Gold: A heavy, malleable metal element that is unalterable by heat, moisture and most corrosive agents. It is used in a wide variety of jewelry styles and processes. Too soft to be used alone, it is often combined with other metals. Gold à Quatre Couleurs: Gold in four different shades used simultaneously in one piece of jewelry. In some cases it refers to three or five different shades of gold combined in one jewelry item. Gold Alloy: Gold that is alloyed with a variety of other metals, including silver, palladium, copper, nickel, iron or others, all depending on the desired strength, color and intention of its final use. Gold Filled: Gold bonded to a base metal by electroplating. It is usually done to a layer of specific fineness. Gold Leaf: An extremely thin tissue of gold used for gilding. Karat: The measurement for the fineness and purity of gold and gold alloy, as expressed by a number (e.g., 24 karat, 18 karat, 14 karat). In appraising gold jewelry, the higher the number of karats, the greater is the value of the piece.

Platinum: A metal element whose rarity and unusual tensile strength make it extremely valuable, with a price exceeding even that of gold. It is a heavy, silver-white element that is malleable and ductile and does not corrode. Nor does it tarnish. It needs great heat to fuse, and this durability -- coupled with its harmonious color -- make it ideal as a diamond setting. When employed for jewelry, it is used in the form of a platinum alloy.

Purity: A measurement of the amount of pure gold in a jewelry item. 24 karat represents 100 percent gold; 18 karat has 75 percent gold, and 14 karat has 58 percent gold.

Quality Mark: By United States law, a "k" mark representing karat must appear on the back of an authentic gold piece, along with the manufacturer's trademark and country of origin to guarantee the authenticity of the gold.

Rose Gold: A gold alloy with additional copper added to it to give it a blushing hue.

Sterling Silver: An alloy of silver with a fineness of 0.925 parts silver (in Great Britain) and 0.075 parts copper. In the U.S.A. the measurement is 0.921 parts silver.

White Gold: An alloy of gold with a large percentage of silver or other white metals.