Natural Diamond Prices Begin to Stabilise, But Has the Market Turned?

After several challenging years for the natural diamond industry, there are growing signs that the market may finally be reaching a period of stabilisation.

De Beers Group CEO Al Cook recently said natural diamond prices had stabilised and were beginning to rise, pointing to improving demand in key markets and declining mine supply.

Speaking in Beijing on 15 September during the signing of the Beijing Declaration on Natural Diamonds and Sustainable Development, Cook said:

“In the last few months, we’ve seen the price stabilise and begin to grow.”

Cook attributed the change to stronger consumer demand, particularly in the United States and India, combined with declining supply as some older diamond mines approach the end of their productive lives.

He said global diamond supply was currently falling by more than 10%, creating a potentially important change in the supply and demand balance.

However, the broader market remains considerably more complicated.

A Recovery, Or Simply Stabilisation?

De Beers’ own financial results demonstrate why the industry should be cautious about describing current conditions as a full recovery.

During the first half of 2026, De Beers’ average realised rough-diamond price fell significantly compared with the previous year, while its rough-diamond price index also declined.

This means that while some areas of the market are showing signs of improvement, the industry has not yet returned to the pricing environment seen during the post-pandemic period.

There is an important distinction between prices stopping their decline and prices entering a sustained recovery.

Recent market data has shown improvement in some polished natural-diamond categories, particularly certain smaller stones and selected higher-quality goods. Larger and higher-value diamonds have also demonstrated greater resilience.

But other categories remain under pressure.

The United States Remains Important

The United States continues to be one of the most important markets for natural diamonds.

Consumer spending on natural diamond jewellery has remained relatively resilient, particularly at the higher end of the market. This suggests that consumers continue to place value on the rarity, provenance and enduring appeal of natural diamonds.

The market is nevertheless becoming increasingly divided.

Consumers purchasing higher-value jewellery appear more willing to spend, while lower-priced categories face much greater competition from laboratory-grown diamonds and changing consumer expectations.

India: A Critical Part of the Global Diamond Industry

India remains central to the international diamond trade, particularly because of its enormous cutting and polishing industry.

However, natural-diamond exports have faced pressure, reflecting weaker international demand, inventory adjustments and changing market conditions.

At the same time, laboratory-grown diamond production has expanded rapidly.

This is an important development because India is now producing enormous quantities of laboratory-grown diamonds alongside its traditional natural-diamond manufacturing industry.

The two products occupy different positions in the market, but they increasingly compete for consumer attention and jewellery expenditure.

China Remains a Key Challenge

China is another critical part of the global diamond market, but demand has remained subdued.

De Beers has acknowledged the importance of rebuilding consumer confidence in natural diamonds in China, including communicating the rarity and long-term significance of natural diamonds to a new generation of consumers.

The Beijing Declaration reflects the industry’s attempt to strengthen relationships between diamond-producing countries in Africa and the Chinese jewellery market.

For the natural diamond industry, China represents both a major opportunity and a significant challenge.

Natural Diamonds and Laboratory-Grown Diamonds

The growth of laboratory-grown diamonds has fundamentally changed the jewellery market.

Laboratory-grown diamonds are diamonds with essentially the same chemical composition and crystal structure as natural diamonds, but they are produced through technological processes rather than geological formation.

Their ability to be manufactured in large quantities has resulted in substantial price reductions.

This creates a very different proposition for consumers.

A laboratory-grown diamond can provide the physical characteristics of a diamond at a significantly lower price, while a natural diamond represents a finite geological resource formed over billions of years.

For the jewellery industry, the challenge is therefore not simply about price.

It is about what consumers believe they are purchasing and why they value it.

Scarcity Alone Does Not Guarantee Higher Prices

One of the most interesting arguments being made by the natural diamond industry is that declining mine production could eventually create a tighter supply-demand balance.

That is certainly possible.

But scarcity by itself does not guarantee higher prices.

For any scarce product to appreciate, there must also be sustained demand and a willingness among consumers to pay for its scarcity.

This is why the industry’s efforts to communicate the differences between natural and laboratory-grown diamonds are becoming increasingly important.

Natural diamonds have a unique geological history. Every natural diamond is the product of extraordinary geological conditions over immense periods of time. That rarity is fundamentally different from a product that can be manufactured repeatedly in a laboratory.

