From Seed to Sparkle — The Full Journey of a Lab Grown Diamond
Prologue: Two Diamonds, Two Very Different Stories
Somewhere deep in the Jwaneng mine in Botswana, a natural diamond waits. It has been waiting for approximately 1.8 billion years. It formed when the first multicellular organisms were only just beginning to appear on Earth. It survived the age of the dinosaurs, several ice ages, and the invention of instant coffee. Eventually — at enormous financial, environmental, and logistical cost — it will be blasted from kimberlite rock, sorted, shipped across the world, cut, polished, graded, and placed in a ring.
Now consider another diamond. This one begins its life in a laboratory in the 21st century. Its entire journey — from a tiny fragment of carbon to a certified, flawless gemstone sitting in a velvet box — takes roughly eight to twelve weeks.
Same diamond. One is a geological accident that survived a billion years. The other is a triumph of human precision engineered in the time it takes to go through a busy season at work.
This is the story of the second diamond — and it is, in its own way, every bit as extraordinary.
Stage 1: The Seed — The Most Important Tiny Thing in the World
Every lab grown diamond begins with a diamond seed.
Don't picture a seed in the botanical sense — this is not something you plant in soil and water on Sundays. A diamond seed is an extraordinarily thin slice of existing diamond crystal, often no more than 300 microns thick — roughly three times the thickness of a human hair.
The quality of this seed is non-negotiable. It must be chemically pure, structurally flawless, and crystallographically perfect — because any imperfection in the seed will be replicated and amplified as the new diamond grows around it. The seed is, in a very real sense, the genetic blueprint for everything that follows.
Where do seeds come from? They can be sliced from existing lab grown diamonds (creating a virtuous cycle — each generation of diamonds producing seeds for the next) or from very high-quality natural diamonds. Either way, the seed is not consumed in the process. It becomes incorporated into the base of the growing diamond, a tiny founding core buried within a much larger stone.
Fun Fact 💎: The diamond seed used to grow a one-carat gem represents only a fraction of the final stone's mass. But without it, there is no diamond. It is the most valuable tiny thing you will never see in the finished jewel — present but invisible, foundational but forgotten. Rather like the best kind of supporting character.
Stage 2: Into the Chamber — Where the Magic (and the Science) Happens
With seed selected, the real journey begins. The seed is placed inside a specialised growth chamber, and from this point, the process diverges depending on the method being used. (For a deep dive on the two methods, see Post 2: CVD vs HPHT — The Two Ways Science Grows a Diamond.)
The HPHT Route: Earth's Conditions, Recreated
In the HPHT (High Pressure, High Temperature) process, the diamond seed is placed into a growth cell along with a carbon source — usually high-purity graphite — and a metal catalyst flux containing iron, nickel, or cobalt.
This entire assembly is loaded into a hydraulic press capable of generating pressures between 5 and 6 GPa — that's 50,000 to 60,000 times the pressure of the Earth's atmosphere at sea level, or, as the GIA memorably puts it, roughly equivalent to the weight of a commercial jet aircraft balanced on the tip of one finger.
The press then heats the chamber to between 1,300 and 1,600°C — comparable to the temperature of the Earth's upper mantle where natural diamonds form.
Under these conditions, the carbon source dissolves into the metal catalyst flux. The dissolved carbon migrates through the molten metal toward the cooler diamond seed, where it begins to crystallise — attaching to the seed's atomic lattice, layer by growing layer, building a diamond from the inside out.
Over days and weeks, an angular, multi-faceted rough crystal grows from the seed. When the desired size is reached, the press is powered down. The chamber cools. The pressure releases. The newly grown rough diamond is mechanically and chemically separated from the remaining metal flux.
It is, at this point, not beautiful. It is a dull, opaque, angular lump of carbon. But inside that lump is a perfect diamond, waiting.
The CVD Route: Building a Diamond, Atom by Atom
In the CVD (Chemical Vapour Deposition) process, the diamond seed is placed inside a vacuum-sealed reactor chamber. The air is evacuated. Then a carefully controlled mixture of gases — primarily methane (CH₄) and hydrogen (H₂) — is introduced.
