An engraved gem, frequently referred to as an intaglio (pl. intaglios, intagli), 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.Fully half of the antique engraved gems in the Berlin museums and the British Museum are either sard or carnelian, Etta M. Saunders, noted. Saunders, "Goddess Riding a Goat-Bull Monster: A Ceres Zodiac Gem from the Walters Art Gallery" The Journal of the Walters Art Gallery 49/50 (1991/1992;7–11) note 19 The engraving of gemstones was a major luxury art form in the ancient world, and an important one in some later periods.The three preeminent European collections of post-Classical engraved gems are the Cabinet des Médailles at the Bibliothèque nationale, Paris, the Habsburg collection, Vienna, and the British Museum, London, O. M. Dalton observed in "Mediæval and Later Engraved Gems in the British Museum — I" The Burlington Magazine for Connoisseurs 23 No. 123 (June 1913:128-136) and "II" The Burlington Magazine for Connoisseurs 24 No. 127 (October 1913:28–32). It is one type of product of lapidary, the practice of shaping stone including gemstones or minerals, into decorative items.
Strictly speaking, engraving means sculpting in intaglio (with the design cut into the flat background of the stone), but relief carvings (with the design projecting out of the background as in nearly all cameos) are also covered by the term. This article uses cameo in its strict sense, to denote a carving exploiting layers of differently coloured stone. The activity is also called gem carving and the artists gem-cutters. References to antique gems and intaglios in a jewellery context will almost always mean carved gems; when referring to monumental sculpture, the term counter-relief, meaning the same as intaglio, is more likely to be used. Vessels like the Cup of the Ptolemies and heads or figures carved in the round are also known as hardstone carvings.
Glyptics or glyptic art covers the field of small carved stones, including cylinder seals and inscriptions, especially in an archaeological context. 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.
Technique Gems were mostly cut by using abrasive powder from harder stones in conjunction with a hand-drill, probably often set in a lathe. Emery has been mined for abrasive powder on Naxos since antiquity. Some early types of seal were cut by hand, rather than a drill, which does not allow fine detail. There is no evidence that magnifying lenses were used by gem cutters in antiquity. A medieval guide to gem-carving techniques survives from Theophilus Presbyter. Byzantine cutters used a flat-edged wheel on a drill for intaglio work, while Carolingian ones used round-tipped drills; it is unclear where they learnt this technique from. In intaglio gems at least, the recessed cut surface is usually very well preserved, and microscopic examination is revealing of the technique used.Kornbluth, 8-16 quotes passages from Theophilius and others, and discusses various techniques. See Theophilius's article for full on-line texts. The colour of several gemstones can be enhanced by a number of artificial methods, using heat, sugar and dyes. Many of these can be shown to have been used since antiquity – since the 7th millennium BC in the case of heating.Thoresen, "Gemstone enhancement"
History
The technique has an ancient tradition in the Near East, where it is represented in all or most early cultures, and the Indus Valley civilization. The cylinder seal, whose design fully 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 world including the Minoan civilization, parts of Greece and also Cyprus. These were made in various types of stone, not all hardstone, and gold rings were a related development in Minoan seals, which are often very fine. The Greek tradition emerged in Ancient Greek art under Minoan influence on mainland Helladic culture, and reached an apogee of subtlety and refinement in the Hellenistic period. Pre-Hellenic Ancient Egyptian seals tend to have inscriptions in hieroglyphs rather than images. The biblical Book of Exodus describes the form of the hoshen, a ceremonial breastplate worn by the high priest, bearing twelve gems engraved with the names of the Twelve tribes of Israel.
