Ice and Stained Glass together have rendering problems.

Put down a 2x2 square of ice.
Put an ice block on top of a corner, any corner
Fill in the three empty spaces on the second layer with stained glass.
Stand next to the creation.
Jump up or fly up.
Notice the top of the ice blocks are lighter than the sides of the ice blocks, and when you move up the top of the ice blocks look normal again.