Clearstone

You cause a rock or section of stone to become transparent.   This spell affects naturally occurring stone, ore, gemstones in the rough, and even worked stone such as a statue or tunnel wall, but not worked metals, cut gems, or fabricated stone materials such as brick or concrete.   Visibility through the affected stone is perfectly clear and limited only by the available light or by objects and creatures embedded in the stone (such as a creature using meld into stone).   Clearstone grants line of sight, but not line of effect, through the affected stone.   This spell does not change a stone's hardness or other qualities in any way.   Clearstone can be made permanent using permanency (minimum caster level 11th, 1,500 XP).   Arcane Material Component: A small, flat piece of glass.
 

You cause a rock or section of stone in up to four 5-foot Cubes to become transparent. This spell affects naturally occurring stone, ore, gemstones in the rough, and even worked stone such as a statue or tunnel wall, but not worked metals, cut gems, or fabricated stone materials such as brick or concrete. Visibility through the affected stone is perfectly clear and limited only be available light or by objects as creatures embedded in the stone (such as a creature using Meld into Stone). This spell does not alter the hardness or other qualities of the stone in any way.   Clearstone can be made permanent using Permanency.   At Higher Levels. When you cast this spell using a higher level spell slot, you can affect an additional 5-foot Cube of stone per slot level above its base level.