The color change of stone by impregnation with silane was experimentally studied in the laboratory by using colorimeter. The following results were obtained by the experiment: 1) The more amount of silane was impregnated, the greater the difference of color the stone exhibited. 2) The difference of color was dependent mainly on the fall in value, and negligibly on the difference of chroma and hue. 3) After an artificially accelerated deterioration treatment, all the stone samples showed almost the same color, which was nearly the same as their original color, while the hydrophobic effect of the stone samples given by the silane was still found adequately. This study confirms the experientially noticed fact that stone is darkened by impregnation with silane, but regains its original color with time in outdoor conditions while it keeps the effect of treatment with silane. -- AATA