Lab Diamonds

Carbon Perfected. The Mythic Crystal.

Few materials have shaped human ideas of brilliance, strength and permanence as profoundly as diamond.

For centuries, diamond has been valued for its exceptional hardness and unmistakable interaction with light.

Its extraordinary properties arise from an elegantly simple composition:

Carbon

Every atom in a diamond is bonded to four neighbouring carbon atoms within a rigid three-dimensional crystal lattice.

From one element emerges:

  • the hardest gem used in jewellery;

  • exceptional brilliance;

  • remarkable thermal conductivity;

  • high optical transparency;

  • and one of the strongest crystal structures known.

Diamond demonstrates one of the central principles of mineralogy:

Composition matters—but atomic arrangement can matter just as much.

What Is a Lab-Grown Diamond?

A lab-grown diamond is genuine diamond crystallised under controlled technological conditions rather than formed naturally within the Earth.

It possesses essentially the same:

✓ Carbon composition

✓ Diamond crystal structure

✓ Hardness

✓ Refractive index

✓ Dispersion

✓ Density

✓ Thermal conductivity

✓ Optical behaviour

as natural diamond.

Lab-grown diamond is not cubic zirconia.

It is not moissanite.

It is not glass.

Those materials may sometimes be used as diamond alternatives, but they possess different chemical compositions and crystal structures.

Lab-grown diamond is diamond.

The principal distinction is its growth origin.

Natural diamond: crystallised through geological processes within the Earth.

Lab-grown diamond: crystallised using advanced HPHT or CVD technology.

Both consist of carbon arranged in the diamond structure. GIA describes laboratory-grown diamonds as having essentially the same chemical composition, crystal structure and physical properties as natural diamonds.

One Element. Different Structures.

Diamond is composed of carbon—but carbon does not always form diamond.

The same element can also form graphite.

In graphite, carbon atoms are arranged in flat sheets held together relatively weakly between layers. This allows graphite to be soft enough for use in pencils.

In diamond, each carbon atom forms strong covalent bonds with four neighbouring carbon atoms, producing a continuous three-dimensional network.

This arrangement gives diamond its exceptional hardness.

The chemistry is the same.

The atomic architecture is different.

One form is soft, dark and electrically conductive.

The other is transparent, electrically insulating under ordinary conditions and extraordinarily hard.

Diamond is one of the clearest demonstrations that a material cannot be understood from chemical formula alone.

Structure determines behaviour.

Diamond’s Crystal Structure

Diamond belongs to the cubic crystal system.

Its crystal structure is commonly described as diamond cubic, in which carbon atoms form a highly ordered tetrahedral network.

Because cubic crystals possess high symmetry, diamond is normally optically isotropic.

In an ideal, unstressed diamond, light travels with the same refractive behaviour in every crystallographic direction.

Real diamonds, however, are not always perfect theoretical crystals.

Internal strain, growth-sector boundaries, inclusions and lattice defects may produce anomalous optical effects when the stone is examined between crossed polarisers.

These features can preserve evidence of how the crystal grew and what happened to it after growth.

A polished diamond may conceal its original crystal form, but its growth history remains written within its lattice.

Why Diamond Is So Hard

Diamond scores 10 on the Mohs hardness scale, making it the hardest recognised natural mineral and the most scratch-resistant major gem.

Its hardness arises from the strong carbon–carbon bonds extending throughout its three-dimensional crystal structure.

However, hardness must not be confused with toughness.

Hardness describes resistance to scratching.

Toughness describes resistance to breaking, chipping or fracturing.

Diamond is extremely hard, but it possesses perfect cleavage along certain crystallographic planes.

A sufficiently sharp impact in a vulnerable direction can chip or split a diamond.

This is why even diamond should be protected from severe blows, particularly around:

  • sharp corners;

  • pointed tips;

  • thin girdles;

  • exposed culets;

  • and vulnerable facet junctions.

Diamond is exceptionally durable, but it is not indestructible.

Diamond and Light

Diamond’s visual performance arises from a combination of refractive index, dispersion, transparency, cut and surface polish.

