The Natural vs Lab-Grown Handbook

Picture the bench on a grey Sydney morning. Two stones sit on a folded paper parcel under the daylight lamp, near enough in size and colour that you could swap them behind your back and not know it. One of them spent an unimaginable stretch of geological time under a continent. The other spent a few weeks in a steel chamber, quite possibly in an industrial park, watched over by someone with a clipboard and a shift roster. Tip the parcel and they both throw the same light across the desk.

Somebody always asks the same question at this point, and they always ask it the same way: which one is the real one?

I have learnt to slow down before answering, because the question contains a trap that catches buyers far more often than any dodgy seller does. If a laboratory-grown diamond is put in front of me, the truthful gemmological answer is that it is a real diamond. It is carbon in the same crystal structure, with the same hardness, the same refractive index, the same fire. This is not a concession I make reluctantly to be fair-minded. It is settled to the point of being written into law: when the United States Federal Trade Commission revised its Jewelry Guides in July 2018, it removed the word “natural” from the definition of a diamond, precisely because a man-made diamond is a diamond. Anyone who tells you a lab-grown diamond is fake is either confused or hoping you are.

So the honest answer to “which one is real?” is: both of them. And that answer is useless to the person asking, because it is not what they wanted to know. What they wanted to know was: which one should I buy, what am I actually paying for, and will I feel stupid about this in five years? That is a much better question, and it is the question this handbook exists to answer.

What this book is, and what it is not

I have read a great many natural-versus-lab-grown guides while writing this one, and most of them fail in one of two directions. The bridal-market guides are cheerful and thorough about adoption statistics and utterly silent on money — they will tell you what percentage of couples chose a grown stone last year and never once mention what that stone is worth secondhand. The natural-side guides are correct about detection and coy about their own price cycle, implying that mined stones simply hold value while declining to mention that average natural diamond prices fell hard between 2022 and 2024. Both types are advocacy documents wearing a lab coat.

This one tries something less comfortable. Every date, figure, auction result and regulation in the chapters that follow is sourced and attributed in the prose, so you can go and check me. Where the evidence is contested — and on carbon footprints, on resale retention, on whether lab-grown prices have finished falling, it genuinely is — I have set out both sides rather than picking the one that flatters us. Where a number comes from a trade estimate rather than an audited index, I say so. You should be suspicious of any gem guide that never once admits uncertainty, including this one, so I have tried to earn the benefit of the doubt by spending it sparingly.

Where the Ministry stands, said plainly

You are entitled to know my bias before you read another word, so here it is with no hedging. Ministry of Gems sells only natural, earth-mined stones. We do not stock laboratory-grown material of any kind, in any colour, at any price.

That is a commercial position, not a moral verdict, and I want to be careful about the difference. A laboratory-grown stone, honestly described and fairly priced, is a perfectly legitimate product. It is not a scam, it is not a con, and buying one does not make anybody a fool. Millions of people wear grown stones with complete satisfaction and excellent reason — a clean two-carat centre for the price of a modest holiday is a real proposition, and I will not sneer at it. What I object to is not the stone. It is the silence: the seller who lets you assume, the invoice that says only “diamond”, the antique ring described as period without anybody checking what is actually set in it. In gemstones, as in most things, the sin is never the treatment or the origin. The sin is the withheld sentence.

Our own trade sits on the other side of the line for reasons of family more than ideology. Three generations of us have worked the Ceylon gem fields since the 1960s, and what we know how to do is find, judge and price stones that came out of gravel. Nobody in my family has ever run a growth chamber, and I would be a poor guide to one. What I can do is tell you exactly how those chambers work, exactly how the resulting stones are identified, exactly what has happened to their prices with dates attached, and exactly what a seller is legally obliged to tell you in Australia. Then you can decide. If you decide on a grown stone and buy it well, I will consider this handbook to have done its job.

— Anna, FGAA
Ministry of Gems, Sydney

People imagine gem growing as something futuristic, all clean rooms and white coats. Some of it is. But the trade has been manufacturing gemstones commercially since before the First World War, and the technology divides neatly into two families: fast and cheap, or slow and convincing. Understanding which family a stone came from tells you more about what you are holding than any brand name on the box.

The two diamond routes: the press and the plasma

Diamond is grown two ways, and GIA’s technical description of both is the clearest in the trade. The older route is HPHT — high pressure, high temperature — which does more or less what the name promises. A diamond seed and a carbon source are loaded into a press heated to roughly 1,300 to 1,600 degrees Celsius at pressures above 870,000 psi. A molten metal flux, typically an iron, nickel and cobalt mixture, dissolves the carbon and lets it crystallise onto the seed at a lower temperature than brute conversion of pure carbon would demand. The flux is the trick: it is a solvent that makes an impossible reaction merely difficult.

