Rutile single crystals grown by skull melting method were cut parallel and perpendicular to growth axis, and both sides of the cut wafers (${phi}5.5mmx1.0mm$) were then polished to be mirror surfaces. The black wafers were changed into pale yellow color by annealing in air at 1200 and $1300^{circ}C$ for $3{sim}15;and;10{sim}50$ hours, respectively. After annealing, structural and optical properties were examined by specific gravity (S.G), SEM-electron backscattered pattern (SEM-EBSP), X-ray diffraction (XRD), FT-IR transmittance spectra, laser Raman spectroscopy (LRS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). These results are analyzed increase of weight in air, decrease of weight in water and specific gravity, shown secondary phase of needle shape, diffusion of oxygen ion and increase of $Ti^{3+}$. From the above results, we suggest that the skull melting method grown rutile single crystals contain defect centers such as $O_v,;Ti^{3+},;O_v-Ti^{3+}$ interstitials and $F^+-H^+$.