When it comes to buying a special piece of jewelry, gold is a natural choice. It’s precious and beautiful, and it’s had a special place in our hearts for centuries.
Whether you want to treat yourself or give a gift to a loved one, gold is perfect. But when you look at what’s on offer, you’ll quickly discover that there are lots of options. The most basic choice you’ll be faced with is 10k versus 14k versus 18k gold.
So what do these numbers mean? Which is better? And which is the right choice for your own piece of jewelry?
Read on, and we’ll give you the answers to all these questions!
What is the “k”?
The “k” next to all these numbers stands for “karat”. You may also see “ct” on jewelry made outside the United States. This reflects a different spelling, “carat”, but don’t be confused.
You may be more used to seeing carats used to measure the weight of gemstones. But when it appears with this spelling on gold, the meaning is exactly the same as “karat”. Both measure the purity of the gold.
One karat (or carat) is equal to one twenty-fourth of the whole. So if the metal in your ring was divided into 24 parts, the karat rating tells you how many of those would be pure gold.
With 10-karat gold, 10 parts out of every 24 will be pure gold. That’s the same as 41.7 percent. With 14-karat gold, it’s 14 parts out of 24, or 58.3 percent. And with 18-karat gold, it’s 18 parts, or 75 percent.
In other words, the higher the karat rating, the higher the proportion of pure gold in the jewelry.
You’re telling me gold jewelry isn’t gold?!
If you’re feeling alarmed at the idea that your gold jewelry isn’t pure gold, don’t be! You won’t find 24-karat gold used for jewelry at all. That’s because it’s too soft to be worked effectively. And the resulting item would be far too easy to bend or break.
For that reason, the gold is mixed with other metals to make it harder. The precise metals used and their composition varies from piece to piece. And it also differs depending on the effect being sought.
With yellow gold, the aim is to keep the distinctive yellow color of pure gold. With rose gold, copper is added into the mix to give a warm and romantic pink hue. White gold uses metals like palladium, silver and zinc for a contemporary look. And white gold is usually coated in rhodium to give it a high shine.
So what counts as real gold?
With all these other metals added in, you might be wondering what counts as “real” gold. Well, in most countries, a metal must contain a minimum amount of pure gold to classified and sold as gold.
In the United States, that amount is 41.7 percent. In other words, 10-karat gold is the minimum purity considered to be real gold. But that figure isn’t the same everywhere.
In the United Kingdom, Ireland, Portugal, and Austria, the minimum is 9 karats. That’s 37.5 percent pure gold. And in Greece, Germany, and Denmark, it’s 8 karats, or 33 percent pure gold.
In France, gold jewelry must have a purity of 18 karats to be sold domestically. Items of purity down to 9 karats may, however, be produced for export.
How do you tell which is which?
The simplest way to distinguish between different gold purities is to check for labeling or hallmarks. In the United States and many other countries, those selling modern gold items have a legal requirement to state their purity.
In the US, that can be done either by marking the item or through independent signage. That means that if you’re buying gold second-hand, there may not be a record of purity.
In the UK and many other European countries, the gold itself must be marked. But the system of marking – or hallmarking, as it’s known – varies from country to country.
In some cases, you may see a karat marking – a two-digit number often followed by “K” or “ct”. In other cases, you may see a three-digit number. This tells you the number of parts of gold per 1,000 parts of the metal. An item marked 750, for example, would be 75 percent gold, the same as 18-karat.
France has a particularly esoteric approach to hallmarking. French gold is marked with abstract designs of people, animals, birds and insects to denote its purity. 18-karat gold, for example, carries the mark of an eagle’s head.
Is there any other way to tell gold purity?
If you’re buying an antique piece of jewelry, it may not carry any marks, even if it’s real gold. And what happens if you’re not sure whether the marks on your jewelry are trustworthy?
Well, there are different ways to check whether something is gold, and how pure it is. Gold of different purities has particular properties. It’s non-magnetic, for example (although a very strong magnet may detect the other metals present in lower purity gold). And some fake gold is non-magnetic too.
Gold also has a particular density – 19.3 grams per cubic centimeter, to be precise. So one way to check whether the markings on your gold are accurate is with a density test.
To do this, you’ll need accurate weighing scales, measuring in grams, and a measuring cylinder marked with milliliters or cubic centimeters.
Weigh your gold item and record the weight. Then half-fill your measuring cylinder with water and record the volume of the water. (The precise amount of water doesn’t matter. You just want to leave room for the water level to rise without overspilling when you add your gold.)
Gently immerse your gold in the water, taking care that no water splashes out of the cylinder. Now record the new volume of the water.
Deduct the first volume measurement from the second. This will tell you how much water has been displaced by the gold. Then divide the weight of the gold in grams by the volume of the displaced water. The answer will give you the density in grams per milliliter or cubic centimeter.
