Diamond cut grades topic of Centurion breakfast

The Gemological Institute of America introduced some of its key findings on cut grade research at a breakfast seminar during the recent Centurion jewelry show held Feb. 1-5 at the Westin La Paloma Resort in Tucson, Ariz. GIA intends to incorporate expanded cut information on all its grading reports and Diamond Dossiers for all standard round D to Z color diamonds, possibly as early as later this year.

In a move certain to arouse controversy, GIA has definitively stated that a range of proportions can produce a top cut grade, rather than having only one single set of proportions be considered the benchmark.

The introductory breakfast was part of the Centurion series of morning retailer roundtables. Other sessions during the show included such topics as employee relations and training, presented by Kate Peterson of Performance Concepts; hosting a trunk show, with Terry Sisco of ExSELLerate; and the opportunities to be found in the Echo Boom bridal market, presented by Nina Lawrence, publisher of the Conde Nast Bridal Group.GIA’s Tom Moses explained the process by which GIA has been developing its cut grades, a process that includes a combination of proprietary computer models and observation testing.

Visual observation testing has played a much more central role in GIA’s cut grade research in the past few years, whereas its earlier testing was based heavily on computer models. But stones that should have been beautiful according to the computer model sometimes weren’t, whereas stones that theoretically should have been dull or unattractive were sometimes beautiful, said Moses. That led to a revision of much of GIA’s earlier research, with the results expected to produce a scale for evaluating cut later this year.

The new cut grading scale will emphasize the relationship of facet angles and proportions to each other and how a stone looks as a result of those relationships, rather than comparing a stone to a specific set of proportions.

“Having a range [of proportions] means that there are more options available to manufacturers and consumers,” he said. “GIA had manufacturers cut diamonds to various proportions to validate both good and bad cuts according to the computer model,” he explained.

The grading system will also have provisions for considering certain extreme physical attributes that affect the face-up appearance of a stone, whether positively or negatively. Additionally, other attributes such as a thick girdle that makes the stone appear smaller than its carat weight or a knife-edge girdle that makes the stone prone to chipping and breakage will also be taken into account.

A member of the audience asked about established cuts, such as the Ideal cut or the Hearts on Fire cut or other proprietary cuts. Moses said those cuts fall into the top categories for the most part, and they still remain one of the options for having a top cut, but that they are not the only option for a top cut.

The panel included two retailers, Bev Hori from Ben Bridge and Susan Eisen from Susan Eisen Fine Jewels, and one manufacturer, Sheldon Kwiat. Kwiat said that diamond cutters have known for years that ideal is very pretty but so are other proportions, and both Hori and Eisen pointed out that consumers look at a diamond on the hand, not through a loupe.