How to Test if Your Jewelry Is Really 18 Karat Gold?

Have you ever wondered what the numbers and the letter mean when you are buying jewelry? What does 18 mean? Or 24? And what does the "K" stand for? The world of gold is an ancient one, and the rules governing how it is categorized are equally ancient and, dare we say, set in stone.

The jewelry business operates by set standards worldwide in order to give customers confidence in what they are buying. Let's take a look at what it all means, so you can ensure you’re buying authentic, high-quality jewelry at your next purchase.

What Does 18-Karat Mean?

So what is 18-karat gold? The word "karat" has been used in the gold industry for centuries to describe the purity of the gold in question. One hundred percent gold is classified as 24 karats, but pure gold is too soft to use in most jewelry designs.

In order to be used in jewelry, other types of metals are mixed with pure gold. 18- karat gold is 75% pure gold, mixed with 25% of an alloy to strengthen it. Common alloys include nickel, silver, and copper. 18-karat white gold is alloyed with silver or palladium and then often plated with rhodium in order to make it even stronger and give white gold jewelry a brighter appearance.

18 karat gold jewelry

How to Tell if 18K Gold Is Real

So how can you tell if the jewelry you have is really 18- karat gold? Here are a few ways you can easily test your gold right at home.


Gold must be stamped with a hallmark that tells the purchaser what karat the gold is. 18- karat gold will have a small stamp on the inside of the jewelry that reads 18k.

But could a forger include that in their fake gold item? Of course, so try at least one other test to help you determine if your jewelry is truly 18 karats.

Letter Markings

Another way to determine if you have 18k gold is to check for letter markings. Any piece of gold that is marked less than 10k is fake. Ensure your jewelry doesn’t have these markings if you’re searching for 18- karat gold: 

  • GP
  • GF
  • GE
  • GEP
  • HGP
  • HEG

These markings are only used on jewelry that has a very small percentage of real gold in it. 


A good way to tell if 18k gold is real is by its weight. Gold is a heavy metal, so heavy that it will sink in water. If you drop your jewelry in a glass of water, real gold will drop straight down. Remember that 18- karat gold is 75% gold mixed with other alloys.

Some of the lighter karat weights, like 10 or 12 karats, will not drop down as quickly as a piece of jewelry made with 18- karat gold.


Check if your gold is real by performing the magnet test. Real gold will not attract a magnet. To test if 18k gold is real, hold it next to a magnet. If the magnet sticks to your jewelry, then it does not have a high percentage of gold but is made up of other, more magnetic metals.


Acid testing is a great way to test 18k gold. To determine if your 18- karat gold is real, simply place your gold piece of jewelry in nitric acid and observe its reaction. If a green reaction occurs, it is a metal of a lower karat content. No reaction indicates that your jewelry is 18- karat gold or higher.


If you have inherited family jewelry or been given pieces that you are uncertain about, seek out the advice of a certified jewelry appraiser. Many jewelry stores have an appraiser either on staff or on call and will appraise your gold-plated jewelry for an agreed upon fee.

A professional appraisal will not only reassure you that what you own is really 18- karat gold jewelry, but will also result in a certificate that attests to the appraised value of your jewelry.

Buy 18-Karat Gold Jewelry from a Trusted Source

The best way to make sure that what you have is really 18- karat gold jewelry is to buy from a trusted source. True 18- karat gold jewelry looks and feels elegant, and Di Modolo has a wide range of prices and styles to suit your every jewelry mood.

The Allegra 18K White Gold & Diamond Stackable Ring paired with the Allegra 18K White Gold and Diamond Earrings would look impeccable for an elegant evening out on the town. Browse our collection of fine jewelry at Di MODOLO to find the perfect piece for you.

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