Lab-Grown Diamond Morphs from Yellow to Pink

RAPAPORT... The International Gemological Institute (IGI) recently graded a 10.06-carat, fancy-vivid-pink lab-grown diamond that had previously been submitted as a fancy-intense yellow.The stone, which IGI had already fully assessed and graded in its original state, was returned in July for a second round, the lab said Tuesday. IGI found that the lab-grown diamond's color had been shifted using a dual-treatment process of irradiation and annealing - heating the stone to a specific temperature, and then cooling it at a very slow and controlled rate - performed with a 5MeV electron Beam Transfer system.The organization's gemologists determined that the color had been fundamentally changed to pink, and the level of saturation in the stone had increased to vivid. IGI also noted specific inclusions created by the High Pressure-High Temperature (HPHT) process matched in both stones. Image: The diamond in its yellow and pink forms. (IGI Worldwide)