When you bring gold jewelry to a buyer, they need to verify the purity before making an offer. Here's how professional gold testing works.
Visual Inspection of Hallmarks
The first step is a visual inspection. The buyer looks for hallmarks — small stamps on the jewelry that indicate the karat purity. Common stamps include "14K", "18K", "24K", "750" (18K), "585" (14K), and "417" (10K). However, hallmarks can be inaccurate or missing, so testing is always needed.
Electronic Gold Testing
Electronic gold testers use electrical conductivity to estimate purity. The tester has a probe that touches the gold surface, and the device displays an estimated karat range. This method is quick and non-destructive, making it ideal for initial screening.
Acid Testing
Acid testing is a traditional and reliable method. The buyer scratches the gold lightly on a testing stone, leaving a small mark. Then they apply a specific acid solution to the mark. The reaction (or lack of reaction) indicates the karat range. Different acid strengths are used for different karat levels.
Why Testing Matters
Testing ensures that both the buyer and seller know the true purity of the gold. Without testing, a buyer might overpay or underpay. Transparent testing — done in front of you — builds trust and ensures a fair transaction.
What to Expect
At NYC Jewelry Buyer, we test every item in front of you. We explain what we're doing and what the results mean. The entire process takes just a few minutes per item, and there's no obligation to sell. Call (646) 516-4623 to learn more.
Last updated: July 5, 2026
