AGS Labs to issue new cut grades

American Gem Society Laboratories will issue a new cut grade for princess cut diamonds by the end of the first quarter of 2005. It will be followed by the new round brilliant cut grade system to be released in the second half of 2005. The science supporting the new cut grade system reflects AGS Laboratories’ advancement from a proportion-based to a performance-based cut grade system, according to a top AGS official.

“The new grading system for round brilliants will actually increase the integrity of the AGS 0 Cut Grade because it involves more physical measurements and scientific analysis than the old system required, and includes additional criteria based on new, cutting-edge technology,” said Peter Yantzer, Executive Director of AGS Laboratories. “Over the next 6-12 months we will be providing support materials and software for the parameters of the new cut grade system for our manufacturing clients which will assist them in cutting.”

In the new cut grade system, all 58 facets of a diamond are measured in three dimensions rather than two dimensions. The measurements are used by a ray tracing computer program to trace light rays traveling through a diamond, Yantzer explained. The program shows the quantity and quality of the light being returned to the viewer. In addition to proportion, symmetry, and polish, AGS Laboratories will also consider brightness, dispersion, leakage, contrast, and spread in assigning the final cut grade.

The zero cut parameters for the traditional 53-57% tables have been tightened. Advancements in proportion grading eliminate a certain percentage of the original combinations of the round brilliant AGS 0 Cut Grade. Therefore, some diamonds that were previously AGS 0 cuts will no longer meet the new scientific standards, due to lower scores in the light performance categories.

“The science supporting the refinement and realignment of the round brilliant AGS 0 Cut Grade system adds additional table sizes, but only in combination with very limited relationships of angle and facet configuration,” Yantzer said. “Because of the limited combinations of proportion parameters, it will take a very skilled cutter to create the round brilliant AGS 0 Cut Grade in larger table sizes.”

To assist clients in cutting to the new standards, the AGS Laboratories will issue parameter guidelines for the princess cut shortly and will issue the new round brilliant parameters in the first half of 2005.