Garnet is a collective appellation that's used to describe more than ten jewelry stones which share a similar crystalline structure. The word "garnet" is typically associated with a red stone, but this is only true for the two most common members of the garnet group: the "carbuncle stones" pyrope and almandine. Like their relatives (e.g. green tsavorite and brown to yellow hessonite), these gems have good hardness and high refraction. Garnets are found on every continent.

Gemmology is the science of precious stones. The German language has two cognates for this specialty: Gemmologie and Edelsteinkunde. Irregardless of the name, the people who are active in this discipline devote themselves to the identification and technical processing of precious stones and to the investigation of methods which can be used to differentiate between natural precious stones on the one hand, and synthetic or imitation stones on the other.

Gemstones are nonmetallic materials characterized by the beauty and transparency of their colors, by their hardness, and/or by their rarity. In the past, it was common practice to distinguish between gemstones (which are especially clear and hard) and semiprecious stones (which are nontransparent, less resistant, and less valuable). This distinction, however, makes little sense, so the terms "gemstone" and "jewelry stone" have become more common in modern usage. The weight of a gemstone is measured by the carat (0.2 grams). Gemstones are found in rocks and ores. Transparent gemstones are often cut into faceted shapes (e.g. the "brilliant cut") to accentuate their inherent play of lights. Translucent and opaque gemstones are usually cut into a smooth domed shape (cabochon)

The abbreviation GIA refers to the Gemmological Institute of America, which has its headquarters in Carlsbad, California. The institute is recognized throughout the world as an authority in the fields of gemmology and the grading of diamonds. The GIA is also active in science, research, and teaching. As an educational institution, it offers highly respected gemmological training. Founded in 1931, this noncommercial organization operates branch offices throughout the world. The European headquarters of the GIA are in Vicenza, Italy and London, England.

Gold is one of the first metals used by mankind. Human beings have been fascinated by gold since time immemorial. The metal has a gleaming yellow color, is immune to rust, and is extraordinarily ductile and malleable. The name "gold" derives from the Old High German word "ghel," which means "shimmering" or "gleaming." The chemical symbol for gold, "Au," is derived from the Latin word for this metal, "aurum." Pure gold is very soft: before it can be used in jewelry, gold must be blended with other, harder metals to create a harder alloy. The admixture of other metals also influences the color of the alloy: the addition, for example, of silver gives gold a greenish cast.

The goldsmith's profession is a traditional career with a very long history. As early as the third millennium BC, the Ancient Egyptians had already begun to cultivate the goldsmith's art: ancient craftsmen artfully worked gold and silver, along with various precious stones and pearls, to create jewelry, utensils, vessels, and other objects. Techniques such as hammering, casting, chasing, punching, engraving, granulation, and enameling have been practiced since ancient times. Nowadays, the goldsmith's profession is an art and craft which requires an apprenticeship of at least three years' duration.

The grading or evaluation of diamonds is known as "graduation." The appraisal is conducted in accordance with internationally recognized, objective criteria. Based on these criteria, diamonds are graded according to their color, clarity (purity), cut, and carats (weight). These four criteria are summarized under the abbreviation "the 4 Cs."

Pearls are natural products. Although human beings have learned to cultivate pearls and thus to intervene in this natural process, the genesis of a pearl is still subject to the whims of Mother Nature. Cultured pearls grow inside bivalves which are cultivated in underwater "farms." Alternations in water temperature and natural variations in the concentration of nutrients in the water influence the bivalves' production of mother-of-pearl, which is the material that accumulates layer by layer to create a pearl. The serial accumulation of these layers often leads to the formation of the ridges or rings which distinguish a genuine pearl and which are regarded as marks of its natural growth.