Diamond Grading Labs Using Different Standards, Survey Finds



After sending 10 different diamonds to grading labs in the United States and abroad, a Rapaport survey found opinions that differed by as much as three color grades.

The survey results were announced during the Rapaport certification conference at the JCK Las Vegas show on June 2. 

The survey found that the American labs that received the diamonds—the Gemological Institute of America, the International Gemological Institute, and EGL USA—graded the gems “in the same ballpark,” said moderator Saville Stern, although EGL USA was a little softer on color than the other two.

However, diamonds sent to overseas labs—including EGL Israel and EGL Hong Kong—received different results than those provided by the American labs, and in some instances the grades were two to three colors higher. Antwerp’s HRD lab was also a “little softer than GIA,” Stern said.

Stern worried that all the different standards make the industry vulnerable from a consumer confidence standpoint.

“Are all the labs speaking the same language if someone’s E is someone else’s J?” Stern asked. 

“We have to decide where we draw the line and how do we deal with this,” he continued. “Will someone launch a class-action lawsuit? Do we stand behind our product?” 

Stern noted that many dealers “add value” by figuring out which diamonds are best suited to which labs. 

Retailers speaking at the panel called for more consistent standards.

“If you go to a shop for a car, you don’t call a six cylinder an eight cylinder,” said Daniel Gordon, president of Samuel Gordon Jewelers in Oklahoma City, Okla. “If you are shopping for clothing, you don’t call cotton leather.”

He said these issues come up because customers all want a bargain. 

“When someone is selling for price only, a laminated piece of paper becomes a holy grail,” he said. “I see a huge chunk of business that we have lost due to this problem.”

Christian Sterling, head of C. Sterling and Associates, agreed.

“We have done a terrible job educating the consumer on what a true color actually is,” he said. “They walk in the store and we sell the alphabet.”

“If you sell someone a GIA J, they can’t afford it,” Sterling said. “But tell them it’s an EGL G, and they suddenly love it.”

JCK looked at this issue—as well as possible solutions—in its June 2013 issue: Labs Grade Diamonds, But Who Grades the Labs?, as well as the blog post: The Diamond Lab System Is Broken. How Do We Fix It?

JCK News Director