On the basis of beauty, stones cannot be divided into precious and semiprecious for, from stone to stone, there is continuous range of color and glow. Nor indeed can price be the one criterion, for here many elements produce variety. Although the term “gem of the first water” is reserved for the flawless blue-white diamond, as the carats of the single stone increase the flawless ruby and the emerald become even more costly; and varieties and special specimens of other stones, such as the fire opal and imperial jade, move up into comparable range. For certain individuals, of course, a particular stone will have associations of sentiment that render it more precious—in the nontechnical sense—than another stone in the category of “precious.” It is, then, tradition rather than any inherent value that sets a secondary label, “semiprecious,” on all but five of the stones used for human adornment. Let us call these five the gems, to distinguish them from the other stones. _The Gems_ There is no doubt that the five gems—diamond, ruby, emerald, sapphire, and pearl—have grown more fully than all others into our ways of living. They have become, as I shall indicate in this chapter, adornments not only of our persons but of our speech and writing. They are used not only in figures of jewelry but in figures of speech, to express human beauty, or eminence, or virtue. The poet and the orator, as well as the monarch and the lover, have utilized the glamour of the gem. _Diamond_ Supreme in human imagination is the diamond, the hardest of all stones. The word _diamond_ captures this significance, for it is from Greek _adamas_, meaning unconquerable, the tameless stone. The diamond is also the only gem that is entirely composed of a single element. It is carbon, which also appears in its more common and less costly forms as soot, jet, and coal. The diamond is pure carbon crystallized in regular octahedrons, eight-sided figures. For a long time, one word was used to mean both the diamond and the lodestone, the natural magnet. In French today, the gem is _diamant_, and the magnet is _aimant_—which also means loving. Perhaps the word changed because the natural magnet, attracting things to it, was thought of as “the loving stone.” The diamond is the beloved stone. Most diamonds at their best are colorless, with perhaps a bluish glow. They may also be blue, green, violet, less often red—and black. The black diamond is usually unwanted for jewelry, but is used by lapidaries and others for cutting, grinding, and polishing hard stones. If a jeweler speaks of a Matura diamond or a Ceylon diamond, he is using an old trade name for a zircon. Similarly, a Welsh, Irish, Cornish, Quebec, or California diamond is likely to be an attractive piece of rock crystal.