How to Acid Test Precious Metals – The Right Way

In the fascinating world of precious metals, whether you’re a seasoned collector or a novice investor, the importance of acid testing your gold and silver items cannot be overstated. Imagine investing in a piece that you believe is pure gold, only to find out it’s merely gold-plated or even a completely different alloy. The same goes for silver items, where differences in purity can affect both value and desirability.

We talked about what to do when you want to test a coin for silver content. But other gold and silver requires a different methodology.

The good news is that you don’t need to be a metallurgist to determine the authenticity of your precious metals. With some basic tools and a keen eye, you can carry out these acid tests right at home or in your workshop.

In this guide, I’ll walk you through the steps to test the authenticity of both gold and silver items using simple acid tests. I’ll explain the reactions to look out for, provide additional considerations for specific types of jewelry, and share tips to avoid getting duped by unscrupulous sellers. 

Not a reader? Check out my video instead!

TL;DR: How to Acid Test Precious Metals

Acid testing is a vital technique for verifying the authenticity and purity of gold and silver, accessible to both professionals and enthusiasts. It involves using specific tools and safety measures to prepare and test samples on a scratch stone with acid solutions. The reactions help distinguish between genuine, plated, and filled metals, guiding the evaluation of precious items’ true value. Proper cleanup after testing ensures safety and longevity of testing supplies.

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Tools of the Trade

But before diving in, let’s discuss the essential tools you’ll need. You can get both of these on Amazon for less than $20:

Scratch Stone: A special stone plate against which you’ll rub your metal to leave a mark for testing.

Acid Solutions: For gold, you’ll need solutions corresponding to various karats (10K, 14K, 18K, etc.). For silver, although professionals often prefer using 18K gold acid, specialized silver testing solutions are also available.

Safety Disclaimer

While the process is straightforward, it’s important to understand the risks involved when working with acids. Always work in a well-ventilated area and make sure to follow all safety instructions provided with your testing kit. Remember, safety should always be your top priority.

Understanding Real Gold

Before we delve into the actual testing methods for verifying the purity of gold, it’s important to have a fundamental understanding of what constitutes real gold. Knowing this will not only improve your proficiency in testing but also empower you to make more informed decisions when buying or investing in gold items.

What is Real Gold?

Gold is a chemical element with the symbol “Au” and atomic number 79. It is a soft, malleable, and ductile metal with a bright yellow color, traditionally considered valuable for its rarity and aesthetic appeal. Real gold does not corrode or tarnish, and its lasting quality has made it a symbol of wealth and permanence for millennia.

Purity Measures

The purity of gold is often expressed in karats (K), with 24K gold being the purest form. However, pure gold is too soft for many practical uses, so it’s commonly alloyed with other metals like copper or silver to improve its durability. As a result, the karat number will indicate how much of the metal is actually gold. For instance, 18K gold means the item is made of 18 parts gold and 6 parts of another metal(s).

24K: 100% Gold

22K: 91.7% Gold

18K: 75% Gold

14K: 58.3% Gold

10K: 41.7% Gold

Color Variations

Gold’s color can vary depending on the metals it is alloyed with:

Yellow Gold: Pure gold mixed with a small amount of copper or zinc retains its original color.

White Gold: An alloy of gold and a white metal like palladium or nickel.

Rose Gold: Gold combined with a higher percentage of copper takes on a reddish tint.

Gold Plating and Filled Gold

It’s also crucial to differentiate between solid gold items and those that are gold-plated or gold-filled. Gold-plated items have a thin layer of gold over a base metal, which can wear off over time. Gold-filled items contain a thicker layer of gold bonded to a base metal but are not solid gold.

Hallmarks and Stamps

Many gold items come stamped with hallmarks indicating their purity. However, these stamps are not always reliable as unscrupulous individuals may forge them. Therefore, even if an item is marked with a certain karat value, it’s essential to perform further tests to verify its authenticity.

By understanding what real gold is and the factors that contribute to its quality, you are better prepared to ensure the items you invest in are genuine. 

Understanding Real Silver

Before we get into the nitty-gritty of testing silver for its authenticity, it’s essential to grasp what real silver is and how to distinguish it from other similar-looking metals. This foundation will not only make you more adept at testing but will also allow you to make educated decisions when investing in silver items.

What is Real Silver?

Silver is a chemical element with the symbol “Ag” and atomic number 47. Known for its white, metallic luster, it is a relatively soft, malleable, and ductile metal. Silver is prized for its conductivity, reflective properties, and has been historically significant for jewelry, utensils, and monetary systems.

