Gold-plated jewelry consists of a lower-quality base metal coated with a very thin layer of gold through a chemical process, while gold-filled jewelry has a thicker layer of gold bonded to a base metal through heat and pressure. Although both gold-plated and gold-filled jewelry consist of a base layer covered with gold, they differ in the process used to attach the gold and the thickness of the gold.
Copper and silver are often electroplated with gold. Gold-plated silver is called silver-gilt. Gold-plated jewelry is subject to tarnish, and the gold wears off more quickly than in gold-filled jewelry. Brass is the most common base metal used for creating gold-filled pieces. High-quality gold-filled pieces are difficult to distinguish from 14-carat gold.