The newer route is CVD, chemical vapour deposition, and it is more delicate. Flat diamond seed plates go into a vacuum chamber filled with methane and other carbon-bearing gases at roughly 900 to 1,200 degrees Celsius. Plasma energy tears the gas molecules apart and carbon precipitates onto the seed plates, layer upon layer, growing the crystal upwards like sediment in reverse. CVD is why lab-grown diamond production scaled so quickly: the equipment is cheaper than a giant press, the chambers are stackable, and the process is easier to tune.

Here is the part almost no consumer guide mentions. Many CVD diamonds come out of the chamber brownish, and are then given post-growth HPHT treatment — annealing — to improve their colour. GIA is explicit about this. Which means a substantial share of the stones sold as “lab-grown diamonds” are also treated stones: manufactured, then improved. This is not a scandal, and GIA requires the treatment status to be noted on its lab-grown reports precisely because it is material information. But it does puncture the tidy story that grown stones are the pure, honest option and treatment is something that happens to grubby mined material. Treatment happens on both sides of the line. So does the obligation to disclose it, which is a theme you will meet again in this book and in our own treatment register.

The oldest trick in the trade: flame fusion, 1902

Long before anyone grew a diamond, the trade was growing ruby. Auguste Verneuil announced his flame-fusion process for ruby in 1902, and it is still, by volume, the dominant method for making synthetic corundum. Powdered alumina is dropped through an oxyhydrogen flame, melts, and solidifies layer by layer into a carrot-shaped mass called a boule. The whole affair takes hours. Verneuil material remains cheap and plentiful, and it fills the low end of costume jewellery, watch bearings and a great deal of industry.

Reported figures for Verneuil’s own operation — on the order of 1,000 kilograms of synthetic corundum a year by 1907, and around thirty furnaces running by 1910 — should be treated as approximate historical accounts rather than audited production data. The direction, though, is not in doubt: flame-fusion corundum has been an industrial commodity for well over a century. That single fact demolishes one of the most common and most expensive assumptions in the antique jewellery market. “It is old, so it must be natural” is false, and has been false since roughly 1905. Synthetic rubies and sapphires appear in genuinely antique pieces, set by genuinely respectable jewellers, sold entirely legitimately at the time. If you are buying a period ring for the stone, the stone needs testing, and the age of the mount is not evidence of anything.

Slow growth: flux, hydrothermal and the Czochralski pull

The convincing synthetics are the slow ones. Flux growth — used for synthetic ruby, sapphire, emerald and alexandrite, and associated with names like Chatham, Ramaura and Kashan — dissolves nutrients in a molten flux and lets crystals form over periods that can approach a year. Chatham, the best-known branded lab-emerald producer, states that its grown gems take about twelve months using flux, hydrothermal and proprietary processes. That is the producer’s own claim, and worth reading as such, but the order of magnitude is consistent with what the method requires.

Hydrothermal growth is the only way to grow emerald from water solution, and is also used for corundum and quartz. Nutrients dissolve in hot water under pressure in an autoclave over weeks to months, and the crystals that emerge have uniform colour and remarkably natural-looking inclusions. As a class, hydrothermal synthetics are the most convincing coloured stones ever manufactured, and they are the reason a coloured-stone buyer cannot rely on the old comfort that “if it has inclusions, it must be natural”.

Finally there is the Czochralski or pulled-growth method, which draws a growing crystal slowly out of a melt. It is used for synthetic ruby, sapphire and alexandrite, and produces exceptionally clean material — sometimes suspiciously clean, which is its own kind of tell.

Why growth time is the whole price story

Line the methods up by duration and the price ladder within the synthetic category explains itself. Hours in a flame gives you material at the very bottom of the market. Weeks in a plasma chamber gives you a commodity diamond. Months in an autoclave, or a year in a flux crucible, gives you branded coloured stones that cost real money by synthetic standards — a finished Chatham lab-grown emerald solitaire in eighteen-carat gold has been listed around US$1,995 for a 1.15 carat stone, while generic loose hydrothermal emerald trades near US$70 a carat. Same category, wildly different economics.

What none of the methods can manufacture is the one thing the natural market prices above all others: the accident of a particular chemistry in a particular place at a particular moment, never to be repeated. That is not a mystical claim. It is an inventory claim, and Chapter V is where it starts to matter to your wallet.

