How to Test Gold: 5 Simple Methods of Testing Gold for Purity at Home
Read ahead to learn how to test gold using everyday household items. Discover simple methods to determine if your gold is genuine or not. These steps will help you discover the value of jewelry you already own or before you buy it.
Photo by Anastasia Shuraeva
What to Look for on Gold: Hallmarks, Stamps, and Plating Codes
How can you tell if something is real gold without a test?
Before learning how to test gold, there is a simple way to discover the purity of your item: look at it. US Customs and Border Patrol requires gold and silver jewelry to be marked with a quality mark and trademark (source)
These quality marks are usually found on the inside of rings, or near or on the clasp of a necklace or bracelet. On earrings, you may find the information on the post or the back of the earring itself. They are usually tiny, and you may need a magnifying glass or a jeweler’s loupe to view them.
How can you tell the karats of your gold?
Stamps like the one pictured will indicate the karat of gold in your valuable. Common karat values you will see range from 9, 10, 14, 18, and 24, followed by a label of K, KT, or Kt.
Less common karat markings may appear as 3-digit numbers. These markings, named Millesimal Fineness, denote the purity of your gold. Locate the 3-digit number in the table below to find the matching karat value.
| Karat | Millesimal Fineness | Gold Purity (%) |
|---|---|---|
| 24K | 999 or 999.9 | 99.9% |
| 22K | 916 | 91.6% |
| 21K | 875 | 87.5% |
| 18K | 750 | 75.0% |
| 14K | 585 | 58.5% |
| 10K | 417 | 41.7% |
| 9K | 375 | 37.5% |
| 8K | 333 | 33.3% |
How can you tell if something is gold or gold-plated?
When an item is solid gold, it will have a karat marking without any other letters present. If your item is gold-plated, gold-filled, or something else, additional letters are visible. This may look like 24K GP (24 karat gold plated), for example. Other letters may include P, GF, RG, RGP, GE, or HGE, and also mean the gold is not solid.
Density Test – Does Gold Float?
Real gold does not float. If you drop your item into water and it floats, it’s safe to say it is not made of gold. If it floats, you do not have to learn how to test gold by other methods. You have your answer.
You can also use water to test your gold’s density to find out what karat makes up your piece. Here is a simple walk-through of that process.
Gold Karat Density Ranges
Use this chart to compare your gold’s calculated density with common karat values.
| Karat | Gold Purity (%) | Density Range (g/cm³) |
|---|---|---|
| 8K | 33.3% | 10.6 – 11.0 |
| 9K | 37.5% | 10.8 – 11.3 |
| 10K | 41.7% | 11.0 – 12.0 |
| 14K | 58.5% | 12.9 – 14.6 |
| 15K | 62.5% | 13.8 – 14.9 |
| 18K | 75.0% | 15.2 – 15.9 |
| 21K | 87.5% | 16.9 – 17.7 |
| 22K | 91.6% | 17.7 – 18.6 |
| 24K | 99.9% | 19.1 – 19.3 |
Gold and Magnet Test
Does real gold stick to a magnet?
The simple answer is no. Gold is not magnetic. Testing a piece of gold with a magnet provides a quick way to determine if it might contain other metals. If you hold a household magnet next to your piece and it sticks to the magnet, it is not made of gold.
How to Test Gold With Vinegar
Gold is not reactive to common acids. Because of this, vinegar is an approachable testing method for most people. To test, expose your piece to white vinegar and note if there is a color change. Real gold will not tarnish or darken in any way. Other metals may react by turning black or green.
Gold Scratch Test
To perform the gold scratch test, you need an unglazed piece of ceramic and your item. Drag your piece across the rough side until a mark becomes visible. Real gold will leave a gold mark. Other metals will leave a mark that is any other color, from copper to black. Any other color is not gold.
Acid Test for Gold
A gold acid test checks if your item is real gold by applying a small drop of acid to a scratch made on a test stone. Different acid strengths are used for different karats. If the mark stays, the gold is likely real; if it fades or disappears, it’s not.
Gold testing with acid can provide very accurate results at home, but it requires the purchase of a kit. You can buy a kit online for under $20. Inside, you will find various pre-mixed acids, a touchstone, and reference test needles.
Have Your Gold Tested by the Professionals
The DIY examples above for how to test gold are a great way to determine, at home, if your gold is genuine. However, when it’s time to sell, you want to know for sure what karat gold your item is. Knowing the purity of your gold is essential so you can understand the actual value of your piece.
Receive your free valuation and purchase offer today. Licensed experts carefully inspect your items using advanced lab tools, accurate weighing, and x-ray testing. After the evaluation, they’ll give you a free offer with no obligation to sell.
