The short answer
A lab-grown diamond is a diamond. Carbon atoms in the diamond lattice, hardness 10, bending light by exactly the same amount as a stone dug out of the ground. It is not an imitation the way cubic zirconia is an imitation. Every gemmological laboratory in the world grades them as diamonds, on diamond equipment, using the same colour and clarity vocabulary.What differs is where the carbon crystallised and how long it took. That difference is real, a laboratory can prove it, and it explains most of the price gap. It is not a difference in what the stone is, and no instrument examining the finished crystal finds the material lacking.
Both of these are true at onceA lab-grown diamond is a real diamond, and a laboratory can still tell it apart from a mined one. Most of the confusion online comes from people assuming those two statements cannot both stand. They can. Origin leaves a structural fingerprint. It does not leave a different material behind.
Same carbon, same lattice
A gemmologist identifying an unknown stone does not ask where it came from. They measure a short list of physical constants: how hard it is, how much it slows and bends light, how heavy it is for its size, how fast heat moves through it. A diamond has one set of answers and nothing else has that set. Here are the four stones you are actually choosing between, measured the same way.
Four stones, and the numbers that decide what each one isDiamond. Crystallised deep in the mantle and carried up by volcanic rock, somewhere between one and three billion years ago.Diamond. The same crystal, grown onto a diamond seed over a few weeks. Every measurable property in this column is the one to its left.Not diamond. It splits light into colour more than twice as strongly, which is the rainbow flash people describe as looking disco.Not diamond. Getting on for twice the weight of diamond at the same size, and it abrades to a soft grey within a couple of years of daily wear.Standard gemmological constants: Mohs hardness, refractive index measured at 589 nanometres, and specific gravity as a multiple of water. The Mohs scale is a ranking rather than a measurement, so read the bars as an order and not as a ratio: the real gap between 9.25 and 10 is far wider than the drawing can show.
The two right-hand columns are where the practical differences live. Cubic zirconia is close to twice as dense as diamond, which is why a loose CZ feels wrong in the hand before you have looked at it, and why a CZ cut to the millimetre dimensions of a one carat diamond weighs nearly two carats. Moissanite disperses light into colour more than twice as strongly as diamond, so it flashes rainbows where a diamond flashes white. Both are identifiable in seconds by someone who handles stones.The two left-hand columns are the same column printed twice. That is not a simplification made for a guide: it is the reason a diamond tester, which measures thermal conductivity, cannot separate them, and the reason origin has to be established by looking at how the crystal grew rather than at what it is made of. Our guide on telling lab-grown from natural walks through each test and where it stops working.Natural diamondCarbon, cubic lattice
Hardness 10
Bends light2.42
Density3.52
Lab-grown diamondCarbon, cubic lattice
Hardness 10
Bends light2.42
Density3.52
MoissaniteSilicon carbide
Hardness 9.25
Bends light2.65 to 2.69
Density3.21
Cubic zirconiaZirconium dioxide
Hardness 8 to 8.5
Bends light2.15 to 2.18
Density5.6 to 6.0
How the crystal is grown
There are two industrial routes to a gem-quality diamond, and both begin with a piece of diamond already in the chamber. That detail does more work than anything else on this page.
The two ways a diamond is grown above groundConditions are the published operating ranges for gem growth and vary between producers. General Electric made the first reproducible synthetic diamonds in 1954 and the first gem-quality crystals in 1971; CVD gem production is a development of the 2000s and is where most of today's larger colourless material comes from.
