"Gold-filled” is a Canadian industry standard that legally requires 1/20th, or 5% pure gold by weight. It’s a strictly regulated process that involves pressure bonding multiple layers of solid 14k gold with extreme heat over a core of high quality jeweler’s brass resulting in a durable, quality real gold product.
Even though is is labelled Gold Filled, all the gold is on the outside. It is a thick layer of Gold unlike Gold Plated which is a microscopic plating of Gold. Gold Filled refers to a thick outer layer of durable, pressure-bonded, real, solid gold...on the outside. No filling.
The thick layer of Gold is usually on the outside of a brass core.
Gold-filled jewelry is required to have a minimum of 1/20th (5%) gold by weight. The 5% gold in gold-filled jewelry may not sound like a lot, but it’s all on the outside and it's plenty to keep your jewelry looking great for many years.