An important sapphire intaglio. Italy, Milan, third quarter of the 16th century. Crucifixion. The finely carved, deep blue sapphire shows the crucified Christ, standing at the center of the scene. Christ's head is bent slightly forward and turned to the right.
Affixed to the top of the vertical pole of the cross is a rectangular plate. Flanking the central scene are, on the right, the caped Virgin, veiled and with her hands joined in prayer, and to the left, St. John the Evangelist, wearing a belted garment and cape. He raises his right hand towards Christ. At the foot of the cross, a skull, symbolizing memento mori (Calvario). There is a ground line.
The body of Christ is finely detailed, with the major muscles deeply carved. The religious language of the Calvary scene, as given by the Gospel of St. John, is here depicted in the dialogue between the dying Christ, his favourite apostle and the Virgin.
The engraving has been carried out with brilliant flair and great technical competence, considering the very small surface available and the extreme hardness of sapphire.
The gem, of an intense blue color, is enhanced by faceting, both framing the engraved surface, and the back. The choice of engraving this highly meaningful iconography on sapphire is not accidental, as only the highest members of the Church hierarchy were entitled to wear this gem. Considering when and where the intaglio was cut, and following exhaustive study of the sources combined with an analysis of coeval portraiture, it is highly likely that this gem – no doubt originally mounted in a gold ring - was the personal seal of Cardinal and Archbishop Carlo Borromeo (1538-1584), a key-figure of the Counter Reformation of the Roman Catholic Church.
Born to two prominent Lombard banking families (Medici and the Counts of Arona), he was always destined for a prominent public role in Lombard society. As he was not the first-born male, his destiny was, in accordance with traditions in noble families at that time, to enter the priesthood.
In 1545, when he was just seven, he received the tonsure, the priest’s robes, and his first ecclesiastical title, which would later be followed by many others. After receiving his doctorate in civil and canon law in 1559 and following the election of his uncle Cardinal Angelo Medici as Pope Pius VI in the same year, he was summoned to Rome where he was appointed bishop in the Sistine Chapel by Cardinal Giovanni Serbelloni. Three weeks later his uncle raised him to cardinal. He was formally appointed archbishop of Milan in May 1564 and moved there in 1565 with a retinue of 100 people. His task was to run a diocese with authority over another 15 archbishoprics in Lombardy, Piedmont and Liguria.
It is more than likely that on one of these occasions he was given the blue sapphire that was considered the preserve of archbishops and the highest ranks of church officials. These gems provide visual evidence for the then prevailing belief here expressed by the German Andreas Jessner, that:
One should wear blue sapphire chastely to remain healthy for a long time.
That chastity always remained an issue is clear also from the writings of the Dutch theologian Gerrit Janszoon Vossius (1577–1649), who wrote:
sapphire worn in a ring or in any other manner is able to quench concupiscence, and for that reason is proper to be worn by the priesthood and by all persons vowed to perpetual chastity.
Borromeo is shown wearing just such a ring set with a sapphire on a painting by Samaritana Samaritani, now in the Gallery Poveri Vergognosi, Bologna. A second picture of Carlo Borromeo by Bizzozzero Ottavio, currently in the art collection of Hospedale Maggiore, Milan, likewise shows the prelate wearing a sapphire ring.
Arriving in Rome, Borromeo loved society life, hunting, banquets, chess, and humanistic culture. However, following the sudden death of his brother, Federico in 1562, Carlo resolved to follow a particularly frugal Christian lifestyle. He organized the third Council of Trent (1562-3) that codified this austere lifestyle for other entrants to the priesthood.
Throughout his life he emphasized the importance of education for candidates for holy orders and priesthood. He established seminaries and colleges (The Almo Collegio Borromeo in Pavia still exists today). In 1576, following drought and famine, the plague broke out in Milan, and Borromeo spent all of his private fortune to try and feed the more than 60,000 people in desperate need. He personally cared for the sick in the “Lazzarettos,” the areas in which those suffering from the disease were segregated. After his death, in 1584, Pope Clement VIII beatified Carlo in 1602. On November 1, 1610, Carlo Borromeo was canonized by Pope Paul V.

References:
For an early Byzantine prototype cf.: Papanikola-Bakirtzi, D., (ed.) Everyday Life in Byzantium. Athens, 2002.. p. 485, n. 659, 6th-7th c.
For two Middle Byzantine prototypes, cf.: Spier, J. Middle Byzantine (10th-13th century AD) stamp seals in semi-precious stone. p. 114- 126, n. 14-17 and 14-18 in: Entwistle, C. Through a Glass Brightly; Studies in Byzantine and Medieval Art and Archaeology Presented to David Buckton. London, 2003.
Then for contemporary parallels: Kris, E. Catalogue of the Postclassical Cameos in the Milton Weil Collection. Vienna, 1932..p. 14, pl. II, cameo, XIV c. (though a somewhat later date cannot be ruled out in my opinion)
Kagan, J. and Neverov, O. Splendeurs des Collections de Catherine II de Russie. Paris, 2000. p. 154. n. 198/14. 2nd half of the XVI c. Dalton, O.M. Catalogue of the Engraved Gems of the Post-Classical Periods…British Museum. London, 1915. p. 81, pl. XX - n. 567.
12.8 x 10x 5 mm; peso 6.9 carati