Refractive Index

Diamond has a refractive index of approximately:

2.417

This high refractive index causes light to bend strongly when entering and leaving the gem.

When a diamond is cut to suitable proportions, much of the entering light is internally reflected and returned through the crown toward the observer.

This contributes to diamond’s brightness and brilliance.

Dispersion

Diamond has a dispersion value of approximately:

0.044

Dispersion is the separation of white light into spectral colours.

In a well-cut diamond, this may appear as flashes of:

  • Red

  • Orange

  • Yellow

  • Green

  • Blue

  • Violet

This spectral display is commonly called fire.

Scintillation

Scintillation refers to the pattern of bright and dark flashes seen as the gem, observer or light source moves.

The character of scintillation depends strongly on:

  • facet arrangement;

  • symmetry;

  • proportions;

  • contrast pattern;

  • lighting environment;

  • and observation distance.

Diamond does not produce brilliance simply because it is diamond.

The crystal provides the optical potential.

The cutter determines how effectively that potential is expressed.

Cut Is Optical Engineering

A rough diamond may possess outstanding transparency and purity but display little visual brilliance until it is properly cut.

Faceting transforms the crystal into an optical system.

Each facet acts as a precisely positioned reflective or refractive surface.

The cutter must balance:

  • light return;

  • fire;

  • scintillation;

  • symmetry;

  • face-up size;

  • weight retention;

  • inclusion placement;

  • and mechanical durability.

If a diamond is cut too deeply, light may escape through the pavilion.

If it is cut too shallowly, light may also leak rather than returning to the observer.

Well-designed proportions allow internal reflection to direct more light back through the crown.

Brilliance is therefore not merely a property of the material.

It is the result of crystal physics shaped by geometry.

Lab-Grown Diamond: Real Diamond

Lab-grown diamonds are produced by two principal technologies:

  • High Pressure High Temperature — HPHT

  • Chemical Vapour Deposition — CVD

These methods use very different growth environments, but both produce carbon crystallised in the diamond structure. HPHT and CVD are the two principal commercial methods used to grow gem-quality laboratory diamonds.

The resulting diamonds can be cut, polished and graded using the same fundamental principles applied to natural diamonds.

A laboratory-grown diamond may receive assessments for:

  • carat weight;

  • colour;

  • clarity;

  • cut;

  • polish;

  • symmetry;

  • fluorescence;

  • proportions;

  • and identifying growth features.

The growth method is part of the diamond’s scientific identity and should be transparently disclosed.

HPHT Diamond

Recreating Diamond’s High-Pressure Stability

HPHT stands for:

High Pressure High Temperature

This process reproduces the high-pressure, high-temperature conditions under which diamond is thermodynamically stable.

A typical HPHT growth system contains:

  • a diamond seed;

  • a carbon source;

  • a metallic solvent or catalyst;

  • and a high-pressure reaction chamber.

The growth capsule is subjected to pressures commonly around 5–6 gigapascals and temperatures of approximately 1,300–1,600°C.

Under these conditions, carbon dissolves into the molten metallic solvent and migrates toward the cooler diamond seed.

Carbon atoms then crystallise onto the seed in the diamond structure.

Layer by layer, the diamond grows.

Published GIA research describes HPHT growth at pressures of approximately 5–6 GPa and temperatures of roughly 1,300–1,600°C.

Why HPHT Is Excellent for Melee Diamonds

At Gemdrop®, many of our smaller and melee-sized laboratory diamonds are HPHT-grown.

Melee generally refers to small polished diamonds used individually or in groups for:

  • pavé settings;

  • halos;

  • accent gems;

  • eternity bands;

  • cluster jewellery;

  • watch setting;

  • and detailed jewellery designs.

HPHT growth is particularly well suited to producing large quantities of small, bright, consistent diamonds.

Its advantages for melee may include:

✓ Efficient production of smaller crystals

✓ Strong colour potential

✓ Excellent transparency

✓ High consistency across calibrated parcels

✓ Suitability for round and small precision-cut stones

✓ Competitive value

✓ Reliable jewellery performance

This does not mean that every HPHT diamond is inherently superior to every CVD diamond.

