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.

STERLING SILVER: Also known as "Standard Silver," sterling silver is silver alloyed with other metals to increase the hardness and durability. Generally, sterling is 92.5% silver and 7.5% other metals. Some sterling silver jewelry is plated with 14kt-18kt gold and referred to as "vermeil," or "gold over sterling."

CHALCEDONY: a family of minerals that is often milky gray or bluish in color. Chalcedony includes a number of stones including onyx (black), carnelian (waxy red), agate (wide ranging palette) and bloodstone (brownish red.)

CUSHION: A gemstone that features a rounded square shape. The facet arrangement can be either a type of modified brilliant cut or a checkerboard pattern.

ROCK CRYSTAL: A sparkling, clear gemstone, rock crystal has been valued for thousands of years for its beautiful shine and versatility. For jewelry designs, rock crystal can be cut to offer the same icy appeal of a diamond, at a fraction of the cost.

QUARTZ: From the icy shimmer of rock crystal quartz to the delicate pink of rose quartz to the moody hues of smoky quartz, this gemstone offers something for everyone. Quartz, found in endless colors and varieties, is a popular choice for bracelets, necklaces, rings and earrings.

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

ROSE-CUT: An antique gemstone cut dating back to the 1500s, with a flat back and a faceted top.

MOTHER-OF-PEARL: Glowing with an iridescent beauty, mother-of-pearl has been showcased in jewelry designs for thousands of years. As mother-of-pearl is a natural substance, it may vary in appearance, and its distinctive shimmer lends a quiet elegance to fine jewelry.

SLICE: A thin, usually flat piece cut from a gemstone. Often has a free-form shape and reveals the natural beauty of a gemstone's interior.