Top: logarithmic of the 2–10 keV band observed luminosity, log(L(2–10 keV)), versus the ν_S1 (left) and ν_S1.8 (right) components. Bottom: logarithmic of the ratio between the observed luminosity at 6 keV versus the observed luminosity at 2 keV, log (L_{6 keV}/L_{2 keV}), versus the ν_S1 (left) and ν_S1.8 (right) components. We only plot objects with ν_SB < 10 (see text). The optical classes are shown as: S1 (upside down red triangles), S1.8 (orange triangles), S2 (yellow diamonds), and L1.8 (purple stars).