Diamond quality must always be assessed gem by gem.

However, HPHT is often an exceptionally practical and effective growth method for small polished diamonds, where consistency, calibration and production efficiency are especially important.

For this reason, HPHT-grown diamond is widely encountered in small accent and melee sizes.

Characteristics of HPHT-Grown Diamond

HPHT-grown diamonds may display growth features associated with crystallisation in a metallic solvent environment.

These can include:

  • metallic flux inclusions;

  • geometric colour zoning;

  • growth-sector patterns;

  • distinctive ultraviolet fluorescence;

  • phosphorescence;

  • and characteristic spectroscopic features.

Some metallic inclusions may respond to a magnet, although this is not present in every HPHT diamond and is not sufficient as a standalone identification test.

Blue or blue-grey colour in some HPHT diamonds may be associated with boron.

Yellow coloration may be associated with nitrogen.

Colourless HPHT material may be produced through careful control of impurities and growth conditions.

Modern HPHT diamonds can display exceptional colour, clarity and optical performance.

CVD Diamond

Building Diamond From a Carbon-Rich Gas

CVD stands for:

Chemical Vapour Deposition

Unlike HPHT growth, CVD does not require the same immense pressures.

Instead, diamond grows from a carbon-containing gas within a low-pressure reaction chamber.

The process begins with a thin diamond seed plate.

The chamber is filled with gases commonly including hydrogen and a small concentration of methane.

Energy—often supplied through microwave plasma—is used to break the gas molecules into reactive species.

Carbon-containing radicals reach the seed surface.

Under carefully controlled conditions, carbon atoms attach to the seed and extend the diamond lattice.

The crystal grows upward in successive layers.

GIA describes CVD growth as involving the breakdown of carbon-rich gases, such as methane, so that carbon can crystallise on diamond seed material.

Diamond Grown From Plasma

Inside a CVD reactor, the glowing plasma is not itself diamond.

It is an energetic mixture of electrons, ions, atoms, radicals and molecules.

Hydrogen plays a critical role.

It helps suppress non-diamond forms of carbon while stabilising the surface conditions required for diamond growth.

The balance must be controlled precisely.

Variables include:

  • gas composition;

  • chamber pressure;

  • substrate temperature;

  • microwave power;

  • plasma density;

  • seed orientation;

  • growth rate;

  • and trace impurities.

A small change in reactor conditions can influence:

  • colour;

  • clarity;

  • defect concentration;

  • strain;

  • growth layering;

  • fluorescence;

  • and final crystal quality.

CVD diamond is therefore not merely manufactured carbon.

It is the result of highly controlled plasma chemistry, surface science and crystallography.

Why CVD Is Important

CVD technology allows diamond to be grown in flat plates and successive layers.

This makes it highly adaptable for producing gem-quality diamonds across a broad range of sizes.

CVD diamonds may offer:

✓ Excellent transparency

✓ High colour grades

✓ Large polished sizes

✓ Efficient use of seed geometry

✓ Controlled layer-by-layer growth

✓ Strong cutting potential

✓ Advanced technological provenance

CVD growth can sometimes be paused and restarted, allowing several growth stages to build additional thickness. In contrast, conventional HPHT gem growth is usually performed in a single uninterrupted run.

Modern CVD systems continue to improve, and high-quality colourless and near-colourless material can now be produced, including some material requiring no post-growth colour treatment.

Characteristics of CVD-Grown Diamond

CVD diamonds may display features associated with layered growth.

These can include:

  • planar growth bands;

  • fine dark inclusions;

  • internal strain;

  • brown, grey or pink colour components;

  • distinctive fluorescence patterns;

  • and characteristic spectroscopic defects.

Microscopy may reveal dark pinpoint inclusions composed of non-diamond carbon or other growth-related material.

Under specialised ultraviolet imaging, some CVD diamonds display layered or striated growth patterns.

These structures may record separate phases of deposition or changes in reactor conditions.

Modern CVD material, however, can be extremely clean. Growth features may be subtle and may require specialised spectroscopy or fluorescence imaging to detect.

Visual inspection alone cannot reliably determine whether a high-quality diamond is natural, CVD-grown or HPHT-grown.

