The Everlon Diamond Knot made noise—as well as sales—after it was introduced by De Beers last summer. But it’s also providing a nice income for copyright and trademark lawyers.

Everlon is different from past De Beers–advertised products, because it’s meant to be a proprietary product sold exclusively by De Beers’ retailer and manufacturer partners. And from the beginning, De Beers has indicated it would zealously protect Everlon’s intellectual property rights.

“There have been a number of companies who have been brought to our attention as potential infringers of our Everlon IP, and we are dealing with them on a case by case basis to protect our sightholders and their retailers,” says spokeswoman Lynette Gould. “De Beers has filed for various U.S. copyright registrations in the Everlon collection and has applied for U.S. design patents for various pieces of the Everlon collection. Several of the design patents have been allowed and registered and the others will issue in the near future.”

Industry trademark attorney Peter Berger said several of his clients already have received letters about Everlon. Yet, like others, he argues that De Beers is not the first company to use designs inspired by the Hercules knot. “A lot of people claim the ring design has been around a long time,” he says.

In fact, De Beers is not only threatening to file lawsuits over Everlon but also has found itself on the wrong end of one. In December, Orogem, Burbank, Calif., launched a lawsuit claiming Everlon infringes on its copyrighted Larkhead Pendant designs. Also named in the suit were four companies manufacturing Everlon—Rosy Blue, Stuckey Diamonds, Universal Pacific Diamonds and Jewelry, and JB-DM Jewelry—as well as retailers J.C. Penney, Macy’s, Zale Corp., Wal-Mart, Helzberg Diamonds, Ben Bridge Jewelers, Samuels Jewelers, and Fred Meyer Jewelers.

De Beers had not responded to the suit at press time. Orogem declined comment.

All this may make it more difficult for De Beers to clamp down on manufacturers with similar designs. “As far as I know, De Beers has started no lawsuits,” says Berger. “And until there is successful legal action, some companies will probably continue to sell it.”