Understanding Different Gold Chain Purity Levels

Whether your gold chains are priceless heirlooms or cheap knockoffs, knowing their purity level is essential. This can help you determine the value of your jewelry and avoid being duped into buying something worth less than you think.
The karat system is used to categorize gold purity levels. 24 karat is pure gold, while 10K gold has a much lower percentage of pure metals in the alloy.
Hallmark Verification
A hallmark is an official stamp that certifies the gold’s purity and fineness. An independent assaying and hallmarking center usually puts it on jewelry to guarantee authenticity.
You can check for hallmarks on your gold jewelry using a magnifying glass. Look for the quality mark, karat or fineness mark, assay office mark, and date mark.
If you’re unable to see any hallmarks, try the touchstone test. You can also use a cosmetic foundation and drag your gold across it. Real gold should react with the foundation and leave a mark, while fake gold won’t.
Another way to determine gold chain purity is through fire assay. This method is complicated and expensive but provides the most accurate results. A melted and homogenized sample is then assayed for its gold content. The most trustworthy players have advanced imported machines allowing on-the-spot impurities testing. These machines are more accurate than the traditional touchstone and acid tests.
Acid Testing
When purchasing gold chains or other items made with the precious metal, you must know what purity level you are getting. Luckily, there are some quick and easy ways to check for pure gold to ensure you are getting your money’s worth.
An acid testing kit is one such way to test a piece of jewelry for purity. This type of kit uses a combination of hydrochloric and nitric acid to identify different gold karats. Apply a drop of the acid to your item and compare it to a piece of hallmarked gold. If the acid dissolves your gold item quicker than the other one, you have a high-karat gold item, and vice versa.
Another method of testing is to use a porcelain tile test. This requires you to rub your gold item against unglazed porcelain. If the gold leaves a golden yellow streak, it’s likely genuine; however, if it produces a black bar, it is probably fake or low-karat gold.
XRF Analysis
XRF Analysis (X-ray Fluorescence) provides an elemental fingerprint of the metal composition of a gold item, including alloys and trace metals. Unlike assaying (which involves destroying the article) and other analytical methods, XRF offers nondestructive analysis and does not rely on crystalline structure, which can be misleading due to thick plating.
The XRF machine bombards the item with high-energy electrons, which cause the material’s atoms to become ionized. The ionization causes the inner shell electrons to eject, and as they move to fill this vacancy, they emit X-ray energy that the detector in the XRF system detects. The XRF machine processes this X-ray data and converts it to quantitative information, such as the percentage or ppm of the sample’s element. This information is based on the instrument calibrations, factory or empirical, and the stored libraries of parts and materials that comprise the XRF library. This information is critical for determining the purity level of a piece of jewelry.
Nitric Acid Testing
While there are a few scientific methods to determine karat gold purity accurately, these can be costly and require specialized equipment. The acid test is a more straightforward, non-destructive way of testing authenticity. It involves rubbing a piece of jewelry against a black jeweler’s stone, leaving a visible mark. A drop of nitric acid is then applied to the scratch. If the pattern dissolves, it is not real gold and is likely mixed with other metals, such as nickel or copper.
Genuine gold does not react with nitric acid, while copper-based alloys and other materials do. A brutal cupric reaction causes the liquid to turn green, emitting fumes and bubbles. Lower karat pieces may produce a mild cupric response with little to no fumes and minimal bubbling. This is still a good indication that the work is not pure gold and that it is possibly plated with another metal. Nitric acid is a corrosive chemical that can damage the skin and lungs if ingested or inhaled. It should only be used in a well-ventilated area and with appropriate safety precautions.