CVD Versus HPHT

Both methods produce real diamond.

Neither process automatically guarantees a better finished gem.

The quality of an individual diamond depends on factors including:

  • colour;

  • clarity;

  • cut;

  • transparency;

  • strain;

  • inclusions;

  • post-growth treatment;

  • and production quality.

HPHT Is Often Particularly Strong For:

✓ Small and melee diamonds

✓ Calibrated accent gems

✓ Efficient small-crystal production

✓ Excellent colourless material

✓ Certain fancy colours

✓ Strong parcel consistency

CVD Is Often Particularly Strong For:

✓ Medium and larger polished diamonds

✓ Flat seed-based growth

✓ Layered crystal production

✓ Scalable growth area

✓ High-purity type IIa material

✓ Larger modern jewellery gems

These are practical tendencies, not absolute rules.

HPHT can produce large diamonds.

CVD can produce small diamonds.

Both technologies are capable of producing excellent gem material.

The finished diamond should be judged by its measured quality—not by a simplistic assumption that one growth method is always better.

Post-Growth Treatment

Some lab-grown diamonds are treated after crystallisation to modify their colour.

For example, certain CVD diamonds may undergo post-growth HPHT processing to reduce brown coloration or improve apparent colour.

This treatment alters defect populations within the crystal lattice.

It does not convert the material into diamond—it was already diamond before treatment.

Rather, the process changes how existing impurities and defects interact with visible light.

GIA has documented CVD diamonds subjected to post-growth HPHT processing, and major gem laboratories may state evidence of such treatment on their reports.

Other treatments may be used to create or modify fancy colours.

At Gemdrop®, the scientifically responsible approach is disclosure:

  • identify the material as laboratory-grown diamond;

  • disclose the known growth method;

  • record external laboratory reports where present;

  • and report known or documented post-growth treatment.

Diamond Colour

An ideal diamond lattice composed only of carbon would be colourless across the visible spectrum.

Real diamonds may contain trace elements and structural defects that absorb selected wavelengths of light.

Nitrogen

Nitrogen is the most common impurity in natural diamond and may also occur in lab-grown diamond.

Depending on its concentration and atomic arrangement, nitrogen may contribute to yellow or brown coloration.

Boron

Boron can produce blue or blue-grey colour and may also make diamond electrically conductive.

Vacancies and Defect Centres

Missing carbon atoms, displaced atoms and impurity–vacancy combinations can create colour centres.

These may produce:

  • Pink

  • Red

  • Purple

  • Green

  • Blue

  • Yellow

  • Brown

Some colours arise during crystal growth.

Others may be modified or generated through irradiation, annealing or HPHT treatment.

Colour in diamond is therefore not simply “tint.”

It is a visible expression of atomic-scale imperfections.

Diamond Fluorescence

Some diamonds emit visible light when exposed to ultraviolet radiation.

This is known as fluorescence.

Blue is the most familiar fluorescence colour, but diamonds may also fluoresce:

  • Green

  • Yellow

  • Orange

  • Red

  • White

Some diamonds continue emitting light after the ultraviolet source is removed.

This delayed emission is called phosphorescence.

Fluorescence and phosphorescence arise from impurities and defects within the diamond lattice.

Their colour, intensity and spatial pattern can provide important evidence regarding growth and treatment history.

Specialised ultraviolet imaging instruments can reveal growth-sector structures and fluorescence patterns that help laboratories separate natural, HPHT-grown and CVD-grown diamonds.

However, fluorescence alone is not conclusive.

Different diamond categories can show overlapping responses.

The Four Cs

Diamond quality is traditionally assessed using the Four Cs:

Carat

Carat measures weight.

1 carat = 0.20 grams

Carat does not directly measure physical size.

Two diamonds with the same carat weight may have different visible diameters because of differences in shape, proportions and depth.

Colour

For colourless and near-colourless diamonds, colour grading evaluates the presence of body colour.

The commonly used scale runs from:

D — colourless

to

Z — light yellow or brown

Fancy-colour diamonds are evaluated using a different system based on hue, tone and saturation.

