Gold is as valuable as it is beautiful, but there are limits to what it can do. Gold is one of the softest solid metals on the planet, with only lead or cesium edging it out of the top spot. Mercury doesn’t count since it’s liquid at room temperature and that’s cheating. To get around this, gold is often mixed with other metals to make them softer and gold stronger. In jewelry, this usually results in lower fineness, or gold fill jewelry, gold plated jewelry, or vermeil.
But what’s the difference between all those?
Fineness refers to the weight of the precious material compared to the weight of the object. For gold, silver, and platinum, the weights are measured in parts per thousand and then converted to karats (kt). Sterling silver is referred to as 925, since there are 925 parts of silver for every 1000 parts of sterling silver, the remaining 75 being copper. For gold, the karat system is used in the US and UK, so instead of 999, most people know it as 24 kt gold.
However, most jewelry does not contain that high a quality of gold. Because of how soft gold is, if there is any hope of longevity it has to be mixed with another material. For jewelry, this means gold fill, gold plate, or vermeil.
Of the three, gold fill is the most expensive type of gold jewelry. Much like vermeil or gold plate, gold fill is a layer of gold on top of a base metal that helps the piece retain its shape. It differs from the other two significantly in that gold fill uses about twice the amount of gold and it’s using a higher quality.
To be considered “gold fill”, the item must use at least 10 kt gold. If that is the case, at least 10% of the item’s weight must be gold. If the item is using 12 kt gold or higher, then it only needs to be 5% of the item’s weight.
The gold is mechanically bonded to the base metal, usually silver but just about any metal will do. Mechanical bonding doesn’t use chemicals, instead relying on the molecular structure of the materials. Basically, it works like keys and key chains on a key ring. Nothing is adhered, meaning the keys and key chains can move freely over the key ring, but they cannot be separated without breaking the key ring.
This bond is the reason why gold fill jewelry almost never tarnishes.
Gold plated jewelry is the same as gold fill in theory, but they are vastly different processes. It uses a much smaller amount of gold, only needing enough to cover the object. Gold plate can be applied to just about any surface, making it easier to make than gold fill. However, instead of having the incredibly durable key ring bonding the gold to the base, it only has glue, which eventually will fail. Both electroplating and chemical plating use an adhesive, of sorts, to bond the gold to the base material. These methods require less material, allowing for lower prices and easier access, but with the cost of tarnishing. Eventually, gold plated items will need to be refinished.
Vermeil is a type of gold plate. It’s the French term for “silver-gilt”, meaning gold plated silver. The silver used is usually at least sterling silver. In order to qualify as vermeil, at least 10 kt gold must be used to gild the surfaces of the item. Furthermore, the gold layer must be at least 2.5 microns thick, or about 5% of the width of a normal human hair. Because of these standards, vermeil is considered a higher quality form of gold plating. It still uses chemical bonding or electroplating to gild the item in gold, like standard gold plate, but the higher quality and thicker layers make it less likely to tarnish.
Anything made of sterling silver can become vermeil. Most vermeil flatware is simply gold plated sterling silver, as are most trophies, pieces of jewelry, and other fine items.
Want to know more about metals in jewelry? Click here to learn about silver or here to learn about nickel.