amulets, which were believed to have curative and protective power. A number of ancient authors wrote about gems but their texts are fragmentary or have not survived. The best accounts are by the fourth century B.C. philosopher Theophrastos (On Stones) and Pliny the Elder (Natural History), who wrote in the first century A.D. What we know today, however, is mainly deduced from the gems themselves.

The Functions of Engraved Gems
Beyond their aesthetic appeal as beautiful objects and ornaments, the primary function of engraved gems was to serve as seals. They were widely used to mark one's property, to record authority, and secure the privacy of objects and documents. A piece of clay or wax received the impression of an engraved stone or metal ring to signify ownership or authority. Such sealings could easily be broken when they secured a letter or an object, but their violation could not pass unnoticed. Ancient authors refer to the use of signet rings as seals: in one of Aristophanes' comedies, the women complain that the stores of meal, oil, and wine are guarded too well by their husbands' sealings. Another important use of seals was to secure valuable packages in the course of trade. The younger Pliny, as Trajan's official representative in Bithynia, wrote in c. A.D. 112 from Nikomedia that he was sending a gold nugget 'sealed with my own ring, with the device of a quadriga'. In modern terms, a seal on a letter would be akin to a signature or a sealed envelope, and when impressed on an object or a door it was equivalent to a padlock. In the ancient world most people could not write and the use of a personal seal was very handy as an identification mark. Nowadays, when the use of seals is uncommon, when signets are rarely cut and even more rarely used, it is not easy to appreciate the importance attached to them in antiquity. Clay sealings impressed by engraved gems set in rings have survived in great numbers throughout the ancient world. The represent the only remains of Greek and Roman archives once containing rolled and sealed papyrus documents. They usually owe their survival to the burning down of these archives, during which clay would be baked and become more resistant to the passage of time. A number of these archives contained sealings that span several centuries, such as those found at Doliche, a city of Kommagene at Düllük Tepe, probably dating from the late second century B.C. to the early third century A.D. some of these archives have each yielded more than 20,000 sealings. Clay sealings offer a vivid illustration of gems used as seals on official or private documents. Gems were precious objects, and were sometimes valued at astronomical prices. Pliny gives a number of examples of gems being exchanged for large sums of money. The nature and quality of the stone determined its value, whereas craftsmanship, it seems, did not significantly modify it. A story recorded by Herodotos and repeated by many authors, among them Pliny, is a very early testimony to the high esteem in which an engraved gem could be held. Since it involves the island of Samos, a few miles from the shores of Ionia, it is worth repeating here. The inhabitants of the independent island of Samos were under threat from the expanding Persian Empire, which had recently engulfed the kingdom of Lydia. A wealthy citizen of the island, Polykrates, seized power and made himself tyrant. To check the Persian advance, he allied his maritime forces to those of Amasis, Pharaoh of Egypt, who had similar concerns about the conquering Persians. Polykrates proved to be a good ruler and his strategy was effective at stopping the Persians' westward expansion. On being informed of the success of his ally, the superstitious Pharaoh Amasis wrote to Polykrates saying that the gods might be jealous of his success and that he should propitiate them by choosing from his treasures whatever he held most valuable and then disposing of it so that it would never again be seen by men. Polykrates considered carefully which of the treasures that he had in store would grieve him most to lose. After much thought he decided that it was a gold ring with the signet engraved on a fine smaragdos (most probably an emerald, or perhaps a green variety of chalcedony) by Theodoros, a fellow Samian celebrated for his gem-cutting skills. So he decided that throwing his ring into the sea would ensure that it would never be retrieved. This done he returned home and gave vent to his sorrow. But a few days later a local fisherman caught a very large fish which he thought fit for a king. He presented it to Polykrates who was pleased to accept it and in return invited him to partake of the fish at dinner. The cook cut the fish open and found the signet of his master in its belly. The precious ring was restored to Polykrates, but the Pharaoh Amasis, on being informed of these events, felt his ally could not be protected from his own fate and broke off the alliance. The prophecy was in due course realised when Polykrates was murdered by a Persian. Of course not all gems were as valuable as Polykrates', and in later periods many were produced in quantity for a popular market. In the Roman period, gems became more and more affordable, but their quality was proportionate to their price. During the Republic a gem set in a ring was mainly used for sealing. The common material for rings was iron, and to wear a gold ring was a mark of distinction. In the Roman Empire, however, the privilege was extended to people of lower rank and the number of rings worn by an individual increased. In the course of the first and second centuries A.D., gems and jewellery in general became increasingly common and no longer the preserve of a wealthy élite. Finds made in legionary camps throughout the Roman Empire suggest that many soldiers owned finger rings set with gems. These precious objects are very often found in the drains of public bath installations, where they had been accidentally lost. Since some sort of natural adhesive, such as resin or bitumen, was used to secure Roman ring-gems, in the hot and damp atmosphere of the baths they simply came unstuck. Although Romans must have been aware of the danger of losing their ring-gems, they continued to wear them, probably because of the belief that they were more vulnerable to harmful supernatural influences when naked and that their gems would protect them. There is ample evidence that gems were also connected with superstitious uses. Some were believed to have curative and protective powers. Pliny gives a long account of the magical properties of stones. He is generally critical of the superstitious claims made by the Persian magicians, the magi. A certain kind of agate, for instance, was said to be beneficial against bites of spiders and scorpions. Haematite was said to be good for the eyes and liver, caused petitions addressed to kings to succeed, was useful in lawsuits, and mixed with juice of pomegranate would cure those who vomited blood. The healing properties of gems were indeed very much in demand. A haematite gem in St Petersburg has an inscription which makes its function clear: stomachou (of the stomach). In the Roman period we find a marked incraese in teh number of gems used as talismans. In Egypt a particular kind of gem was engraved with syncretistic deities and magical inscriptions. Since these were not to be used as seals, the cutting is mostly in positive on the gem. Love spells were also cast by means of engraved gems, either to attract the favours of a reluctant lover, or take revenge on a cheating partner.