American Gem Society (A.G.S).

American Gem Society (A.G.S.), Diamond Quality Report (DQR), and Diamond Quality Document (DQD) are the best diamond quality certifications nowadays. The A.G.S. was founded by Robert Shipley the initiator of G.I.A. The A.G.S. grading laboratory director is Peter Yantzer, who also was the founding director of G.I.A.'s Gem Trade Laboratory. Today the A.G.S. gem laboratory is considered to be even stricter than G.I.A. The A.G.S. also provides very careful diamond quality reports, in which the complete analysis of diamond proportion, color and clarity as well as the description of all the possible diamond flaws, their position, size and shape is contained. AGS quality reports are most often used by cutters who want to affirm whether the absolutely ideal or almost ideal cut diamonds.

The A.G.S. is the only gem laboratory that defines a cut grade as a numerical account between 0 and 10. This system is patterned after the theoretical ideal brilliant of Towkowsky. Theoretical ideal brilliant is considered to be a standard with ideal proportions and facet angles calculated mathematically by Marcel Tolkowsky in 1919. The deal diamond polish and symmetry are also included in the term. An ideal cut diamond is assigned cut grade 0 . Small incremental deviations from the ideal cut means that the diamond must be assigned cut grades 1 and 2, which are still considered very fine.

Though, the cost of a G.I.A. or A.G.S. diamond quality report is high ($100 to $200), Sun Jewelry advices to chose a diamond with a G.I.A. Diamond Report or A.G.S. Diamond Certification as the perfect examples of ideal quality.