Undoped and doped with Eu2O3 oxide glasses of the mK(2)O-kP(2)O(5)-nB(2)O(3)-xPbO composition were manufactured and studied. The glass-ceramics nanocomposites were manufactured by addition of the doped Eu3+ ions with KCa(BO3) micro/nanosized crystals into the noted glasses. All the samples were characterized with use of scanning electron microscopy (SEM), X-ray diffraction (XRD), diffuse reflection, and photoluminescence (PL) procedures. The XRD patterns of the glass-ceramics samples showed the peaks corresponding to crystalline component of the composite. Wide bands of intrinsic PL were found in the PL spectra of glasses, while the narrow lines of f-f radiation transition were observed in the spectra of the glasses containing europium oxide and in the spectra of the glass-ceramics. It was concluded that the Eu3+ ions in glass-ceramics locate both in the glass matrix and the crystalline particles. Moreover, the luminescent features of the Eu3+ ions located in interphase layers were found. This finding creates a basis for monitoring interphase layers formed in glass-ceramics containing Eu3+ or other luminescent rare-earth ions.