(IDEX Online) - Gemologists from the IGI lab in Thailand spotted their biggest ever impostor stone - a 6.18-carat lab-grown that was being presented as a natural gem.It had been submitted for verification and came with a GIA certificate stating it was a natural diamond, D color, flawless clarity and triple excellent cut.The genuine stone had been fraudulently replaced with a lab-grown that had been deliberately cut and polished as an extremely good replica. "The diamond was lab-grown and was cut and polished specifically to match the data on the GIA report with meticulous precision previously never seen," the lab said."To further the deception, the stone was inscribed with a fake laser number."Bob Van Es, IGI Thailand and Hong Kong managing director, said: "This is the largest lab-grown diamond ever certified by a leading gemological laboratory, where the sole purpose was to pass off a lab-grown stone as natural." Pic courtesy IGI