Late 18th-century double-rock crystal cruciform theca decorated by fine silver wire border and housing substantial particles of the True Cross of Jesus Christ. Authenticated with a red seal of Spanish wax with an imprint of a coat of arms of Bishop Nicola Angelo Maria Landini, O.E.S.A. (†1782), Titular Bishop of Parthyrion and Vicar General of the Vatican Curia. and conserved in the original fitted diamond-shaped case.
The True Cross is the name for physical remnants that, by the Church tradition, are believed to be from the cross upon which Jesus was crucified. Empress Helena, mother of Constantine, the first Christian Emperor of Rome, traveled to the Holy Land in 326–28, where she discovered the hiding place of three crosses that were believed to be used at the crucifixion of Jesus and of two thieves, St. Dismas and Gestas, executed with him, and a miracle revealed which of the three was the True Cross. Fragments of the Cross were broken up, and the pieces were widely distributed; in 348, in one of his Catecheses, Cyril of Jerusalem remarked that the "whole earth is full of the relics of the Cross of Christ." Most of the very small relics of the True Cross in Europe came from Constantinople after the city was captured and sacked in 1204 during the Fourth Crusade. They were carved up by the present bishops and divided with other very precious relics among the knights; who, after their return to the homeland, donated them to churches and monasteries.