Parent comment probably meant "colorimeter" which will measure colors in either spectral distribution or XYZ color space. So you could say something like RAL c

Parent comment probably meant "colorimeter" which will measure colors in either spectral distribution or XYZ color space. So you could say something like RAL color # 123 +- 5% in XYZ space. Or you can just specify: That color needs to be closer to RAL #123 than to any other RAL number, so then you'd also have an implicit definition of the valid color range.