It is simple to test silver coins for authenticity if you know what to look for. A limited number of coin denominations were ever made of silver, and then only during certain years. Silver coins have different physical qualities than coins made from other metals. Most fakes can be exposed through research and a few basic tests. If you doubt the authenticity of a coin, it is always best to take it to a professional dealer for an assessment.
Research the coin. Look up the denomination, year and mint mark in a coin guide, like the "Red Book," or a coin web site, like PCGSCoinGuide.com. Both are well-recognised authoritative resources. If the coin is not listed in those resources, then it is not made of silver.
Scrutinise the surface of the coin with a magnifying glass. Silver is naturally more lustrous than the copper-nickel alloy used in dimes and quarters made after 1964, and half dollars made after 1970. Fake silver coins that are cast from dies often have weak detail and bumpy surfaces.
Pay careful attention to the date and mint mark. Many genuine silver coins are altered to appear to have a much rarer combination of date and mint mark. Details can be removed from one coin and glued onto another. Look for scratches where markings could have been removed and squashed glue beneath details that could have been added.
Feel the edges of the coin. If there is a seam along the edge, it could be two cast sides that are glued together. If there is a small protuberance along the edge, it could be where the metal was poured into a mould to make the fake coin. A genuine silver coin will have a uniform edge.
Measure the diameter of the coin. It should match the mint specifications exactly to the millimetre. Fake coins can be slightly larger or smaller due to the unpredictable nature of metal when it is removed from a die and cooled. This can also make a fake coin slightly concave or convex.
Weigh the coin with a sensitive scale. This can be a coin, jewellery or postage scale. It should match the mint specifications to the gram. Fake coins are often lighter or heavier than genuine silver coins since they are made of other metals.
Listen to the sound the coin makes when it lands on a hard surface. They should make a ringing sound. Fake coins make a thudding sound. Do not perform this test if the coin is in mint condition. It could damage the coin and significantly reduce its value.