What is 24K, 18K, 14K gold and other carat measurements

What does 18 carat, 18 carat and 18k mean for gold?

Here in Peru, I notice a bit of confusion about what is 24 carat (24K), 18 carat (18k) gold and other measures such as 14k and 12k. It is nothing more than the concentration of gold that a piece has: or in other words, the purity of the gold. In this entry I explain the meaning of these symbols.

Why is the purity of gold measured?

Pure gold is 24K. But pure gold is very soft and does not hold its shape well. So we jewelers combine the gold with other metals to harden the gold. We typically combine gold with silver and copper to create "yellow gold." But by adding those metals, the gold is no longer pure. And since gold is the most expensive metal among the three, the buyer has a right to know how much gold is in a piece. An honest jewelry store always provides this information.

Why is the purity of gold measured in karats and not in percentage?

That is a good question. It would make more sense to say 100 gold, right? It is my understanding that it comes from ancient Roman culture. 

So what is 22k, 18k, 14k and 12k gold?

These numbers signify the concentration, by weight, of the gold in a jewel. I hope this table clarifies the matter:

The calculation is as follows: take the title in carats and divide by 24. That gives the percentage of gold in the jewel. For example 22/24 = 91.7%

An 18k gold jewel weighing 10 grams will have 7.5g of pure gold and 2.5g of other metals.

Why should I buy 22 karat or 18 karat gold considering that 14k and 12k are gold too?

Gold does not oxidize like silver. It may lose its luster a little after many years. But it does not corrode. By adding other metals, the characteristics of the other metals begin to show. 14 or 12k gold has a high level of silver, so that jewelry can oxidize. But 14k is harder so it's harder to scratch or bruise compared to 18k.

In my opinion, the shine and color of 22k and 18k gold is more pleasing. I work with 18k and also 22k on request. 18k is the standard in most parts of the world and that quality of gold does not oxidize. If a jeweler says that he sells jewelry with pure gold, the jeweler is probably not trustworthy; it is not possible to make a jewel of pure gold because the 24k jewel does not keep its shape.

How do I know that the gold they sell me is really what they say?

The jewelry business is based more than anything on trust. Legally, all gold jewelry requires a stamp designating the purity of the piece. Typically, the jeweler places the stamp on an inside or front part. This is not how the seal looks when the jewel is on. But really the way to know is to find a responsible and honest jeweler.

Apparatus and methods exist for testing the quality of metal. But each test has its advantages and disadvantages. For example, there are electronic devices to test the purity of gold. But these devices can only test the surface and do not detect whether the gold is plated.

Also it can be tested with nitric acid because that acid hardly reacts with pure gold. But a jeweler has to file a part of the surface to ensure that the gold is not plated.

Another option is to weigh two jewels of the same size. For a silver and a gold jewel, equal in shape, volume and appearance, the gold one weighs more. Gold is denser than silver.

And what is gold plated?

Gold plating is a chemical process where a thin layer of gold is deposited on top of another metal. Usually the other metal is silver. The thin layer of gold will wear off over time. A jeweler has to scrape and/or cut the jewel to tell if a jewel is plated. I will give more details in a future post.

What is the difference between yellow gold and red gold?

It is also a topic for another post. But it has nothing to do with carats. But it has to do with what metals we add to gold to harden it and manipulate its color. An 18k yellow gold and 18k red gold jewel means that the piece is 75% gold by weight and 25% other metals.

Source: edgartica