Since entering the world of precious metals, I have wondered about some of the terminology and how it came to be. I had always thought “carat” and “karat” were interchangeable but I quickly found out that this is not the case.
A carat is a unit of weight used to describe diamonds and other precious gemstones, such as pearls. One carat is equal to 200 milligrams, which is the same as 0.2 grams. A two-carat diamond would weigh 400 milligrams (0.4 grams).
A karat, on the other hand, is a measure of purity when referring to gold. You may have seen different types of jewelry referred to as 14-karat gold or 18-karat gold. What does that mean and what’s the highest karat gold that exists?
Pure gold is known as 24-karat gold. Gold is a fairly soft metal, though, so it’s not often used to make jewelry in the US. However, in certain countries 24 karat is quite popular. Jewelry made of pure gold can be easily bent and scratched.
Gold is often mixed with other metals, such as copper or silver, to form an alloy that can be used to make jewelry. A karat is equal to 1/24 pure gold, so an 18-karat gold ring would be made with 18 parts gold and 6 parts of another metal.
The amount of gold in jewelry affects its value greatly. For example, 10-karat gold jewelry is less than half gold. On the other hand, 18-karat gold is 75% gold. The purest gold jewelry commonly available is 18-karat gold, and it’s usually much more expensive than lower-karat varieties.
So how did such a measurement of purity come about? Over 1,000 years ago, a German gold coin called a mark was very common. It happened to weigh 24 carats (4.8 grams) and was pure gold. People decided to describe the purity of the gold in the coin based upon its weight in carats and over time changed the “c” in “carat” to a “k” to distinguish the two different measurements.
In the United States, the Federal Trade Commission (FTC) sets the rules for marking jewelry with a karat value. Under FTC regulations, pieces of jewelry that are 10-karat or greater should be stamped with either a “K” or “Kt.”
For more cool facts… Source: Woneropolis.org