What is a Gem?

   A gem is a precious or semiprecious stone used chiefly as a personal ornament. Pearls and some engraved shells are also considered gems. Gem stones are usually cut and polished to show their beauty. They are used principally in settings of metal for jewelry. In their natural state, be­fore they are cut and polished, gem stones are normally dull and rough, coated with a crust that causes them to look like ordinary rocks. The cutting and polishing are difficult and delicate operations.

   When men first began to use gems is not certain, but gems were already known and used in the days of the Babylonian, Assyrian, and Egyptian empires. These early gems were often engraved and used as seals to stamp personal marks on clay tab-lets. Museums and private collections in Europe and America contain large numbers of gems from the Greek and Roman periods. Most of these are beautifully engraved with figures of people and animals. In the Western world the art of gem en-graving was apparently lost after the collapse of Rome and was not revived until the time of the Italian Renaissance. Some of the ancient gems were then discovered in Florence, and Florentine artists were inspired to do similar work.

   Precious stones are those that have great value because they are rare, beautiful, or durable. The most valuable of them are the diamond, ruby, sapphire, and emerald. Other stones of less value, such as agate, amethyst, opal, jade, and moonstone, are considered to be semi­precious stones. In general these are more abundant and are not so hard.

   The manufacture of artificial gems is an important business. In 1955 a process using tremendous pressure was developed to produce synthetic diamonds but at a cost greater than that of the natural ones. The production of synthetic rubies represents the greatest success in making artificial gems. Syn­thetic rubies are true rubies, not imitations or paste. They differ from the natural stone only in that they are made by man and not by the slow processes of nature.