There are a number of ways to test the purity of silver.
The first way, and the least expensive, is to check for a stamp.
To do this, you inspect the piece to be tested with a magnifying glass. If there are numbers on it such as 925 that number indicates the percentage of Fine silver in the piece. A piece marked 925 is 92.5% pure silver. a.k.a. Sterling Silver. (See our blog on how to identify silver purity from the markings)
Another method of testing would be the Magnetic Test.
To perform this test, you would use the rare earth magnet and put it on the piece to be tested. Silver exhibits only weak magnetic effects so if your magnet sticks to it the item is not silver. It should be noted that there are a few other metals the do not stick to a magnet and can be made to look like silver so it is best to perform the magnetic test in conjunction with another test to make sure the item is silver.
The next method of testing is the Ring Test.
This method is used primarily with coins. Silver makes a bell like ringing sound when struck. For this test, you would drop the coin on a flat surface from about 6 inches above. If it makes a sound like a bell then you have a silver coin . If the sound is dull then it is most likely an alloy. There is a device by Fisch called the ringer that would provide another way to perform this test.
The next test is an acid test.
To perform this test, you rub the item to be tested on a rubbing stone and then use silver testing acid on it. Depending on the purity of the silver, the acid will turn different colors. You would then match up the color of the acid to the chart that comes with your acid testing kit to determine the silver content. (See our blog what is an acid test?)
The last test that we will Touch on here is the XRF test.
This test is by far the most accurate and expensive of all the tests. The test consist of shooting the item to be tested with an XRF gun reading the digital readout on the Digital screen. (See our blog what is an XRF test)