Fluorescent light sources have spectral power distributions with strong spikes. This paper proposes an analysis method for examining the reliability of color temperature estimation of any scene illuminant including fluorescent light sources. We define a color-rendering index for evaluating any light source relative to the blackbody radiators reference illuminants. We show that the sensor correlation method can be used for estimating the color temperature of fluorescent scene illuminants with high color-rendering indices. Both the color-rendering index and the gamut correlation coefficients are useful for examining the reliability of illuminant color temperature estimates. The feasibility of the proposed method is demonstrated in experiments where the Macbeth Color Checker and a natural scene are illuminated with several real fluorescent lamps.