This is the chapter people arrive for, usually with a specific anxiety: if nobody can tell, does it matter? Or the darker version, whispered: how do I know the thing I already own is what I was told it was?

The answer is genuinely two-layered, and the two layers get deliberately confused by people selling on both sides.

Two true sentences that sound like a contradiction

Sentence one: to the naked eye, and to a jeweller with a loupe, a well-grown laboratory diamond is indistinguishable from a mined one. Lab-grown marketing says this constantly and it is entirely correct.

Sentence two: in a properly equipped gem laboratory, laboratory-grown diamonds are identifiable. The Natural Diamond Council puts this at a hundred per cent of the time, and the well-equipped labs agree: growth structure, fluorescence imaging and spectroscopy separate grown from mined stones reliably.

Both sentences are true. They simply describe different rooms. The fight between them is a marketing fight, not a scientific one, and the useful lesson for a buyer is that certainty has an address. It lives in a laboratory equipped with instruments that cost more than most of the stones they examine. It does not live in a shopping centre, and it does not live in your pocket.

There is one wrinkle worth knowing, because it shows how the arms race actually runs. Post-growth HPHT treatment of CVD diamonds can suppress the tell-tale spectroscopic markers a lab might look for — the silicon-vacancy peak at 737 nanometres, for instance. That sounds alarming until you read the rest of the GIA lab notes, which show that fluorescence imaging still reveals the striated growth pattern characteristic of CVD. The treatment hides one fingerprint and leaves another. This matters commercially, not just academically: GIA’s Hong Kong laboratory once received forty-three undisclosed HPHT-treated CVD stones, from 0.70 to 2.63 carats, from a single client. Somebody was testing the fence, at scale.

Why the diamond tester in the shop says “diamond” — and is right

Every few months somebody tells me their handheld tester “proved” a stone was natural. It proved nothing of the sort, and the fault is not the instrument’s.

A classic thermal diamond tester measures thermal conductivity. Diamond conducts heat extraordinarily well, and the pen beeps when it finds that signature. A laboratory-grown diamond conducts heat exactly as well as a mined one, because it is diamond. The pen beeps. The pen is correct. The pen was never designed to answer the question you were asking; it was designed to separate diamond from cubic zirconia, and at that job it is excellent. It will not separate diamond from moissanite either — moissanite conducts heat almost as well as diamond does, which is why modern testers add an electrical-conductivity probe. Asking it about origin is like asking a set of bathroom scales whether you are happy.

Screening refers. Laboratories identify.

The distinction that no consumer guide seems willing to make is between screening and identification, and it is the single most useful idea in this chapter. A screening device sorts a parcel into “this is natural, pass” and “this needs a real laboratory to look at it”. It is designed never to clear a synthetic by mistake, and it is not designed to conclusively identify anything. The referral is the product.

The numbers from the Diamond Producers Association’s ASSURE testing, published in 2019 and reported by Rapaport and National Jeweler, make the trade-off visible. De Beers’ DiamondView returned zero false positives and a hundred per cent diamond accuracy — but it costs in the region of US$35,000 to $36,000 and needs a trained operator to interpret what it shows. De Beers’ SYNTHdetect also returned zero false positives, with a 4.7 per cent referral rate, meaning roughly one stone in twenty gets sent onward for a proper look. GIA’s iD100, at US$5,495, returned zero false positives and 96.7 per cent diamond accuracy.

Read those figures the right way round. Zero false positives is the important column: none of these instruments will tell you a grown stone is natural. What they will do is hand a percentage of perfectly natural stones to a laboratory for confirmation, which is exactly the correct engineering choice for a screening tool. If a jeweller tells you their in-store device “certified” a stone as natural, they have misunderstood their own equipment.

Melee: where the trade actually gets caught

The undisclosed synthetics scandal in diamonds has never really been about centre stones. It has been about melee — the small accent stones scattered down a shoulder or set in a halo, individually worth very little, collectively worth a great deal, and almost never tested one by one because the cost of testing exceeds the value of the stone.

Two GIA cases became the trade’s permanent cautionary tales. In 2017 the laboratory found 101 CVD synthetics mixed into a parcel of 323 natural melee — 31.3 per cent contamination in a parcel presented as natural. In 2018 a submitted “natural” melee parcel of 1,093 stones turned out to contain 1,092 HPHT synthetics. One stone in that parcel was natural. One.

