ping test= gently dropping the coin from a close/safe distance on a hard surface like a glass or metal desk. When the coin is dropped it will roll around until it eventually levels out on one side or the other. AS it rolls around a trained ear can determine whether or not it is silver. Genuine silver coins will have a higher octave 'ping' as it rotates around on the hard surface. Fake silver coins tend to have a lower octave 'ping' that would be best described as sounding 'flat'.
Best way to train your ear is to drop a fake/counterfeit morgan on a hard service and listen. Then drop a genuine morgan and compare the difference in octave. The genuine morgan will make a higher-pitched ping sound that is comparable to a women's soprano voice. While the fake coin would be more comparable to an alto's voice and will sound somewhat 'flat'.