Clarity

Clarity describes internal and surface features.

Internal features are called inclusions.

External features are called blemishes.

Clarity grades depend on factors including:

  • size;

  • number;

  • position;

  • relief;

  • and nature of the features.

Cut

Cut describes how effectively the polished diamond’s proportions, facet arrangement and finish control light.

Cut should not be confused with shape.

A diamond may have a round, oval, pear, princess, emerald or other shape.

Its cut quality concerns how well the geometry performs.

For visual appearance, cut is often among the most influential factors.

Melee Diamonds: Small Crystals, Extreme Precision

Small diamonds may weigh only a fraction of a carat, but cutting them remains an advanced technical process.

Melee diamonds must often be:

  • closely matched in diameter;

  • consistent in colour;

  • compatible in clarity;

  • accurately faceted;

  • and suitable for secure setting.

In pavé and halo jewellery, the visual effect is produced by many small diamonds functioning together as a coordinated optical field.

A difference of only a fraction of a millimetre may affect setting quality and pattern consistency.

For this reason, calibrated HPHT melee represents a significant achievement in crystal growth, sorting and precision manufacturing.

Small does not mean scientifically simple.

A one-millimetre diamond contains the same tetrahedrally bonded carbon architecture as a far larger gem.

Diamond Properties

Mineral: Diamond

Chemical Composition: Carbon, C

Crystal System: Cubic

Crystal Structure: Diamond cubic

Optical Character: Isotropic under ideal unstressed conditions

Mohs Hardness: 10

Refractive Index: Approximately 2.417

Dispersion: Approximately 0.044

Specific Gravity: Approximately 3.52

Cleavage: Perfect in four octahedral directions

Thermal Conductivity: Exceptionally high

Electrical Conductivity: Usually very low; boron-bearing type IIb diamond may be semiconductive

Lustre: Adamantine

Durability: Excellent, with care required around cleavage-sensitive directions

Diamond as an Advanced Technology Material

Diamond is far more than a jewellery gem.

Its unusual combination of properties makes laboratory-grown diamond important in advanced technology.

Synthetic diamond may be used in:

  • cutting and abrasive systems;

  • thermal management;

  • high-power electronics;

  • optical windows;

  • precision machining;

  • electrochemistry;

  • radiation detection;

  • quantum sensing;

  • and semiconductor research.

Its extreme hardness is only one part of its technological importance.

Diamond also possesses:

  • exceptional heat conduction;

  • broad optical transparency;

  • chemical resistance;

  • radiation tolerance;

  • and the ability to host optically active defect centres.

Laboratory growth allows scientists to engineer diamond for purposes that geological diamond could never supply consistently or economically. Industrial synthetic-diamond research now extends into areas including quantum technologies, semiconductors, photonics and thermal management.

A jewellery diamond and an advanced technological diamond are expressions of the same remarkable carbon lattice.

How Gemdrop® Verifies Diamond

Diamond identification requires a different approach from ordinary coloured-stone testing.

Traditional thermal-conductivity testing can help separate diamond from some simulants, but it cannot by itself determine whether a diamond is natural or laboratory-grown.

Moissanite also conducts heat strongly, so combined thermal and electrical testing may be needed to distinguish it from diamond.

Separating natural, HPHT-grown and CVD-grown diamond may require analysis of:

  • growth morphology;

  • ultraviolet fluorescence patterns;

  • phosphorescence;

  • absorption spectra;

  • photoluminescence defects;

  • strain patterns;

  • inclusions;

  • and trace impurities.

Gemdrop® assessment may include:

  • Visual Examination

  • Magnification

  • Thermal-Conductivity Testing

  • Electrical-Conductivity Testing

  • Ultraviolet Fluorescence

  • Phosphorescence Observation

  • Polariscope or Strain Examination

  • External Report Verification

  • Laser-Inscription Examination

  • Optical Assessment

  • Dimensional and Weight Measurement

Where appropriate, advanced laboratory techniques may include:

  • Photoluminescence Spectroscopy

  • FTIR Spectroscopy

  • UV-Vis-NIR Spectroscopy

  • Raman Spectroscopy

  • Short-Wave Ultraviolet Imaging

  • Diamond Growth-Pattern Analysis

No single simple test should be treated as universally conclusive.