Purity Measures

The purity of silver is usually expressed in terms of fineness, which measures the amount of pure silver content in an alloy. The most common form of high-purity silver is “Sterling Silver,” which has a purity of 92.5%, denoted as .925. Other forms include:

Fine Silver: 99.9% purity, marked as .999

Coin Silver: Roughly 90% silver, marked as .900

Britannia Silver: 95.8% purity, marked as .958

Silver Alloys

Because pure silver is soft and can be easily damaged, it is often alloyed with other metals, most commonly copper, to improve its durability. The alloying process, however, can affect the color, weight, and resistance to tarnish.

Color and Tarnish

Real silver has a brilliant white metallic luster but is susceptible to tarnish when exposed to oxygen or sulfur, resulting in a darkened appearance over time. This tarnish is generally easy to remove and should not be considered an indicator that the item is not genuine silver.

Plating and Filled Silver

Beware of items labeled as “Silver-plated” or “Silver-filled.” These have a base metal coated with a layer of silver and will not hold the same value as solid silver items.

Hallmarks and Stamps

Similar to gold, silver items often come with hallmarks or stamps indicating their purity. However, just like with gold, these marks are not definitive proof of an item’s authenticity. Forged stamps exist, making it critical to test the item further to ascertain its purity.

By knowing the ins and outs of what real silver is and how its quality and authenticity are measured, you’re well-equipped to proceed with the actual testing processes. Armed with this foundational knowledge, you can now better interpret the results of any tests you perform.

What is Ductility?

If you’ve come this far, you’ve probably seen me mention the term “Ductile” a couple of times.

This may seem like a complicated word, but it’s pretty simple. In short:

Ductility is a property of metals, indicating their ability to be stretched into a thin wire without breaking. This characteristic is due to the metal’s ability to deform under tensile stress, retaining durability while being shaped. Gold and silver are prime examples of highly ductile metals, often used in jewelry and industrial applications due to their ability to be drawn into fine wires without losing integrity.

Testing Gold

Determining the purity of gold is crucial for a variety of reasons, whether you’re investing, collecting, or selling. The following section outlines a step-by-step guide on how to test gold to ensure its authenticity and purity. Please remember to read the safety guidelines and ensure you’re in a well-ventilated area while conducting these tests.

1. Prepare the Scratch Stone

Before you start, you’ll need a scratch stone that provides a solid surface against which you can test the gold item. Make sure the stone is clean, as any impurities can affect the accuracy of the results. 

Silverpicker pro tip:
When testing a gold item, particularly jewelry, it’s best to choose an area that is less visible when worn. This ensures that the item’s aesthetic value isn’t compromised.

2. Find an Inconspicuous Part of the Jewelry to Scratch

gold bracelet

3. Create a Long, Thick Line on the Scratch Stone

Gently but firmly press the gold item against the scratch stone and draw a line. Make sure the line is long and thick enough to be clearly visible. This scratch is what you’ll be applying the acid to, so it needs to be significant.

acid test scratch stone

4. Test with Acid Solutions

Gold testing kits usually come with a variety of acid solutions designated for different karat values, typically 10K, 14K, and 18K. Each of these acids will react differently based on the purity of the gold.

Applying 18K Acid Solution

Put on your protective gloves and goggles. Carefully apply a small drop of the 18K acid solution onto the scratch line on the stone. Watch for a change in color or any fizzing.

If the scratch disappears or changes color significantly, it indicates that the item is less than 18K, like our 14K gold band.

18k gold acid test

Meanwhile, an actually 18k bracelet looks like this:

18k gold

Applying 14K Gold Acid Solution

In the case of an item you suspect to be 14K gold, apply the 14K acid solution in the same manner. If the line remains without significant changes, you can confirm the item is 14K gold.

18k gold

Wiping Off the Acid and Observing the Result

Observe the line; if it is still clearly visible and unchanged, the gold item is of the karat value that corresponds with the acid solution used. The test is now complete and you can clean the stone for the next use. Use a neutralizing agent or water to remove the acid from the stone. 

Additional Considerations

Testing Bracelets or Necklaces

When testing items like bracelets or necklaces, make sure to test both the clasp and the chain, as sometimes different parts of the item can have different karat values.

Unscrupulous Jewelers and False Markings

If an item is marked as higher than the test results indicate, it’s likely that you have an item that is less pure than indicated. Proceed cautiously and consider additional tests or professional consultation.

Here’s some fake gold I tested. See how the acid ate right through it.

fake gold

By following the steps above, you can conduct a fairly accurate home test to determine the purity of gold items. Always remember to exercise caution and prioritize safety while working with acids and other reactive substances.