I quote these not to frighten anybody out of buying jewellery with small stones in it, but to explain why serious houses now buy melee from suppliers who screen it, and why an honest jeweller will tell you plainly whether the accent stones in a piece have been screened or simply assumed. Ask. It is a fair question and it has a one-sentence answer.

Behind all of this sits a quiet piece of infrastructure worth knowing about: the Laboratory Manual Harmonisation Committee, founded in 2001, whose members include GIA, the Gübelin Gem Lab, SSEF, CGL Japan, CISGEM, DSEF and GIT Thailand. The LMHC publishes harmonised information sheets that standardise how the major laboratories word treatments and identifications, so that the same stone described by two labs does not come back in two private languages. When people ask why we send stones to laboratories rather than relying on assertion, this is a large part of the answer — there is a shared vocabulary, and it is written down. Our own gem lexicon exists to translate that vocabulary into English for buyers.

If you take one chapter from this handbook, take this one, because it is the chapter the cheerful guides leave out. What follows is not an argument. It is a series of dated numbers from named sources, and you can reach whatever conclusion you like from them.

The index, with dates attached

Edahn Golan’s lab-grown diamond wholesale price index began tracking in July 2018. By the second quarter of 2026 it was down 96 per cent from that starting point, having fallen a further 13 per cent year-on-year in that quarter alone, though Golan notes the rate of decline is decelerating.

Put a single stone through that. A one-carat lab-grown diamond that wholesaled around US$4,200 in 2018 had fallen to as little as roughly US$168 wholesale by 2025 — the same product, from the same kind of chamber, about 96 per cent cheaper in seven years. Paul Zimnisky, working from a 2015 baseline, puts the fall at 90 to 95 per cent, with a 58 per cent wholesale drop in 2023 alone.

At retail the gap is narrower but still enormous. Into early 2026, a well-cut certified one-carat lab-grown diamond typically retails for around US$700 to $1,500, against roughly US$4,200 to $4,600 for a comparable natural stone. That is a saving of seventy to eighty per cent or better for identical optics, identical hardness, identical chemistry. Anyone who pretends that is not a compelling offer is not being straight with you. The question this chapter asks is a different one: what happens to a product whose wholesale cost fell 96 per cent while its retail price fell far less?

Lightbox: the experiment its inventor closed

De Beers launched Lightbox in 2018 at a flat US$800 per carat — US$200 for a quarter-carat — a deliberately linear price ladder designed to position lab-grown as fashion jewellery rather than as a rival to mined stones. It was, whatever else you think of it, an honest piece of pricing: a flat rate per carat tells you the product is a commodity.

By May 2024 Lightbox had cut prices by 25 to 40 per cent, to roughly US$500 a carat. On 8 May 2025 De Beers announced it would close Lightbox entirely, citing the roughly 90 per cent fall in lab-grown wholesale prices since 2018, and refocus on natural diamonds; the Element Six facility in Oregon now grows diamond for industrial and technology uses. Trade commentary has cited financial statements putting Lightbox’s 2023 loss at US$101.3 million, though that figure rests on a single source and I would not lean on it.

You do not need to like De Beers to find the closure informative. The company with the deepest pockets in the trade, the best distribution, and every commercial reason to make a branded lab-grown line work, looked at the price curve and walked away from it.

The day GIA stopped using the 4Cs

On 2 June 2025 GIA announced that it would stop applying its natural-diamond colour and clarity nomenclature to laboratory-grown stones. From 1 October 2025, GIA’s lab-grown service describes stones only as “premium” or “standard” — or awards no grade at all. GIA’s stated reasoning is that it “will no longer use the nomenclature created for natural diamonds” for a manufactured product, and that more than 95 per cent of lab-growns fall within a very narrow band of high colour and clarity anyway, which makes fine 4C distinctions close to meaningless.

This is contested ground and I will not pretend otherwise. GIA frames the change as honest description. Critics — including lab-grown retailers and some graders — read it as a deliberate demotion designed to protect natural diamond values. Meanwhile IGI continues to grade lab-grown diamonds on the full 4Cs. The practical consequence for a buyer is awkward and worth knowing: the market now runs two incompatible grading regimes for the same product, so a lab-grown stone with an IGI report showing “F VS2” and one with a GIA report showing “premium” cannot be lined up against each other in any straightforward way.

Has it bottomed?

Honestly: nobody knows, and as of August 2026 the evidence points both ways.

