How to Test Gold at Home

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Test an item of gold for authenticity using everyday tools

Co-authored by Kennon Young

Last Updated: March 22, 2024 Approved

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Inspecting the Surface

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Conducting Deeper Testing

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Performing Acid Testing

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Video

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Expert Q&A

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Tips

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Warnings

Gold is a precious metal that comes in a variety of colors and different levels of fineness. The value of a piece of jewelry or another object will depend greatly on whether or not it is plated or pure gold. To identify the quality of a metal object, start by taking a close look at its surface. If you're still unsure, move on to more in-depth testing, such as a vinegar application. As a final option, consider applying acid to the metal item and watching for a reaction.

How do you test gold purity at home?

Inspect the gold closely for a stamp (or "hallmark") that indicates its purity, or lack thereof. A gold-plated item may have "GF" or "HGP" stamped on it, while pure gold pieces may have "24K" stamped on them. You can also hold the gold item up to a magnet—if it seems drawn to the magnet, it isn't pure gold.

Method 1

Method 1 of 3:

Inspecting the Surface

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1
Look for a hallmark. A piece of gold will usually be stamped with a mark indicating its type. A stamp of “GF” or “HGP” indicates that the piece is gold-plated, not pure gold. In contrast, a pure gold piece of jewelry may show a “24K” or other marking indicating fineness. Hallmarks are usually located inside the band of rings or near the clasp on necklaces.^{[1]
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- However, be aware that some hallmarks can be faked. This is why it’s important to use a mark as only one of many indicators of authenticity.
- The hallmark may be very small. You might even need a magnifying glass in order to see it clearly.
Turn on a bright light or lamp. Hold the piece close to the lamp’s light. Rotate it in your hand, so that you can examine all of the edges in particular. If you see that the gold appears faded or worn away at the edges, then it’s likely wear on the plating. This means that piece isn’t pure gold.^{[2]
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If you hold the piece under a bright light, do you notice white or red spots anywhere on it? The spots may be very tiny and difficult to see. That is why it’s important to examine the piece under a bright light and maybe with a magnifying glass. These spots indicate that the gold plating may be wearing away showing the metal underneath.^{[3]
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Hold a magnet directly above the piece. Lower the magnet until it is almost touches the surface of the item. If you feel as if the magnet is being drawn or pulled downward, then the item is not pure. The other metals in the item, such as nickel, are responding to the magnet. A pure gold piece will not draw the magnet, since non-ferrous.^{[4]
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Method 2

Method 2 of 3:

Conducting Deeper Testing

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Apply some vinegar to the surface and look for a color change. Get a dropper and fill it up with white vinegar. Hold your metal object firmly in your hand or set it on a table. Place a few drops of vinegar onto the object. If the drops change the color of the metal, then it is not pure gold. If the color stays the same, then it is pure gold.^{[5]
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Rub your gold against a jeweler’s stone. Position a black jeweler’s stone on a table. Hold your gold piece firmly in your hand. Wipe it across the stone firmly enough to leave a mark. If the mark that you’ve left on the stone is solid and gold in color, then the piece is pure. If there is no line or only a faint one, then the piece is likely plated or not gold at all.^{[6]
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- Be careful with this method as you run the risk of damaging your jewelry. You also have to use the right type of stone or the marks will be meaningless. You can get a jeweler’s stone through a jewelry supply store online or by talking with your local jeweler.
Set an unglazed ceramic plate firmly on a countertop or table. Hold your gold item in your hand. Scrape the item against the plate. Watch to see if a streak or line of any type appears. A black line indicates that the item is not gold or is plated.^{[7]
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Coat the top of your hand with a thin layer of liquid foundation. Wait until the foundation is dry. Press your metal item against the foundation and rub. Authentic pure gold will leave a line in the makeup. If you do not see a line, then the object is plated or another metal.^{[8]
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Use an electronic gold tester. This is a small hand-held device with a probe at the end that you can buy online or through a jewelry supply store. To analyze a metal, you rub a conductive “tester” gel on to the metal item. This gel is usually available for purchase from the same places that sell testing devices. After you’ve applied the gel, rub the probe against the item. How the metal responds to the electricity will indicate whether or not it is pure metal.^{[9]
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- Use the instructions that come with your tester to determine the exact results. Gold is a conductive metal, so a pure gold piece will have higher readings than a plated one.
This is a machine that many jewelers use to instantly determine the quality of a metal sample. Because of its cost this method may not be suitable for home use, unless you plan on using it regularly. To use an XRF scanner, place the piece of metal inside, activate the machine, and wait for the read out.^{[10]
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If you keep getting mixed results or if you’d like to verify your finding, talk to your jeweler about getting another professional opinion.^{[11]
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Expert Source

