The term “gold filled” describes metal that is made up of a solid layer of gold (10, 12 or 14kt) bonded with heat and pressure to a base metal core. This base metal is usually brass.
To be called gold filled, the gold portion of the metal must equal at least 1/20 the weight of the total piece. To identify a piece of jewelry that is made of gold filled material, the manufacturer stamps the piece “1/20 12kt GF.” The karat notation will vary depending upon the karat of the gold used in the piece.
Gold filled wire and clasps are made from sheets of gold filled material. This process differs from “gold plate.” Plated items are made from base metal and the gold is added to the surface after the piece is fabricated. The plating is adhered using a chemical or electric process and the layer of gold on the piece is much thinner and not as durable as gold filled.
Gold filled metals will eventually lose their luster. To extend the life of the piece, avoid immersing in water or jewelry cleaning solution. Clean pieces by gently rubbing with a polishing cloth.