Engraved gem

An engraved gem, frequently referred to as an intaglio, is a small and usually semi-precious gemstone that has been carved, in the Western tradition normally with images or inscriptions only on one face.

Though they were keenly collected in antiquity, most carved gems originally functioned as seals, often mounted in a ring; intaglio designs register most clearly when viewed by the recipient of a letter as an impression in hardened wax.

A finely carved seal was practical, as it made forgery more difficult – the distinctive personal signature did not really exist in antiquity.

The cylinder seal, whose design appears only when it is rolled over damp clay, from which the flat ring type developed, was the usual form in Mesopotamia, Assyria and other cultures, and spread to the Aegean and Minoan world, including parts of Greece and Cyprus.

Round or oval Greek gems (along with similar objects in bone and ivory) are found from the 8th and 7th centuries BC, usually with animals in energetic geometric poses, often with a border marked by dots or a rim.

[12] Roman gems generally continued Hellenistic styles, and can be hard to date, until their quality sharply declines at the end of the 2nd century AD.

Gems were used to decorate elaborate pieces of goldsmith work such as votive crowns, book-covers and crosses, sometimes very inappropriately given their subject matter.

Matthew Paris illustrated a number of gems owned by St Albans Abbey, including one large Late Roman imperial cameo (now lost) called Kaadmau which was used to induce overdue childbirths – it was slowly lowered, with a prayer to St Alban, on its chain down the woman's cleavage, as it was believed that the infant would flee downwards to escape it,[14] a belief in accordance with the views of the "father of mineralogy", Georgius Agricola (1494–1555) on jasper.

[18] Some gems in a remarkably effective evocation of classical style were made in Southern Italy for the court of Frederick II, Holy Roman Emperor in the first half of the 13th century, several in the Cabinet des Médailles in Paris.

The British Museum has what is probably a seated portrait of John, Duke of Berry in intaglio on a sapphire, and the Hermitage has a cameo head of Charles VII of France.

Along with the Roman statues and sarcophagi being newly excavated, antique gems were prime sources for artists eager to regain a classical figurative vocabulary.

[20] Among very many examples of borrowings that can be traced confidently, the Felix or Diomedes gem owned by Lorenzo de' Medici (see below), with an unusual pose, was copied by Leonardo da Vinci and may well have provided the "starting point" for one of Michelangelo's ignudi on the Sistine Chapel ceiling.

[22] By the 16th century carved and engraved gems were keenly collected across Europe for dedicated sections of a cabinet of curiosities, and their production revived, in classical styles; 16th-century gem-cutters working with the same types of sardonyx and other hardstones and using virtually the same techniques, produced classicizing works of glyptic art, often intended as forgeries, in such quantity that they compromised the market for them, as Gisela Richter observed in 1922.

[25] Engraved gems occur in the Bible, especially when the hoshen and ephod worn by the High Priest are described; though these were inscribed with the names of the tribes of Israel in letters, rather than any images.

A few identifiably Jewish gems survive from the classical world, including Persia, mostly with the owner's name in Hebrew, but some with symbols such as the menorah.

As private objects, produced no doubt by artists trained in the tradition of Hellenistic monarchies, their iconography is less inhibited than the public state art of the period about showing divine attributes as well as sexual matters.

A number of gems from the same period contain scenes apparently from the lost epic on the Sack of Troy, of which the finest is by Dioskurides (Chatsworth House).

Famous collectors begin with King Mithridates VI of Pontus (d. 63 BC), whose collection was part of the booty of Pompey the Great, who donated it to the Temple of Jupiter in Rome.

One of the largest, the Coupe des Ptolémées was probably donated to the Basilica of Saint-Denis, near Paris, by Charles the Bald, as the inscription on its former gem-studded gold Carolingian mounting stated; it may have belonged to Charlemagne.

One of the best collections of such vessels, though mostly plain without carved decoration, was looted from Constantinople in the Fourth Crusade, and is in the Treasury of the Basilica of San Marco in Venice.

First known in the collection of Isabella d'Este, it passed to the Gonzaga Dukes of Mantua, Emperor Rudolf II, Queen Christina of Sweden, Cardinal Decio Azzolini, Livio Odescalchi, Duke of Bracciano, and Pope Pius VI before Napoleon carried it off to Paris, where his Empress Joséphine gave it to Alexander I of Russia after Napoleon's downfall, as a token of goodwill.

The largest flat engraved gem known from antiquity is the Great Cameo of France, which entered (or re-entered) the French royal collection in 1791 from the treasury of Sainte-Chapelle, where it had been since at least 1291.

In the eighteenth century British aristocrats were able to outcompete even the agents for royal and princely collectors on the Continent, aided by connoisseur-dealers like Count Antonio Maria Zanetti and Philipp von Stosch.

Gori, Le gemme antiche di Anton Maria Zanetti (Venice, 1750), illustrated with eighty plates of engravings from his own drawings.

Baron Philipp von Stosch (1691–1757), a Prussian who lived in Rome and then Florence, was a major collector, as well as a dealer in engraved gems: "busy, unscrupulous, and in his spare time a spy for England in Italy".

Leone Leoni said he personally spent two months on a double-sided cameo gem with portraits of Holy Roman Emperor Charles V and his wife and son.

[57] The technique was revived in the 18th and especially 19th centuries in England and elsewhere,[58] and was most effectively used in French Art Nouveau glass that made no attempt to follow classical styles.

[59] Another offshoot of the mania for engraved gems is the fine-grained slightly translucent stoneware called jasperware that was developed by Josiah Wedgwood and perfected in 1775.

[60] Though white-on-blue matte jasperware is the most familiar Wedgwood ceramic line, still in production today and widely imitated since the mid-19th century, white-on-black was also produced.

Major progress in understanding Greek gems was made in the work of Adolf Furtwängler (1853–1907, father of the conductor, Wilhelm).