Using buffer solutions, consisting of pH 4, 5, 6, 7, and 8, silk fiber fabric specimens, pre-mordanted with one of the mordanting agents, Sn, Al, Cu, Cr, and Fe, were dyed using cochineal dyestuff. The color of the dyed silk fabric specimens was predominantly red(R) for the acidic range of pH 4 and 5, and predominantly purple(RP) for the neutral range of pH 6,7, with 8, with the pH boundary differentiating between the shades being between pH 5 and 6. As a general trend, the chroma value decreased as the pH changed from acid to alkali, and the highest chroma value us attained between pH 4 and 5. Regardless of the mordanting conditions, the trend was that $ {Delta}E$ showed the highest measured value in the acidic range of pH 4 and 5, and it dropped abruptly after the pH 6.