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How to Test 18k Gold?

Published in Gold Testing Methods 2 mins read

To test 18k gold based on the provided information, you can use the acid testing method with nitric acid.

Acid testing is a widely used method to help determine the karat purity of gold. Specifically for 18k gold, the test involves observing the reaction of the metal when exposed to nitric acid.

Here's how to perform the test as described:

  1. Prepare the gold piece: Ensure the gold jewelry piece you want to test is accessible.
  2. Apply the acid: Place your gold piece of jewelry in nitric acid. You typically place a small drop of the acid on a discreet part of the item (often after rubbing it on a testing stone first, although the reference only mentions placing the jewelry in the acid).
  3. Observe the reaction: Carefully watch what happens when the acid contacts the gold.

Understanding the Results

The way the gold reacts (or doesn't react) to the nitric acid indicates its approximate karat content:

  • Green reaction: If a green reaction occurs, it suggests the metal is of a lower karat content than 18k. This green color often comes from the acid reacting with base metals mixed in with the gold, such as copper.
  • No reaction: If no reaction indicates (meaning the acid does not cause any visible change or bubbling), it suggests that your jewelry is 18-karat gold or higher.

This method provides a quick way to gauge if a piece is likely 18k gold or if it contains significantly more base metals, indicating a lower purity.