Irradiated South Sea cultured pearls (SSCPs) from the Pinctada maxima mollusk typically show colors from light gray to silver. It is difficult to identify gamma-ray irradiation of SSCPs using standard gemological methods because of their thick nacre. Therefore, an advanced analytical technique such as electron spin resonance (ESR) spectroscopy is needed to detect the treatment. ESR measurements of minute amounts of SSCP powders revealed the formation of CO 2 -radicals, and the parameter known as the g -factor was measured at 2.0015 ± 0.0005. Higher levels of CO 2 -radicals were detected in the pearl nacre than in the nucleus. Therefore, the existence of CO 2 -radicals is an indicator of irradiated SSCPs.
Irradiated South Sea cultured pearls (SSCPs) from the Pinctada maxima mollusk typically show colors from light gray to silver. It is difficult to identify gamma-ray irradiation of SSCPs using standard gemological methods because of their thick nacre. Therefore, an advanced analytical technique such as electron spin resonance (ESR) spectroscopy is needed to detect the treatment. ESR measurements of minute amounts of SSCP powders revealed the formation of CO 2 -radicals, and the parameter known as the g -factor was measured at 2.0015 ± 0.0005. Higher levels of CO 2 -radicals were detected in the pearl nacre than in the nucleus. Therefore, the existence of CO 2 -radicals is an indicator of irradiated SSCPs.