For stabilisation: in the second quarter of 2026, wholesale one-carat lab-grown rounds actually rose one per cent year-on-year, and mid-2026 brought the first sustained producer price increases of the era, with Chinese growers raising rough lab-grown prices by at least 30 per cent and Diamond Foundry by around 25 per cent. Roughly 40 per cent of lab-grown producers exited the market across 2023 and 2024, and manufacturers cut output by about 35 per cent in late 2024 — a classic supply-side shakeout that usually precedes a floor.

Against: two-carat wholesale stones still fell 20 per cent year-on-year in that same quarter, and the 1.5 to 1.99 carat band fell 11 per cent. Trade estimates put the hard production-cost floor at around US$100 to $150 a carat for cutting and polishing alone, which leaves considerable room for retail prices to keep eroding. India’s export figures tell the same story from the cutting hub: polished lab-grown exports fell 13.79 per cent in FY24 to US$1.40 billion from US$1.68 billion, the average export price of polished lab-growns dropped below US$74 a carat by 2025, and May 2025 polished exports fell 32.76 per cent year-on-year.

And here is the strangest part, which cuts against the simple “lab-grown is dying” narrative you may have heard. Demand has not collapsed at all. United States specialty retailers’ lab-grown jewellery unit sales rose 24 per cent in the second quarter of 2026. People are buying more pieces than ever; they simply refuse to spend more per piece. Tenoris data shows average US engagement-ring spend falling from US$5,200 in 2024 to US$4,600 in 2025. That is a market discovering, in real time, that a product it loves is a consumable rather than an heirloom. Which is fine — most of what we own is a consumable — provided nobody sold it to you as the other thing.

Let me put the disclaimer at the top rather than burying it at the bottom, because it governs everything in this chapter. Nothing here is investment advice. I am a gemmologist, not a financial adviser, and I am not licensed to tell anybody what to buy in order to make money. What I can do is report what stones have actually sold for, with dates and sources, and let you draw conclusions about the thing you are considering buying. Gemstones of every kind — grown or mined, common or rare — should be bought because you want to wear them. Anyone who sells you a stone as a financial product is selling you something other than a stone.

What lab-grown recovers

The reported range for lab-grown diamond resale is 10 to 40 per cent of the original retail price, where a buyer can be found at all. The top of that range comes from Labrilliante, a lab-grown wholesaler claiming 30 to 40 per cent retention — a figure worth noting precisely because it comes from a source with every commercial reason to state the highest defensible number. The bottom of the range comes from estate buyers and jewellers who report essentially no secondary demand.

More telling than any percentage is what a number of jewellers now do rather than say. Buchroeders Jewelers, for example, excludes lab-grown stones from purchase entirely and from its dollar-for-dollar upgrade programme. When a retailer declines to buy back the thing it sells, that is a pricing signal expressed as policy.

In Australia, the Jewellers Association of Australia has warned consumers that synthetic diamonds have “negligible resale value” and must not be marketed as investment stones — a warning reported by ABC News in December 2025. That is the domestic trade body, on the record, about a product many of its members sell.

The verifiable core beneath the competing marketing claims is narrow but solid: there is no auction market for lab-grown diamonds, there is no trade-in parity, and recovery is a double-digit percentage of retail at best. If you buy a grown stone, buy it as jewellery you intend to keep and enjoy, and price the pleasure rather than the exit.

The auction door, closed

The auction houses have been unusually blunt about this. Christie’s has said that for the foreseeable future it will not offer lab-grown stones in its sales, and Sotheby’s has been equally direct about not seeing them as part of its sales at any point in the future. Both positions were given to JCK and both remain the houses’ practice.

This matters more than it might appear. Auction houses are not making an aesthetic judgement; they are making an inventory judgement. Their business depends on scarcity and on the confidence that the object in the catalogue cannot simply be manufactured again next quarter. A product that can be reordered has no place in a market built on the opposite premise.

Natural is scarcer, not immune

Now the part that natural-side guides skip, and the part I would rather you heard from us than discovered on your own.

Natural diamonds fell too. The average one-carat natural diamond price peaked at roughly US$6,819 in May 2022 and had fallen to about US$4,997 by December 2024 — a 26 per cent decline. The Zimnisky Global Rough Diamond Price Index sat roughly 40 per cent below its all-time high after falling around 15 per cent in 2023 and 18 per cent in 2024, before stabilising and edging up two to three per cent in early 2025.

So the sentence “natural holds its value” is not one I will write, because for commodity-grade natural stones it is not reliably true. The defensible version is narrower and duller: rare natural material — unheated, fine origin, fancy colour, exceptional size — has a functioning secondary market, and commodity-grade natural material is not an investment either. If a seller tells you a mid-grade stone is a store of value, treat that as a marketing claim rather than a fact.

