This letter provides a brief summary on early work and developments on both controlling and studying the optical properties of resonant metal nanoparticles and reports on all progress achieved since two years. Our approach is based on controlled nanoscale photopolymerization triggered by local enhanced electromagnetic fields of silver nanoparticles excited close to their dipolar plasmon resonance. By anisotropic polymerization, symmetry of the refractive index of the surrounding medium was broken: C1v symmetry turned to C2v symmetry. This approach has overcome all the difficulties faced by scanning probe methodologies to reproduce the form of the near field of the localized surface plasmons and provides a new way to quantify its magnitude. Furthermore, this approach leads to the production of polymer/metal hybrid nano-systems of new optical properties.