U.K. Watchdog Group Rules Against Lab-Grown Diamond Ads

By Karen Dybis | May 13, 2026

Britain’s Advertising Standards Authority (ASA) has barred two lab-grown jewelry companies from continuing to run certain ads again and ordered them to use “clear and prominent” qualifiers such as synthetic or laboratory-created in their promotions.

The Natural Diamond Council (NDC), which along with the London Diamond Bourse had filed complaints with ASA about the ads, called the rulings a victory for the public.

“It’s vital that consumers can make informed choices in total confidence,” Amber Pepper, CEO of the Natural Diamond Council, said in a statement. “This is not the first time we have successfully challenged advertising that blurs the distinction between mass-produced products grown in a factory and products of nature formed deep in the earth over billions of years.

The ads in question came from Australian company Novita Diamonds and Hong Kong-based Linjer Ltd. NDC and the London Diamond Bourse had said they did not disclose that the brands’ diamonds were lab-grown.

On Wednesday, ASA upheld both complaints. The watchdog agency has issued similar rulings in cases brought by NDC in the past.

“We applaud the regulator for once again standing up for consumers–something we too will continue to do as part of our wider mission to educate and inspire people on the values of natural diamonds and their positive impact,” Pepper said.

London Diamond Bourse president David Troostwyk added: “These rulings should send a strong message to manufacturers and retailers. Misleading practices exploit the timeless value people associate with natural diamonds to unduly benefit companies at the expense of consumers. We hope the message is now cutting through that irresponsible advertising will not be tolerated.”

The Novita complaint related to two social media ads that ran in January 2026, one that read “Novita Diamonds Ready-to-Ship Engagement Rings 1-10 days,” and the other a video featuring the on-screen text “Premium Diamonds” and “Shop our ready-to-ship collection today – Novita Diamonds.”

“Neither of the ads included an explicit qualification that Novita Diamonds were synthetic, laboratory-created, or similar, nor was there anything within their content that made clear they were synthetic. We therefore considered that consumers would not be aware from the ads that the diamonds were synthetic diamonds,” ASA said in its ruling.

The Novita decision clarifies that even if an ad does not explicitly mention diamond but the brand name contains the word diamonds, a qualifier is required.

In a separate ruling, ASA said Linjer didn’t identify its diamonds as lab-grown in two Google ads from January that included the phrase “Discover our brilliant diamonds.”

The agency noted that Novita and Linjer were in breach of the U.K. Code of Non-Broadcast Advertising and Direct & Promotional Marketing, aka the CAP code.

“Linjer Ltd. did not realize that their ads breached the code. They said they would work with their ad agency to include language around the diamonds being lab-grown to their Google ads, and had implemented internal checks to ensure the terminology was consistently applied going forward,” ASA wrote.

In the U.K., the National Association of Jewellers’ Diamond Terminology Guideline says synthetic diamond marketing must have authorized qualifiers, such as synthetic, laboratory-grown, or laboratory-created.

(Photo: Getty Images)