), bloodstone, and jade--both the nephrite variety from New Zealand and Russia and the jadeite variety found at Bahmo, Burma. Occasionally the seals of rings are made of fine sapphires, emeralds, or rubies, and sell for from $1,000 to $10,000, or even more. Seal rings were extensively worn in the period from about 1865 to 1885. Frequently these had absolutely nothing engraved upon them. The setting was often an oblong, rectangular onyx, sometimes one inch or one and a quarter inches long. Occasionally upon this was inset a rose diamond initial; or else the initial was cut upon the stone--when the onyx was black on top--rarely a crest. In many cases the stone was white above and pink below, a sardonyx, and the initial was cut through the light layer. Or else it was white or pale gray on a black ground. The general effect was thus gray, the gem being of the type known as nicolo. Then came the cameo rings, with designs either black on white or brown on white, sardonyx; or white on green, chrysonyx. Later again taste developed for intaglio rings. In this instance, instead of stones of a brownish or whitish gray,--chalcedony,--those of a pale brown or a dark brown were chosen and these were called sard. Because of the brown hue, the term onyx was also applied to them. This must not be confused with the antique sard which resulted from burning a stone of a different hue, as in the case of the antique carnelian also. The translucent or opaque varieties, with rich red or dark brown top, were called sard, whereas the paler translucent and almost transparent varieties,--when pale red, yellowish red or almost yellow,--were called carnelian.