The universality of the quasi-linear relation between the order parameter and the normalized birefringence , is confirmed. It is verified that the refractive index of liquid crystals distributed with regular polyhedral symmetry is isotropic and it is given as. and of angular weighted liquid crystals that are initially distributed with regular polyhedral symmetry, are numerically calculated. Also and of liquid crystals that are conically distributed, keeping the rotational symmetry about z-axis are calculated as the apex angle of the cone is varied. Based on these calculated results, it is confirmed that the quasi-linear relation between and is universal, independent of the details of the distribution function.