How to Test 18-Karat Gold
Gold, or Au in scientific terms, is a precious metal that in pure form is soft, pliable, ductile, and resistant to oxidation. While its pure form properties make gold useful in a variety of ways that include crafting it into pure, or 24-karat gold jewelry, most is not gold in pure form, but rather a gold alloy. An example of a gold alloy is 18-karat gold, made from 75 percent gold and 25 percent silver or copper. It is not possible to determine authenticity with a visual inspection, but there are ways to test 18-karat gold and determine its authenticity. Does this Spark an idea?
Things You'll Need
- 18-karat acid
- Black acid testing stone
- 18k gold testing needles
- magnet (optional)
- unglazed porcelain (optional)
Instructions
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1
Position the Black Acid testing stone on a solid surface. Run the gold item you are testing across the surface of the stone with enough pressure to produce a scratch.
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2
Make another scratch on the testing stone using the 18k testing needle.
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3
Apply one or two drops of 18-karat testing acid to both scratches.
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4
Wait 30 seconds and observe changes to the testing stone. The scratch made with the 18k gold testing needle will not disappear. If the scratch made using the 18-karat gold piece disappears, it is not 18-karat gold.
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Tips & Warnings
While the following tests cannot determine the purity of gold, they can tell you whether the item contains gold or is a "fake." To determine whether your item contains gold, first hold a magnet next to the gold item. Gold is not magnetic, so it should not attract the magnet. Another test you can perform is to rub the gold item on a piece of unglazed ceramic, such as a floor tile. Real gold will leave a gold-colored streak on the tile, while "fake" gold will produce a black streak.
If you perform the test more than one time, be sure to wash the testing stone thoroughly before using it again.
You can also purchase a gold testing kit that contains the testing stone, needles, and additional acids to test for 10, 12, and 14-karat gold.
References
Resources
- Photo Credit gold image by ennavanduinen from Fotolia.com