What Is Happening to the Jewellery Market?

The wider jewellery market is also changing.

Consumers around the world are becoming more price conscious, particularly as the cost of living and precious-metal prices remain elevated.

Gold provides an interesting comparison. Although jewellery demand measured by weight has fallen in some major markets, the value of jewellery purchases has remained much stronger because of significantly higher gold prices.

The same trend can be seen within diamonds.

Consumers are not necessarily abandoning fine jewellery. Instead, they are becoming more selective about what they purchase, where they purchase it and what they believe gives a piece lasting value.

This is creating a more polarised market, with strong interest in exceptional natural diamonds and luxury jewellery at one end, and highly price-sensitive consumers choosing laboratory-grown diamonds at the other.

What Does This Mean for Natural Diamonds?

The latest evidence suggests that the natural diamond industry may be moving away from the severe price declines experienced over recent years.

There are encouraging signs in certain categories and markets, and declining mine production could eventually become an important factor.

However, it would be premature to describe the entire natural diamond market as being in a confirmed recovery.

The industry is still dealing with excess inventory, weaker demand in some major markets, changing consumer behaviour and intense competition from laboratory-grown diamonds.

For DCLA, one point remains particularly important:

A diamond’s identity matters.

Whether a stone is natural or laboratory-grown should be clearly disclosed and independently verified. Consumers should understand exactly what they are purchasing and the characteristics that distinguish one from the other.

The future of the natural diamond market may ultimately depend not simply on declining supply, but on whether consumers continue to value the extraordinary rarity, geological origin and individuality of a natural diamond.

For now, the evidence points to stabilisation and early signs of improvement rather than a confirmed return to the strong diamond market of previous years.

The next stage will depend on consumer confidence, global economic conditions, mine supply, jewellery demand and how the industry communicates the fundamental difference between a diamond created by nature over billions of years and one created by modern technology.

When Good Ideas Do Not Always Solve the Problems in the Diamond Trade

 

The diamond industry has spent decades trying to address questions around sustainability, traceability, ethics and responsible sourcing. These are important issues, but the experience of the SCS-007 certification programme demonstrates that creating another standard or certification does not necessarily solve the problems it was designed to address.

SCS Global Services recently ended its SCS-007 Sustainably Produced Gemstones certification programme, which had operated for several years. The programme was intended to provide independent, product-level verification of environmental, social, governance, climate and traceability claims.

SCS said the decision was made because the market conditions required to support the voluntary standard at scale had not developed.

Two issues were highlighted: certification had not been adopted by the mining sector, and there was no clear regulatory framework for product-level chain-of-custody claims across an increasingly fragmented supply chain.

That is significant.

A certification system can only be effective if enough of the industry participates. If producers, miners, manufacturers, wholesalers and retailers are not all operating within the same system, the certification can become another layer of complexity rather than a complete solution.

SCS had achieved participation from lab-grown diamond producers, diamond handlers and retailers. In March 2024, it reported eight lab-grown diamond producers, 12 diamond handlers and 65 retailers across 14 countries, with more than 100,000 certified diamonds sold through more than 500 stores.

Yet there was a fundamental gap: participation from the natural diamond mining sector was not comparable.

The programme had begun in 2020 as a trial-use standard for diamonds. It subsequently expanded across the supply chain, with certification covering producers, cutters, polishers, wholesalers and retailers. In 2024, a final diamond standard covering both natural and lab-grown diamonds was published, followed in 2025 by an expansion into emeralds, rubies and sapphires.

Ultimately, however, the programme was discontinued.

The lesson for the diamond industry

The lesson is not that sustainability, responsible sourcing or traceability are unimportant. Quite the opposite.

The lesson may be that the solution cannot always be another certification programme.

The diamond trade is an extraordinarily complex international supply chain. Diamonds can pass through mining companies, government-controlled systems, rough dealers, manufacturers, polishers, wholesalers, laboratories and retailers before reaching the consumer.

Trying to solve every issue with paperwork, certification and increasingly complicated compliance systems can create the appearance of control without necessarily addressing the underlying problem.

The history of the “blood diamond” debate provides another example of how complicated these issues can become.

