London Diamond Bourse adopts “synthetic diamond” terminology as best practice for all members.

The London Diamond Bourse has adopted “synthetic diamond” as the term it will use for man-made stones and is encouraging all its members across the UK trade to do the same. The Bourse is understood to be the first trade body in the United Kingdom to express a preference for one term.

Existing UK guidance permits three “synthetic”, “laboratory-grown” and “laboratory-created” and treats them as equally acceptable. The Bourse’s position is that of the three, “synthetic” is the most technically accurate, historically established and internationally understood. The decision has been made to promote clear, consistent and transparent nomenclature throughout the diamond trade. The term “synthetic diamond” clearly distinguishes a manufactured product, from a natural diamond without ambiguity or reliance on marketing terminology.

Charlotte Rose, President of the London Diamond Bourse, said: “Consumers should never be left in any doubt about whether the diamond they are purchasing is a natural diamond, or a man-made product. Clear and unambiguous terminology allows consumers to make a genuinely informed choice, while protecting confidence in the wider diamond and jewellery sector. We strongly welcome the implementation of this best practice. It’s a positive, long overdue step towards greater clarity, consistency and consumer protection within our industry.”

The Bourse’s decision also aligns with the World Federation of Diamond Bourses, whose affiliated bourses voted unanimously at the 41st World Diamond Congress in Singapore in July that “Synthetic Diamond” should be the federation’s preferred terminology

That recommendation came to Congress from a proposal submitted by past President of the London Diamond Bourse Alan Cohen. The proposal was based on work being done by the CIBJO Diamond Commission, which the London Diamond Bourse fully support. This was then proposed at congress by David Troostwyk, Chair of the WFDB’s Trade and Business Committee and current Vice President of the London Diamond Bourse.

David Troostwyk said: “I proposed this because I think our industry has been quietly avoiding a conversation it needed to have. Synthetic diamond is technically accurate, historically accurate and internationally understood. Theres a reason Global customs authorities already use it. France recognises it by decree. The FTC never prohibited it, the trade simply drifted towards laboratory grown on the assumption that it had. We adopted a marketing expression by accident and then treated it as settled.

I have spent my career in natural diamonds, and I have no interest in attacking a competing product. I do believe however that a manufactured stone should be described as a manufactured stone, clearly and without softening. Softening perception is not our job as the WFDB or any trade body for that matter. Consumer clarity is and should be paramount. I am pleased this was carried in Singapore and will now be adopted by the WFDB and its member bourses. It is a small change on paper; in practice it is the kind of thing that hopefully will have an impact in terms of clarity.”

Two countries have already made the term a legal requirement in consumer sales, and a third position applies worldwide at the border.

In France, man-made stones must be described as “diamants synthétiques”, and terms including “created”, “grown”, “real”, “precious” and “true” are prohibited. In October 2023 the French Ministry of the Economy and Finance considered a request to permit “laboratory-created” as an alternative and rejected it, leaving the requirement intact.

Russia has gone considerably further and does so from next week. A government resolution approved on 30 May 2026 and taking effect on 1 September requires jewellery containing man-made stones to be labelled “synthetic”, reserves the word “diamond” and its derivatives for natural stones alone, and prohibits “precious”, “real”, “genuine”, “natural”, and “eco-friendly” in describing them. The same rules bar the 4Cs grading vocabulary for synthetic stones and require their weight to be stated in grams rather than car

Internationally, the word Synthetic is in any case the legal default at every border. Under the Harmonized System - the customs nomenclature used by more than two hundred countries and territories, including the United Kingdom, man-made diamonds are classified under heading 7104 as “synthetic or reconstructed”. Every synthetic diamond imported into Britain is declared as a synthetic diamond. This reinforces the long-established international trade and customs distinction between natural diamonds and manufactured synthetic products.

Charlotte Rose added: “I strongly encourage other UK jewellery trade bodies to follow suit and adopt the same position. A consistent approach across the industry is essential; terminology should not change depending on which retailer, organisation or part of the trade a consumer encounters. Voluntary action is an important step, but I also encourage the UK Government to look seriously at whether the term “Synthetic” should ultimately be mandated for non-natural diamonds. Synthetic is not a dirty word, it’s a description. This is not about restricting consumer choice, it is about making sure they know exactly what they are buying. Transparency protects consumers, supports responsible businesses and, ultimately, strengthens trust in our industry.”

The announcement follows closer regulatory attention to how man-made stones are advertised in Britain. In May 2026 the Advertising Standards Authority upheld complaints against two retailers, over advertisements that presented man-made stones as diamonds without adequate qualification. The London Diamond Bourse, alongside the Natural Diamond Council was among the parties that brought one of those cases to the regulator’s attention

The Bourse is writing to all members and will apply the terminology in its own publications, member communications and public statements with immediate effect.