The effect on colorimetric accuracy of spectrophotometric errors (+/- 0.5 and +/- 1% reference white, +/- 0.25 and +/-0.5% reference black, and +/- 0.5 and +/- 1 nm wavelength) was simulated for the BCRA Sei-ies II tile set by using previously investigated models for these errors. Delta E(94)* color differences of up to 5.2 could result. Because the errors are linearly related to CIELAB differences for each tile, a technique was derived that enabled Delta L* Delta a*, and Delta b* coordinates between a calibrated tile and its measured value to be transformed into estimates of reference white, reference black, and wavelength error. The cyan tile was identified as the most effective tile for this technique. ＇＇Universal＇＇ equations are included for 45/Normal and Normal/Total geometries traceable to the National Institute of Standards and Technology (NIST), and Normal/45, Normal/Total, and Normal/Diffuse geometries traceable to the National Physical Laboratory (NPL). Measuring the cyan tile on a regular basis and transforming its colorimetric coordinates into spectrophotometric error metrics provides a useful method to validate the accuracy and reproducibility of a color-measurement instrument.