Where a real secondary market still exists

At the top end, the market behaves very differently, and the evidence is public.

On 27 May 2025, a 35.09 carat unheated Kashmir sapphire known as The Regent Kashmir sold at Christie’s Hong Kong for US$9.5 million — US$271,515 per carat — a world-record price per carat for any sapphire, beating the US$243,703 per carat set by the Jewel of Kashmir in 2015. Ten years between records, in a category where nobody can grow another Kashmir deposit.

Supply on the natural side is genuinely contracting, and the dates are specific. The Argyle mine in Western Australia ceased mining on 3 November 2020 after producing 865 million carats since 1983 and supplying roughly 90 per cent of the world’s pink diamonds. Dealer-tracked indices — trade data, not an exchange index, and I flag that deliberately — recorded fancy pinks rising about 23 per cent, fancy intense pinks about 29 per cent and fancy vivid pinks about 39 per cent in the year after closure. Global rough production was forecast at around 107 million carats in 2024, the lowest since 1995, against roughly 152 million carats at the 2017 peak, with essentially no major new mines in the pipeline outside Angola. Rio Tinto’s Diavik mine in Canada, which produced over 150 million carats since 2003, ceased mining on 26 March 2026.

Closer to our own bench: traditional Ratnapura and Elahera workings in Ceylon yield fewer unheated stones each year, with trade reports putting supply from traditional mines down around 20 per cent since 2021, and unheated Ceylon stones commanding two to five times the price of comparable heated stones — dealer estimates rather than an index, but consistent with what we pay at the source. Sri Lanka’s declared gem, diamond and jewellery exports were US$381.9 million in 2024, down more than 23 per cent from around US$500 million in 2023, with an estimated billion dollars and more moving through undeclared channels, which is a reminder that official figures understate this trade rather than overstate it.

I set all of that out because it is true and sourced, and then I want to immediately undercut the conclusion you might be tempted to draw from it. Scarcity data is not a forecast. None of this is investment advice, and I am not licensed to give any. Buy an unheated sapphire because you have looked into it and cannot put it down. If it also happens to sit in a category with a functioning resale market, treat that as a consolation rather than a plan.

Almost every guide to this subject is a guide to diamonds wearing a general title. That is a real gap, and it matters, because the coloured-stone market ran the same experiment as the diamond market a hundred years earlier and got a completely different result.

Why colour never had a 2018

Laboratory-grown corundum has been available in commercial quantities since before the First World War. If cheap synthetics were going to destroy natural gemstone prices, sapphire and ruby had over a century in which to be destroyed. It did not happen. Synthetics and naturals have simply coexisted, in different aisles, at different prices, serving different buyers.

The price gap is startling once you see it side by side. Lab-created corundum retails at roughly US$10 to $50 per carat — flame-fusion material at the bottom, branded flux and hydrothermal material like Chatham considerably higher — against fine natural sapphire at roughly US$200 to $2,000 per carat and exceptional stones above US$10,000. That is a gap of twenty to a hundred times, far wider than the diamond gap has ever been.

Why? Partly because coloured-stone buyers were never sold a single-variable product. Diamond marketing spent generations teaching the world that a diamond is a diamond is a diamond, defined by four measurable Cs, which is exactly the kind of product a factory can replicate. Colour resists that flattening. Two sapphires of the same weight, clarity grade and nominal hue can carry very different prices because one of them has a particular quality of light in it that no grading sheet captures. When the product is fundamentally about the individual stone, mass production has nothing to compete with.

Meanwhile colour has been gaining ground on its own merits rather than as a budget substitute. Sapphire was the most popular non-diamond engagement centre stone in recent United States survey data, at 23 per cent. People are choosing colour because they want colour.

The easy identifications

The good news for coloured-stone buyers is that the cheapest and most common synthetics are also the easiest to catch, and a trained gemmologist with a microscope needs about ninety seconds.

Classic Verneuil flame-fusion corundum shows curved growth striae — curved bands of colour, like the lines in a boiled sweet — along with gas bubbles. Natural corundum grows with straight, angular zoning following the crystal’s own geometry. Curved lines in corundum are not a subtle hint; they are a signature no natural stone produces. Gas bubbles, likewise, are a melt feature. This is bread-and-butter identification, taught in every gemmology course, and it disposes of the vast majority of synthetic corundum in circulation.

The hard ones

And then there are the stones that keep laboratories honest.

