Understanding Gold Purity - 9K, 10K, 14K, 18K, 22K, 24K Gold

Updated on March 16, 2016

Many of us at one point or another will find ourselves shopping for gold, and likely in the jewelry department. You are probably quite familiar with the word “karat” in terms of gold, that the higher the karat, the more expensive it will be, but have you ever wondered why? Sure, the short answer is that higher karats means more gold, but there’s more to it.

What does it all really mean? What is all of that fine print stamped into your piece of gold? What are karats really? How do you know how pure that gold really is? I am taking this golden opportunity to answer all of these questions and more in this simple guide on gold!

Gold Purity Terminology

The measure of purity, or fineness, of gold simply means finding out the gold-to-metal additive ratio.

You may have previously thought that gold is gold, but the fact of the matter is not all gold is created equal! Some pieces of gold will contain more actual gold than others, and some pieces will have more additive metals than others. Before I delve into the nitty gritty on gold, let’s take a look at a few terms that you may come across when studying about or shopping for gold:

  • Assay: A test which determines metal content and quality.

  • Bullion: Precious metals in a bulk, uncoined form such as gold bars, considered in mass rather than value.

  • Carat: Not to be confused with Karat in North America, a Carat is a unit of measurement used for precious stones. Equal to 200 milligrams. Outside of North America, Carat is used in the same context as Karat.

  • Ductile/Ductility: How capable a metal is to being deformed using tensile force. Ex. Ductile materials can be stretched into thin wires without fracture.

  • Hallmark: A symbol or mark stamped on a piece of precious metal which certifies its standard of purity.

  • Karat: Unit of measurement for fineness of gold, with the higher numbers containing more gold and 24K being the finest.

  • Malleable/Malleability: How capable a metal is of being deformed using compressive force. Ex. Malleable metals can be hammered or rolled into thin sheets.

  • Millesimal Fineness: A system used to show the purity of precious metals by parts per thousand rather than karats.

  • Troy Ounce: 31.1034768 grams, or approximately 1.09714 standard “avoirdupois” ounces.

  • Troy Weight: A system of measurement used for gemstones and precious metals, where a full Troy Pound consists of 12 “troy” ounces rather than the 16 “avoirdupois“ ounces in a standard pound.


Common Gold Purities

Although a bit more than 75% of gold used each year is for making jewelry, there’s many other purposes. Gold is a very flexible resource and is used in many different industries for various purposes, depending on the purity. Here’s a list of stamps that you might find on a piece of gold, what they mean, and what they can be used for.

  • EPNS: If someone is trying to sell you a piece of “gold” marked “EPNS,” run away. It stands for “Electroplated Nickel Silver” which is silverplate. I.e. it’s not gold and it’s worthless.

  • EPBM: Again, if someone is trying to sell you “gold” marked “EPBM,” go elsewhere. This stands for “Electroplated Britannia Metal” which is not gold at all, rather a silver/tin alloy consisting of copper, lead, or zinc.

  • GE: Gold Electroplate. This is a piece consisting of a base metal, often brass, with a certain thickness of gold electrolytically deposited onto the base. The minimum standards require to be considered GE is 7 millionths of an inch and at least 10K gold as the plating.

  • HGE: Heavy Gold Electroplate. This is the same as GE above, but may only be classified as “heavy” if the plating is at least 100 millionths of an inch.

  • GF: Gold Filled. This is similar to gold plate, but the gold is heat and pressure bonded to the base metal. It must have a minimum purity of 10K gold and the gold content must be at least 1/20th of the weight of the metal piece.

  • 375: 37.5% gold, or 9K. In the US, the minimum standard for gold is 10K. Many other countries allow this to be marketed as gold and it’s been used from jewelry to dental purposes.

  • 417: 41.7% gold, or 10K gold. Very commonly used in jewelry in the US and very strong. Great for jewelry for those who work industrious jobs who need something that will hold up.

  • 585: 58.5% gold, or 14K gold. Good, strong gold but with a bit more gold than 10K.

  • 750: 75.0% gold, or 18K gold. Much more pure than 14K, still has good strength with a wonderful balance in purity.

  • 916: 91.6% gold, or 22K gold. This is probably the softest and most pure gold that you would want to have for a piece of jewelry.

  • 999: 99.9% gold, or 24K gold. This is the purest that you can buy, and although purity can be up to six nines fine, or 999.999, it’s highly rare to find it so pure. Such fineness in gold was last refined in the 1950’s by The Perth Mint in Australia.

What are Karats?

Karats, spelled ‘carats’ outside of North America, are the little numbers stamped on a piece of gold in the format of ‘xxK’ or ‘xxKT’ and it serves as a reference for the type of gold it is stamped on. It refers to the actual gold content in that particular piece of jewelry. Here’s some info on Karats:

  • The higher the Karat, the more pure the gold.

  • Lower Karat jewelry contains less gold and more of an alloy metal, such as copper, nickel(not as common anymore), silver, or palladium.

  • Other metals are added to gold to strengthen it from its malleable state or even to enhance color, such as in rose gold.

Karats serve as a way to determine just how pure that gold really is! 24 Karats is the highest Karat you can buy with the most purity that is readily available for purchase. Knowing this little piece of information is vital to you being able to calculate the gold content on your very own! Say you purchase a ring that is 14K gold, since the maximum amount of Karats you can have is 24K, you divide the 14 Karats by the 24 max Karats, and you get .583, or 58.3% pure gold. Is it getting a bit easier to understand now? Let’s move on!

