A new method is proposed for predicting corresponding colors from magnitude estimation data conducted under two adapting illuminants on the same group of object color samples. Called the F*G* method, it was applied under illuminants D65 and A to magnitude estimation data by Kuo et al. and Luo et al., a part of the LUTCHI data. Both derived F*G* equations were also applied in an experiment with the CSAJ data under illuminants D65 and A. Analyses of these experiments clarified two points: (1) the magnitude estimation method is inaccurate for predicting corresponding colors including with the Kuo et al. and Luo et al. data; and (2) unacceptable extrapolations had been made by Luo et al. in deriving their corresponding colors.