A fast, accurate model for computing Logvinenko's optimal metamers is introduced. The spectral reflectance of an optimal metamer is uniquely determined from a class of metamers with common tristimulus values. A set of optimal metamers is useful for evaluating the color reproduction and gamut of object colors under different illuminants. In conventional methods, optimal metamers are calculated by interpolating the coordinates of precomputed optimal colors. This model optimizes the spectral reflectance parameters efficiently without switching between bandpass (Type I) and bandstop (Type II) optimal metamers, or requiring any stored optimal-color datasets. Some optimal metamer loci computed using MATLAB are presented.