Kennon Young
Certified Jeweler

Expert Interview. 11 September 2019.} An assayer will perform a deep analysis of the content of the metal. This can be a costly option, so only use it if you believe your item may be worthwhile.^{[12]
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Method 3

Method 3 of 3:

Performing Acid Testing

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1
Buy an acid testing kit for a more precise estimate of gold karat purity. You can purchase one of these kits through a jewelry tool supplier. The kit will contain all of the materials that you’ll need along with a set of detailed instructions. Make sure to read the instructions carefully before beginning and conduct an inventory of the supplies before starting.^{[13]
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Gemological Institute of America
Nonprofit institute responsible for gemological research and education and setting gemstone buying and selling standards

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- These kits can be quite affordable, if ordered online. They start at around $30.
Your kit will contain a number of needles that you’ll use for testing different types of gold. Look for a karat value marking on the side of the needle. Each needle will also have a colored gold sample at the tip. Use the yellow needle for yellow gold and the white needle for white gold.^{[14]
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Gemological Institute of America
Nonprofit institute responsible for gemological research and education and setting gemstone buying and selling standards

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Turn the piece around until you find a less noticeable spot. Hold an engraving tool firmly in your hand and make a small divot in the metal. The goal is to expose the deeper layers of the metal.^{[15]
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Gemological Institute of America
Nonprofit institute responsible for gemological research and education and setting gemstone buying and selling standards

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Since you are working with acid, it’s important to don thick, but fitted, gloves. Eye protection is also a good idea, just to be extra cautious. Avoid touching your face or your eyes while working with the acid.^{[16]
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Gemological Institute of America
Nonprofit institute responsible for gemological research and education and setting gemstone buying and selling standards

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Select the proper needle for the gold type. Then, hold the needle tip directly over the notch. Push the plunger of the needle down until a single drop of acid drops into the divot.^{[17]
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Gemological Institute of America
Nonprofit institute responsible for gemological research and education and setting gemstone buying and selling standards

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Read the results. Look closely at the divot that you made earlier and where you just applied the acid. The acid will react with the metal and may turn a particular color. Generally, if the acid turns a green color, this indicates that the piece is not pure metal, but instead gold plated or another metal entirely. Since testing kits have different color indications, make sure to read the color guide carefully as you interpret the test results.^{[18]
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Gemological Institute of America
Nonprofit institute responsible for gemological research and education and setting gemstone buying and selling standards

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- You can also do the nitric acid test. Nitric acid can help determine the presence of base metals in gold items. Apply a small amount of nitric acid to a discreet part of the item. Observe any color changes; if the acid causes the metal to turn green, it may indicate a lower gold content.^{[19]
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Expert Q&A

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Question

How can you tell if something is gold without hallmark?

Kennon Young
Master Gemologist Appraiser
Kennon Young is a Master Gemologist Appraiser and the Owner of Vermont Gemological Laboratory in Burlington, Vermont. With over 20 years of experience in the industry, Kennon and his team specialize in handmade engagement rings, wedding bands, and custom jewelry. He attended the Revere Academy of Jewelry Arts, the Gemological Institute of America, and the Rhode Island School of Design Extension. He is a Jewelers of America (JA) Certified Bench Jeweler Technician and received the highest credential in the jewelry appraisal industry, the ASA Master Gemologist Appraiser, in 2016.

Kennon Young

Master Gemologist Appraiser

Expert Answer

It would be needed to test it in a scientific way - by acid testing, or electronic testing, or laser testing. Typically you'll want to find a jewelry appraiser to do that for you. It costs money, but it is highly recommended if you are going to sell jewelry. It would be a poor financial decision to make assumptions on your own.

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