The term became internationally recognised because of the role diamonds played in financing armed conflicts in parts of Africa. The Kimberley Process was subsequently established to restrict the trade in rough diamonds associated with rebel movements.

That was an important response to a genuine problem. However, the broader political and humanitarian circumstances surrounding diamond-producing countries were considerably more complicated than the simple idea of “conflict diamonds” suggested. Governments, armed groups, political interests and international businesses could all have competing interests, and a certification system alone could not resolve corruption, conflict or human-rights abuses within sovereign states.

This is where the diamond industry needs to be careful.

A diamond certificate can verify a diamond. It cannot, by itself, fix a government, end corruption, prevent political abuse or solve the social problems of a mining region.

Likewise, a sustainability label may provide useful information, but it does not automatically make a product more ethical, more environmentally responsible or more socially beneficial.

The challenge for the industry is therefore to distinguish between genuine solutions and systems that simply create another layer of administration.

Consumers deserve transparency. Mining communities deserve responsible treatment. Manufacturers and retailers need reliable information. And legitimate businesses should be able to demonstrate where their products come from.

But these objectives need practical systems that work across the entire supply chain.

The experience of SCS-007 is a reminder that good intentions are not enough. A system must be commercially viable, widely adopted, independently verifiable and capable of addressing the real problem it was created to solve.

In the diamond trade, sometimes the most important question is not “What new certification can we create?”

It is:

“What problem are we actually trying to solve, and will this system genuinely solve it?”

Source: DCLA

The Transformation of Diamond Cut Quality Grading

 

From the Tolkowsky Ideal to Modern Cut Grades, Why Proportions Still Matter

For more than a century, diamond cutters, gemologists and scientists have attempted to answer one fundamental question:

What makes a diamond well cut?

The answer has evolved considerably.

What began with the scientific study of diamond proportions and the development of the Ideal Cut has become a sophisticated system of modern cut grading that considers light performance, proportions, symmetry, polish, durability and the way the human eye perceives brilliance and scintillation.

Yet beneath all of the modern technology, one fundamental principle remains:

A diamond is a three-dimensional optical instrument, and its proportions determine how light travels through it.

This is why the measurement of proportions remains such an important part of understanding diamond cut.

The beginning of scientific diamond proportions

Long before today’s sophisticated computer modelling, diamond cutters were experimenting with angles and proportions to improve the appearance of the round brilliant.

In the late nineteenth century, Henry Morse used a goniometer to investigate diamond angles and proportions and developed cutting principles intended to maximise brilliance. His work became associated with what was subsequently known as the American Cut, Scientific Cut and eventually the Ideal Cut.

This work was followed by the mathematical and optical studies of Herbert Whitlock, Frank Wade and, most famously, Marcel Tolkowsky.

In 1919, Tolkowsky published Diamond Design, analysing the geometry of the round brilliant and the relationship between its proportions, angles and the return of light.

The importance of this work was not simply that Tolkowsky produced a set of numbers.

It was that diamond cutting was increasingly being treated as a measurable optical science rather than simply an artistic craft.

DCLA’s own educational material traces this development and explains how the Ideal Cut became associated with variations of the original Tolkowsky model.

What is the Tolkowsky Ideal?

The Tolkowsky model became one of the most influential references in modern round-brilliant cutting.

The principle was relatively straightforward: the pavilion and crown geometry, together with the table and other proportions, must work together so that light entering the diamond has the greatest opportunity to be reflected internally and returned through the crown.

The commonly referenced Tolkowsky proportions are approximately:

• Crown angle: approximately 34.5°
• Pavilion angle: approximately 40.75°
• Table: approximately 53–57%
• Total depth: approximately 59.3%

These figures should not, however, be treated as a rigid recipe.

Modern research has demonstrated that the optical performance of a diamond is determined by the relationship between its proportions, rather than by one measurement considered in isolation.

DCLA similarly explains that table, depth, crown angle, pavilion geometry and other elements work together to determine the diamond’s interaction with light.

This is an important distinction.

The science is in the relationships.

From proportion analysis to cut grading

For much of the twentieth century, diamond professionals relied heavily on measured proportions when assessing the quality of a round brilliant.

A diamond could be measured, its angles calculated and its proportions compared with recognised standards.

