What is gold-fill?

Gold Filled Metal is the next best thing to karat gold and far superior to any plating.
In the US, gold-fill content is regulated by the FTC. By law, gold-fill metal must contain a certain ratio of karat gold, by weight*.
The outer layer of solid karat gold is mechanically pressure- bonded to a base metal or silver core. The most common core is jeweler’s brass (an alloy of 15% zinc & 85% copper).
Because gold-fill metal is limited to components which can be manufactured from one of the above forms, it is not possible to cast items in gold-fill. A cast item that is labeled “gold-fill” is most definitely plated.
*14/20 gold-fill means that 1/20th (5%) of the weight must be 14k gold.
*12/20 gold-fill means that 1/20th (5%) of the weight must be 12k gold.