  We compare the light extinction spectra of elongated gold nanoparticles with
different shapes (cylinder, spherocylinder and ellipsoid) and sizes of 10 to
100~nm. We argue that the equivalence of the various moments of mass
distribution is the natural comparison criterion -rather than the
length-to-diameter (aspect) ratio generally used in the literature- and that it
leads to better spectral correspondence between the various shapes.