Flux-grown synthetic ruby is the genuinely difficult case in coloured stones. GIA’s Summer 2024 lab note documents a Ramaura flux synthetic ruby displaying what the laboratory itself called natural-looking angular milky clouds, wispy veils and negative crystals — features that a less careful eye could read as natural feathers. Lotus Gemology in Bangkok has published on a heated flux-grown synthetic ruby whose inclusion scene resembled neither typical natural ruby nor common flame-fusion synthetics; identifying it required reference collections and inclusion databases rather than a single diagnostic feature.

Hydrothermal synthetic emerald is the other serious challenge, and the identification criteria are correspondingly specific: chevron or zig-zag growth zoning, nailhead spicules — cone-shaped voids with a tiny crystal at the head — and diagnostic infrared absorption features in the water-band region between roughly 2,500 and 3,100 wavenumbers. That last one is not a loupe observation. It is a spectrometer observation, which is the honest point of this section: for slow-grown coloured synthetics, the answer often lives in an instrument rather than an eye.

I include all this not to alarm you but to explain why we insist on laboratory reports for significant coloured stones, and why “my jeweller looked at it and said it was fine” is a weaker assurance than it sounds. It may well be fine. But for flux ruby and hydrothermal emerald in particular, a confident glance is not evidence.

The antique trap, and the branded premium

Two practical traps close this chapter.

The first is the one I flagged in Chapter II and will now say more bluntly, because it costs Australian buyers real money at estate sales and online auctions every week. Flame-fusion synthetic corundum has been in commercial circulation since around 1905. It was set, in period, by respectable jewellers, into genuinely antique mounts, and sold entirely lawfully. Therefore the age of a ring tells you precisely nothing about the origin of the stone in it. “It has been in the family for eighty years” is a lovely provenance story and not a gemmological argument. If you are paying for the stone, test the stone. Our treatment register exists partly because inherited pieces arrive at our bench with confident family histories and surprising contents.

The second trap is inside the synthetic category itself. There is a large premium for branded lab material over generic lab material: a 1.15 carat Chatham lab-grown emerald solitaire in eighteen-carat gold has been offered around US$1,995 as finished jewellery, while loose generic hydrothermal emerald sells for something near US$70 a carat. Some of that premium buys real things — consistency, a known grower, a longer and better-controlled growth process. But if you are buying lab-grown on the logic that it is the rational, unsentimental choice, it is worth noticing when brand sentiment has been quietly reintroduced at the top of the price list.

Estimates of the overall synthetic gemstone market — on the order of US$23.4 billion in 2024 rising to roughly US$24.5 billion in 2025, across all uses including industrial crystal — come from market-research firms of varying rigour and should be read as order-of-magnitude only. I include the figure because people ask for it, and I flag its softness because it deserves flagging.

This is the chapter where I am most likely to annoy everybody, which I take as a sign it is worth writing. The ethics debate around gemstones is conducted almost entirely in cartoons: rapacious mining versus clean technology, or authentic earth versus factory fakery. Neither cartoon survives contact with the evidence.

The Kimberley Process gap is real

Start with the strongest argument on the lab-grown side, stated as its advocates would state it, because it deserves that respect.

The Kimberley Process defines conflict diamonds narrowly: rough diamonds used by rebel movements to finance wars against legitimate governments. Global Witness and the International Peace Institute have both documented what that definition leaves out — state-sponsored abuses, labour rights, environmental damage, and cut and polished stones altogether. A stone can be entirely Kimberley Process compliant and still carry a history you would not want to wear.

So “KP-certified” is not a full ethics guarantee, and anybody in my trade who waves that certificate as though it settles the question is overselling it. This gap is a legitimate, evidence-based reason for a buyer to prefer a stone whose entire history fits inside a documented industrial process. I do not think that reasoning is naive. I think it is a reasonable response to a real deficiency.

And Botswana is also real

Now the counterweight, which the lab-grown case tends to skip.

Natural stones underpin actual economies. Diamonds account for roughly 30 per cent of Botswana’s GDP, around 80 per cent of its exports and about a third of its fiscal revenue. That is schools, hospitals and public servants’ salaries, funded by a mining industry. “Mining only causes harm” is not a serious position when a national budget is built on it.

Closer to my own family’s work: Ceylon’s gem fields are largely small-scale and artisanal, worked by people whose livelihoods depend on buyers continuing to want what comes out of the gravel. Sri Lanka’s declared gem, diamond and jewellery exports were US$381.9 million in 2024, with an estimated billion dollars and more moving outside declared channels. Whatever you think about the industry’s formality, a very large number of households sit inside those figures. A wholesale shift of demand from mined to manufactured stones is not a costless act of conscience; it moves income from one group of people to another. That is not an argument against it. It is an argument against pretending the choice is free.

