Three-dimensional corrosion was previously derived as directed collapse of the layer density gradient field F=∇(1/N) in (x,y,z) space. Here we extend this framework to five dimensions by incorporating time t and optical wavelength λ (color). Color is shown to be a direct readout of the local N-field state: the wavelength of light at a corroding surface encodes the instantaneous magnitude and direction of ∇(1/N) at that point. Color distribution = 3D N-gradient map. Color change rate = corrosion velocity. Color stabilization = corrosion arrest. Gold does not corrode because ∇(1/N)≈0. The framework provides the first unified physical basis for optical corrosion diagnostics and non-invasive monitoring criteria for KHDS v1.0 cardiac implants.