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Carbon-Bearing Material
Carbon is present within deep-Earth fluids, melts and rocks. Geological conditions determine whether that carbon can become diamond.
Diamond Education
Everything You Need to Know About Mined Diamonds
Mined diamonds, also called natural diamonds, formed deep within the Earth through natural geological processes. They were later transported closer to the surface and recovered from natural deposits.
Each natural diamond has a geological history shaped by pressure, temperature, chemistry, crystal growth and its journey through the Earth. After recovery, rough diamonds are sorted, planned, cut, polished and evaluated before they become fine jewellery.
This guide explains how mined diamonds form, where they are found, how they are recovered, how rough diamonds become polished gemstones and what to consider before purchasing one.
Understanding the Basics
What Is a Mined Diamond?
A mined diamond is a naturally formed diamond recovered from the Earth.
Diamond is a mineral made primarily from carbon atoms arranged in a strong crystal structure. Natural diamonds formed where combinations of pressure, temperature and chemical conditions allowed carbon-bearing material to crystallise as diamond.
The term “mined diamond” is commonly used to distinguish a naturally formed diamond from a laboratory-grown diamond. The terms “natural diamond” and “mined diamond” generally refer to the same diamond category.
A mined diamond may be colourless, near-colourless, brown, yellow, pink, blue, green or another colour. It may also contain internal features created during its natural formation and geological journey.
Important distinction:
“Mined” describes origin. A mined diamond formed naturally in the Earth,
while a laboratory-grown diamond was created in a controlled production
environment.
Diamond Identity
Are Mined Diamonds Natural Diamonds?
Yes. A mined diamond is a naturally formed diamond that has been recovered from a natural deposit.
Its composition, crystal structure and properties developed without human-controlled diamond-growth technology. Human involvement begins with exploration, recovery, sorting, cutting, polishing and jewellery manufacturing.
Natural diamonds should not be confused with moissanite, cubic zirconia, glass or other materials used to imitate diamond. Those materials have different chemical compositions and crystal structures.
Natural Formation
Created through geological processes
Diamond Crystal
Primarily crystallised carbon
Recovered From Earth
Found in natural diamond deposits
Natural Formation
How Do Natural Diamonds Form?
Natural diamonds form when carbon-bearing material encounters the right geological conditions deep inside the Earth.
High Pressure
Deep within the Earth, pressure can become high enough to support the crystal structure of diamond.
Suitable Temperature
Temperature must fall within a range that allows diamond to form and remain stable instead of becoming another form of carbon.
Crystal Growth
Carbon atoms bond in the diamond structure and the crystal grows through one or more natural formation events.
Long-Term Preservation
After formation, stable geological conditions can preserve a diamond deep within the Earth for an extremely long period.
Rapid Transport
Certain volcanic eruptions can transport diamond-bearing material towards the surface before the diamonds are destroyed or changed.
Journey to the Surface
How Do Diamonds Reach the Earth’s Surface?
Diamonds generally do not form inside the volcanic rock in which they are later found.
Instead, rapidly rising magma can collect diamonds and pieces of deep mantle rock while moving towards the surface. When this magma cools, it may create volcanic bodies known as kimberlite or lamproite.
These volcanic rocks act as a delivery system. The diamond is an older crystal transported from the mantle rather than a crystal newly formed during the surface eruption.
Over time, weathering and erosion can break down diamond-bearing rock. Because diamond is durable, some crystals survive and are moved into river gravels, coastal areas or marine deposits.
Deep Formation
Diamond grows in the mantle
→
Volcanic Transport
Kimberlite or lamproite rises
→
Primary Deposit
Diamond-bearing rock cools
→
Erosion
Some diamonds move elsewhere
Geological History
How Old Are Mined Diamonds?
Many natural diamonds are extremely ancient and formed long before the volcanic events that transported them closer to the surface.
The age of a diamond is not normally determined from its appearance or standard jewellery grading report. Scientists may study mineral inclusions and surrounding geological material to understand its formation history.
Two diamonds recovered from the same deposit may have formed during different geological events. A single deposit can contain multiple populations of diamonds with different histories.
A diamond’s geological age and the age of the volcanic rock that carried
it to the surface are not necessarily the same.
