AGSL: The American Gem Society Laboratories is recognized by the jewellery industry as one of the foremost authorities in diamond grading. Known industry-wide as the laboratory with the highest standards of evaluating diamond quality, the AGSL employs leading-edge research and technology on diamond grading, diamond cut grade research and the light performance of a diamond, all to benefit you in your diamond purchase.  An example of an AGSL report is: The Diamond Quality® Document (DQD).  It provides a complete diamond grading analysis of the 4Cs with special detail to cut including information about light performance, proportions, polish and symmetry.  All Ideal Cut diamonds come with a Diamond Quality® Document.