A small box/tube that extends a little way below the die would do the trick.
A IR LED on one side, a phototrans on the other. They would be set about 3/8 to 1/2" below the die bottom and you would set them both back ~1/4" from a narrow (1/16") aperture to avoid 'reflections'. That way it should see anything from .22 to whatever your max is without a glitch.
Power could stolen from the counter circuit without trouble.
Although I might add a single opamp as a comparator to clean up the signal before the counter gets it.