Transparent glass-ceramics containing LiGasO8: Cr 3 § crystallites have been prepared by heat treatment of Li20-Ga203-SiO2-Cr2Oa glassy material. Average crystallite size evaluated from the full-width at half-maximum of the X-ray diffraction lines varies from about 3-7 nm as the heat-treatment temperature increases from 650 ~ to 800 ~ The ligand field strength of the Cr 3 § ion estimated from optical absorption measurements increases with an increase in the heat-treatment temperature. The fluorescence spectra of the glass-ceramics resemble that of LiGasOs: Cr 3+ polycrystal. In particular, for the specimen containing a crystallite of 7 nm, intense emission due to the 2E ~A2 transition has been observed. These optical measurements demonstrate that the Cr 3+ ions are incorporated into LiGasO8 microcrystals in the present glass-ceramics. For the transparent glass-ceramics and LiGasOs:Cr 3 § polycrystal, the temperature dependence of the peak position of the zero-phonon line (R-line) has been analysed assuming that the electronic transition is described by the Raman process and the vibrational density of state is expressed by the Debye model. The Debye temperature of the transparent glass-ceramics is slightly lower than that of LiGasOs: Cr 3 § polycrystal, indicating that the softening of the phonon occurs in the LiGasO8:Cr 3+ microcrystal precipitated in the transparent glass-ceramics.