Responsible assessment distinguishes between:

  • confirmation that the material is diamond;

  • screening for possible laboratory growth;

  • determination of HPHT or CVD origin;

  • detection of post-growth treatment;

  • and full grading of quality.

These are related, but scientifically separate, questions.

The Gemdrop® Approach

At Gemdrop®, laboratory-grown diamond is never represented as mined diamond.

Each gem is transparently described according to the information and evidence available.

For full transparency, we disclose:

✓ Laboratory-grown origin

✓ HPHT or CVD growth method

✓ Carat weight

✓ Dimensions

✓ Shape and cut style

✓ Colour and clarity information

✓ External laboratory report number

✓ Laser inscription

✓ Treatment information

✓ Gemdrop® verification details

Every Gemdrop® diamond receives a unique verification record providing transparent identification and traceability.

For very small melee diamonds, some measurements and advanced origin determinations may require specialist automated laboratory equipment. The verification record should clearly distinguish direct GemDrop® observations from information supplied by an accredited external laboratory.

Confidence begins with honest scientific disclosure.

Why Choose Lab-Grown Diamond?

Lab-grown diamond offers:

✓ Genuine diamond composition

✓ Authentic diamond crystal structure

✓ Maximum scratch resistance

✓ Exceptional brilliance

✓ Classic diamond fire

✓ Precision cutting

✓ Advanced HPHT or CVD growth technology

✓ Greater size and design freedom

✓ Transparent laboratory origin

✓ Outstanding value relative to comparable mined diamond

Customers can choose larger gems, higher specifications or more complex jewellery designs without paying primarily for geological scarcity.

The result is not a visual substitute for diamond.

It is mythic level diamond created with advanced technology and modern crystal engineering.

HPHT or CVD: Which Should You Choose?

For most jewellery buyers, the finished quality of the diamond matters more than the growth method alone.

Choose according to:

  • cut performance;

  • colour;

  • clarity;

  • dimensions;

  • shape;

  • transparency;

  • report information;

  • and intended use.

At GemDrop®, we particularly value:

HPHT diamond for smaller calibrated and melee gemss, where it offers outstanding consistency, brightness and value.

CVD diamond for many medium and larger gems, where modern deposition technology can produce exceptional clarity, size and optical performance.

Neither method should be judged by outdated assumptions.

Modern HPHT and CVD technologies are both capable of producing extraordinary diamonds.

The correct question is not simply:

“Was it HPHT or CVD?”

The better question is:

“How well was this particular diamond grown, cut and verified?”

The Crystal of Possibility

Ruby teaches us that a trace element can transform colour.

Emerald shows that complexity can create character.

Opal reveals how microscopic order can generate a universe of light.

Alexandrite teaches us that perspective changes what we see.

Diamond teaches us about structure.

Carbon is one of the most familiar elements in existence.

It is present in living organisms, fuels, graphite and the atmosphere.

Yet when carbon atoms are arranged in exactly the right architecture, they become diamond.

The material does not become extraordinary because a new element is added.

It becomes extraordinary because familiar atoms are connected differently.

The same principle appears throughout life.

Strength is often not created by adding more.

It is created through structure.

Good habits arranged consistently.

Knowledge connected carefully.

People working together.

Pressure directed toward purpose.

A clear structure can transform ordinary components into something remarkable.

Diamond does not deny pressure.

Its identity is built through it.

Modern laboratory growth adds another chapter to that story.

Human beings learned the conditions under which diamond can form, translated those principles into technology and built one of nature’s most extraordinary crystal structures under controlled conditions.

Not an imitation.

Not an illusion.

Carbon, ordered with precision.

A triumph of crystallography.

A masterpiece of light.

This is diamond.

Shop Gemdrop® Lab-Grown Diamonds

Explore our collection of verified HPHT and CVD laboratory-grown diamonds, including calibrated melee, accent diamonds and larger individual gems.

Every gem includes transparent material identification and access to the Gemdrop® Verification Database.