CountDown List Prefabs

Hello, how are you !! I would like to know how I could get accessed the elements of my List, in this case I have a list with 4 elements (white, black, red and blue) and each element with 8 pieces of my board, I try to generate a gameover screen when my pieces are less than 1 element the same color. But at the time of the elimination of the piece marks me a missing (object of game). I hope you can help me access the contents of my list.