Diamond Terminology Guideline

Eight of the leading diamond industry organisations (AWDC, CIBJO, DPA, GJEPC, IDI, IDMA, WDC and WFDB) have developed the present guideline to encourage full, fair and effective use of a clear and accessible terminology for diamonds, synthetic diamonds and imitations of diamonds by all sector bodies, organizations and traders. 

This Diamond Terminology Guideline serves as a reference document for the diamond and jewelry trade when referring to diamonds and synthetic diamonds. It is built on two internationally accepted standards: the ISO 18323 Standard ("Jewellery - Consumer confidence in the diamond industry") and the CIBJO Diamond Blue Book.

Natural Diamonds

Are natural diamonds rare? Yes, and that’s what makes them extraordinary.

Natural diamonds are formed 100 to 200 kilometers below the Earth’s surface, under intense heat and pressure. They take between 500 million and 3.7 billion years to form - that’s older than life on Earth itself.

A common misconception is that extracting diamonds relies on chemicals. In reality, diamond mining is a mechanical process.

All the 1-carat natural diamonds discovered in a year could fit into a single 50-litre suitcase. That’s how rare they are. Their natural scarcity, combined with their incredible journey from Earth’s depths to your hand, gives them a timeless, emotional value. This rarity is part of their magic. Consumer research consistently shows that rarity significantly contributes to the perceived emotional value of fine jewelry purchases.

Source: NDC, Returns of a Different Kind. 
 

Synthetic Diamonds

How are laboratory-grown diamonds made?

Scientists have spent decades engineering synthetic alternatives to replicate the hardness, optical properties, and thermal conductivity of natural diamonds in a more scalable and affordable manner, enabling their use in industrial and technological applications.

There are two main processes used to create laboratory-grown diamonds. The production method used does not affect the look or cost of the polished product.

Both methods require a tiny diamond crystal, called a “seed,” to serve as a base upon which the stone can be grown. The seed can be natural, but it is commonly grown in a laboratory.

The size of a laboratory-grown diamond depends on the time allowed for growth.
 

High Pressure, High Temperature (HPHT) Method

To create a diamond using the HPHT method, reactors replicate extreme natural conditions, such as immense pressure (5–6 GPa) and temperatures nearing 1,650°C (3,000°F). This process transforms graphite into a distinctively shaped laboratory-grown diamond crystal in a fraction of the time it takes nature.
 

Chemical Vapor Deposition (CVD) Method

This newer method involves breaking down the molecules of carbon-rich gas, such as methane, into carbon and hydrogen atoms at temperatures of around 1,100°C (2,000°F). These atoms are then deposited onto a seed plate to produce a square-shaped diamond crystal.

Source: NDC Report p. 12 - 13
 

Laboratory-grown diamonds are manufactured products that have the same crystal structure as natural diamonds and have nearly the same chemical, physical, and optical properties when polished. However, they are not identical and can be distinguished using professional equipment. They are created in weeks, not billions of years. Think of them more like a high-tech product than a natural wonder.

These diamonds are manufactured in factories, often using high-energy processes that rely on fossil fuels, since the reactors must sustain high temperatures for weeks. Cooling the reactors requires large amounts of water. Because they can be produced on demand and at scale, synthetic diamonds are not rare, and their abundance affects both pricing and perceived value.

Over 70% of synthetic diamonds are produced in India and China, where fossil fuels are a primary source of energy. However, some producers use renewable energy sources. To verify sustainability, ask your jeweler for:

• A sustainability certification verifying that the synthetic diamond’s carbon footprint is offset
• Confirmation that the diamond can be traced throughout the supply chain
• Proof that it meets strict social and environmental standards
• Documentation that the diamond was produced with a net-zero environmental impact
   

But what should you be looking for? 

Confusing terminology? We’ve made a Diamond Glossary that could help! 

No. Claims that laboratory-grown and natural diamonds are identical and impossible to tell apart are false.  

Diamond crystals grow differently in nature than in a lab. Their grain patterns, like those in wood, vary. While these differences may not always be visible to the naked eye, they can be detected using specialized instruments.

