The new Gemological Institute of America cut grade will leave significant room for individual preference, a trio of heavyweight Institute researchers announced to a capacity crowd at a seminar Thursday.
Tom Moses, vice president of GIA’s Gem Trade Lab, said that GIA is instituting the grade because it feels it will serve the public interest and provide greater consumer confidence.
“We believe the industry is best served with unbiased information about cut,” he said. But he added, “We at GIA are very sensitive to the changes and challenges the grade will bring.”
The idea is to “create an international standard [for cut], like our grades for color and clarity,” said Barak Green, the Gem Trade Lab’s communications manager.
There will be five overall cut grades: excellent, very good, good, fair, and poor. Most diamonds will fall into the top three categories.
The researchers consistently declined to specify what parameters would fall into what category, saying that information will be revealed when GIA releases its cut grading “reference system” software in the near future. But they gave no specific date for its release, or for when the cut grade will be formally instituted.
The research behind the project divined five key factors that affect a diamond’s appearance:
* Brightness. This was defined as the “reflection of white light that comes through the diamond.”
* Fire. This is the colored light that comes through the diamond. Both fire and brilliance are calculated using computer-modeled ray tracing.
* Scintillation. “The appearance, or extent, of spots of light seen in a polished diamond when viewed face-up as the diamond, observer or light source moves.” Also, the size, arrangement, and contrast of bright and dark areas.
* Design. This encompasses weight ratio and durability.
* Craftsmanship. This includes polish and symmetry.
The GIA research was backed up by more than 70,000 observation tests, where over 3,000 tradespeople and consumers indicated which diamond they found most visually pleasing.
“Our research reflects not only what science told us, but what [people] told us,” GIA researcher Al Gilbertson said. “The observation tests validated our science.”
One key finding GIA made is that there is a wide range of proportions that lead to a visually pleasing diamond.
“When people looked at diamonds [in the observation tests], there was no one stone that everyone agreed was the best diamond,” said Green. “People could not agree on the best set of diamond proportions.”
As a result, the stones that receive the top grade of “excellent” can look quite different. This will give retailers an opportunity to stress to consumers the importance of visually examining each diamond and personally choosing a stone, the researchers said.
“If consumers rely solely on the paper, they will see a wide variety of appearances, and they will be puzzled at that,” Gilbertson said. “So, what a concept—people will need to look at the diamond they are going to wear for the rest of their life.”
The researchers noted that their new cut grade will not cover fancy shapes, fancy-colored stones, or rounds modified with different facet arrangements.