At Rennie & Co, we work exclusively with natural mined diamonds and have chosen not to offer lab-grown (synthetic) options. While we respect that the choice between natural and lab-grown stones is personal, we feel the narrative around lab-grown diamonds isn’t always fully transparent.
As a trusted jeweller with a heritage dating back to 1958, we are often asked about our stance on lab-grown stones and why we choose to work only with natural diamonds. To understand this deeper, we must first consider what a lab-grown diamond actually is.
A lab-grown diamond, also known as a synthetic or man-made diamond, is created in an environment that replicates the natural conditions under which diamonds form in the Earth’s mantle. Using machinery such as High Pressure High Temperature (HPHT) presses or Chemical Vapour Deposition (CVD) reactors, lab-grown diamonds are produced to have the same physical, chemical, and optical properties as natural diamonds. Whereas a natural diamond would take millions of years to form, a synthetic diamond can be produced in a matter of days or weeks.
We’ve broken our reasoning into three key points to explain why we have chosen not to offer lab-grown diamonds:
Intrinsic Value
When we talk about intrinsic value, we’re not implying that natural diamonds are inherently more meaningful than lab-grown diamonds. Choosing a diamond—whether natural or lab-grown—is about expressing love, commitment, and the desire to build a future together.
When lab-grown diamonds gained prominence in jewellery in the mid-2010s, their production costs were substantial due to the sophisticated machinery and innovative technology required. Consequently, they were priced roughly 10–20% below natural diamonds. Over time, the initial high costs of research, development, and machinery have decreased as these assets have become more widely produced and adopted, driving a significant increase in lab-grown diamond production, particularly in China and India. As a result, synthetic diamonds have flooded the market, leading to wholesale prices collapsing by a staggering 87% since 2018, as stated in Tenoris' report.
While natural diamond prices can vary, they have historically demonstrated a tendency to retain or appreciate in value over the long term. The rise of lab-grown diamonds has recently exerted downward pressure on natural diamond prices, driven by market uncertainties. However, when examined through the lens of decades-long pricing records, this current trend appears atypical and is likely to be short-lived.
As a family of jewellers since 1958, we have built our business on a foundation of reputation and trust. While we respect the choice between natural and lab-grown diamonds, we are concerned about the lack of transparency in the market. Customers are spending thousands of pounds on synthetic diamonds, which carry exorbitant profit margins, especially when compared to natural diamonds, while their true value often remains concealed. To protect our client base and uphold our reputation, we have chosen not to work with lab-grown diamonds. Few clients would be pleased to have spent £6,000 on a diamond in 2018, only to find that the same diamond is now available brand new for £800. This downward trend is set to continue.
While it doesn’t diminish the sentimental and symbolic value of your engagement ring, it can be disheartening to consider that, despite the investment of your hard-earned money, a lab-grown diamond holds little intrinsic value as an heirloom to pass down through generations. While the emotional worth of an engagement ring is priceless, the reality is that over time, prices are expected to fall so dramatically that lab-grown diamonds could ultimately replace the cubic zirconia market.
Ethical and Humanitarian
Since our beginnings in 1958, Rennie & Co have consistently conducted business with integrity, prioritising the sourcing of ethical diamonds. We do, however, recognise that challenges and controversies have historically affected not only the diamond trade but also many other fields.
In the 1990s, an estimated 15% of diamond sales were 'conflict diamonds'. These diamonds were mined in war zones and sold to finance armed conflict, fuelling violence, human rights abuses, and prolonged wars. This alarming issue led to coordinated action by the global diamond industry, governments, and non-governmental organisations. The result was the introduction of the Kimberley Process Certification Scheme (KPCS) in 2003, which aimed to prevent the trade of conflict diamonds by requiring certification for diamond shipments. Under this system, diamonds must be accompanied by a Kimberley certificate verifying that they were sourced from conflict-free zones.
The Kimberley Process operates by setting strict criteria for member countries and overseeing compliance through regular reviews and audits. If a member fails to meet the established standards, they can be suspended or expelled from the process. For example, in 2004, the Democratic Republic of the Congo was suspended from the Kimberley Process due to widespread concerns over the involvement of rebel groups in diamond mining and trade, which funded armed conflict and contributed to violence in the region. The Democratic Republic of the Congo was only allowed to rejoin after implementing measures to address these issues.
In addition to the Kimberley Process, the System of Warranties was established in 2000 as a vital safeguard in the diamond industry. This system requires businesses throughout the diamond supply chain to provide written assurances that their diamonds are conflict-free. These warranties, embedded in invoices and documentation, strengthen the commitment of jewellers and traders to ethical practices.
