Gold nanoparticles electrostatically stabilized with negatively charged ruthenium complexes were individually monitored based on their characteristic plasmon bands, by means of hyperspectral dark field microscopy. Very strong SERS enhancements were observed for the isolated gold nanoparticles at exciting wavelengths in resonance with the surface plasmon band, using confocal Raman microscopy, revealing a contrasting behaviour between the agglomerated and non-agglomerated systems. The results highlighted the relevant role played by the surface enhanced resonance Raman mechanisms (SERRS) in isolated nanoparticles, more than compensating for the lack of local hot spots, in relation to the agglomerated systems.