A recent ruling by the UK Advertising Standards Authority (ASA) against two jewelry companies over advertisements promoting synthetic diamonds without clearly identifying them as such has raised concerns the phenomenon may be more widespread.
The issue of clearly identifying non-natural stones in order to ensure that consumers are fully aware of what they are being offered for purchase has been a concern for the non-Lab Grown Diamond (LGD) sector for the past decade.
Industry bodies, such as the World Federation of Diamond Bourses (WFDB), were quick to see the inroads some years ago that LGDs could make. They spoke about their fears that consumer confidence would be hit hard if buyers misunderstood what they were buying – or even worse were not fully informed and crucial information was not provided during the purchase.
The result would be buyers going back to stores a few years later and being shocked to find they had bought jewelry set with an LGD whose value had since dropped by 75% - or more.
Rulings On Recent Cases
The ASA recently acted against Linjer Jewelers, a Hong Kong-based company, which ran two campaigns. One used the phrase “Discover our brilliant diamonds” alongside an image of rings featuring clear gemstones. Meanwhile, another described its jewelry as “sustainable” and “ethically sourced.” The UK’s advertising regulator said both ads were misleading and were referred to the ASA by the Natural Diamond Council and the London Diamond Bourse.
Linjer responded that it was unaware the wording violated advertising rules, which require synthetic stones to be clearly labeled with terms such as “lab-grown” or “lab-created.” The ASA ordered the company to take down the advertisements.
The regulator explained that while “brilliant” can refer to a diamond cut, consumers were likely to interpret “brilliant diamonds” as natural diamonds, and that whether a diamond is natural or synthetic is important information for buyers.
In a separate case, the ASA also reviewed two paid Meta ads from Novita Diamonds. One featured engagement rings with the text “ready-to-ship engagement rings 1–10 days,” while another used video footage of diamond rings with the caption “timeless designs premium diamonds.”
Novita argued that its ads were not misleading, stating they did not claim the diamonds were mined or natural, and that lab-grown diamonds have the same chemical and physical properties as mined ones. The company also noted there is no official UK definition restricting the term “diamond” to natural stones.
However, the ASA said that although lab-grown diamonds may be chemically identical to natural ones, differences in value matter to consumers. It also noted that while customers could find more information on Novita’s website, key details should have been clearly stated in the ads themselves. The ASA concluded that the omission of the term “synthetic” made the ads misleading.
Novita has since updated its advertising to include the term “lab-grown diamonds.”
One source in the UK diamond industry said that although the ASA was working hard to monitor developments, there are so many jewelry sellers and that’s what makes it difficult for regulators to follow all cases. “Imagine how many sellers there are,” he commented. “Not just physical stores but also all the online sellers. That makes it very hard for the regulators which need to invest time and resources in each case.
“We also need to take into account that relatively few cases are taken to the regulator because not all consumers are aware of this issue and don’t necessarily understand the importance of accurate terminology. And even if they do, they don’t always know who to turn to. To put it bluntly, this is a widespread issue,” he added.
Companies Failed To Use Clear Qualifiers
According to the ASA, both companies ran ads that used the word “diamond” without a sufficiently clear qualifier such as “synthetic,” “laboratory-grown,” or “laboratory-created.” The regulator concluded that consumers could reasonably assume the diamonds were natural/mined diamonds.
The ASA ruled that:
- The omission of the synthetic/lab-grown nature of the stones was “material information.”
- The ads breached sections of the UK CAP Code covering misleading advertising and inadequate qualifications.
- The ads must not appear again in the same form.
- The companies should not use “diamond” in isolation for synthetic stones without a clear and prominent qualifier.
As stated above, the complaints were brought by the Natural Diamond Council, which has been actively challenging marketing language used by lab-grown diamond sellers. This is part of a broader regulatory and industry dispute over terminology.
The mined-diamond industry argues that consumers may be misled if “diamond” is used without clarification.
Lab-grown diamond companies often argue that lab-grown diamonds are chemically and physically real diamonds, and that terms like “synthetic” can themselves be misleading to consumers because they may imply “fake.”
Previous ASA rulings
The ASA has also previously scrutinized other jewelry brands over similar terminology issues, including:
- Kinetique
- Lark & Berry
- Skydiamond
- Idyl
In those cases, the focus was likewise on whether advertising clearly communicated that the stones were laboratory-grown rather than natural.
- Kinetique Ltd (2021)
This is an important earlier ASA precedent because the company used phrases including:
- “Just a Diamond. Minus the Mining.”
- “Carbon Neutral Diamonds”
The ASA ruled that:
- “diamond” should not be used in isolation for synthetic stones,
- descriptors such as “laboratory-grown diamond” or “synthetic diamond” should appear clearly,
- consumers should not have to click through multiple pages to discover the stones are lab-grown.
That ruling reportedly laid much of the groundwork for the 2026 enforcement approach.
The ASA’s position on LGDs
The UK Advertising Standards Authority and the related CAP (Committee of Advertising Practice) guidance now take a fairly clear position: if a diamond is lab-grown/synthetic, advertisers must make that fact clear and prominent from the outset.
The ASA’s concern is not whether lab-grown diamonds are “real” diamonds chemically. The rulings acknowledge they share the same physical and chemical properties as mined diamonds. The issue is consumer understanding and whether omitting the origin is misleading.
CAP Code Provisions Involved
The rulings mainly rely on Section 3 of the UK CAP Code:
- Rule 3.1 — ads must not materially mislead
- Rule 3.3 — ads must not mislead by omitting material information
- Rule 3.9 — qualifications must be clear and prominent
The ASA treats diamond origin as “material information” because:
- diamonds are expensive purchases,
- provenance may affect value perceptions,
- ethical and resale considerations influence buying decisions.
Terminology Acceptable To The ASA
The ASA guidance says acceptable qualifiers include:
- “laboratory-grown diamond”
- “lab-grown diamond”
- “laboratory-created diamond”
- “synthetic diamond”
The key requirement is that the qualifier be: clear, prominent, immediate, and consistent throughout the customer journey.
The Position Of The Natural Diamond Industry
Groups like the Natural Diamond Council argue the following:
- “diamond” alone implies natural origin to consumers
- lab-grown products must be explicitly identified
- failing to disclose origin unfairly blurs distinctions in rarity and value
The Lab-Grown Diamond Industry’s Position
Many lab-grown advocates argue:
- lab-grown diamonds are scientifically real diamonds
- “synthetic” can imply fake or imitation
How does the UK policy compare with the U.S. FTC
The UK ASA approach is somewhat stricter in presentation than U.S. Federal Trade Commission (FTC) guidance.
The U.S. Federal Trade Commission allows lab-grown products to be called “diamonds” provided they are clearly qualified with terms such as:
- “lab-grown”
- “laboratory-created”
- “synthetic” (used carefully).
But the FTC has also warned against unqualified “diamond” usage where it may mislead consumers about origin.
So the UK and U.S. approaches are broadly aligned, though the ASA has recently become more aggressive in enforcement visibility.
Philip Carter for Rough&Polished from London