Where Diamonds Are Found
Types of Natural Diamond Deposits
Diamond deposits are commonly grouped according to whether the stones remain in their original volcanic host or have been moved by natural erosion.
Primary Deposits
Diamonds remain within or close to the volcanic rock that brought them towards the surface, commonly kimberlite or lamproite.
Alluvial Deposits
Weathering releases diamonds from their host rock. Rivers and streams move them into gravel, sediment and riverbed deposits.
Coastal Deposits
Rivers and erosion can transport diamonds towards coastal areas where waves and currents concentrate heavy minerals.
Marine Deposits
Some diamonds are recovered from sediment on or beneath the seabed, often near regions where diamond-bearing rivers reached the ocean.
Diamond Recovery
How Are Mined Diamonds Recovered?
The recovery method depends on the deposit’s geology, location, depth, size and economic viability.
OPEN-PIT MINING
Surface Recovery
When a diamond-bearing deposit is accessible from the surface, layers of soil and rock may be removed to create a large open pit.
Diamond-bearing ore is excavated and transported to a processing facility where the rock is broken down and examined.
UNDERGROUND MINING
Deeper Deposits
As an open pit becomes deeper or the deposit continues below the practical limits of surface mining, tunnels and underground systems may be developed.
Ore is removed below ground and transported to the surface for processing.
ALLUVIAL MINING
River and Gravel Deposits
Diamond-bearing gravel, sand and sediment are excavated from areas where natural water movement concentrated the stones.
Material is washed and separated so heavier minerals, including diamond, can be examined.
MARINE MINING
Ocean Deposits
Specialised vessels or coastal equipment may recover diamond-bearing sediment from the seabed.
The material is processed using systems designed to separate diamonds from sand, gravel and other minerals.
Before Mining Begins
How Are Diamond Deposits Located?
Finding a possible diamond deposit requires geological research, sampling and exploration. Most locations investigated do not become operating mines.
Exploration may include:
- Regional geological mapping
- Searching for kimberlite or lamproite bodies
- Collecting soil, stream and rock samples
- Studying indicator minerals associated with mantle rocks
- Airborne and ground geophysical surveys
- Drilling and testing possible deposits
- Estimating diamond concentration and potential quality
- Economic, environmental and engineering assessments
The presence of kimberlite does not automatically mean a profitable diamond mine can be developed. The deposit must contain enough suitable diamonds to support recovery and processing costs.
After Recovery
How Are Diamonds Separated From Rock?
Diamond-bearing ore or gravel must be processed carefully so diamonds can be recovered without unnecessary damage.
Transport the Ore
Rock or gravel is moved from the recovery area to a processing plant.
Reduce the Material
Large pieces of ore are crushed or broken into smaller sizes while protecting valuable diamond crystals.
Wash and Screen
Water, screens and sizing equipment remove fine or oversized material and organise the remaining concentrate.
Concentrate Heavy Minerals
Density-based systems can separate heavier minerals from lighter waste material.
Identify Diamonds
Sensor-based systems, X-ray technology or trained sorters may help identify diamonds in the concentrate.
Secure and Sort Rough
Recovered diamonds are cleaned, recorded and sorted according to physical and quality characteristics.
Before Polishing
What Does a Rough Diamond Look Like?
A rough diamond is the uncut crystal recovered from a natural deposit. It does not yet have the polished facets associated with finished jewellery.
Some rough diamonds show recognisable crystal forms such as octahedral shapes. Others may be broken, rounded, twinned, irregular or modified by natural resorption during their geological history.
Rough diamonds can vary greatly in size, transparency, colour, shape, surface condition and internal characteristics. Not every rough diamond is suitable for a large polished gemstone.
Manufacturers study the rough to determine whether it should become one polished diamond, several smaller diamonds or an industrial product.
Rough Diamond Evaluation
How Are Rough Diamonds Sorted?
Sorting helps determine how each crystal may be used and how it should enter the cutting and manufacturing process.
Size
Rough diamonds are grouped according to weight and physical dimensions.
Shape
Natural crystal form, breakage and surface condition influence potential polished shapes.
Colour
The visible body colour may influence value, cutting strategy and final jewellery use.
Transparency
Transparent, translucent and included material may be separated for different manufacturing purposes.
Internal Features
Inclusions, fractures and stress can affect cutting risk and polished yield.