That created something extremely valuable for the trade:

repeatability.

If two qualified people measured the same diamond correctly, they could arrive at essentially the same numerical proportions.

The diamond did not change because the person looking at it had a different opinion.

The pavilion angle remained the pavilion angle.

The crown angle remained the crown angle.

The table remained the table.

The depth remained the depth.

This is one of the great strengths of proportion analysis.

DCLA describes proportions as the relationships between the dimensions and angles of a finished diamond and identifies them as fundamental to understanding brilliance, fire and scintillation.

The arrival of modern cut grades

The development of modern grading systems changed the way diamond cut was communicated to consumers.

Rather than presenting the purchaser with a collection of angles, percentages and measurements, laboratories increasingly sought to reduce the information into a single overall grade.

Today, major laboratories use cut-grading systems that combine measurable characteristics with assessments of the diamond’s overall appearance and performance.

GIA’s research into cut grading illustrates how the industry moved from proportion-based approaches towards increasingly sophisticated systems incorporating three-dimensional modelling and human observation.

This was a major development.

It made cut quality easier to communicate.

But it also introduced an important philosophical difference between measuring a diamond’s physical proportions and assigning an overall quality grade to the diamond.

They are not necessarily the same thing.

A grade is a category — proportions are measurements

This distinction is frequently misunderstood.

A cut grade is a classification.

A proportion measurement is a physical observation.

For example, diamonds can fall within the same broad cut-grade category while having different crown angles, pavilion angles, table sizes and other proportions.

GIA’s research into cut grading specifically recognises that diamonds within a single grade can have variations in appearance and proportion combinations.

This means that a broad cut grade does not describe one exact geometry.

It describes a range of diamonds that fall within the laboratory’s defined parameters and assessment methodology.

Consequently, two diamonds carrying the same broad cut grade are not necessarily proportionally identical.

Why scientific proportions remain important

This is where proportion analysis remains particularly valuable to the professional.

A numerical proportion report tells us what the diamond actually is.

It provides the measurable geometry of the stone.

For a round brilliant, this can include:

• Table percentage
• Total depth percentage
• Crown angle
• Crown height
• Pavilion angle
• Pavilion depth
• Star length
• Lower-half percentage
• Girdle thickness
• Culet
• Diameter measurements

These measurements provide a permanent technical record of the diamond’s physical construction.

They can be independently measured, compared and reproduced.

That makes them particularly valuable to manufacturers, cutters, gemologists and laboratories.

DCLA’s educational material on proportion grading explains the importance of these measurements in assessing the balance of a round brilliant diamond.

Proportions are not simply numbers

It would also be wrong to suggest that one number determines whether a diamond is beautiful.

A pavilion angle cannot be assessed independently from the crown angle.

A table percentage cannot be considered without considering the crown and pavilion geometry.

Likewise, total depth alone does not tell us whether a diamond will perform well optically.

Modern research has reinforced this point.

GIA’s work demonstrates that the various proportion parameters are interrelated and that a complete understanding of diamond appearance requires more than looking at one measurement in isolation.

Therefore, the correct scientific approach is not:

“What is the table?”

or:

“What is the pavilion angle?”

It is:

“How do all of these proportions work together?”

The Tolkowsky model and modern science

It is important to recognise that Tolkowsky’s work was conducted using the scientific knowledge and optical modelling available in the early twentieth century.

Modern diamond science has gone considerably further.

Three-dimensional ray tracing, computer modelling, automated proportion measurement and optical-performance analysis allow researchers to model an enormous range of possible combinations.

GIA’s current historical review of cut grading describes the transition from early two-dimensional ray tracing to increasingly sophisticated three-dimensional approaches to understanding how light travels through a round brilliant diamond.

That does not make the Tolkowsky principles obsolete.

Rather, it places them into their historical context.

The fundamental concept that diamond geometry controls the behaviour of light remains central.

The science has simply become considerably more sophisticated.

Where modern grading becomes more subjective

Modern cut grading has another important dimension:

human perception.

A diamond does not exist in isolation from the person viewing it.

Brightness, fire and scintillation are visual phenomena.

GIA therefore incorporated extensive observation testing into the development of its cut system, recognising that appearance is ultimately experienced by the human observer.

