We report on fabrication, morphological and spectroscopic assessment of micro and nanospheres. Spheres with size ranging from few hundreds of nm to few hundreds of mm were prepared by different methods i.e. sol-gel, melting and core-shell techniques. The following systems are discussed: (i) coated micro and nanospheres where the silica core, obtained both by telecom fiber melting and by sol-gel, is coated with an Er3+-70SiO2-30HfO2 or an Er3+-SiO2 film, respectively; (ii) Er3+ and Er3+/Yb3+ -activated microspheres obtained by silicate-modified glasses and phosphate glasses using a plasma torch; (iii) Er3+ sol-gel derived silica spheres. The presented fabrication techniques are friendly methods leading to high quality surfaces of the spheres. When the spheres exhibit the suitable optical parameters also whispering gallery mode spectra were analysed as a function of sphere diameter, thickness of coating and erbium content. It is demonstrated that it is possible to select the radial order n tailoring the whispering gallery modes. The quasi-independent behaviour, observed for coated micro-spheres, and due to thermal effect linked to the injected pump, brings a major interest for lasing applications. Sol gel-derived core-shell-like Er3+-activated silica spheres was obtained by seeded growth. Typical photoluminescence spectrum of erbium, with a lifetime of 12.8 ms, was observed leading to a quantum efficiency of 71%. As far as concerns Er3+- sol-gel silica derived spherical spheres a quantum efficiency of 76% was estimated. Application of nanospheres to fabrication of specific photonic crystals structures will be also presented.