As a result of these interventions, reports indicate that the proportion of conflict diamond sales has dropped dramatically, from 15% in the 1990s to 0.4% by 2009, with current projections suggesting it is now below 0.2% of diamond sales.
While no regulation is flawless, significant progress has been made through the Kimberley Process and the System of Warranties. In more recent years, the Responsible Jewellery Council (RJC), established to promote responsible and sustainable practices in the jewellery supply chain, has strengthened these efforts. Many of our suppliers are accredited members of the RJC, ensuring high standards of quality and responsible practices. While improvements are ongoing, public perception is often rooted in challenges from 20-30 years ago. The industry has since evolved, becoming one of the most regulated sectors today.
Given the history of challenges within the natural diamond industry, lab-grown diamonds are often marketed as 'ethical diamonds'. The idea of ethical sourcing is highly compelling, as it aligns with the aspiration for all diamonds to be entirely free from exploitation. However, the claim that lab-grown diamonds are 'ethical diamonds' must withstand thorough examination and be backed by robust, transparent evidence.
When considering lab-grown diamonds, one must first reflect on the ethical and humanitarian aspects of where these diamonds are manufactured. Most lab-grown diamond production occurs in China and India, the two largest producers worldwide. Both countries have faced significant scrutiny over the years for human rights issues, including forced labour, exploitation, dangerous working conditions, and child labour. While this does not imply that all lab-grown diamonds from these countries are linked to unethical practices, it raises questions about the validity of blanket ethical claims. Lab-grown diamonds are also produced in countries with stronger labour laws, such as the United States, where standards are regulated to ensure ethical practices. However, this currently accounts for only a small fraction of global production.
If over 99.8% of natural diamonds are now conflict-free, can we be confident that 99.8% of lab-grown diamonds produced in China and India are free from exploitation and human rights abuses?
Environmental
Lab-grown diamonds are often marketed as environmentally friendly, suggesting that they come with no environmental impact. However, this perception is more nuanced than it might first appear.
Alluvial mining is one method of natural diamond extraction, involving the recovery of diamonds from surface deposits such as riverbeds, beaches, and other sediment-rich areas, where they have been transported over millions of years by water.
The second method is traditional mining, where diamonds form deep within the Earth’s mantle, shaped by intense pressure and heat, and are brought to the surface through volcanic activity before being extracted through mining operations. Similar extraction processes are used in other industries to obtain raw materials for everyday products, such as lithium for phone batteries or iron for steel production in construction. While natural diamond mining does have environmental impacts, including habitat disruption and ecosystem damage, significant advancements in responsible mining practices have been made to reduce these effects.
The term lab-grown diamond evokes an image of a modern laboratory setting designed with sustainability and eco-consciousness in mind, where each stone is produced by renewable energy.
While the absence of mining is a clear advantage, the reality is that the largest producers of lab-grown diamonds, China and India, rely on energy-intensive facilities that are heavily dependent on non-renewable fossil fuels. The machines used, such as High Pressure High Temperature (HPHT) presses and Chemical Vapour Deposition (CVD) reactors, require substantial energy to replicate the extreme conditions under which natural diamonds form. These processes, which operate at temperatures averaging 1,300 to 1,600°C and immense pressures, often run continuously for several days or weeks to grow a diamond.
It’s a complex matter, and opinions will vary. The environmental concerns of natural diamond mining should not be glossed over. While lab-grown diamonds offer the advantage of not being mined, what is often not communicated by sellers is their reliance on non-renewable energy during production and the significant emissions this generates. Marketing lab-grown diamonds as environmentally friendly can be misleading—some may interpret this as a product with no negative impact, which is not the case.
Concluding Thoughts
We are not opposed to lab-grown diamonds as a product; they can offer genuine benefits and advantages for certain purposes. What we fundamentally take issue with is how they are marketed and sold to the end consumer. This practice is one we would feel uncomfortable supporting, as we have built our business on reputation and trust. We can see the current trends and foresee what will continue to happen in the market.
We aim to be the jeweller you turn to for life’s most significant moments, beginning with the purchase of an engagement ring and returning to us for all the precious occasions that follow. We want to be a name you trust, not one diminished by the issues we have outlined as the reality of lab-grown diamonds becomes clearer.
We recognise that natural diamonds are not without their complexities. However, we firmly believe in their inherent value, rarity, and qualities that lab-grown diamonds, in our view, cannot replicate. Ultimately, we want our customers to feel empowered to make informed decisions that align with their values and desires.
