In spite of several papers, the origin of visible luminescence from germanium nanocrystals in a SiO2 matrix is controversial even today. Some authors attribute the luminescence to quantum confinement of charge carriers in these nanocrystals. On the other hand, surface or defect states formed during the growth process have also been proposed as the source of luminescence in this system. We have addressed this long-standing query by simultaneous photoluminescence and Raman measurements on germanium nanocrystals embedded in the SiO2 matrix, grown by two different techniques: (i) low-energy ion implantation and (ii) atom beam sputtering. Along with our own experimental observations, we have summarized some of the works done by other authors and proposed a hybrid model to explain the visible photoluminescence from nanocrystalline germanium in the SiO2 matrix.