The Sample-Independent Color Rendering Index (CRI) is a measure that is independent of the choice of test color samples and that can be used for assessing one important aspect of color-rendering properties of illumination, the aspect of accuracy of color rendering in a broad sense. This Sample-Independent CRI works by measuring the degree of conformity between the maximum color solid attainable under a test illuminant and that under a reference illuminant. The derivation of the Sample-Independent CRT, the calculation procedure involved, and some calculated results are presented.