If it was a missing clad, then the color would be red. Note the edge to see what color the copper layer is showing on your coin? If the same color all over, then it is a normal coin that was discolored by being affected by the elements. If found metal detecting, they are brown in color.
When put back into circulation they turn black in color. Note you can see the gray color coming back to the coin. If it were missing a clad, then the color would be red in color.
Also the strike would appear weaker because of the missing thickness of the coin.