Roman glass in the context of "Baltimore"

The art of Ancient Rome, and the territories of its Republic and later Empire, includes architecture, painting, sculpture and mosaic work. Luxury objects in metal-work, gem engraving, ivory carvings, and glass are sometimes considered to be minor forms of Roman art, although they were not considered as such at the time. Sculpture was perhaps considered as the highest form of art by Romans, but figure painting was also highly regarded. A very large body of sculpture has survived from about the 1st century BC onward, though very little from before, but very little painting remains, and probably nothing that a contemporary would have considered to be of the highest quality.

Ancient Roman pottery was not a luxury product, but a vast production of "fine wares" in terra sigillata were decorated with reliefs that reflected the latest taste, and provided a large group in society with stylish objects at what was evidently an affordable price. Roman coins were an important means of propaganda, and have survived in enormous numbers.

Roman commerce was a major sector of the Roman economy during the later generations of the Republic and throughout most of the imperial period. Fashions and trends in historiography and in popular culture have tended to neglect the economic basis of the empire in favor of the lingua franca of Latin and the exploits of the Roman legions. The language and the legions were supported by trade and were part of its backbone. The Romans were businessmen, and the longevity of their empire was caused by their commercial trade.

Whereas in theory members of the Roman Senate and their sons were restricted when engaging in trade, the members of the equestrian order were involved in businesses despite their upper-class values, which laid the emphasis on military pursuits and leisure activities. Plebeians and freedmen held shop or manned stalls at markets, and vast numbers of slaves did most of the hard work. The slaves were themselves also the subject of commercial transactions. Probably because of their high proportion in society compared to that in Classical Greece, the reality of runaways, and the Servile Wars and minor uprisings, they gave a distinct flavor to Roman commerce.

Engraved glass is a type of decorated glass that involves shallowly engraving the surface of a glass object, either by holding it against a rotating wheel, or manipulating a "diamond point" in the style of an engraving burin. It is a subgroup of glass art, which refers to all artistic glass, much of it made by "hot" techniques such as moulding and blowing melting glass, and with other "cold" techniques such as glass etching which uses acidic, caustic, or abrasive substances to achieve artistic effects, and cut glass, which is cut with an abrasive wheel, but more deeply than in engraved glass, where the engraving normally only cuts deeply enough into the surface to leave a mark. Usually the engraved surface is left "frosted" so a difference is visible, while in cut glass the cut surface is polished to restore transparency. Some pieces may combine two or more techniques.

There are several different techniques of glass engraving. It has been practised since ancient times, including Roman glass, and professionally engraved glass has always been an expensive luxury, requiring lavish amounts of labour by a highly skilled craftsman or artist. In recent centuries the most notable periods and places of production started in the 16th century, initially mostly in Venetian glass, then later in Germany and Bohemian glass. From about 1645 it was used in the Netherlands, which was producing the finest engraving by 1700, by which time some engraving was used in most glass-making centres in Europe. The late 17th and early 18th centuries were in some ways the peak period of achievement and popularity. From 1730 onwards it received some competition from the new geometric cut glass style developed in England. These related techniques were often combined in a single piece, but the engraving tended to be relegated to less prominent positions.

A cage cup, also vas diatretum, plural diatreta, or "reticulated cup" is a type of luxury late Roman glass vessel, found from roughly the 4th century, and "the pinnacle of Roman achievements in glass-making". Diatreta consist of an inner beaker and an outer cage or shell of decoration that stands out from the body of the cup, to which it is attached by short stems or shanks. About fifty cups or, more often, fragments have survived, and there are only a few in near-complete condition. Most have a cage with circular geometrical patterns, often with an "inscription", or phrase in letters above the reticulated area as well. Some have a flange, or zone of projecting open-cut moulding, above the lower patterns and below the lettering (only illustrated here by the Cologne cup in the gallery).

Even rarer are examples with scenes with figures, of which the Lycurgus Cup in the British Museum is the only complete example to survive, though there are other fragments. In this the rest of the "cage" is made up of a vine that entraps Lycurgus. None have a foot. All were clearly difficult to make, and no doubt very expensive, like the other spectacular type of luxury Roman glass, cameo glass objects like the Portland Vase. Both the technology used to make them and the way they were used are still the subject of some debate among specialists.

