Gold-filled jewellery differs from gold vermeil in both the quantity of gold involved and the process which bonds it to the base metal. Where gold vermeil is achieved by an electrochemical process known as electroplating, gold-filled jewellery is made using a mechanical process that uses intense heat and pressure to attach the gold surface layer to the base metal.
For a piece of jewelry to be legally stamped with the telltale ‘GF’ marking, its weight must be at least 1/20th gold. This explains the typical stamp you’d expect to see on gold filled articles: “1/20 12 kt GF”, which means that 5 percent of the piece is 12 karat gold. Because the surface layer of gold-filled jewelry is about 100 times thicker than that of gold vermeil jewelry, gold-filled pieces tend to last much longer, and are considered ‘lifetime jewelry.’
Naturally, they are also more expensive than gold vermeil as they simply contain more gold. The price still represents a significant break when compared with solid gold, however, and since gold-filled jewelry is virtually indistinguishable from pure gold in terms of appearance, feel, and wear, it is thought to be a great balance of cost and quality.