How Does Gold Testing Acid Work?

The mark is tested by applying nitric acid, which dissolves the mark of any item that is not gold. If the mark remains, it is tested by applying aqua regia

(nitric acid and hydrochloric acid). If the mark is removed, then this test dissolves the gold, proving the item to be genuine gold.

How accurate is acid testing for gold?

To top it off, acid testing isn't always accurate. Most acid kits contain materials to test 10k, 14k, 18k,and 22k gold. The acid rounds to the nearest testing solution; it can't tell you if it's 13K or 18.5K. You have to trust that your employees will know all this and interpret the results correctly.

What type of acid do you use to test gold?

The purer the gold, the stronger the acid required to dissolve it. Measured strengths of nitric acid are used to test for 14k and lower. Aqua regia, a mixture of one part nitric acid and three parts hydrochloric acid, is used to test higher karat purity through the process of comparison and elimination.