We characterize engineered nanostructures with sizes smaller than half a wavelength using spectrally resolved interferometry. We analyze the response of the meta-atom of interest, which has a raspberry-like geometry. To identify the origin of the response, the study of individual building blocks, namely individual gold and silica nano-spheres, are first examined in this paper. Due to the fact that the size of the object is smaller than the resolution limit, phase information plays an important role in our analysis.