JCK Show: GIA cut study, It’s not finished till it’s finished.

“We’re not finished yet,” announced Dr. Eileen Reinitz, leaning into the microphone. Speaking to a full house during Wednesday’s “GIA on Diamond Cut” seminar, Reinitz, Dr. Mary Johnson, and Al Gilbertson, the three leading researchers for GIA’s cut study, echoed the same cry: There will be no single “ideal cut,” and GIA still doesn’t have all the answers to make a judgment about what proportions diamond cutters should be using to create the most beautiful diamonds.

The presentation offered three concepts that GIA’s researchers say retailers could take back to their stores:

1. Every facet counts. Tolkowsky measured only the pavilion mains and the crown’s bezel and table facets, while GIA’s research accounts for all 58 facets as well as girdle thickness. All these facets work together to affect a diamond’s appearance. According to research, a cutter can compensate for a choice made for one particular proportion by varying another.

2. Environment affects appearance. Diamonds look different in different environments. The environment that brings out fire may not be the best one to reveal brilliance. “In our experience,” said the GIA researchers, “for any set of given proportions, we can find a specific environment in which the diamond looks pleasing.”

3. Real people need to look at real diamonds in real environments. During their real-life study, GIA’s researchers found that when environments are fairly consistent, skilled observers basically agree. And when environments are variable, so are the results. “Still, the best machine for looking at diamonds is your eyes,” noted Reinitz.

So what does all this mean for the trade? “First, it still appears that there are many sets of proportions that perform well, not just one single `ideal cut,’ ” said Johnson. “Second, cutters are going to have to take into account more parameters. However, they’ll have more choices. And third-stay tuned. There’s more to come.”