It is a layer of 10Kt or better gold mechanically bonded under heat & pressure to one or more surfaces of supporting base metal, then rolled or drawn to a given thickness. In the jewelry industry the quantity of gold must be at least 1/20th by weight of the total product. Under FTC (Federal Trade Commission) regulations, a product may be marked as 14, 12 or 10Kt Gold-Filled. Karat measurement of the gold content MUST be part of the marking or designation. (Beware of items offered as simply 'Gold-Filled' rather than 14Kt Gold-Filled or 10 or 12Kt Gold-Filled when trying to compare prices!) The finished product thus has a surface layer of gold of the the appropriate karatage, which is very thick compared to rolled gold plate or the heaviest electroplate ( = gold plated) material. These are minimum standards. Thus one might find 14/20GF or even 14/10GF as a stamp to denote 1/20 14KT Gold-Filled or 1/10 14KT Gold-Filled. Gold-Filled items are generally considered life-time products, and the gold layer will not quickly wear off, as it will in electroplated products. We do very rarely find an individual who cannot wear this material .