Natural Diamond Council has welcomed two rulings from the UK’s advertising watchdog backing its efforts to protect consumers from misleading adverts of synthetic diamonds.

The not-for-profit organisation, which exists to promote and protect the integrity of the global natural diamond industry, complained to the Advertising Standards Authority (ASA) about adverts by two retailers that failed to mention their products were laboratory-grown.

On May 13, 2026, the regulator upheld both complaints. It agreed that UK-based Novita Diamonds and Hong Kong-based Linjer Ltd had misled consumers and were in breach of the UK Code of Non-broadcast Advertising and Direct & Promotional Marketing (CAP Code).

The companies were told their adverts must not appear again with the same wording. The ASA also told them not to “misleadingly” use the term ‘diamond’ to describe their synthetic diamonds in isolation without a clear and prominent qualifier, such as ‘synthetic’ or ‘laboratory-created’.

Amber Pepper, CEO, Natural Diamond Council said:

“This is a victory for consumers. Diamonds carry deep emotional significance and are often bought to mark life’s meaningful moments. It’s vital that consumers can make informed choices in total confidence.

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. 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.”

Novita Diamonds Advert

The Novita Diamonds ruling concerned two paid-for Meta ads. The first showed an image of a diamond ring with a description that included the words:

“Novita Diamonds Ready-to-Ship Engagement Rings 1-10 days”

The second ad featured a video showing clips of diamond rings with on-screen text including:

“Premium Diamonds”
“Shop our ready-to-ship collection today – Novita Diamonds”

Linjer Advert

The Linjer ruling related to two paid-for Google ads. Both included the phrase:

“Discover our brilliant diamonds”

What the Rulings Mean for Trade Participants

In both cases, the ASA referenced the National Association of Jewellers’ (NAJ) Diamond Terminology Guideline, which is assured and recognised by Trading Standards in the UK market.

It states that when referring to synthetic diamonds:

• Use one of the following authorised qualifiers: ‘synthetic’, ‘laboratory-grown’ or ‘laboratory-created’
• Do not use abbreviations such as ‘lab-grown’ and ‘lab-created’
• Do not use the terms ‘cultured diamonds’ and ‘cultivated diamonds’
• Do not use the terms ‘real’, ‘genuine’, ‘precious’, ‘authentic’ and ‘natural’ for synthetic diamonds

The ASA ruled that whether a diamond was natural or synthetic would be a key consideration for many consumers. To avoid misleading advertising, this information must be clearly stated upfront in the advertisement itself — not only on the website consumers visit later.

The Novita Diamonds ruling also clarified that even if an advertisement does not explicitly mention the word “diamond,” a qualifier is still required if the brand name includes the word “Diamonds.”

The ruling against Linjer further confirmed that ASA regulations apply to UK-targeted paid media, including Meta and Google ads, even if the advertiser is based overseas.

A Track Record of Consumer Protection

Natural Diamond Council has challenged misleading advertising several times in recent years.

In 2024, the ASA upheld a complaint against Skydiamond for failing to clearly identify its products as laboratory-grown. While not conducting a separate investigation on UK jeweller Stephen Webster, the regulator informed the company that the same ruling applied to its advertising materials.

The ASA also investigated complaints against Lark & Berry and Idyl, which it considered likely to be in breach of its code. In both cases, the rulings were published as informally resolved after the companies agreed to amend their advertisements.

“These rulings should send a strong message to manufacturers and retailers,” said David Troostwyk, President of the London Diamond Bourse, which jointly filed the latest complaints against Linjer and Novita Diamonds. “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.”