Answer:
Gold-Filled Wire Explained
Gold-filled wire is essentially a core of base metal, usually pure jeweler's brass, encased in a thick layer of gold, typically 14k, but sometimes 12k or 10k. The gold and base metal are bonded together through heat and pressure to form a durable, solid material.
In the United States, the Federal Trade Commission (FTC) defines quality standards for gold-filled items. For example:
10KGF (10 Karat Gold-Filled) means the gold layer must be at least 1/10th of the total weight of the item.
12KGF means the gold layer must be at least 1/20th of the item's weight.
In Europe, the same concept is referred to as "rolled gold."
The key benefit is that all visible and skin-contacting surfaces are genuine karat gold. Unlike gold plating, the gold layer on gold-filled wire does not chip or wash away easily.
With regular, everyday wear, a 14/20 gold-filled jewelry piece can last anywhere from 5 to 30 years, offering an affordable yet long-lasting alternative to solid gold.
Rolled gold 'plate' however, is just as it is called: plated. When a base metal is coated with a thin layer of gold via electrolysis it has been 'plated'. If the base metal used is sterling silver and 18K gold is bonded to it, it is called Vermeil. Gold plate will wear off quite quickly, and the base metal below will tarnish.
14k gold-filled items contain 50,000 to 100,000 times more gold than regular gold plating, depending on the manufacturer, and are 17,000 to 25,000 times thicker than heavy gold electroplated items. I have been using 14/20 gold-filled wire for jewelry making for many years and have never had any pieces returned due to issues with the gold wearing off or coming loose. (Yes, I also occasionally work with 14k and 18k solid gold, but that can be extremely expensive.)