Know How to Test Gold, Platinum and Silver Purity? Instructions for Scratch Testing

When you inherit a fine piece of antique jewelry or purchase one it might not be in the best condition simply due to age. That might make determining the purity of the metal and even whether it is actually gold, platinum and silver a bit tricky. Even when antique jewelry is a good condition the untrained eye (and sometime even the trained eye) might have some difficulty determining the purity of the metal.

Even experienced antique jewelry buyers can sometimes have trouble with determining the purity of it. That is why there is, what is popularly referred to, as a scratch test to establish the purity of gold, platinum and silver. It is a very valuable tool that is used for antique jewelry valuation. If you have a truly beautiful piece of antique jewelry it might be the key to figuring out it if is truly made of gold, platinum or silver. In this article we will provide instructions for scratch testing your jewelry.

#1- Kit for Testing Gold, Platinum and Silver

This first thing that you need when you want to use scratch test on your antique jewelry is a kit for a scratch test. The kit should contain a black slate stone (similar to a knife sharpening stone, various bottles of acid solution, and instructions. There should be one bottle of solution to test platinum, one bottle of solution to test for silver, and several bottles of solutions to test for 22 karat gold, 18 karat gold, 14 karat gold, and 10 karat gold. Because you are working with acid, you will want to wear latex gloves for protection when doing the scratch test.

                                                                                                                                                Image courtesy of Amazon

#2- Antique jewelry testing- Gold

So, you have a beautiful piece of antique jewelry that you want to sell or maybe there is one that you want to buy. It is yellow so it can’t be platinum or silver. It must be gold or some metal like brass that also looks yellow. How can you do the scratch test on it? Put on your latex gloves and follow these easy steps:

• Step one: Take your kit and layout the stone.
• Step two: Take out the four bottles to test for gold and put them aside.
• Step three: Take the jewelry and scratch it against the stone until there is a clear mark on the stone from the ring.
• Step four: Repeat step three until you have a total of four lines on the stone.
• Step five: Take the bottle with the solution to test for 22 karat gold and pour a drop over the first mark that you made.
• Step six: Watch what happens! If the acid dissolves the mark, then the jewelry isn’t 22 karat gold. If it doesn’t dissolve the mark, then the jewelry is 22 karat gold.
• Step seven: If the first mark does dissolve, then take the solution to test for 18 karat gold and put a drop on the next mark. If it does dissolve, then the jewelry isn’t 18 karat gold. If it doesn’t dissolve, the jewelry is 18 karat (or better) gold.
• Step eight: If the second mark does dissolve, then take the solution to test for 14 karat gold and put a drop on the next mark. If the third mark does dissolve, then the jewelry isn’t 14 karat gold. If it doesn’t dissolve then the jewelry is 14 karat (or better) gold. A note: Prior to 1982 it was legal to mark jewelry that was 13.5 karat gold as 14 karat gold. When testing jewelry that is 13.5 karat with the solution for 14 karat gold the mark will not completely dissolve but it will lose it brightness and become yellow-rust color.
• Step nine: If the third mark does dissolve, then take the solution to test for 10 karat gold and place a drop on the fourth and final mark. If it does dissolve then the jewelry is less than 10 karats or likely not gold at all. If doesn’t dissolve then the jewelry is 10 karats or better.

#3- Antique jewelry testing- Platinum and White Gold

If that beautiful piece of antique jewelry that you want to sell or may buy is white it might be platinum or it might white gold that is 18 karats or less (22 karat gold is never white). To test for platinum or white gold use the following steps:

• Step one: Take out your kit and layout the stone.
• Step two: Take out the bottle to test for platinum gold.
• Step three: Take the jewelry and scratch it against the stone until there is a clear mark on the stone from the jewelry.
• Step four: Place a drop of the platinum solution on the mark. Watch what happens! If the jewelry is platinum then the mark should keep its bright, white color. If the jewelry is 18 karat white gold, then the mark should start to change to a light bronze color in about 3 minutes. If the jewelry is 14 karat white gold then the mark should disappear in about 15 seconds.

#4- Antique jewelry testing- Silver

If that beautiful piece of antique jewelry is silver in color and you want to be sure that it is genuine silver you can test it by following these steps:

• Step one: Take out your kit and layout the stone.
• Step two: Take out the bottle to test for silver.
• Step three: Take the jewelry and scratch it against the stone until there is a clear mark on the stone from the jewelry.
• Step four: Place a drop of the silver solution on the mark. Watch what happens! If the jewelry is silver, you will see the mark change to the following color, depending on the purity of the silver.

Fine Silver (.999) = Bright Red
Silver 925 = Dark Red
Silver 800 = Brown
Silver 500 = Green

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