Gold filled jewelry is created using a sheet of solid gold, which must constitute at least 5% (1/20) of the item's total weight, which is pressure and heat bonded to a sterling silver or base metal core (such as jeweler's brass). Creating gold filled materials is a unique and technical process, and only a few mills in the world do this. Gold filled items are 5-10 times thicker gold layer than regular gold plating and 15-25 times thicker than gold electroplate, making it much more valuable and longer lasting because it is a layer of actual karat gold, not a microscopic film. Gold filled does not de-laminate or peel like plated or "dipped" pieces, and with proper care it can last for as long as 30 years.