Black Onyx and 1.90 ct. t.w. Multi-Stone Leaf Ring in 18kt Gold Over Sterling. Size 6

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."

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.

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

GARNET: the birthstone of January. One glance at the deep red seeds nestled inside of a pomegranate explains why the word "garnet" comes from the Latin word "granatus," meaning "grain" or "seed." This name was given to the garnet because of its close resemblance to the succulent seed.

TOPAZ: Available in a stunning selection of shades, the topaz's sky blue hue is one of the most popular colors for jewelry designs. Once thought to offer protection, today topaz is favored for its durability and affordability. Yellow topaz is the birthstone for November while blue topaz is for December.

AMETHYST: A natural variety of quartz, amethyst ranges in color from deep purple to pale lavender, and even to warm greens. Amethyst has been used during meditation to provide a sense of spiritual balance. Amethyst is the birthstone of February.