Testing Precious Metals

Testing Precious Metals : In my business I come across all types of silver, gold and platinum on a daily basis, although most items are hallmarked it is still necessary to test every item to verify it’s quality.

You can test precious metals in a number of ways, the first and easiest preliminary test is using a magnet, if an item sticks to a magnet it has no value as far as it relates to Precious Metals.

One exception I have found is when cobalt is alloyed in the mixture. I have found some Platinum jewelry (95% Platinum alloyed with 5% Cobalt), even this low amount of Cobalt proved to be extremely magnetic.

Watching For Fakes

Heavily Plated Items

As with all walks of life there are unscrupulous people trying to pass off various jewelry and bullion fakes. One that fooled me that comes to mind was a heavily gold plated necklace on top of copper, copper is not magnetic so it passed the first test. The heavy gold plate passed my acid test.

To be certain with larger items you need to file the item approximately 1/8 inch deep and apply the acid to the filed section, if I had done this I would have seen the copper inside react to the acid by turning green. A lesson learned.

International Gold Scams

Another common fraud that passes my desk weekly are people from countries like Ghana and other African destinations with offers to purchase their gold flakes, dust etc at an extremely reasonable rate as long as I’m willing to travel to them to inspect their wares, something I certainly wouldn’t care to do.

What they do have are bags full of copper shavings with a small amount of gold. To the untrained it could prove an extremely costly mistake, best advice, stay away from offers that seem too good to be true.

Another twist these same fraudsters use is using actual gold shavings on your first transaction then offering you a ‘too good to be true’ lower price on your next transaction, this is when they will substitute the copper/gold mixture of shavings and you’ll get stung. I know of one fellow who remortgaged his house only to find himself left with kilo’s of useless material. The best advice is to avoid dealing or involving yourself in the importing of any kind of material from outside the country and at the very least never pay for such material until you have performed a proper assay on the material.

Okay, enough about the bad, now I’ll explain how I go about testing jewelry precious metals…

Testing Jewelry Precious Metals

As mentioned above the quickest and easiest way of testing precious metals is using a magnet, the stronger the magnet the better.

If the item does not stick to the magnet it’s time for the next test which is using acid. I have several different acids for different karats and materials, for example I have 10k, 14k, 18k and 22k acids for gold, there are more available but these suit me. I also have silver and platinum acids.

I will outline procedures for testing precious metals i.e. gold, platinum and silver using an acid testing kit and needles. (After enough experience you won’t require the needles for every item)

You’ll need the following items for your tests; a black or white acid testing stone (it’s recommended to clean it frequently, I use emery cloth and warm water and it cleans up nicely, the white stone is actually better for visibility but hard to find), acids (as mentioned above), gold testing needles.

Acid Testing Kit

Testing Precious Metals: Gold

Testing 10k, 14k and 18k gold jewelry: Scratch the gold piece to be tested on your stone, use several strong rubs to get a nice sample. Next to your sample scratch the appropriate needle. Next, place a drop or two of the appropriate acid on the stone where your samples are rubbed. If the gold is the same karat or higher the color of the test item will appear the same as the mark from the needle. If the piece is lower in karat the scratch will become fainter and start to disappear.

Testing 22k: For 22k I scratch the test item on the stone as mentioned above, I then apply my 22k acid to the sample, from my experience all 22k jewelry melts away when I apply the 22k acid. I then apply my 18k acid, if the sample remains on the stone I will pay people on the basis that the item is 20k, this has always worked out fairly for me. From my experience Mid Eastern gold with Arabic hallmarks is generally 21 to 22k but gold from India and Pakistan that is marked 22k tends to be in the 20k range.

Testing 24k Gold Jewelry: I don’t have 24k acid as it isn’t always available and I rarely get any jewelry that is truly 24k, if hallmarked 24k I test it first with my 22k acid, if the sample remains on the stone I pay on the 24k rate.

Testing White Gold: For 18k White Gold, scratch the test item on the stone and apply your acid, the sample on the stone should start turning a bronze color within 1-3 minutes. For 14k White Gold, the material will turn bronze quickly and then start to disappear in about 15 to 30 seconds.

Gold Testing Needles 10, 14 and 18K

Testing Precious Metals: Platinum

Platinum is expensive so you have to make sure you’re getting what you pay for, the first test as always is using your magnet, the second test is using acid. Scratch the test item on your stone, apply a drop or two of acid on your sample, if the item is platinum it will keep it’s bright white color.

A selection of testing Stones

Testing Precious Metals: Silver

You won’t use your testing stone for silver, you will apply your Silver acid directly to the item in question:

If it’s 90-100% silver the acid will turn/show a creamy color
If it’s 75-90% silver the acid will turn a gray color
If it’s 60-75% silver it will turn a light green color

Note: The methods outlined in this article are for reference only, please use caution and care when using acids to test precious metals. The best and ultimately only way to certain of the true content of your precious metals is perform a fire assay and use a XRF machine to analyze your jewelry precious metals. End of testing precious metals page.

Advanced Technology Used To Test Precious Metals

Using the acid testing method has worked for me for over a decade with respect to jewelry, gold coins and even platinum labware and thermocouple wire. If however you are testing melted ingots or melting your own bars you’ll likely want to invest in an xrf analyzer, they don’t come cheap but with the rising cost of precious metals it could very well prove to be your best investment.

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