When purchasing or selling gold, authenticity is crucial. The acid test is among the oldest and most common tests for gold purity. But just how reliable is acid testing for gold? At AU Bullion, where we deal with precious metals on a daily basis, we understand the importance of accurate testing—and in this blog, we’ll tell you how acid testing is carried out, how reliable it is, and when it is best utilized.

What is Acid Testing?

Acid testing, or the nitric acid test, is a chemical test for determining whether a gold item is genuine and what karat it may be. It is accomplished by applying a small drop of acid (normally nitric, hydrochloric, or sulfuric acid, based on the test kit) on the gold. The reaction (or lack of reaction) identifies whether the piece is genuine and what karat weight it may be (10K, 14K, 18K, etc.).

How the Test Works

Scratch the Gold: A small portion of the gold is scratched on a test stone to leave a mark.

Apply Acid: Specific acid solutions are then applied to the mark. Each solution corresponds to a different karat weight.

Watch the Reaction: The mark will dissolve if the gold is less than the acid karat. It will remain the same if the gold is the same or more than that karat.

Is Acid Testing Reliable? 

Yes—with limitations. Acid testing is widely employed for a reason: it provides rapid, inexpensive, and reasonably good results for the determination of gold content. But it is not perfect.

Here’s its breakdown of reliability factors:

✅ Ideal for Preliminary Testing: Acid testing is ideal for a preliminary test to see if an item is likely to be genuine gold.

✅ Convenient for Spot Checks: Especially for scrap gold or jewelry items with unclear hallmarks.

❌ Not Entirely Accurate: It can only give you an estimate of gold purity—it won’t tell you the exact percentage or detect sophisticated counterfeit items (such as gold-plated tungsten).

❌ Damage Risk: The scratch test can cause minor damage to the item, which is why it’s not recommended to test collectible coins or items of high value.

When Acid Testing Is Not Enough

As sophisticated counterfeiting techniques rise, acid testing is not enough for bullion dealers or investors who are serious. For example, some fake gold bars have heavy metals like tungsten which cannot be identified by acid testing because the surface is actual gold.

At AU Bullion, we use a combination of acid testing and newer technologies such as:

• X-ray fluorescence (XRF) analysis
• Ultrasonic thickness measuring
• Digital gold testers
• This layered system ensures that we deliver accurate results and protect buyers and sellers.

Our Suggestion:

Use Acid Testing as a Starting Point While acid testing is a good preliminary method of gold verification, it must be one step in a more extensive test regime. Here at AU Bullion, we take the time to treat each item with the attention it deserves—following up traditional and proven techniques with modern test equipment to provide you with full transparency and assurance. Whether you’re selling scrap gold, bullion, or previously used gold jewelry, you can count on honest appraisals and top-dollar offers from us—backed by solid testing procedures.