Acid Testing Jewelry for Gold Purity

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.

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?”

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: • 10k gold• 14k gold• 18k gold• 22k gold

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.

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.

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!

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:

• 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.

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

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.