Pink Chalcedony Ring in 18kt Yellow Gold Over Sterling Silver. Size 9

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.