The changes in color of cultured pearls by #betta#-ray irradiation with 60Co, (2)

Raw cream-colored pearls were irradiated by #betta# rays of 60Co. The values of x, y and Y were measured and also the spectral reflectance curves of pearls, nacreous layers and nuclei were measured with 16 interference filters, which were arranged at intervals of 20 nm in the range of wavelength from 400 nm to 700 nm. The spectral reflectance of nacreous layer hardly changed, but those of the nucleus decreased with exposure doses. When the quantity of reflected light from inner surfaces of nacreous layers became smaller, the color of them changed to pale bluish color. Therefore, the reflection factors of the pearls exposed to #betta# ray greatly decreased and also their color changed to pale bluish purple color with exposure doses. (author)