The Santo Caliz of Valencia is a cup whose upper bowl is a piece of dark, banded agate, set in the Middle Ages upon an elaborate foot of gold studded with pearls and gems and joined by a knopped stem. It is venerated as the very cup Christ used at the Last Supper, and among the many vessels that have claimed to be the Holy Grail it is the one most seriously entertained, because the agate bowl is a genuine antique of the eastern Mediterranean rather than a medieval fabrication. The chalice is enshrined in a dedicated Gothic chapel of Valencia Cathedral and is used liturgically on special occasions; both John Paul II and Benedict XVI celebrated Mass with it. The Roman Missal's wording for the "precious chalice" has even been linked by tradition to this cup, reinforcing its standing as the leading Grail candidate in the Catholic world.
The chalice's upper bowl, a piece of dark red agate, has been assessed stylistically, notably by the Spanish scholar Antonio Beltran, as the work of an Eastern Mediterranean workshop, with published estimates for its manufacture ranging from roughly the fourth century BCE to the first century CE; because the vessel is carved stone rather than organic material, it cannot be radiocarbon-dated, and its age rests on stylistic and comparative analysis rather than on a physical scientific test. The elaborate gold mount, set with pearls and gemstones, that today supports the ancient bowl was added considerably later, in the medieval period, joining an ancient object to a medieval setting in a single composite relic.