How to Test Gold Jewelry for its Purity

If you’ve inherited a piece of jewelry—or simply want to know how much gold it contains—you may be curious about its karat value. While a jeweler can test it for you, it’s also possible to perform a basic test at home if you enjoy a hands-on approach.

What You’ll Need

To get started, purchase a gold testing kit, which typically includes nitric acid solutions for multiple karat levels. These kits are affordable and usually cost under $25. Once you have your kit, gather the jewelry pieces you want to test and examine them one at a time.

Because you’ll be working with acid, take proper safety precautions:

• Wear rubber gloves

• Keep water nearby in case of skin contact

• Work in a well-ventilated area

• Keep all materials away from children

• Always read the kit’s instructions before beginning

How the Gold Testing Process Works

1. Prepare the test stone
   Use the provided testing stone to rub or lightly scrape a tiny amount of metal from the jewelry in an inconspicuous spot.

2. Apply the acid
   Testing kits come with acid bottles labeled by karat value (such as 10K, 14K, etc.). Start with the lowest karat acid, usually 10K. Place a small drop on the metal mark.

3. Observe the reaction

   • If the mark remains mostly unchanged, the gold is at least that karat

   • If it fades or disappears, the gold content is lower than that karat

   • If there’s no reaction at all, the gold content is higher

4. Repeat with higher karat acids
   Continue testing with higher karat acids until you find the highest level at which the mark remains intact. This gives you an approximate gold purity.

Understanding What the Results Mean

Pure gold is 24 karats, meaning it contains no other metals. However, pure gold is too soft for jewelry, so it’s always alloyed with harder metals like copper or silver. Your test helps determine how much gold is actually present in the piece.

In general:

• Higher karat = more gold content

• Higher karat = higher value

Check for Gold Stamps Before Testing

Before testing, inspect your jewelry for markings. Many pieces are already stamped with their karat value, such as:

• 10K, 14K, 18K

• Or numeric marks like 417 (10K), 585 (14K), or 750 (18K)

These numbers represent parts per thousand of pure gold and are calculated by dividing the karat number by 24, then multiplying by 1,000.

Final Thoughts

Testing gold jewelry at home is a useful skill that can save time and money. While it won’t replace professional testing for high-value pieces, it’s a great way to estimate gold purity and better understand what you own.