We aim to develop a method for distinguishing quality of stone artifacts. A value of stone artifacts depends on the
polishing quality of the surface. However, it is difficult to evaluate quantitatively and its evaluation is performed by
sensibility of experts. According to a theory, experts can sense a minute difference of optical characteristic of polished
stone surface. We propose a simultaneous measurement of spectral reflectivity and birefringence of polished stone
surface using the polarization phase-shifting interferometer. In the polarization phase-shifting interferometry, the phase-shifter
gives a phase difference between perpendicular polarized beams. This phase difference can be considered the
optical retardation. When the linearly polarized beam passes though a sample which has birefringence, the initial phase
of interferogram is shifted. Thus, retardations in each wavelength can be calculated by Fourier analyzing a interferogram.
First, we constructed a coaxial illumination type optical system for verification experiments. As a result, we confirmed
the reflected light from surface is stronger than light from inner. Therefore, it cannot measure inner reflected light which
has valuable optical characteristics. Based on these results, we improved the illumination method of optical system to
oblique illumination. Finally, we can obtain the 2-dimentional spectral reflectivity and birefringence characteristics.