Glass art refers to individual works of art that are substantially or wholly made of glass. It ranges in size from monumental works and installation pieces to wall hangings and windows, to works of art made in studios and factories, including glass jewelry and tableware.

As a decorative and functional medium, glass was extensively developed in Egypt and Assyria. Glassblowing was perhaps invented in the 1st century BC, and featured heavily in Roman glass, which was highly developed with forms such as the cage cup for a luxury market. Islamic glass was the most sophisticated of the early Middle Ages. Then the builders of the great Norman and Gothic cathedrals of Europe took the art of glass to new heights with the use of stained glass windows as a major architectural and decorative element. Glass from Murano, in the Venetian Lagoon, (also known as Venetian glass) is the result of hundreds of years of refinement and invention. Murano is still held as the birthplace of modern glass art.

Between the Roman Empire and the Han dynasty, as well as between the later Eastern Roman Empire and various successive Chinese dynasties, there were (primarily indirect) contacts and flows of trade goods, information, and occasional travelers. These empires inched progressively closer to each other in the course of the Roman expansion into ancient Western Asia and of the simultaneous Han military incursions into Central Asia. Mutual awareness remained low, and firm knowledge about each other was limited. Surviving records document only a few attempts at direct contact. Intermediate empires such as the Parthians and Kushans, seeking to maintain control over the lucrative silk trade, inhibited direct contact between the two ancient Eurasian powers. In 97 AD, the Chinese general Ban Chao tried to send his envoy Gan Ying to Rome, but Parthians dissuaded Gan from venturing beyond the Persian Gulf. Ancient Chinese historians recorded several alleged Roman emissaries to China. The first one on record, supposedly either from the Roman emperor Antoninus Pius or from his adopted son Marcus Aurelius, arrived in 166 AD. Others are recorded as arriving in 226 and 284 AD, followed by a long hiatus until the first recorded Byzantine embassy in 643 AD.

The indirect exchange of goods on land along the Silk Road and sea routes involved (for example) Chinese silk, Roman glassware and high-quality cloth. Roman coins minted from the 1st century AD onwards have been found in China, as well as a coin of Maximian (Roman emperor from 286 to 305 AD) and medallions from the reigns of Antoninus Pius (r. 138–161 AD) and Marcus Aurelius (r. 161–180 AD) in Jiaozhi (in present-day Vietnam), the same region at which Chinese sources claim the Romans first landed. Roman glassware and silverware have been discovered at Chinese archaeological sites dated to the Han period (202 BC to 220 AD). Roman coins and glass beads have also been found in the Japanese archipelago.

Islamic glass is glass made in the Islamic world, especially in periods up to the 19th century. It built on pre-Islamic cultures in the Middle East, especially ancient Egyptian, Persian and Roman glass, and developed distinct styles, characterized by the introduction of new techniques and the reinterpreting of old traditions. It came under European influence by the end of the Middle Ages, with imports of Venetian glass documented by the late 15th century.

It rarely has religious content, other than inscriptions, although the mosque lamp was mainly used in religious contexts, to light mosques, but it uses the decorative styles of Islamic art from the same times and places. The makers were not necessarily Muslims themselves.

The Lycurgus Cup is a Roman glass 4th-century cage cup made of a dichroic glass, which shows a different colour depending on whether or not light is passing through it: red when lit from behind and green when lit from in front. It is the only complete Roman glass object made from this type of glass, and the one exhibiting the most impressive change in colour; it has been described as "the most spectacular glass of the period, fittingly decorated, which we know to have existed".

The cup is also a very rare example of a complete Roman cage-cup, or diatretum, where the glass has been painstakingly cut and ground back to leave only a decorative "cage" at the original surface-level. Many parts of the cage have been completely undercut. Most cage-cups have a cage with a geometric abstract design, but here there is a composition with figures, showing the mythical King Lycurgus, who (depending on the version) tried to kill Ambrosia, a follower of the god Dionysus (Bacchus to the Romans). She was transformed into a vine that twined around the enraged king and restrained him, eventually killing him. Dionysus and two followers are shown taunting the king. The cup is the "only well-preserved figural example" of a cage cup.