Expected Use
Material may be suitable for jewellery, smaller accent diamonds or industrial applications.
Diamond Craftsmanship
How Does Rough Become a Polished Diamond?
Turning natural rough into a polished gemstone requires planning, technology and skilled craftsmanship.
Examine the Rough
The diamond is studied for shape, dimensions, inclusions, stress, colour and surface features.
Scan and Map
Three-dimensional scanning can identify internal features and possible cutting options.
Plan the Polished Stones
The manufacturer balances potential size, clarity, shape, beauty and polished yield.
Saw or Cleave
The rough may be divided with laser equipment or other controlled techniques.
Shape the Diamond
The early outline of the chosen round, oval, emerald, pear or other shape is created.
Place and Polish Facets
Facets are created in a planned sequence to produce the final proportions and light performance.
Inspect the Finish
Polish, symmetry, measurements and surface condition are checked.
Grade or Set the Diamond
The polished diamond may be independently graded before being sold loose or placed in jewellery.
Understanding Quality
The 4Cs of Mined Diamonds
Natural diamonds are commonly evaluated using cut, colour, clarity and carat weight.
Cut
Cut describes how effectively the diamond’s proportions and facets interact with light. It strongly affects brightness, fire and sparkle.
Color
For colourless diamonds, colour grading evaluates visible body colour. Fancy-colour diamonds are evaluated using different colour considerations.
Clarity
Clarity considers internal and surface characteristics according to their size, type, number, position and visibility.
Carat
Carat measures weight. Face-up dimensions, proportions and shape also influence how large a diamond appears.
Buying tip:
Carat weight alone does not determine beauty. A well-cut diamond can
appear brighter and more attractive than a heavier diamond with weak
proportions.
Natural Characteristics
Do Mined Diamonds Have Inclusions?
Yes. Natural diamonds can contain features formed during crystal growth or later geological events.
Common clarity characteristics may include:
- Mineral crystals
- Pinpoints and clouds
- Feathers or small fractures
- Needles
- Internal graining
- Natural surface features
- Indented naturals
- Extra facets or polishing features
These characteristics vary in visibility and importance. A diamond may be eye-clean while still containing inclusions visible under magnification.
Some mineral inclusions also provide scientists with information about the environment in which the diamond formed.
Diamond Documentation
Do Mined Diamonds Come With Grading Reports?
Many natural diamonds are accompanied by an independent gemological grading report. Availability depends on the individual stone, size, value, product type and seller.
A grading report may include:
- Natural diamond identification
- Shape and cutting style
- Measurements and carat weight
- Colour grade
- Clarity grade
- Cut grade where applicable
- Polish and symmetry grades
- Fluorescence information
- Clarity characteristics or plotting information
- Report number and possible laser inscription
A grading report describes the submitted diamond. It does not guarantee investment performance, future resale value or country of origin unless a separate origin service and matching process are provided.
Source and Supply Chain
Can You Determine Where a Diamond Was Mined?
Country of origin generally cannot be established simply by examining a polished natural diamond.
Natural diamonds from different locations can have similar physical and gemological characteristics. Once a diamond has been removed from its original geological and supply-chain context, geographic origin may be difficult to prove.
Reliable origin programs generally require information to be collected and preserved from the rough-diamond stage. The rough and polished diamond may then be scientifically matched or tracked through a documented chain of custody.
When geographic origin matters, ask for product-specific documentation rather than relying only on a general claim about where a seller usually sources diamonds.
A standard diamond grading report and a country-of-origin report are not
automatically the same document.
Responsible Buying
What Should Traceability Information Include?
Source Documentation
Information identifying the mine, country, supplier or documented source where applicable.
Chain of Custody
Records describing how the diamond moved through sorting, manufacturing and sale.
Rough-to-Polished Matching
Technology or controlled procedures connecting a polished diamond with its original rough material.
Independent Verification
Review or confirmation by a recognised laboratory, auditor, certification system or traceability provider.
Supplier Policies
Written standards covering sourcing, labour, environment, compliance and supplier due diligence.
Product-Specific Records
Documentation linked to the individual diamond rather than broad marketing language applying to an entire brand.
International Rough-Diamond Trade
What Is the Kimberley Process?
