Gemstone enhancement codes referring to enhancements disclosed by our gem suppliers: N=Not Enhanced, B=Bleaching, C=Coating, D=Dyeing, F=Filling, H=Heating, H=Heat&Pressure, I=Impregnation, L=Lasering, O=Oiling/Resin Infusion, R=Irradiation, U=Diffusion, SC=Special Care Required, W=Waxing/Oiling in Opaque Stones. For additional information, please refer to “Gemstone Information Manual (GIM)” at www.agta.org/info.