More than 20 verification tools are available to industry professionals. These assessments examine spectral signatures, composition, grain patterns, and ultraviolet fluorescence to determine whether a diamond formed billions of years ago on Earth or was recently synthesized in a laboratory.

For example, the production of colorless synthetic diamonds requires the near-complete removal of nitrogen, which is present in about 99% of natural diamonds. Natural impurities and growth conditions also affect fluorescence.

The Natural Diamond Council’s (NDC) ASSURE program evaluates diamond verification tools to guide industry professionals. These tools are essential for maintaining supply chain integrity and preventing the mixing of natural and synthetic stones.

Source: NDC Report p. 11

Did you know: Some natural diamonds fluoresce when they are exposed to long-wave ultraviolet (UV) rays from sources like the sun. Only 25% to 35% of natural diamonds show some degree of fluorescence, of which more than 95% fluoresce blue. A rare few fluoresce other colors such as yellow or green.

Fluorescence is not a grading factor like the 4Cs (color, clarity, cut, and carat weight), but it is an identifying characteristic. Diamond Grading Reports describe a diamond’s fluorescence by its intensity under long-wave UV light (None, Faint, Medium, Strong, and Very Strong). 

Why is this interesting? Because consumers are now actively seeking diamonds with fluorescence and inclusions, to be certain they are buying natural diamonds. They are even willing to pay a premium for this.

Source: GIA

The term “diamond” used on its own must always refer to a natural diamond.

Only three terms are accepted for synthetic diamonds:

• Laboratory-grown diamonds
• Laboratory-created diamonds
• Synthetic diamonds*

*Terminology may vary by national regulation.
 

Terms such as “man-made,” “cultured,” or “above-ground” should not be used in isolation, as they may be confusing.

Why does this matter? Some websites list “diamond rings,” only revealing in their FAQs that all stones are synthetic. We believe consumers deserve complete transparency.
 

New Legislation

As of May 1, 2023, in Belgium, sellers must disclose the following before finalizing any sale involving natural or synthetic diamonds:

• Whether the item contains natural or synthetic diamonds
• Whether the diamonds are treated or untreated
• The number and weight of the diamonds
• The nature of any treatments applied
   

Tip for the consumer: The jewelers need to provide this information to you on paper (not just digitally). However, if they don’t, you have the right to request it from them (and you should).

More details: AWDC Legislation   

France, the United States, the United Kingdom all have their own version of the same. 

Source: NDC Report, P. 8-9
 

Understanding the Difference Between Price and Value

Let’s talk about cost vs. worth.

A synthetic diamond ring that costs just €230 to produce (€140 for the 14-karat gold setting and €90 for the 0.06-gram lab-grown diamond) might retail for €2,300. Ten years later, the cost to produce that same synthetic diamond could drop to as little as €5.

Since 2018, the average price for a 1-carat, near-colorless, synthetic diamond with VS1 clarity (F/G/H color) has decreased by 95% at wholesale and 76% at retail.

What does this mean? VS1 clarity refers to the inclusion grade. F/G/H refers to the shade of “white” diamonds. These are not the “best” diamonds, but are commercially friendly options. 

More info on how to read a Diamond Grading certificate can be found here: Certification Guide.

In contrast, natural diamonds, though not guaranteed to retain full value, typically keep around 70% of their original value.

Sources: Edahn Golan, Paul Zimnisky, Bain & Company
 

Production Costs

The production costs of synthetic diamonds have fallen dramatically since the early 2000s, particularly with the advancement of CVD technology. Machines formerly used for industrial stones are now producing gem-quality diamonds, intensifying competition.

Bain & Company reports that between 2008 and 2018, the average production cost for a 1-carat synthetic diamond decreased by 90%.
 

Recent Price Trends

According to the NDC, since 2018, the average price for a 1-carat, near-colorless, synthetic diamond with VS1 clarity (F/G/H color) has decreased by 95% at wholesale and 76% at retail.

