Optical micrographs showing transition of stage-2 GIC to stage-1 HOPG GIC. Reflected light. The stage-2 areas are greenish-white. The stage-1 areas are blue. The red-colored areas are the mixed stage. Note, the greenish tint of graphite surface on panels (a,b) is the artifact of the digital processing; the actual color is almost white. The white shapeless feature on the right of the micrographs is an air bubble. Acquired with the SPI-3 HOPG sample.