A microwave beam energises the gas mixture, transforming it into a superheated plasma cloud at temperatures between 900 and 1,200°C. This plasma breaks apart the methane molecules, liberating individual carbon atoms.
Those carbon atoms drift downward through the plasma, guided by physics and temperature gradients, and settle onto the diamond seed below. Each carbon atom bonds to the crystal lattice in precise alignment. One atomic layer at a time, the diamond grows upward.
The hydrogen in the gas mixture plays a critical supporting role throughout this process — it suppresses the formation of graphite, ensuring that the depositing carbon organises itself into diamond structure rather than the softer, darker alternative.
Periodically, the growing crystal must be removed from the chamber and cleaned, as a layer of graphite builds up on its surface that, if left untreated, would contaminate the crystal's growth. Then it goes back in, and the process continues.
After several weeks, the CVD diamond is complete — a rectangular slab of rough diamond, flat-topped, with a distinctive layered internal structure that records every week of its formation.
Fun Fact 🔬: CVD diamond growth has been demonstrated using a remarkable range of carbon sources beyond the standard methane — including ethanol, acetone, and most famously, tequila. Researchers in Mexico demonstrated CVD diamond growth using ultra-pure tequila as the carbon source. The diamonds weren't gem quality (tequila, it turns out, has too many impurities for a D-colour stone), but the principle held. Science: finding new ways to justify the drinks cabinet since 2008.
Stage 3: Post-Growth Treatment — The Colour Correction
Before a freshly grown diamond is ready for the cutter, it may undergo post-growth HPHT treatment — a second application of heat and pressure, this time specifically to improve the stone's colour.
CVD diamonds in particular often emerge from the reactor with a slight brownish or greyish tint. This isn't a flaw in the diamond itself — it's a consequence of structural distortions that accumulate during the layer-by-layer growth process. The HPHT treatment corrects these distortions, realigning the crystal structure and removing the tint to produce a whiter, more colourless stone.
This treatment is permanent, stable, and completely standard in the industry. Approximately 75% of CVD diamonds undergo it. You'll see it noted transparently on IGI certificates: "post-growth treatment." Far from being a red flag, it's a disclosure — the kind of honest, upfront transparency that the lab grown diamond industry is rightly proud of.
HPHT-grown diamonds, growing under conditions closer to those of natural diamond formation, are more likely to be sold as-grown — their certificates noting "No indication of post-growth treatment."
Stage 4: Sorting and Planning — The Diamond Gets Assessed
The rough diamond now leaves the growth laboratory and enters the hands of cutting specialists. But before a single facet is cut, there is a critical stage of assessment and planning that determines everything about the finished stone.
Expert gemologists and cutting planners examine the rough diamond from every angle. They assess:
- Shape and dimensions — What is the most efficient cut for this particular crystal's form?
- Inclusions and clarity — Are there any internal characteristics that need to be worked around or eliminated?
- Colour distribution — Is colour even throughout the crystal, or are there zones that need to be oriented carefully?
- Optimal yield — How do we cut this rough stone to produce the highest value in the finished gem?
Modern cutting facilities use sophisticated 3D laser scanning and AI-guided planning software to map the rough diamond's internal structure and calculate the optimal cut plan. The goal is to maximise both the yield — the percentage of the rough diamond's weight retained in the finished stone — and the optical performance of the cut.
Fun Fact 💎: This planning stage is one of the most intellectually demanding jobs in the entire jewellery supply chain. The yield from a rough diamond to a finished polished stone typically ranges from 40 to 60% of the original rough weight. That means, on a good day, you get a 0.6 carat polished diamond from a 1 carat rough stone — and the rest becomes diamond dust and cutting debris. The planner's job is to minimise that loss while maximising the beauty and value of the finished piece. Every millimetre matters.
The decision on whether to cut a rough stone in one or two pieces — sometimes a single rough crystal can yield two separate polished diamonds — is made at this stage. Then the stone is marked with a pen to guide the cutter, and the transformation begins.
Stage 5: Cutting — Where Art Meets Engineering
Diamond cutting is one of the oldest specialised crafts in the world, and one that remains as much art as science. The fundamental principle is unchanged from the craft practised in Antwerp in the 15th century: use another diamond (the only material hard enough) to cut and shape the stone.
