A lab report or certificate is a blueprint of a diamond that identifies the stone's statistics only. A lab report does not describe beauty. The lab report tells you the diamond's exact measurements and weight. It describes all of the individual characteristics of the stone. The Gemological Institute of America (GIA) and the American Gem Society (AGS) are the two most reputable diamond-grading labs in the world. Long's Jewelers hand selects diamonds that are only GIA or AGS certified.