The Kimberley Process Certification Scheme is an international system created to reduce the trade in conflict diamonds.
It regulates international shipments of rough diamonds between participating countries. Qualifying shipments must be handled according to participant requirements and accompanied by an authorised certificate.
The scheme focuses on rough diamonds and uses a specific definition of conflict diamonds connected with armed conflict against legitimate governments.
Kimberley Process compliance should therefore be treated as one part of responsible sourcing rather than a complete guarantee covering every environmental, labour, community or human-rights issue.
Buying tip:
Ask the jeweller about additional supplier due diligence, warranties,
sourcing policies and product-specific traceability.
Environmental Considerations
What Is the Environmental Impact of Diamond Mining?
Environmental impact varies significantly according to deposit type, mining method, mine scale, location, energy use and management practices.
Land Disturbance
Surface operations can change landscapes and require removal or movement of soil and rock.
Water Management
Mines may use water for processing and must manage runoff, sediment, water quality and local availability.
Energy and Fuel
Excavation, transport, crushing and processing require energy, equipment and fuel.
Waste Material
Rock, soil and processing residues must be managed throughout the mine’s operating life.
Biodiversity
Mining plans may need to address habitat disturbance, wildlife, vegetation and ecosystem protection.
Closure and Rehabilitation
Responsible mine planning includes closure, stabilisation, monitoring and rehabilitation of affected land.
Avoid assuming that every mine has the same environmental performance.
Review current mine-specific reporting and independent evidence where
environmental impact is important to your decision.
Communities and Work
What Are the Social Considerations?
Diamond mining can create employment, infrastructure and government revenue, but social outcomes depend on governance, labour standards, community participation and responsible business practices.
Potential Benefits
Economic and Community Contributions
- Direct and indirect employment
- Training and skill development
- Local business opportunities
- Tax and export revenue
- Infrastructure investment
- Support for education or healthcare programs
Potential Risks
Issues Requiring Oversight
- Unsafe working conditions
- Weak labour protections
- Community displacement
- Unequal distribution of benefits
- Informal or unregulated mining
- Limited transparency or accountability
Responsible sourcing requires more than knowing that a diamond was mined. The quality of the mine operator, government oversight, supplier due diligence and documented chain of custody also matter.
Diamond Treatments
Can Mined Diamonds Be Treated?
Yes. Natural origin does not automatically mean a diamond is untreated.
Some natural diamonds receive treatment intended to alter colour or apparent clarity. Treatments may include high-pressure high-temperature processing, irradiation, annealing, laser drilling, fracture filling or surface coating.
Different treatments have different stability and care requirements. Some are permanent under normal wear, while others may be affected by heat, chemicals, repair or cleaning procedures.
Relevant treatments should be clearly disclosed. Review the product description and grading report before purchasing.
A treated natural diamond remains natural in origin, but treatment
information can affect price, care and purchasing decisions.
Price and Value
What Determines the Price of a Mined Diamond?
Natural diamond pricing is influenced by more than carat weight. Quality, rarity, market demand, cutting and documentation all contribute.
- Cut quality and proportions
- Colour grade or fancy-colour strength
- Clarity grade and visible characteristics
- Carat weight and face-up dimensions
- Diamond shape
- Fluorescence
- Natural rarity
- Treatment status
- Grading laboratory and documentation
- Brand, jewellery design and craftsmanship
- Current supply and customer demand
Two diamonds with similar grades can still look different and receive different prices because of proportions, undertones, inclusion placement and overall visual performance.
Long-Term Considerations
Do Mined Diamonds Hold Their Value?
Natural diamonds have an established secondary market, but resale value is never guaranteed.
Retail prices may include costs for design, manufacturing, brand, marketing, setting, packaging and customer service. These costs may not be fully recovered when jewellery is resold.
Resale offers depend on diamond quality, condition, documentation, current demand, buyer margins and whether the stone can be easily resold.
Purchase diamond jewellery primarily for personal meaning, design and
enjoyment rather than assuming guaranteed investment returns.
Buying Guidance
How to Choose a Mined Diamond
Facts and Misconceptions
Common Myths About Mined Diamonds
Myth
“Diamonds form inside kimberlite.”
Most natural diamonds formed deeper and earlier. Kimberlite transported them towards the surface.
