Start with the stamp and a magnet. For a real answer on karat, an inexpensive acid test kit is the most reliable at-home method.
1. Look for a stamp
Use a 10x jeweler’s loupe or your phone’s zoom to check the clasp, inside of a ring, or earring posts. See what gold stamps mean.
2. Try a magnet
Gold isn’t magnetic. If a strong magnet grabs the piece, it’s not solid gold, or the part the magnet grabs (often a steel clasp spring) isn’t. A piece that doesn’t stick isn’t proven to be gold, though: many other metals aren’t magnetic either.
3. Check for wear
Look at edges and high points that rub. If you see a different-colored metal showing through, the piece is plated.
4. Use an acid test kit
An acid test kit is the most common at-home test for karat:
- Rub the piece on the test stone in an unseen spot to leave a streak.
- Apply the acid for the karat you expect (for example, the 14K acid).
- If the streak stays, the gold is at least that karat. If it dissolves, it’s lower.
Follow the kit’s safety instructions. The acids are corrosive, so wear gloves and eye protection.
What buyers use
Many buyers use electronic testers or X-ray (XRF) machines that measure the metal without damaging it. If a buyer’s result disagrees with your stamp, ask to see the reading.