Additional Solution Testing Info

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How to check your gold jewelry purity.

If you are not sure about your gold jewelry purity you can check it with a simple Gold Test Kit.

The Kits that include a test stone, set of gold test needles and 10kt, 14kt, and 18kt acids.

The acid solutions include Hydrochloric Acid Nitric Acid combined together since there is no single acid that can eat gold or platinum.

The test stone is usually black. Referred to as a touchstone. A touchstone is a small tablet of dark stone such as fieldstone, Slate or Lydite used for assaying precious metal alloys. It has a finely grained surface on which soft metals leave a visible trace.

When testing First check if there is any gold purity mark on the jewelry to know which solution to start with. then choose an unimportant part on the jewelry and polish it on the test stone until you can see a clear mark on the test stone. If using test needles polish the nearest Karat needle next to the mark from jewelry mark. There is another option, if you do not have gold test needles you can use another piece of gold that you are sure of the purity level for your second mark. Next place a drip of acid Karat rating we want to check. If the mark disappear then that means the acid dissolved it, So the gold purity level is lower than the acid Karat rating of the solution. If the acid did not dissolve the gold then the gold Karat level is higher than the acid Karat level of the solution that was dropped on it.

Different Karat ratings:

  • 24 karat = 100% gold: usually considered to soft for jewelry

  • 22 karat = 91.7% gold: also soft and not recommended for jewelry

  • 18 karat = 75.0% gold: this level is usually recommended for fine jewelry

  • 14 karat = 58.3% gold: 14K is very popular and recommended for most jewelry

  • 12 karat = 50.0% gold: 12K is usually used for lower cost jewelry

  • 10 karat = 41.7% gold: The legal karat limit considered as real gold in the United States. Used in many low cost jewelry settings.

More interesting info on the solutions:

Gold Plating or filling:
Scratch the object with a file and apply a drop of Nitric Acid. If the object turns a bright green it is gold plated or gold filled on base metal. If the object turns a pinkish cream color it is plated or gold filled on silver. 10 karat gold will turn dark brown. 12 karat gold will turn light brown. 14 karat or higher will have little or no reaction.


A test stone can be used to test a streak of metal laid down from the jewelery, or a small groove can be filed on an inconspicuous place of the jewelery and tested.


Testing White and Green Gold:

White and green gold react slowly, but will still leave a brown mark after applying acid.


Testing Platinum
Rub the article on the test stone and apply a drop of Aqua-Regia. A platinum mark will remain the same white color with no reaction.
Testing Palladium
Rub the article on the test stone and apply a drop of Aqua-Regia. If it is genuine, the scratch will turn red.

Testing Silver
Scratch the article with a file and apply a drop of Nitric Acid. If it turns green, it is plated. If a cloudy cream, it is sterling or better. Remember, most Mexican silver generally contains less than 90% fine silver.

Testing Below 14 Karat and Base Metals with Schwerter Salts:
File a deep notch in the test piece and apply a drop of Schwerter's Solution in the notch. The color reaction of the solution with the metal will be as follows:
Brass - Dark Brown
Copper - Brown
Nickel - Blue
Palladium - None
Gold - None
Silver Pure - Bright Red
Silver .925 - Dark Red
Silver .800 - Brown
Silver .500 - Green
Lead - Yellow
Tin - Yellow

The above information is for informational purpose and we do not guarantee results from testing. As with most things with practice you will become better at testing and get an eye for the results. Any new user should consult a professional before assuming any result is correct.


Add to Cart:

  • Model: ADDTST
  • Shipping Weight: 0.2lbs
  • 322 Units in Stock
  • Manufactured by: GTS

This product was added to our catalog on Monday 14 July, 2008.

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