By a special privilege the ring ordinarily worn by a pope may bear a cameo, that usually worn by Pius IX showed an image of the Virgin Mary. The Fisherman’s Ring is but rarely worn. When after a pope’s death, the ring has been broken, as we have noted, a cheap facsimile, or the broken ring, is sometimes buried with the pope.[424] Of the three main classes of ecclesiastical rings, the pontifical ring with its single precious stone, worn over a glove and exclusively at pontifical ceremonies, is so large that its stone setting covers the first phalanx of the fourth finger of the right hand, on which it is worn. The “gemmed ring,” a mark of distinction, may have but one stone, or a central stone surrounded by brilliants, just as the regulations provide. A third class of ecclesiastical rings are those of plain gold, commonly with a smooth chaton; sometimes, however, this may be engraved with armorial bearings, so that the ring can be used as a signet. In Rome those who have received the degree of doctor of divinity have the word ~ROMA~ engraved upon the chaton of the ring.[425] One of the earliest notices of a bishop’s ring, not however in the strictly ecclesiastical sense, but of one worn by a bishop, is given in a letter written by St. Avit, Archbishop of Vienne (494–525), to his colleague, Apollinaris, Bishop of Valencia (ca. 520): “The ring you have been kind enough to offer me should be made as follows: In the middle of a very thin iron hoop, representing two dolphins facing each other, a double seal should be set by means of two pivots, so that either side may be shown or hidden at will and in turn, and offer, alternately, to the eyes a green stone or a pale electrum. Let not this metal be as I have sometimes seen it, easily tarnished in the cleanest hands, and similar to the impure mixture of gold that has not been exposed to the fire; let it not resemble the alloy which formerly the king of the Goths introduced into his coinage, an emblem of his downfall. Let my electrum be of a medium color, having at once the tawny hue of gold and the whiteness of silver, precious by their union and enhancing the brilliant green of the emerald when it appears. Let my monogram be engraved on the seal surrounded by my name, so that it may be read. Opposite the setting, the middle of the ring shall be formed by the tails of the dolphins; to set between these an oblong stone shall be sought, pointed at the extremities.”[426] It will be noted that this was not a gold ring, but an iron one, and thus essentially different from the recognized episcopal rings.