This was the most valuable object in the whole of the Grand Dauphin’s collection. Its mounting is now lost. It is a monolithic piece in the form of a jug with a bell-shaped body and tall neck that opens out in three everted gadroons forming a trefoil mouth. The handle, carved in the same block, ascends straight from the shoulder of the body to the edge of the mouth, where it curves slightly. A very schematic lanceolate motif appears at the base of the handle, which is carved with straight edges. This is a magnificent piece of agate of the variety traditionally called sardonyx. Although ancient, its volumes and proportions are not classical, though certain details might seem to indicate the contrary, such as the gadrooning at the end of the neck, the trefoil mouth and the schematic lanceolate palmette at the base of the handle. It may have been slightly retouched and repolished in addition to the manipulation necessary for adding the mounts.

This was the object that opened the 1689 inventory of the Cabinet of Versailles, and the most valuable piece in the Dauphin’s collection. Other ancient vessels at the Louvre originating in the royal collection testify to the interest in such objects of both Louis XIV and his son. Among the surviving pieces from Philip V’s inheritance at the Prado, there are a number of vessels made from ancient stones, such as O3, O7, O16, O43, O44, O46, O47, O48 and possibly O6. Some of the ancient sardonyx vessels at the Louvre have similar volumes, such as MR 443, MR 115, MR 116 and MR 133. Louis XIV had various contacts in the Orient, and especially in Constantinople (Istanbul), such as the Parisian jeweller Sylvestre Base, and also Antoine Galland (1646-1715), whom he commissioned to buy medals, agate vases and other curiosities. It is likely, although supporting documentation is lacking, that his son, the Dauphin, also benefited from these dispatches.

The ewer had a flat agate lid with three silver gilt mounts and a finial formed by a female bust with an incrusted ruby in the head. These were stolen in 1918, like the mount on the base. Their form and volume can be appreciated from the case and seen in historic photographs. These vanished mounts were made in the late 17th or early 18th century, later than the 1689 Versailles inventory. Of the Parisian type, they were similar to those of other pieces in the Dauphin’s Treasure, such as the rock crystal dish with an engraved eagle, O72, and the pair of lapis lazuli salvers, O60 and O61, which makes it probable that the mount on the base had silversmith’s marks. As for the female bust that crowned the lid, it recalls similar finials on other pieces at the Prado, like those on the tazzas with cameos (O35 and the one which disappeared in 1815, I1416), which Arbeteta attributed to the Milanese workshop of the Miseroni family. Cup O7 also has a female bust for a finial. This type of adornment was to the taste of the Italian workshops, especially in Venice and Milan, where it was produced in abundance. The state of the work in the 19th century can be seen through the photography of Juan Laurent y Minier, "Vase agate sardoine, montures d’or avec émaux et pierreries, XVIe siècle, règne de Henri II", c. 1879, Museo del Prado, HF0835/22.