Gold Acid Test Guide
How professional acid testing works and what the results mean
The acid test is a traditional method used by jewelers and pawn shops to verify gold purity. It works because gold is resistant to most acids, while base metals dissolve. Different strength nitric acid solutions are used for different karats. The gold is scratched onto a touchstone, then acid is applied to the streak. If the streak dissolves, the gold is below that karat. If it remains, it's at least that purity. For 10K: weak nitric acid. For 14K: medium nitric acid. For 18K: strong nitric acid. For 22K+: aqua regia (nitric + hydrochloric acid). This test is accurate but slightly destructive — it leaves a small scratch. Professional jewelers now prefer XRF testing which is non-destructive.
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Frequently asked questions
How does the acid test for gold work?▾
Gold is scratched onto a touchstone, then acid is applied. Real gold resists the acid; base metals dissolve.
Is the acid test safe to do at home?▾
Acid test kits are available but require caution. Nitric acid is corrosive. Wear gloves and eye protection. Work in a ventilated area.
How accurate is the acid test?▾
Very accurate for determining karat range. It can distinguish between 10K, 14K, 18K, and 22K+ gold.
Does the acid test damage gold?▾
It requires a small scratch on the item or a streak on a touchstone. The damage is minor but visible.
What is a better alternative to the acid test?▾
XRF (X-ray fluorescence) analysis is non-destructive and more accurate. Most modern jewelers use XRF.