What is the difference between traditional karat gold, gold filled and gold plated?
First let's clarify that no jewelry in retail today is made from pure gold. The most popular karats used are 18kt, 14kt and 10kt with 14kt being the most common.
What is a karat? A karat measures the purity of gold. Pure gold being 24 karats.
So, what is the difference between karat gold, gold-filled and gold plated? Pure gold is usually mixed with a metal like copper, silver and/or zinc to make jewelry The other metals increase the strength of the gold because 24 karat gold is too soft. Each karat represents 1/24th of the whole. Karat gold is essentially an alloy of mixed metals. Now, with that said, here are the differences that my research has revealed:
Gold is an elemental metal. That means that pure gold is only made up of gold atoms. In its natural form, gold is buttery yellow and has a bright shine or high luster. It is extremely soft and malleable and scratches easily. Gold in its pure state is rarely used for jewelry making. Any jewelry created using pure gold would not be able to hold its shape and any gemstones that would be set in it would probably end up falling out. So, other metals are added to increase its strength creating a "gold alloy". An alloy is the combination of any two metals. Gold alloys are created by melting pure gold and mixing it with another metal (usually silver, copper, tin, or zinc. Almost 100% of all fine jewelry made today is made from some sort of gold alloy.
Gold filled jewelry is created by wrapping one or more sheets of solid karat gold (18K, 14K, 12K, etc.) around a base metal (usually brass) under very intense pressure. These gold sheets are now effectively "filled" with something other than gold. Unlike gold plated jewelry, gold filled jewelry has a measurable amount of actual gold in it. Here in the United States, the law requires that items marked with G.F. (marking for gold filled) must be at least 1/20th gold by weight. Example: 14K gold filled is 14/20 gold by weight. Gold filled is permanent and does not flake off, rub off or turn colors. It will last for decades.
Gold plated jewelry is created using a base metal (e.g. copper or silver) that has a molecule layer of gold applied on top. The layer is so thin that it can actually be rubbed off with a coarse pencil eraser in just a few strokes. Gold plated jewelry should be considered nothing more that a coloring of gold to a base metal. There is almost no value to the gold applied no matter if it's labeled 24K, 14K or 18K.
Now that we know the difference between them all, here are a couple of visual examples.