Black Onyx Disc Collar Necklace in 18kt Gold Over Sterling. 16"

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."

LOBSTER CLASP: named after the pinching style of the hook, this clasp is often shaped like a lobster's claw. Use your finger to work the lever to open the clasp.

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.

CHECKERBOARD: A technique that creates a contrast of dark and light when light hits the pattern of square or diamond-shaped facets.