Professional assayers use an acid testing kit to determine the purity level of the gold they buy. This presentation will explain how the test works and how to interpret the results.

1. Acid Testing Jewelry for
Gold Purity

2. The Acid Test
• The acid test is the most common method used by
jewelers, refiners, pawnbrokers, and others in the
precious metals trades to quickly and cheaply test
the purity level (or authenticity) of jewelry.

3. Acid Testing Kits
• A standard acid testing kit comes with four
different bottles of acid.
• A common question inexperienced testers ask is:
“What’s the difference between the acids?”

4. Nitric Acid Concentrations
• The bottles all contain nitric acid, but at different
concentrations/strengths.
• Acid testing kits for gold usually come with four
different bottles of acid at different potencies – one
each for testing:
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10k gold
14k gold
18k gold
22k gold

5. How to do an Acid Test
• To conduct an acid test, the piece of gold in
question is scraped against a touchstone.
• A touchstone is most any stone with a finely grained
surface that contrasts well with gold. Some examples
would be fieldstone, slate, radiolarite, or basalt.
• This first step is why the acid test is also sometimes
referred to as the “scratch test.”
• Next, the acid is applied to the mark left behind by
the gold.

6. Interpreting Test Results
By measuring the reaction of the streak and the acid, an
experienced assayer (tester) can accurately determine
the purity level of a gold sample.
• If the streak dissolves from contact with 10k acid, the
sample is not gold.
• However, if no reaction occurs, then it’s at least 10k.
• If you apply 14k acid to the same streak and it
dissolves, then the gold in question is between 10k and
14k.
• If no reaction occurs, then the gold is at least 14k pure or
greater.

7. Interpreting Test Results
• The potency of the acid is increased until the
correct karat level of the gold sample can be
determined.
• Twenty-four karat gold will be completely unaffected by
nitric acid – it can only be dissolved by aqua regia (a
mixture of concentrated nitric acid and hydrochloric
acid).
• So, if the jewelry in question has no reaction to the
acid test, it’s probably very valuable!

8. About MGS
Manhattan Gold & Silver (MGS) is a precious metals refiner that has been based in
Manhattan’s historic Diamond District since 1985. We are a B2B company that
buys and recycles precious metal scraps that accumulate in other businesses.
We serve:
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Jewelers
Pawnbrokers
Dentists
The industrial sector
Antique dealers
Machinists
Domestic mining
And more!
• MGS also creates charts, calculators, and other online tools for our customers to
use.
• Try our Precious Metals Prices app, which lets you monitor the real-time precious metals
market situation from anywhere, right from your iPhone, iPad, or Android device.

9. Recycle your Precious
Metals for Profit
• MGS accepts gold, silver, platinum, and palladium.
• Payouts are based on the London Fixing.
• Up to 99% payout (among the highest in the US)
• Up to 98.5% for gold brought in for hand testing.
• Not in NYC? Ship us your precious metals using our Ship &
Sell service which offers:
• Same day wired payment (once lot is received)
• Discounted, insured shipping
• Payout calculator

10. Connect with MGS
• For amazing facts, history and news, read our gold and precious metals blog.
• Join the conversation about precious metals on the MGS page on Facebook.
• Follow gold, silver, and other precious metal trends at the MGS Twitter account.
• Circle MGS on Google+ to hear our latest updates.
• If you do business with us, connect with us on the MGS LinkedIn page.
• To see precious metal melting and refinement in action, visit the MGS YouTube
channel.