That is an important scientific distinction.

It means there is a difference between:

What can be measured

and

What a person perceives.

The first can be quantified.

The second involves human observation.

Consistency is the strength of proportion grading

This is why proportion grading remains so important in professional diamond assessment.

A proportion measurement is not an opinion about whether somebody likes the diamond.

It is a measurement of the diamond’s physical geometry.

When modern non-contact scanners and optical measuring systems are used correctly, the diamond can be measured with a high degree of precision.

This creates an important bridge between traditional craftsmanship and modern technology.

The cutter can see what has been produced.

The manufacturer can compare stones.

The laboratory can record the geometry.

And the consumer can be given measurable information rather than relying entirely on terminology.

The difference between a scientific measurement and a grade

This distinction deserves emphasis.

A proportion is a measurement.

A cut grade is an interpretation based on a grading methodology.

Both can be useful.

But they answer different questions.

A proportion analysis asks:

What are the physical dimensions and angles of this diamond?

A cut grade asks:

How does this diamond fit within a particular laboratory’s definition of cut quality?

Neither question should automatically be confused with:

Which diamond will an individual person find most beautiful?

That final question involves visual preference, lighting, movement and perception.

The modern laboratory approach

Today, the most comprehensive understanding of diamond cut comes from combining the disciplines.

Measurement tells us the geometry.

Optical modelling helps us understand how light interacts with that geometry.

Symmetry and polish tell us about execution and finish.

Light-performance analysis examines brightness, fire and scintillation.

Human observation helps establish how those differences are actually perceived.

This progression can be seen in the development of modern cut-grading research, where numerical proportions have increasingly been combined with optical modelling and observations of diamond appearance.

Why proportions still matter at DCLA

At the Diamond Certification Laboratory of Australia, we believe that understanding a diamond begins with understanding what the diamond actually is.

A laboratory report should not replace knowledge of the stone.

It should enhance it.

DCLA’s educational material explains that cut refers to proportions, symmetry and finish, and that these characteristics influence how light travels through the diamond and ultimately its brilliance and fire.

The modern transformation of cut grading has given the industry valuable tools for communicating diamond quality.

But a single word such as “Excellent” cannot communicate every physical characteristic of a diamond.

The actual proportions remain important.

They tell us how the diamond has been constructed.

They allow professionals to compare diamonds on a consistent technical basis.

They assist manufacturers in analysing cutting decisions.

And they provide a numerical record that can be independently measured and reproduced.

From the Ideal Cut to the diamond of today

The history of diamond cutting is therefore not a story of old science being replaced by new grading.

It is a progression.

Morse, Wade, Whitlock and Tolkowsky helped establish the scientific study of diamond proportions.

Modern laboratories expanded that work through computer modelling, ray tracing, observation testing and sophisticated measurement technology.

The result is a much deeper understanding of diamond appearance.

But one principle remains unchanged:

The beauty we see in a diamond begins with the geometry we cannot see.

A diamond’s proportions determine the pathways available to light.

The cutter determines those proportions.

The measuring instrument records them.

The scientist can model them.

The laboratory can assess them.

And ultimately, the observer sees the result.

For more than a century, the industry has continued to refine the relationship between proportion, light and beauty.

The Tolkowsky Ideal was an important milestone in that journey.

Modern cut grading is the next chapter.

And at DCLA, understanding both is essential to understanding the diamond itself.

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Further reading and DCLA resources

DCLA — Diamond Proportions
Understanding Diamond Proportions

DCLA — Proportion Grade
How DCLA assesses proportion grade

DCLA — Ideal Cut
The Ideal Cut and the Tolkowsky model

DCLA — Diamond Cut
DCLA guide to diamond cut

DCLA — Cut Grade
Understanding Diamond Cut Grade

DCLA — Diamond Light Return
How cut, angles and facets control diamond light return

DCLA — Buying a Diamond: Cut, Colour, Clarity & Carat
DCLA’s guide to buying a diamond

GIA — The Transformation of Diamond Cut Quality Grading
GIA research on the evolution of diamond cut grading

GIA — A Foundation for Grading the Overall Cut Quality of Round Brilliant Cut Diamonds
GIA’s foundational research into round brilliant cut grading