Contrary to what the name suggests, gold-filled is actually where all the gold is on the outside. It is a thick, outer layer of durable gold that covers another metal, usually a brass core. The gold is pressure bonded to the inside metal. The gold layer is 14k, and per industry standards, typically constitutes at least 1/20th or 5% of pure gold by weight. It is different from gold-plated in that it has 100x more gold so it is much thicker. Gold-filled jewelry is very durable and long lasting.
