What treatments does GIA test for?

Diamonds are tested/examined for laser drilling, glass filling, surface coating, High Pressure/High Temperature (HPHT) processing, and irradiation.

Colored gemstones are tested/examined for heating, irradiation, fracture filling/clarity enhancement, coating, dyeing, and diffusion.

Pearls are tested/examined for bleaching, heating, dyeing, irradiation, coating, peeling, filling and impregnation.