The purpose of this paper is to show a possible way to move forward to a usable method for lighting practitioners to characterise and optimise the colour quality of white light sources for general interior lighting. First, correlations between recent colour rendition (colour quality) metrics are analysed. Second, linear and quadratic combinations of the two recently published Illuminating Engineering Society of North America metrics (R_f and R_g) are suggested to approximate two selected visually relevant colour quality metrics, the Memory Colour Quality Index and the NIST Colour Quality Scale Q_p index. Numeric values of the optimum coefficients of these (R_f, R_g) combinations are provided for a comprehensive set of 546 light source spectral power distributions in two correlated colour temperature groups, warm white and cool white. The performance of the different combinations used to describe the metrics ranged between poor and good.