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.Boardman, 39 See Beazley for more detail. Early examples are mostly in softer stones. Gems of the 6th century are more often oval,"Lenticular" or "lentoid" gems have the form of a lens. with a scarab back (in the past this type was called a "scarabaeus"), and human or divine figures as well as animals; the scarab form was apparently adopted from Phoenicia.Beazley, Later Archaic Greek gems: introduction. The forms are sophisticated for the period, despite the usually small size of the gems.Boardman, 68-69 In the 5th century gems became somewhat larger, but still only 2-3 centimetres tall. Despite this, very fine detail is shown, including the eyelashes on one male head, perhaps a portrait. Four gems signed by Dexamenos of Chios are the finest of the period, two showing herons.Boardman, 129-130
Relief carving became common in 5th century BC Greece, and gradually most of the spectacular carved gems in the Western tradition were in relief, although the Sassanian and other traditions remained faithful to the intaglio form. Generally a relief image is more impressive than an intaglio one; in the earlier form the recipient of a document saw this in the impressed sealing wax, while in the later reliefs it was the owner of the seal who kept it for himself, probably marking the emergence of gems meant to be collected or worn as jewellery pendants in necklaces and the like, rather than used as seals – later ones are sometimes rather large to use to seal letters. However inscriptions are usually still in reverse ("mirror-writing") so they only read correctly on impressions (or, in the case of transparent stones, by viewing from behind). This aspect also partly explains the collecting of impressions in plaster or wax from gems, which may be easier to appreciate than the original.
The cameo, which is rare in intaglio form, seems to have reached Greece around the 3rd century; the Farnese Tazza is the only major surviving Hellenistic example (depending on the date assigned to the Gonzaga Cameo – see below), but other glass-paste imitations with portraits suggest that gem-type cameos were made in this period.Boardman, 187-188 The conquests of Alexander the Great had opened up new trade routes to the Greek world and increased the range of gemstones available.Beazley, "Hellenistic gems: introduction" 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. Philosophers are sometimes shown; Cicero refers to people having portraits of their favourite on their cups and rings.Boardman, 275-6 The Romans invented cameo glass, best known from the Portland Vase, as a cheaper material for cameos, and one that allowed consistent and predictable layers on even round objects.
During the European Middle Ages antique engraved gems were one classical art form which was always highly valued, and a large but unknown number of ancient gems have (unlike most surviving classical works of art) never been buried and then excavated. 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,Henderson, 112-113 a belief in accordance with the views of the "father of mineralogy", Georgius Agricola (1494–1555) on jasper.De Natura fossilium Bk 1 Some gems were engraved, mostly with religious scenes in intaglio, during the period both in Byzantium and Europe.Examples: 14th century French Crucifixion, Rosary pendant, 15th century, both onyx and in the MMA New York.
In the West production revived from the Carolingian period, when rock crystal was the commonest material. The Lothair Crystal (or Suzanna Crystal, British Museum, 11.5 cm diameter), clearly not designed for use as a seal, is the best known of 20 surviving Carolingian large intaglio gems with complex figural scenes, although most were used for seals.Kornbluth, 1, 4. Susanna Crystal, British Museum. Several crystals were designed, like the Susanna Crystal, to be viewed through the gem from the unengraved side, so their inscriptions were reversed like the seals. In wills and inventories, engraved gems were often given pride of place at the head of a list of treasures.Kornbluth, 1, 4-6
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. Meanwhile, the church led the development of large, often double-sided, metal seal matrices for wax seals that were left permanently attached to charters and similar legal documents, dangling by a cord, though smaller ring seals that were broken when a letter was opened remained in use. It is not clear to what extent this also continued practices in the ancient world.
Renaissance revival
The late medieval French and Burgundian courts collected and commissioned gems, and began to use them for portraits. 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.Campbell, 411
Interest had also revived in Early Renaissance Italy, where Venice soon became a particular centre of production. Along with the Roman statues and sarcophagi being newly excavated, antique gems were prime sources for artists eager to regain a classical figurative vocabulary. Cast bronze copies of gems were made, which circulated around Italy, and later Europe.Draper, James David. "Cameo Appearances". In Heilbrunn Timeline of Art History. New York: The Metropolitan Museum of Art, 2000–. (August 2008) 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.Claire Clark, Kenneth in J. Farago (ed)Leonardo's projects, c. 1500-1519. Volume 3 of Leonardo da Vinci, selected scholarship, Publisher Taylor & Francis, 1999, , . p. 28/160 Google books. Image and description by Boardman Another of Lorenzo's gems supplied, probably via a drawing by Perugino, a pose used by Raphael.Henk Th. van Veen. The translation of Raphael's Roman style. Volume 22 of Groningen studies in cultural change, GSCC; 22, p. 26, Peeters Publishers, 2007. , . Google books