Meanwhile, retail margins have surged from 46% to 84% over the past five years.
 

Pricing Structures

Natural diamond prices reflect rarity. Larger stones are exponentially rarer, and thus more expensive. In contrast, the prices of synthetic diamonds scale linearly with production costs.

Always buy a diamond (natural or synthetic) with a grading report.

A certificate verifies the 4Cs and confirms whether a stone is natural or synthetic.

Color, Clarity, Cut and Carat Weight are collectively called the 4Cs of diamond quality. Color measures a diamond’s absence of color. Clarity considers a diamond’s inclusions and blemishes and how they affect its appearance. Cut describes the diamonds fire, brilliance and proportions. Carat weight is the measurement of how much a diamond weighs in metric carats. (Source: GIA) 

Choose reports from independent, trusted labs such as:

• GIA (Gemological Institute of America)
• IGI (International Gemological Institute)
• HRD Antwerp

Self-issued jeweler certificates have limited credibility and may affect insurance and resale value.

Here are some tips to keep in mind:

• Always ask for a certificate from a reputable grading institute.
• Understand the 4 C’s and how they interact to affect value.
• Verify the origin of the diamond to ensure ethical sourcing.
• Consult an expert  if you’re unsure about a diamond’s quality or legitimacy.
• Not all certification labs adhere to the same grading standards. Less reputable labs may issue overly generous grades, inflating the perceived value of a diamond. Always prioritize reports from recognized institutes like GIA, IGI or HRD Antwerp.
• Be cautious of vague terms like "certified diamonds" without specifying the issuing institute. A certificate is only as credible as the organization behind it.
• Advances in technology have made synthetic and treated diamonds indistinguishable to the naked eye. Ensure that the certificate explicitly states whether a diamond is natural or synthetic and discloses any treatments.
• Forgery is a real concern in the diamond trade. Always verify the authenticity of a certificate with the issuing institute by using their online report verification tools.

More info: AWDC Certification Guide

Not always.

Sustainability depends on various factors, including energy source, water usage, chemical handling, and working conditions. Synthetic production is highly energy-intensive, often relying on fossil fuels for its operations.
 

Carbon Claims

Synthetic diamonds often require temperatures exceeding 2,000°F. Over 70% are produced in China and India, countries where energy grids rely heavily on coal.

“Carbon-neutral” claims are typically achieved through offsetting and often apply only to rough production, rather than the entire supply chain.
 

Carbon Capture

Some companies claim carbon capture as an environmental benefit. However, 1 carat of synthetic diamond stores just 0.2 grams of carbon, equal to one or two emails. A mature tree absorbs 48 pounds (over 21,000 grams) of CO2 annually.
 

Other Greenwashing Risks

• Claims of “mine-free” overlook the need for mined materials in reactors.
• Water-intensive cooling systems operate in water-stressed regions.
• Energy efficiency varies widely between facilities.
   

Social Impact

Synthetic diamond manufacturing supports fewer jobs and offers limited community benefits. In contrast, the natural diamond industry supports about 10 million people globally, providing jobs, education, and infrastructure.

Source: World Diamond Council
 

Responsible Natural Diamond Mining: A Commitment Beyond Extraction

Today’s leading diamond mines operate under strict environmental and labor standards, with a clear focus on sustainability, even after mining ends.

Take the renowned Argyle Mine in Australia, famous for its rare pink diamonds. Though operations ceased in November 2020 after 37 years, closure was far from simple.

Responsible mine closure at Argyle includes:

• Full Decommissioning: All processing infrastructure was dismantled, with materials safely disposed of, repurposed, or recycled.
• Land Restoration: Over 9 million cubic meters of land were reshaped across former waste and tailings sites.
• Revegetation Efforts: A multi-year program is underway to re-establish native ecosystems.
• Ongoing Rehabilitation: 542 hectares have been restored so far, with a target of 2,000 hectares.
• Long-Term Oversight: Monitoring and maintenance will continue for at least 10 years.

This level of environmental accountability reflects the standards upheld by responsible natural diamond producers around the world.

Source: NDC