A color simulation tool has been created which accurately renders the color appearance of prototype displays. The tool can be used in the early stages of display design or to predict the effect of design or process changes on existing display performance. The tool includes calibration procedures and algorithms to directly render the closest in-gamut CRT color available, provides accurate color simulation across a broad luminance range, and preserves the relative dynamic luminance range among simulated color samples. The tool is shown to display simulated in-gamut color to within 2.0 CIELUV DeltaE* units at screen center. We describe the results of this color simulation tool as applied to the on-axis color performance of an active matrix LCD with a variety of adjustable display parameters.