What grows is not a copy of a diamond. It is a continuation of the seed crystal, one carbon atom at a time, into the only arrangement carbon takes under those conditions. The atoms have no way of knowing whether the pressure around them comes from a hydraulic press or from two hundred kilometres of rock, so they do the same thing either way. A billion years and three weeks arrive at the same lattice.One consequence surprises people. Because growth conditions are controlled, lab-grown stones are often chemically purer than the natural ones they sit beside in a tray. Nitrogen is the impurity that gives most natural diamonds their faint yellow; the type of diamond essentially free of it, called type IIa, is a small fraction of natural production and is common in CVD growth. The stone in the cheaper column is frequently the more perfect crystal, which is an awkward fact for anyone arguing that lab-grown is a lesser material.HPHTHigh pressure, high temperature
Carbon and a molten metal flux are squeezed around a diamond seed until carbon dissolves and re-crystallises onto it. It is the mantle's recipe, run inside a press.Conditions
Around 1,500 °C at 5 to 6 gigapascals, roughly 50,000 atmospheresTime
Days to about two weeks for a gem-sized crystalLeaves behind
Tiny metallic flux inclusions, which is why some HPHT stones respond faintly to a magnet.CVDChemical vapour deposition
Methane and hydrogen are broken into a plasma and carbon settles onto a flat diamond seed plate, one atomic layer at a time, the way frost builds on glass.Conditions
Around 800 to 1,200 °C, at less than atmospheric pressureTime
Several weeks, building up in layersLeaves behind
Fine growth striations, and sometimes a brown cast that is lifted afterwards with heat and pressure.Who decides what the word means
Almost every argument about whether these stones are real is an argument about vocabulary that neither side has noticed is about vocabulary. Chemically the question was settled decades ago. What is still contested is whether the unqualified word diamond belongs only to stones the earth made, and the bodies that write the rules do not agree with one another.For a buyer in Australia the practical version is short. Nobody here can be prosecuted for the word they chose, only for the belief they created. So the question to ask a seller is not whether the stone is real, which invites a speech, but whether it is laboratory-grown or mined, which invites a one-word answer that then has to appear on your invoice and on the grading report.
Who sets the wording, and what each one is worth to a buyer
ISO 18323International terminology standard, 2015
Written to stop the trade arguing about vocabulary. It reserves the bare word diamond for stones formed in the earth, and sets out the permitted descriptions for everything else: laboratory-grown, laboratory-created, synthetic. It prohibits cultured and cultivated outright.This is why a careful seller writes lab-grown diamond in full rather than just diamond. The standard is voluntary, and no Australian law adopts it.US Federal Trade CommissionAmerican advertising regulator
Revised its Jewelry Guides in 2018, striking the word natural out of its definition of a diamond and warning sellers off the word synthetic, on the grounds that ordinary shoppers hear synthetic and understand fake.Two serious bodies reading the same word in opposite directions. Most of the argument you find online is a rerun of this one.Australian Consumer LawWhat actually binds a seller here
Australia has no statute defining the word diamond and no mandatory nomenclature standard. What we have is the prohibition on misleading and deceptive conduct, enforced by the ACCC, which is indifferent to which words were used and interested only in the impression they left.A seller here may call it a lab-grown diamond. They may not let you believe it was mined. Ask for origin in writing on the invoice, and keep it.GIA and IGIThe laboratories that grade the stone
Both grade lab-grown diamonds and both state origin on the face of the report. Most graded stones also carry the report number laser-inscribed on the girdle, readable at 10x, alongside a note that the stone is laboratory-grown.The report settles what you own. Sales copy does not, and neither does a verbal assurance at the counter.ISO 18323:2015, Jewellery: consumer confidence in the diamond industry. The US Federal Trade Commission's 2018 revision of its Jewelry Guides. The Australian Consumer Law, schedule 2 of the Competition and Consumer Act 2010. Nomenclature in this field is still being revised, so treat these as the current position rather than a closed question.
Why people call them fake
People do not usually mean the chemistry. When someone says fake they are generally reaching for one of about seven ideas, and they are worth separating because two of them are sound arguments and the rest fall over on contact.
Every version of the complaint, sorted by how much survivesThe claims are as they arrive in our inbox and appear on Australian wedding forums, grouped by how much of each one holds up once checked.
Notice which tier is which. The objections with substance are about money and rarity, and those are legitimate reasons to buy a natural stone. None of them is a claim about the material, which is why the word fake is the wrong word for the argument people are actually having. If your reason for hesitating sits in the top group, natural is a reasonable answer. If it sits in the bottom group, it is worth knowing before you spend three times as much.There is one more version of the objection, and it is the most honest of them: some people simply want the object to have been rare. That is not irrational and no amount of chemistry answers it. Our guide on choosing between the two is written for the person who feels that pull and wants to weigh it against the money.What survives checking
Two objections, and both are about money and scarcity rather than about what the stone is.“It will be worth almost nothing if we ever sell it”True, and more so than most people expect. Wholesale prices have fallen every year as production capacity grew, so the stone you buy is competing against a cheaper version of itself next year. Buy the ring to keep, not to hold value.
“It is not rare”Correct, and scarcity is precisely what the natural premium buys. If part of what you want to give is a thing that cannot be made again, no lab-grown stone supplies it at any price.