The process typically involves several distinct sub-stages:
Cleaving or Sawing
The rough diamond is first divided into workable pieces — either by cleaving (splitting the stone along its natural crystal planes with a sharp blow, requiring extraordinary skill and nerve) or by sawing using a diamond-coated blade or laser. Modern facilities increasingly use laser cutting, which offers greater precision and reduces the risk of the catastrophic fractures that a cleaving error can cause.
Bruting (Girdling)
The stone is given its overall outline shape — round, oval, pear, and so on — by spinning it against another diamond (or a laser), wearing away the edges until the desired silhouette emerges. This stage creates the girdle: the widest circumference of the finished diamond.
Blocking
The major facets are cut — establishing the table (the flat top facet), the culet (the bottom point), and the main crown and pavilion facets that form the diamond's primary optical architecture.
Brillianteering
This is the final — and most technically demanding — cutting stage. The polisher works through the remaining facets in sequence, using a rotating cast-iron wheel (called a scaife) embedded with diamond dust to grind each facet to its precise angle and finish.
A standard round brilliant cut diamond receives 57 or 58 individual facets — 33 on the crown (upper half) and 25 on the pavilion (lower half), including the optional culet at the very tip. Each of these facets must be cut to exact angles, because the entire optical performance of the finished stone — its brilliance, fire, and scintillation — depends on how precisely those angles interact with light.
Trivia 💡: The angles in a round brilliant cut are so carefully calculated that gemologists can assess a diamond's cut quality — from Excellent to Poor — purely by measuring the proportions. A pavilion main facet angled at 40.75 degrees, a table of 56–58% of the diameter, a crown angle of 34–35 degrees — these are the parameters of optical perfection. A fraction of a degree off, and light leaks from the pavilion instead of returning through the crown as sparkle. Diamond cutting is, at its most precise, applied optics.
Quality Control
After brillianteering, the cut diamond undergoes rigorous quality control. Gemologists check the weight against the predicted yield, assess the symmetry and proportions, and examine the polish of every facet. If anything falls short of the target grade, the stone goes back for re-cutting or re-polishing. Only when it passes quality control does it move on.
Stage 6: Certification — Getting the Diamond's Official Passport
A lab grown diamond that has not been independently certified is like a car without a service history — you might believe it's excellent, but you have no proof. Certification is the diamond's official identity document, and it is non-negotiable for any reputable purchase.
The finished diamond is submitted to an independent gemological laboratory — most commonly the GIA (Gemological Institute of America) or the IGI (International Gemological Institute) — where it undergoes comprehensive assessment by trained gemologists using calibrated instruments.
The grading report that emerges documents:
- Carat weight — measured to the nearest hundredth of a carat on precision scales
- Colour grade — assessed on the D-to-Z scale under controlled lighting conditions
- Clarity grade — examined under 10x magnification to map inclusions and blemishes
- Cut grade — assessed for proportions, symmetry, and polish quality
- Growth method — identified (CVD or HPHT) and any post-growth treatments disclosed
- Laser inscription — a unique identifying number, laser-engraved invisibly on the girdle, linking the physical stone permanently to its certificate
This laser inscription is one of the lab grown diamond industry's most elegant consumer protections. That tiny engraved number on the girdle — invisible to the naked eye, visible under 10x magnification — permanently and irrefutably connects your specific stone to its specific certificate. No confusion, no substitution, no ambiguity.
Fun Fact 💎: GIA gemologists who grade diamonds are not told the identity or origin of the stones they're assessing. Each stone is graded blind — a protocol that eliminates bias and ensures the grade reflects only the objective properties of the stone. The same rigour applied to the world's most famous mined diamonds is applied to every lab grown diamond that passes through a GIA laboratory.
Stage 7: Setting — The Diamond Finds Its Home
The certified, laser-inscribed, fully documented diamond is now ready for its final transformation: being set into jewellery.
At H&H Jewellery, this is where our craftspeople take over. A skilled setter examines the stone, selects the appropriate setting style, and works — sometimes over several hours — to seat the diamond securely and precisely in its metal home.
