What is a carat?
and why more is not always better
The carat is one of those measurements that we all know, but that we cannot always define. “24 karat gold.” “A 10 carat diamond.” We know that it has to do with jewelry and that it somehow indicates “quality”.
Very well. But what is a carat exactly? We are going to see it in this article, as well as the reason why more carats does not always mean something better.
The origin of the carat
The word carat comes from the Greek: “keration”, which was the name given to the seed of the carob tree.
These seeds have two peculiarities:
- That they are very homogeneous, all of them weighing practically the same: around 0.2 grams, that is, 1 carat weighs 0.2 grams, the same as 1 carob seed. And 1 gram equals 5 carats.
- Found throughout the Mediterranean, since the carob was a widespread common tree
This made them very useful for ancient goldsmiths and merchants, since there were no precision tools that could indicate the weight of a jewel. By balancing the scales with these carob seeds, they were able to weigh pieces as small and valuable as a gem quite accurately.
The carat today
Now the story has changed. And, in fact, we must differentiate two types of carats.
On the one hand there is the carat in gemology. This is still a weight unit equivalent to those 0.2 grams. So an emerald of, say, 34 carats, will weigh 6.8 grams (and it will be an important stone!).
But on the other hand there is the carat of goldsmithing. And this, which is the one that everyone knows the most, is the one that changes the most in meaning.
Carat in noble metals
In goldsmithing, we call carat the unit of purity of the precious metal in a given alloy. Through a very special system of proportions, divided into 24 parts. The reason?
As you are sure you know, pure noble metals are rarely used in jewelry. A gold ring is almost never made of pure gold: the metal is mostly gold, but it includes proportions of other metals such as silver, platinum, copper, zinc, tin, etc.Well, karat indicates how many parts of that piece are pure gold:
- 24k gold means that out of 24 parts, all 24 are fine gold.
- 18k gold means that of 24 parts, 18 are gold, while the remaining 6 are other metals (which is approximately 75% pure or fine gold)
- In 12k gold, we speak of 50% purity: 12 parts are gold, and 12 parts are alloy.
Why doesn’t always more carats mean a better jewel
Since gold is one of the most valuable metals in the world, the first thought tells us that a jewel made in 24 karat gold is more valuable than one made in 18 karat gold.
And it will be more valuable, at least strictly speaking of the value of the metal.
But it happens that pure gold is a very malleable metal. Have you ever seen a pirate biting a gold coin in a movie? It is that to check if it was pure gold they just had to bite it: the mark of the teeth was imprinted on the metal.
Therefore, a piece of pure gold will be more valuable “by weight” in the market. But as a jewel… Do you really want a jewel that you can bite?
A jewel of pure gold simply falls apart over time. Marks, signs, scratches, etc. appear.
For a gold jewel to be resistant, as well as beautiful, it is necessary to lower the proportion of pure gold and allocate it with other metals, which give it the characteristics of resistance and hardness that a jewel needs to be able to wear it.
In addition, in these alloys a lot of art is hidden, since depending on the chosen metal, and its proportion, we obtain different shades of gold that go from white to pink, and that allow create truly spectacular jewelry.
But about all this, it will be better to talk in another article in the coming weeks.