You can now compare your answer to the known densities of different purities of gold. Bear in mind that, particularly with lower purity gold, the density can vary according to the other metals it’s mixed with. But if your answer is a long way away from the given ranges, you’ll know it isn’t right.
22-karat gold will have a density of about 15.6 grams per cubic centimeter. 14-karat gold can have a density between 12.9 and 14.6 grams per cubic centimeter.
Using gold testing kits
Home assay kits are available for those who want a straightforward way to test the purity of their gold. These use nitric acid and sometimes include needles made from gold of different purities.
The tests with needles are more expensive. They do, though, allow you to compare the results of your item against that of gold of known purity.
The testing process is relatively quick and easy, although it does involve some damage to the item being tested. You’ll need to start by scraping your gold across the surface of a touchstone. This will remove a small amount of gold in order for it to be tested. You’ll see the gold as a line on the stone.
The testing kit will contain different solutions of nitric acid. Each bottle will be marked with a karat rating. Begin with the solution for the highest purity of gold, usually 18K.
Take a tiny drop and place it on the jewelry where you’ve made the scratch. Make sure you use latex gloves when handling the acid. If the acid turns green and fizzes, your jewelry is made of base metal, not gold.
If there’s little or no reaction, it’s now time to test the mark on the touchstone. Take the bottle of acid for the lowest purity gold. This is usually marked 10 karats. Now apply a small drop to the line of gold on the stone.
If the mark dissolves, the gold is 10-karat or below. If it remains visible, it’s purer than 10 karats. In that case, repeat the process with the 14-karat testing bottle. Make sure you add your acid to a different spot on the gold line.
If the acid from the 14K bottle dissolves the line, you’ll know that your gold is between 10 and 14-karats. If the line is still visible, repeat the process with the acid marked 18-karats. If the gold line is still visible, the gold is purer than 18-karat.
Which gold should I choose for my jewelry?
Now you know how to test your gold. But what is the best gold to choose for your jewelry in the first place?
Well, that depends on what you’re looking for from your jewelry. If you have sensitive skin, it’s best to choose the highest purity gold you can afford. The metals used in gold alloys can irritate sensitive skin. Rose gold, in particular, can cause problems, because of its copper content.
10-karat gold, though, can be a good choice if you’re looking for jewelry that’s more resilient. It’s harder, so it’s slightly better at resisting scratches. (Gold is still gold, however, and is relatively soft. So you’ll still need to treat it with care.)
Price is also an important factor to consider. As you might expect, higher purity gold is more expensive. There’s about 17 percent more pure gold in 14-karat than 10-karat jewelry. And about the same difference again between 14-karat and 18-karat.
The higher cost of the raw materials will be reflected in the price. And some jewelers add a premium for the status of higher purity gold. The same ring maybe 10, 15, 20, or even 50 percent more expensive in 18-karat than 14-karat gold.
That doesn’t necessarily, however, mean that choosing 18-karat gold will give you a more impressive piece of jewelry.
In theory, higher purity gold has a more intense yellow color. But the reality is that most people will be unable to tell the difference between different purities of gold on sight.
And if you’re buying a piece of jewelry with gemstones – an engagement ring for example – lower purity gold can allow you to spend more on the stone. A larger diamond may give you more bang for your buck than a ring with a slightly yellower band.
Different colored golds
One last thing to bear in mind, is that gold comes in different colors as well as purities. Like yellow gold, white and rose golds also come with different karat ratings. The proportions are exactly the same as for yellow gold. So an 18-karat white gold ring, for example, will still contain 75 percent pure gold.
The main difference between different colored golds is, of course, the appearance. Some people love rose gold for its warm tones and romantic style. Others prefer the cool elegance of white gold. Still, others prefer the classic look of yellow gold.
But as we’ve already seen, the copper in rose gold can irritate some people with skin sensitivities. White gold may contain nickel and zinc, which can have the same effect. But in most cases, white gold is plated with rhodium, which is hypoallergenic. That can make it a better choice for those with sensitive skin.
The key thing to bear in mind with white gold, however, is that the rhodium plating will wear off over time. How long it will last will depend on how much wear it receives, as well as the thickness of the plating.
But you will need to get it replated at some point. Once a year or so is a reasonable average. And if you have sensitive skin, it’s wise not to leave it any longer than this.
Ready to choose between 10, 14 and 18-karat gold?
We hope you’ve enjoyed our look at 10k versus 14k versus 18k gold. There’s no simple answer to the question of which is “best”. The different metals have different pros and cons. But as a good balance between price, purity and practicality, we think 14k is a great option.
Whichever gold you choose, seek out a reputable dealer so you can be confident in what you’re buying. And if you’re in any doubt, carry out your own tests or get an independent jeweler to test your item for you.
Most importantly, enjoy your beautiful gold jewelry! With good care, it will give you many years of joy.