Testing Silver

Silver is another precious metal that holds value, and verifying its authenticity is important for collectors, investors, and sellers alike. This section provides a comprehensive guide on how to test silver items for purity.

Silverpicker pro tip: Why Professionals Don’t Use Silver Testing Solutions
Many professionals avoid using silver-specific testing solutions. This is mainly because silver testing solutions can be unreliable and provide false positives. Therefore, an industry trick is to use 18K gold testing solution to check silver purity as well.

Testing the Silver Item

To test a silver item, you’ll essentially use the same scratch stone method used for gold. The focus should be on a less visible part of the jewelry or item so as to not diminish its aesthetic value.

Testing Both the Clasp and the Actual Item

In the case of necklaces and bracelets, it’s important to test both the clasp and the chain, or the main body of the item. This ensures that all parts are authentic silver.

silver for testing

Applying the 18K Gold Testing Solution

Once you’ve created a visible line on the scratch stone by rubbing the silver item against it, you can proceed to use the 18K gold testing solution. With protective gear on, place a small drop of this solution onto the line on the scratch stone.

acid testing silver

The Importance of Observing a Baby Blue Color

If the item is genuine silver, the 18K gold solution will produce a light or “baby blue” color on the scratch line. This is a good indicator that you are dealing with real silver.

silver acid test result

Warning About Flakiness as a Sign of Silver-Plated Items

If you notice any flakiness or if the scratch line disappears entirely, it’s likely that you have a silver-plated item rather than solid silver. This is an important observation and can help you differentiate between plated and pure items.

By following this procedure, you can effectively determine whether your silver item is genuine or not. However, like with gold testing, always prioritize safety. Use protective gear and make sure to neutralize or clean up any acid solution used during the testing process.

Remember, while this method is highly effective, when in doubt, consulting a professional is the best course of action for confirming the purity of precious metals.


After you have successfully tested your gold and silver items, it’s crucial to clean up properly to ensure both the longevity of your testing tools and your own safety.

Wiping the Scratch Stone

Using a paper towel or a piece of steel wool, thoroughly wipe the scratch stone to remove any leftover metal particles or acid. If you’ve used steel wool, make sure to dispose of it safely.

Got Some Real Gold or Silver? Now What?

So you know you’ve got some precious metal on your hand – congrats! But how do you know how much its worth?

Well, with my new scrap silver calculator and gold calculator, you can find out exactly how much your item is worth. So get calculating, and make that money!

Where to Buy Real Gold & Silver

I’ll make it easy for you. Apmex is your best bet for ensuring that the precious metals you buy are the real deal. If you want to guarantee authenticity and don’t want to take any risks with your purchases, look no further. 

Silverpicker pro tip:
If you do want to sniff out a potential deal, check out Whatnot. Live auctions from sellers all around the world mean that you can get your hands on some pretty great stuff. I also host a regular auction of my own collection, guaranteeing that what you buy is the real thing. 

And, to sweeten the deal, you can get $15 towards your first Whatnot order with my link. Given that I’m often selling items worth less than this, you’re almost certain to get your hands on some FREE gold or silver. 

Test for Yourself

This guide has covered the importance of testing, the tools you’ll need, and the methods for both gold and silver testing.

Recap of the Simple Steps to Test Gold and Silver

Remember, the key steps are:

  1. Preparing your scratch stone
  2. Choosing an inconspicuous part of the jewelry to test
  3. Applying the appropriate acid solutions
  4. Observing the results

Safety First

It’s imperative to underscore the safety risks involved in using acid solutions and other testing chemicals. Always wear appropriate protective gear, like gloves and goggles, and work in a well-ventilated area. Keep these substances out of reach of children and pets, and dispose of them responsibly.

How to acid test precious metals

Practice, Practice, Practice!

Finally, it’s always a good idea to practice these testing methods on items whose purity you already know. Jewelry, whatever you’ve got in the house. This will help you become proficient in testing and give you the confidence to assess new items.

By following these steps and guidelines, you can become a savvy gold and silver tester, ensuring the authenticity and value of your precious metal items. Happy testing!

A Note on Testing Precious Metals

All of my content comes from a place of knowledge and personal experimentation across more than a decade of working with precious metals, coins and collectibles. In this instance particularly, I’ve spent countless hours identifying gold and silver using the exact methods listed above. Along with the video above, my entire YouTube channel is full of examples teaching you how to make the most of your precious metals collecting journey – and avoid the scams along the way.

Show some love and buy your precious metals with my Apmex link!

(it's the same thing, but you get a thank you from me!)

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