Half right
Claims about how a stone is received rather than what it is made of.“People will be able to tell”Only the ones you tell. Nobody identifies origin by looking, including jewellers, and lab-grown is now an ordinary answer rather than a confession.
“Jewellers say they are not real diamonds”Some do, and it is not a disinterested view: the stone earns them less and never comes back through the door as a trade-in. Ask which test they are relying on and the conversation usually stops.
Simply wrong
Repeated constantly, and untrue on any test a laboratory can run.“It is an expensive cubic zirconia”Different element, different crystal, different everything. Cubic zirconia is zirconium dioxide and it goes dull. A lab-grown diamond is carbon in the diamond lattice and it does not.
“It will cloud or yellow over the years”There is no mechanism for it. Nothing in a kitchen, a gym or a garden attacks diamond. A stone that has gone dull is a stone with hand cream behind it.
“A jeweller will spot it across the counter”No one can, by eye or by loupe. Origin is settled by instruments reading growth structure and photoluminescence, and a handheld diamond tester reads lab-grown and mined identically.
When your own stone looks fake
A different group of people asks this question, and they are the ones we most want to reach: they have already bought the ring, they are wearing it, and something about it reads as costume jewellery. That feeling is real and worth taking seriously. It almost never has anything to do with where the stone was grown.
A ring reads as expensive at conversational distance because of proportion and finish. Almost nobody is close enough to be reading the stone.If you want one diagnostic, take the ring outside on an overcast day and look at it while your hand moves. Diamond returns mostly white light with brief flecks of colour. If what comes back is continuous rainbow, you are probably not looking at a diamond at all, and the stone to suspect is moissanite rather than a lab-grown diamond. That is a testable question, and the next section is how to settle it.
What people report, and what is actually causing itDrawn from the rings customers send us photographs of and ask about. Only one of these four traces back to origin at all, and it does so through what the market stocks rather than through anything in the crystal.
“It looks too big to be real”
Far and away the most common reason, and it is arithmetic rather than gemmology. The same budget buys several times the stone, and your eye is calibrated against the rings of people you know. Two carats on a hand that expected one reads as costume, whatever it is made of.Not origin
Nothing is wrong with the stone. If it keeps bothering you, the answer is a smaller centre in a better setting, not a different origin.
“It looks too white”
The one complaint that does trace back to origin, indirectly. Colourless is cheap to grow, so almost everything on the market is D to F, while most natural stones people own sit lower. A D colour stone beside inherited jewellery can look startlingly bright, especially in yellow gold.Origin
Ask for G or H next time. It reads warmer against gold and against older rings, and it costs less.
“It goes flat and glassy in photographs”
Cut, not origin. Lab-grown rough is cheap enough that plenty of cutters keep weight rather than proportions, so a shallow stone at an attractive price is easy to end up with. A shallow stone leaks light out of the back instead of returning it to you.Not origin
Ask for the cut grade and for a video of that exact stone moving under ordinary indoor light, not a lightbox.
“The whole ring looks cheap”
Money that went into carats came out of the mount. Thin claws, a hollow gallery and a head set low against the finger make any centre stone look pasted on, and the setting is what people see first at conversational distance.Not origin
Resetting a stone you already own into a properly made mount is one of the cheapest transformations in jewellery.
Flawless, and can it chip
Two specific worries come up often enough to answer directly. Can a lab-grown diamond be flawless? Yes. Internally flawless and VVS clarity are considerably more common in lab-grown than in nature, because growth conditions are controlled rather than geological, and this is one reason step cuts like the emerald have become affordable. The stones are not inclusion-free by default: HPHT growth can leave metallic flux specks and CVD can leave pinpoints. They are graded for clarity the same way and by the same laboratories.Can it crack or chip? Yes, exactly as often as a natural diamond can, which is rarely but not never. Hardness and toughness are different properties. Diamond is the hardest material there is, meaning almost nothing scratches it, and it also has four cleavage planes, meaning a sharp knock on the girdle at the wrong angle can take a piece off. That is a fact about diamond, not about laboratories. Setting style does more for the survival of a stone than origin ever will.
Where the two origins are the same, and where they are not
So are they as good? On every property you can measure, yes. On the two things you cannot measure, scarcity and how the object will be received, they are different, and no amount of argument collapses that difference. Deciding which column matters more to you is the actual decision, and it is a much better use of an afternoon than relitigating the chemistry.Identical, and measurably so
Hardness at 10 on the Mohs scale, and the same four cleavage planes underneath it.
