Gold-filled jewelry is made by plating a core of base metal, such as brass, with a relatively thick layer of solid gold. The layer of solid gold plating on gold-filled jewelry is considerably thicker than that on gold-plated jewelry. Consequently, gold-filled jewelry is more resistant to discoloration and fading
Gold filled jewelry is made from karat gold which has been bonded to the surface of a supporting base metal through a process of fusing and rolling. It is always marked with the karat designation and an indication that it meets the legal standard. Look for marks such as 1/20 12K G.F. or 12 Kt. Gold Filled. Rolled gold plate is also made by fusing and rolling gold onto base metal, but the plating is significantly thinner. Rolled gold plate may be marked 12 Kt. R.G.P. or 1/40 12K R.G.P. Another mark you will sometimes encounter is G.E., or gold electroplate. This is the thinnest of all gold plating techniques. The gold or gold alloy is not fused and rolled onto the base metal beneath, but rather plated in solution using an electrical charge to make the bond. By law, gold electroplate must be at least 7/1,000,000-inch thick, but this is extremely thin when compared with gold filled.