C. 1980 Vintage 16x12mm Cultured South Sea Pearl and .93 ct. t.w. Diamond Swirl Ring in 18kt Yellow Gold. Size 5.5

18KT: Karat (abbreviated kt or K) is a unit that indicates the purity of gold in the metal. 18kt is 75% gold. In Europe, 18K yellow gold is most favored and used in jewelry.

YELLOW GOLD: Gold is a precious metal with a natural yellow color. It is quite soft and often alloyed with other metals to increase its strength. The purity of the metal is indicated by a unit called a "karat," with 24kt having the highest percentage of natural gold.

SOUTH SEA PEARLS: With a dramatic 9mm-20mm size and glowing satiny luster, South Sea pearls are among the rarest and most coveted of cultured pearls. Found in shades of white, silver and gold, South Sea pearls are an exquisite sight in jewelry designs.

Diamond: The hardest and most brilliant of all gemstones, a diamond can make the heart race with its pure and fiery spark. An ancient symbol of love, a diamond is the preferred gemstone for tokens of affection, such as rings, earrings, necklaces and bracelets. Diamond is the birthstone for April.

BRILLIANT: A gemstone cut to enhance brilliance without sacrificing much carat weight. Typically has 58 facets.

Color Grade G-H: Near-colorless

CLARITY SI2: Slightly Included. Inclusions are noticeable under 10x magnification.

BAGUETTE: An elongated rectangle step-cut. Typically used for smaller diamonds, but can be found in other gemstone as well.

Color Grade H-I: Near-colorless

CLARITY SI1-SI2: Slightly Included. Inclusions are noticeable under 10x magnification.

MARQUISE: An elliptical shape that comes to a point at the top and bottom. Sometimes referred to as a "navette."

CLARITY SI1: Slightly Included. Inclusions are noticeable under 10x magnification.