Refractive index, dispersion and every part of how the stone handles light.
The four Cs, graded on the same instruments by the same laboratories.
How it ages. Neither origin clouds, yellows, softens or tires.
What a jeweller can do with it: the same cutting, setting, resizing and repair.
Genuinely different
Resale. There is almost no second-hand market, and new stones keep getting cheaper.
Scarcity. One is finite. The other can be grown again next month.
Price. A comparable natural stone costs several times more, and the gap is still widening.
Paperwork. Grading conventions for lab-grown are being rewritten, so today's report may not read like one issued in five years.
How some people feel about it, which is not nothing when the object is an engagement ring.
Checking a stone you own
People asking how to tell whether a diamond is real are usually asking one of two quite different questions. Is this a diamond at all, or a lookalike? Or: is this diamond mined or grown? The first you can largely settle yourself. The second you cannot, and neither can your jeweller without sending it away.Start with the paperwork, because it is faster and more conclusive than anything you can do with the stone.If there is no report, a jeweller will put a tester on it. Understand what the tester says. A thermal probe separates diamond from cubic zirconia instantly and reads lab-grown and mined identically, because both conduct heat like diamond. Thermal-only testers also read moissanite as diamond, which is why a combination tester adding electrical conductivity is the one to ask for. None of these instruments has any opinion about origin.Ignore the home tests circulating online. The fog test fails because a greasy simulant also clears quickly. The newspaper test only catches flat glass. The float test needs a loose stone, a control and a steadier hand than anyone has when they are worried about their own ring. If it matters, pay a laboratory.The other half of checking is reading the listing before you buy, and the wording is more informative than most people realise.
1Find the report numberPrinted on the report, usually top right. Seven to ten digits, no spaces.
2Look it up on the lab's own siteGIA and IGI both publish a free report lookup. The stone's shape, weight, colour, clarity and cut must match the paper in front of you, digit for digit.
3Read the girdle inscriptionMost graded stones carry the report number laser-etched on the girdle. Ask the jeweller to show it to you at 10x. It should be the same number.
4Check the measurements against the stoneMillimetre dimensions and weight are the hardest things to fake, because they have to match the physical stone. A swapped stone fails here.
What each phrase on a listing actually means
Lab-grown diamondThe wording standards ask for
A diamond. Carbon in the diamond lattice, grown above ground, graded on the same scale as any other diamond. Laboratory-created and laboratory-grown mean the same thing.Synthetic diamondThe older trade term
Also a diamond. The word is technically correct and commercially unhelpful, which is why the FTC discourages it. On a laboratory report it means laboratory-grown.Cultured diamondBorrowed from pearls
Usually a lab-grown diamond described in a word the international standard prohibits. Read it as information about the seller rather than about the stone.Diamond simulantTrade term for a lookalike
Not a diamond. Any material cut to resemble one, most often cubic zirconia, sometimes white sapphire or glass.Diamond hybrid, diamond essenceCoined brand names
Not diamonds. Names built to survive a skim-read, usually attached to a coated or composite simulant. The word diamond is doing no work in either phrase.MoissaniteSilicon carbide
Not a diamond, and honest about it by name. A legitimate stone in its own right at a fraction of even a lab-grown diamond's price, and the one most often confused with lab-grown by people shopping quickly.The plain words are lab-grown diamond. A seller who reaches for a different phrase has a reason, and it is worth a minute of your time to find out what it is.
What we would tell a friend
Lab-grown diamonds are diamonds, and the question of whether to buy one is not a question about authenticity. It is a question about scarcity, about resale you will probably never use, and about how you want to feel telling someone where the stone came from. Those are worth thinking about honestly. The chemistry is not in dispute and has not been for years.
Our view, since it would be evasive not to have oneIf you would be uneasy saying the stone was grown, buy natural and buy smaller. Nobody has ever regretted a well-cut one carat. If that does not trouble you, buy the lab-grown stone, then spend the difference on cut quality and on a mount made properly, because those are the two things anyone will actually see.
And if you have a stone already and cannot settle what it is, that is a solvable problem rather than a thing to live with. A grading report costs a fraction of the ring and ends the question permanently.Not sure what you are looking at?Send us the report, or a photograph of the ring and whatever paperwork came with it. We will tell you what the stone is, whether the report matches it, and what it would cost to have the question settled properly.
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