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Purity of Gold

Many of you are probably familiar with the word “karat” in the context of gold. What we know is that the higher the karat, the more expensive it will be. Or that higher karats mean more gold. But there is much more you should know when dealing with gold.

Karats in Gold

Karats are the numbers stamped on gold in the format of "xxK" or "xxKT". These numbers indicate the type of gold and gold content. Karats are measured on a scale from 0 to 24. The higher the karat number, the more gold there is and the less other metal content. That makes 24-karat gold is the purest gold you can find in the market.​

Gold is malleable in its pure state. That’s why other metals are usually added to strengthen it and in some cases to enhance color. Other metals and alloys could include copper, nickel (not common anymore), silver, or palladium. For example, "rose gold" comprises gold and copper.

Low and High Karat Gold:

  • The lower the karat, the stronger it will be, while higher karat gold will be softer.

  • Lower karat gold is not tarnish-resistant. Higher karat gold is much more resistant to tarnishing.

  • Lower karat gold is not worth as much monetarily. Higher karat gold is more valuable because it is purer.

  • Higher karat gold will appear more yellow.

Gold Purity Measurement

The number of karats is key to calculating the gold content. Let’s make an example. Say you purchase a ring that is 14K gold. Since the number amount of karats you can have is 24K, divide the 14 Karats by the 24. You will get .583. This means that gold is 58.3% pure.

Gold Purity Terms

  • 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.

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

  • 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.

  • 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.

Stamps on Gold

  • EPNS stands for “Electroplated Nickel Silver” which is silverplate. This means the piece is not gold, and it’s worthless.

  • EPBM stands for “Electroplated Britannia Metal” which is not gold at all. It is a silver/tin alloy consisting of copper, lead, or zinc.

  • GE or Gold Electroplate is a piece consisting of 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 also refers to Heavy Gold Electroplate, the same as GE above, but it can only make the "heavy" classification if the plating is at least 100 millionths of an inch.

  • GF means Gold Filled and is like a 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 means the gold is 37.5% pure, or 9K. In the US, the minimum standard for gold is 10K. Many other countries allow marketing this as gold and it’s been used in both jewelry and dental applications.

  • 417 means that the gold is 41.7% pure, or 10K. In the US, jewelers use this purity because it is very strong. It is great for jewelry for those who work industrious jobs or who need something that will hold up.

  • 585 means that the gold is 58.5% pure, or 14K. Good, strong gold but with more gold than 10K.

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

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

  • 999 means the gold is 99.9% pure, or 24K. 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 1950s by The Perth Mint in Australia.

Use of Gold

Over 75% of the gold used every year to make jewelry. Although gold is very flexible and is used in many industries for various purposes, depending on purity.

  • Coins: Currency is one of the greatest uses as gold will always hold value even if the dollar collapses.

  • Computers/technology: Since gold is a good 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, various circuit boards for spacecrafts use gold as a shield to keep the temperature of the spacecraft stable.

  • Dental: Besides golden grills gold is 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.

  • Food: Some restaurants use gold as a decorative, but edible garnish for food since the food-grade gold is non-toxic.


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