Agate blocks and redirecting light.

Agate blocks would be a geode but 1 block in size. It would be filled with quartz and have different color variations. For simplicity, it can be found in as a white with the ability to dye it to different hues. The block would be encased in a stone shell. One or two sides would have the agate exposed. Should it have two sides exposed it could redirect light through it. This could make for interesting contractions. I once saw a movie where the cast used mirrors to light up an Egyptian tomb. States could be used like those mirrors, or make interesting redstone contraptions using light. With dyed agate blocks, it could act like colored beacon light.