The setting profoundly affects how the diamond is experienced:
- A solitaire setting lets the diamond command all attention — every photon of light entering the stone has nowhere to escape but back through the crown as brilliance
- A pavé or halo setting surrounds the centre stone with smaller diamonds, multiplying the play of light across the piece
- A bezel setting encircles the diamond's girdle in metal, offering a modern aesthetic and exceptional security
- A channel setting embeds stones flush within the band, creating a seamless ribbon of light
The choice of metal — platinum, white gold, yellow gold, or rose gold — affects both the diamond's perceived colour and the ring's overall aesthetic. A colourless (D–F) diamond in a platinum setting glows with cold, arctic fire. The same stone in yellow gold takes on a warmer character.
Epilogue: Eight Weeks from Seed to Your Finger
Let's bring this full circle.
The natural diamond you considered at the start of this story took 1.8 billion years to form, required industrial-scale mining to extract, travelled across multiple continents through an often opaque supply chain, and carries with it all the environmental and ethical questions that attend that process.
The lab grown diamond took eight to twelve weeks, from the placement of a 300-micron seed crystal into a controlled growth chamber, to the handing over of a certified, laser-inscribed stone in a velvet box. Every step of its journey is documented. Every parameter of its quality is independently verified. Every atom of its carbon was precisely directed into a crystal structure of extraordinary beauty.
From a tiny diamond seed thinner than a human hair to a breathtaking faceted gemstone, each step showcases the dedication and craftsmanship of lab grown diamonds.
The romance of a diamond has never been in its geological age. It has always been in what it means — to the person giving it, and to the person wearing it.
At H&H Jewellery, we believe that a diamond whose entire story you can tell — seed, growth, cut, certification, setting — carries a meaning that is richer, not poorer, for its transparency.
Same sparkle. Better story.
Frequently Asked Questions
Q: How long does it take to grow a lab grown diamond?
A: Growth alone typically takes 1–4 weeks depending on the method (HPHT is generally faster; CVD takes longer). Including cutting, polishing, and certification, the full journey from seed to finished stone is usually 8–12 weeks.
Q: Is a lab grown diamond seed visible in the finished stone?
A: The seed crystal is incorporated into the base of the grown diamond and is present in the finished stone, but it is not visible — either to the naked eye or under a jeweller's loupe. It is indistinguishable from the rest of the diamond material.
Q: How much weight is lost when cutting a lab grown diamond?
A: Significant weight is lost during cutting — typically 40–60% of the rough stone's weight is removed in the process of shaping and faceting. This is why the planning stage is so critical: every percentage point of yield represents real value.
Q: Do all lab grown diamonds receive certification?
A: Reputable retailers — including H&H Jewellery — only sell lab grown diamonds with full certification from recognised independent laboratories (GIA or IGI). Certification is your assurance of quality, authenticity, and transparency.
Q: What does the laser inscription on a lab grown diamond say?
A: The girdle inscription typically includes the certificate number and an identifier denoting the stone as laboratory-grown. Under 10x magnification, it's clearly visible; to the naked eye, it's imperceptible.
Conclusion: The Journey Is Part of the Story
A diamond's journey is not just a technical process — it is a narrative. And the story of a lab grown diamond is one of human ingenuity applied to nature's most extraordinary material: scientists recreating conditions that take the Earth a billion years to produce, in a controlled chamber the size of a wardrobe; master cutters applying six centuries of craft knowledge to unlock brilliance from an angular lump of crystal; gemologists assessing each stone with the same precision and rigour they'd bring to the rarest jewels on earth.
At H&H Jewellery, every lab grown diamond we offer has completed this journey. It carries its certificate, its laser inscription, its independently verified 4Cs — and it carries the transparency and integrity that every modern diamond buyer deserves.
Your diamond's story starts with a seed. It ends on your finger.
Everything in between is science, craft, and a little bit of wonder.
Explore H&H Jewellery's Lab Grown Diamond Collection →
Every stone certified. Every journey documented. Beautifully yours.
H&H Jewellery's content is researched and written with reference to the Gemological Institute of America (GIA), the International Gemological Institute (IGI), Labrilliante diamond cutting resources, peer-reviewed materials science literature, and reputable industry sources. We are committed to accuracy, transparency, and genuine expertise in everything we publish.