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THE ALLOYS OF GOLD

The following is a 2 part series describing the wear ability of the most commonly used precious metals.

PRECIOUS METALS

The usual concept is that jewelry makers select the Precious Metal they use in their jewelry based on price or color design, but there is a third reason that is just as important. The third reason pertains to how well the wearers’ body will tolerate the exposure to that metal.

Precious metals are considered to be non-reactive metals (easily tolerated) that is why dentists and surgeons use them. But not all people can wear them without a problem. Those people who can’t tolerate them can get dark metallic stains on their skin, plus a nasty rash or other allergic reactions. This is most true with precious metal alloys, such as Karat Gold and Sterling Silver. These alloys are created by adding other metals (many are reactive) to a precious metal to strengthen it and/or lower its’ costs. On many occasions, the wearer can tolerate the actual precious metal, but they can’t tolerate the other metals in the alloy. For example, higher karat Gold can be more easily tolerated because it has less reactive metals than their lower karat cousins.
I friend of mine in Arizona creates beautiful beaded jewelry, but she can’t wear any of her creations. Like a number of other people, her perspiration eats right through the solid Gold layer in Gold Fill, and it pits all solid Gold and Silver alloys. In order to wear and demonstrate her own creations, she must make special, limited edition, 24 karat Gold versions of her jewelry. Otherwise she will end up with a dark stain and rash anywhere the Gold or Silver alloy touches her skin.

THE ALLOYS OF GOLD

Gold is usually alloyed for three reasons. The first is to strengthen it. Gold is a very soft metal, so by alloying it with other metals it gains strength. The second is to produce gold in different colors, such as yellow, white, rose, green, etc. The different colors of Gold are produced by the addition of specific metals, in differing proportions, to the Gold alloy. The third is to lower the cost of the precious metal.

These alloys of gold are designated by the term “Karat.” Pure Gold (100%) has 24 karats, or 24/24 parts gold. The karat number is based on the percentage of Gold in the alloy, but the specific metals in the alloy aren’t important. The most common metals found in karat Gold alloys are Silver; Copper; Nickel, and Iron, but almost any other metal can be used. Below are examples of karat Gold alloys:

10 karat Gold is 41.67% pure Gold & 58.33% “other metals” (primarily copper, some Silver, and probably Zinc.
14 karat Gold is 58.33% pure Gold & 41.67% “other metals”
18 karat Gold is 75% pure Gold & 25% “other metals”

As you can see, the lower karat gold alloys have greater percentages of “other metals” in their mix. These “other metals” in the alloy can react to pollutants in the air and environment at a much greater rate than the higher karat alloys. For example, the higher percentages of Copper, Silver, and other non-gold metals in the mix, can oxidize (tarnish) and/or corrode, especially during hot weather when those metals react to the salt and acids in perspiration.

As I stated earlier, some people cannot tolerate these “other metals” and “can get dark metallic stains on their skin, plus a nasty rash or other allergic reactions.” Also, people who have problems when wearing silver jewelry will usually have problems when they wear low karat, or white gold, too. The “whitening” metal added to the white gold alloy is usually nickel, and nickel allergies are the most common among the metals. In reality, White Gold isn’t white. It is a pale gold color and must be plated with Rhodium to appear “white”. Very soon, a new truly white Gold alloy, named “Great White” should be available.