Gold Acid Testing
As a relatively accurate, traditional method to testing the karat value in a gold piece, gold acid testing gives you the assurance that a gold piece is real and valuable. Here’s how to do the gold acid testing yourself:
What You Need:
- Set of testing needles with different tips of exact karat
- One test stone
- Testing acids
What To Look For:
There are a few signs that you should keep a lookout for that helps you identify the karat value:
- When both the needle mark and test sample mark react the same as the acid, this indicates that test sample’s gold content – or karat value – is the same as the needle.
- When the test sample reacts faster than the needle mark, it means that the test sample has a lower gold content value.
- When the needle mark reacts faster than the test sample, this means that the test sample has a higher karat value. You can repeat this test to help you find a close approximation of the gold piece’s karat value.
- If the gold piece sample does not have a reaction to the acid, this signifies that the sample has a higher karat value than the acid. When this happens, use a higher testing needle and acid until a reaction occurs.
- If you’re testing gold that has a value of 10k, 14k, 18k or 22k, you can use pre-mixed acids that come in secure plastic bottles and color-coded caps. These pre-mixed acids are used to reveal the base metal, if any, in a gold piece.
Procedures For Gold Testing:
- Press and scratch your gold piece sample on the testing stone, hard enough to leave a visible deposit on it. The scratch line should be 1.5 inches long.
- If you’re looking for the most accurate testing method, use testing needles, which are used for comparative testing.
- If you’re looking for the most sensitive testing method, make a scratch line with a testing needle next to the original line you made with the test sample. When using this method, observe how fast each scratch dissolves and take note of it. If the test sample scratch dissolves more quickly than the needle scratch, you can come to the conclusion that the sample has a lower karat value than the needle.
- If you’re testing the authenticity of heavy-weight items, such as volume chains or coins, the plating can seal away the true metal in the item. In this case, scratch a deep notch in the sample and test the metal inside it.
- Apply a drop of the 10K solution on the scratch. Two possible results should occur:
- If the scratch dissolves, this means that the test sample is less than 10K or not authentic gold.
- If the scratch doesn’t dissolve, this means that the test sample is either exactly 10K or more than 10k.
- If necessary, you can repeat these steps with the 14k, 18k or 22k solution.
- Note that, when you use any of these solutions, there’s a possibility that the gold test sample scratch dissolves gradually and leaves behind rusty-colored particles. When this occurs, it signifies that the gold sample is most likely 2k less than the solution value that you use.