It's a little harder to tell if a silver coin was dug. I believe everyone may be referring to what an older copper or bronze coin looks like coming out of the ground (2 cent pieces and newer indian head pennies were bronze). For example, I've dug a few large cents that still have a remarkable amount of detail left on them but due to the color (usually green or even almost black sometimes) the grading companies mark them with "environmental damage" on the slab.
Just be careful not to scratch the coin when removing whatever dirt is left on it before submitting it. It might cost you more than the coin is worth just to have it slabbed. I would suggest a 2x2 coin flip also.