Myth
“Every mined diamond is flawless.”
Natural diamonds can contain inclusions, fractures, graining and other features created during growth or later geological events.
Myth
“A larger diamond is always better.”
Carat measures weight. Cut, colour, clarity and proportions strongly influence appearance.
Myth
“Natural diamonds are never treated.”
Some natural diamonds receive colour or clarity treatments, which should be disclosed.
Myth
“A grading report proves the mine of origin.”
Standard grading describes identity and quality. Geographic-origin confirmation generally requires separate traceability procedures.
Myth
“Every mined diamond increases in value.”
Resale value depends on quality, demand and market conditions and is not guaranteed.
Jewellery Care
How to Care for Mined Diamond Jewellery
Diamond is highly resistant to scratching, but jewellery settings, exposed edges and other gemstones can still be damaged.
Oil, soap, lotion, dust and cosmetics can collect on a diamond’s surface and reduce visible sparkle until the jewellery is cleaned.
- Clean gently with lukewarm water and mild soap.
- Use a soft brush around the diamond and setting.
- Rinse carefully and dry with a lint-free cloth.
- Avoid harsh chemicals and abrasive products.
- Remove jewellery before exercise or heavy physical work.
- Store pieces separately to reduce scratching.
- Have prongs, clasps and settings inspected periodically.
- Tell the jeweller about known treatments before repair or cleaning.
Frequently Asked Questions
Mined Diamond FAQs
What is a mined diamond? +
A mined diamond is a naturally formed diamond recovered from a
natural deposit in or on the Earth.
Is a mined diamond the same as a natural diamond? +
Yes. In jewellery terminology, mined diamond and natural diamond
generally describe the same diamond category.
Where do natural diamonds form? +
Most gem-quality natural diamonds formed deep within the Earth under
suitable conditions of pressure, temperature and chemistry.
Do diamonds form inside kimberlite? +
Kimberlite generally acts as a transport system. The diamonds formed
deeper in the Earth before being carried towards the surface by
volcanic magma.
How are mined diamonds recovered? +
Recovery methods include open-pit, underground, alluvial and marine
mining, depending on the location and type of deposit.
What is an alluvial diamond? +
It is a diamond released from its original host rock and moved into
river, gravel or sediment deposits through natural erosion and
water movement.
What is a rough diamond? +
A rough diamond is an uncut and unpolished diamond crystal recovered
from a natural deposit.
Are all rough diamonds suitable for jewellery? +
No. Rough material varies in transparency, shape, size, colour and
inclusions. Some is used for jewellery and some for industrial
purposes.
Do mined diamonds have inclusions? +
Yes. They can contain crystals, feathers, clouds, graining and other
natural characteristics.
Can mined diamonds be treated? +
Yes. Some natural diamonds receive treatments to alter colour or
apparent clarity. Relevant treatments should be disclosed.
Can a grading report identify the country of origin? +
A standard grading report does not automatically establish the mine
or country of origin. Origin services require additional records and
traceability procedures.
What is the Kimberley Process? +
It is an international certification scheme regulating trade in
rough diamonds to reduce the flow of conflict diamonds between
participating countries.
Does Kimberley Process certification cover every ethical issue? +
No. It focuses on international rough-diamond trade and a defined
category of conflict diamonds. Additional due diligence is needed
for wider labour, environmental and community considerations.
Are mined diamonds environmentally friendly? +
Mining has environmental impacts, but performance varies by mine,
method, energy use, water management, rehabilitation and regulatory
oversight.
Do mined diamonds hold their value? +
They have an established secondary market, but resale value is not
guaranteed and may be below the original retail price.
Are mined diamonds suitable for engagement rings? +
Yes. Diamond hardness, brilliance and availability in many shapes
make natural diamonds suitable for engagement rings and fine
jewellery.
Do mined diamonds become cloudy? +
A diamond does not normally become permanently cloudy through
ordinary wear. Surface oils and residue may temporarily reduce
sparkle.
What should I check before buying? +
Review the 4Cs, measurements, treatment disclosure, grading report,
sourcing information, seller policies and the diamond’s actual
appearance.
Educational note: Natural diamond formation, mining methods, traceability, environmental performance, treatments and documentation vary. Review current product-specific information before purchasing.
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