Low Karats vs. High Karats

More purity of gold does not necessarily mean better, it simply means more pure, worth more money, and more expensive! With gold, the phrase “less is more” can certainly apply. As stated earlier, the less pure the gold is, the more alloy metals it contains, which means it’s stronger! This is good especially when it comes to jewelry as 24K gold is way too soft to make jewelry with. The lower the karats in that ring, the stronger it will be with other metals. Let’s compare lower and higher Karats:

  • The lower the Karat, the stronger it will be, while higher Karats will be softer.

  • Lower Karats are not very tarnish-resistant, but higher Karats are much more resistant to tarnishing.

  • Lower Karats are not worth as much monetarily, while higher Karats are worth much more as they are more pure.

  • Higher Karat gold will appear more yellow.

The purity of gold you should go for all depends on what you intend to use it for, if it will be subjected to a lot of force that can damage it, and your personal preferences as far as gold goes!

Purity Conversion: Millesimal Fineness to Karats

Sometimes the numbers can get confusing, especially if you are used to one system such as Karats, but are shopping in a foreign place which uses an entirely different purity identification system. To make it easier, here is a chart that lays it all out.

Gold Purity Conversion Chart

Millesimal Fineness
% Gold
Parts Gold
Karats (Carats)

As you can clearly see by the above chart, Millesimal Fineness basically lists the percent of gold, while Karats lists how many parts of gold are contained in the piece. The remaining percent or parts that are not gold are alloys. Converting between the two is rather easy when you convert the percent to fraction form or vice versa.


Common Uses for Gold

Gold is used in many industries from jewelry-making to food! Although about 75% of gold used annually is for making jewelry, other industries include:

  • Coins/bullion: Currency is one of the greatest uses as gold will always hold value even if the dollar collapses. Take American Buffalo coins, for example; they are 24K gold, pure as pure can be!

  • Computers/technology: Since gold is a terrific conductor of electricity, it is often found in computers and technology. You will even find small amounts in cell phones, about $.50 worth!

  • Aerospace: Being such a great conductor, gold is used in various circuit boards for spacecraft and also as a shield to keep the temperature of the spacecraft stable.

  • Dental: We’ve all seen rappers with golden grills. Gold is not just for looks, though! It’s highly useful in the mouth and can be found in fillings, crowns, bridges and other dental applications.

  • Medical: Not only is gold used in medical appliances and instruments, but it is also literally used as a “drug” for medical purposes for various conditions, including radiation treatment for certain types of cancer!

As far as food goes, don’t go eating that engagement ring in a life or death situation! Gold leaf is often used as a decorative, but edible garnish for food since the food-grade gold is non-toxic. You may also be familiar with the liquor Goldschläger, which contains visible pieces of gold flakes. So forget the cake, you can have your gold and eat it too!

Purpose of Stamps or Hallmarks

While you may come across some pieces of gold that are not stamped with purity, most gold, especially jewelry, will come stamped with what's called a 'hallmark' as a reference point and even a selling point. All gold found in a jewelry store or big box store in the US will be stamped. While US gold standards enforce the stamping of purity somewhere on the jewelry, you may still come across a piece of jewelry that is not marked, such as in really antique or handmade pieces.

The types of stamps and any laws behind stamping jewelry will vary by country, and if you come across a piece of gold being marketed as a certain purity, but it is unstamped, it’s best to proceed with caution and test the gold using a gold testing kit.

In some instances, you may come across a piece of jewelry that is stamped with a certain purity but it turns out to be fake or misrepresented. This is more known to happen when ordering online from a foreign country, and usually in cases like these, a price is a good indicator of faux metals! The old adage “you get what you pay for” holds true, especially when dealing in precious metals. Should you find yourself in the receiving end of such a situation, it’s a good idea to file a report with the Federal Trade Commission (FTC).

Hallmarks Explained

If you’ve shopped for jewelry in Europe, or even imported pieces over to the US, then chances are, you've come across a few seemingly strange pictures which may or may not be accompanied with an actual purity number stamp. These are called hallmarks and do not need to be accompanied with a specific purity stamp because if you know the hallmarks, you will know just which purity is being guaranteed by such hallmark.

The types of symbols you will come across will vary by country and point-in-time in which they were purchased. In other words, not only are hallmarks great for identifying the type of gold or precious metal used in the piece of jewelry, they are also a good tool for dating the jewelry! If a three digit number is included in the hallmark, it is most likely the purity of gold. For example, if you have a piece with an octagon shape (indicating gold) with the number “585” inside the octagon, this indicates that you have a piece of gold that is 14K, or .585 in purity.

Not only are hallmarks good identifiers of the metal and time period of purchase, but you will also find other symbols stamped into the gold indicating which company submitted the piece for hallmarking, and which Assay Office tested and stamped the hallmark of approval. Hallmarks give you peace of mind that the gold you bought is genuine and has been tested and certified.

How to Test Gold Purity

Learn More About Gold Investing

Now that you know all about how gold purity is determined, shopping for gold cannot get any easier! Please check out the more in-depth articles about each type of gold purity to gain a further understanding about each individual purity of gold!


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    • profile image

      craig 6 weeks ago

      There was no mention of Vermeil in your definition.

    • profile image

      Najbu 5 months ago

      Simply defined, very informatic


    • profile image

      Dana Ratliff 12 months ago

      Have a 1910 European ring with an owl stamped in it, appears to be 18kt gold?