C. 1980 Vintage Black Onyx and .70 ct. t.w. Diamond Knot Clip Earrings in 18kt Yellow Gold

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.

CLIP: An earring that clips-on with a clamp backing, relying on tension and friction to hold it in place. Perfect for people who don't have pierced ears.

ONYX: A favorite of the ancient Greeks and Romans, this gemstone adds a sophisticated shine to rings, necklaces, bracelets and earrings. A dyed form of chalcedony, onyx is most popularly found in black although it can be green, white or red, as well.

TRIANGLE: A three-sided, pointed shape.

CABOCHON: A style of cutting gemstones to achieve a smooth, domed surface with an absence of facets.

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 VS2: Very slightly included. Inclusions are observed with effort under 10x magnification, but can be characterized as minor.

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