Resonant Raman Scattering (RRS), and selectively excited photoluminescence (PL), spectra were obtained for cubic c-InxGa1-xN with x = 0.07, x = 0.19 and x = 0.33. The emission of blue and green light observed at room temperature and T = 30 K, is attributed here to quantum confinement effects due to the self-formation of quantum dots of c-InGaN. The average In content within the dots, (x) over bar, was measured directly by a selective resonant enhancement of the Raman scattering. The values for (x) over bar were found to be the same for all samples. This method allowed also the detection of an important composition inhomogeneity of the dots.