The carbon argument, in both directions

Here the evidence is genuinely contested, and I am going to lay out both sides and then decline to give you a verdict, because I do not have one that would survive scrutiny.

The most-cited figure against lab-grown is a Trucost estimate putting lab-grown emissions at around 511 kilograms of CO2 per polished carat against roughly 160 kilograms for mined. That study was commissioned by the Diamond Producers Association — the natural side — which is exactly the kind of fact that should be printed next to the number every time it is used. The study dates from 2019, in a sector whose energy mix has moved since.

The structural point behind it, though, is harder to dismiss: industry analyses note that the majority of lab-grown diamonds are grown in regions with coal-heavy electricity grids, principally China and India, and growth is an energy-intensive process. A stone grown on coal power is not an environmental improvement on anything.

But the reverse case is equally real. Verified-sustainable lab production genuinely exists. The SCS-007 Sustainability Rated Diamond standard from SCS Global Services requires verified climate-neutral production and audited energy sourcing, and SCS reports that ALTR was the first lab-grown producer certified to it, with a sustainability score of 100. A renewable-powered grower can beat mined footprints by a wide margin. The variable that decides the answer is not the growth chamber. It is the power station behind it, stone by stone and factory by factory.

Which is presumably why the regulator has swung at unqualified claims. On 2 April 2019 the FTC sent warning letters to eight jewellery marketers, partly over unqualified “eco-friendly”, “eco-conscious” and “sustainable” claims for lab-grown diamonds, which it said were highly unlikely to be substantiable across all reasonable interpretations. Those letters have never been rescinded.

What I would actually ask

If the environmental question is the one driving your decision, the useful move is to stop arguing about categories and start asking about specifics. For a grown stone: where was it grown, on what grid, and is there third-party certification of the energy sourcing rather than a claim on a website? For a mined stone: who mined it, in what kind of operation, and can the seller tell you anything about the mine and the hands the stone passed through?

Most sellers on both sides will not be able to answer. That is the actual finding. Nobody in this fight has clean hands, and the honest position for a buyer is scepticism applied evenly rather than scepticism applied to the side you were already inclined against.

Disclosure is where this whole subject stops being philosophical. A grown stone honestly labelled is a product. The same stone unlabelled is a fraud. The line between them is drawn by rules that most buyers have never read, so here they are.

The United States: the FTC Jewelry Guides

The revised FTC Jewelry Guides were issued on 24 July 2018 and published in the Federal Register on 16 August 2018. Three changes matter to a buyer.

First, the FTC removed the word “natural” from the definition of a diamond — the change I opened this book with. Second, it requires that a lab-grown diamond’s man-made origin be disclosed clearly and conspicuously, immediately preceding the word “diamond”, using terms such as “laboratory-grown”, “laboratory-created” or “[manufacturer]-created”. The placement rule is the clever part: the qualifier must sit next to the word it qualifies, so a seller cannot put “diamond” in the headline and “lab-grown” three lines down in grey six-point type. Third, it removed “synthetic” from its recommended qualifier list while still permitting the word, and barred sellers from using “synthetic” to imply that a competitor’s lab-grown diamond is fake.

Those guides govern American advertising, not Australian, but they set the global tone for how these products are described online — and most Australians shop in an online market that is substantially American.

The trade standard, and the reversal coming in September 2026

Alongside the regulator sits the trade’s own rulebook. The CIBJO Diamond Blue Book, aligned with ISO 18323:2015 on consumer confidence in the diamond industry, is the de facto global standard. In the 2024 edition, the only authorised qualifiers for man-made diamond are “synthetic”, “laboratory-grown” and “laboratory-created”. Abbreviations such as “lab-grown” and “lab-created” are not sanctioned. “Cultured diamond” is prohibited, as is calling a synthetic stone “real” or “genuine”. Origin must be disclosed unambiguously at every point of sale. A Diamond Terminology Guideline built on the same foundations was issued jointly by nine industry bodies, CIBJO, the WFDB, the DPA and IDMA among them.

And now the collision. At and around its 2025 Congress, CIBJO moved to repeal “laboratory-grown” and “laboratory-created” from the Blue Book and revert to “synthetic” as the unambiguous term, with the change slated to take effect in the Blue Book from September 2026. That runs directly against FTC-era American practice, in which “lab-grown” is the standard commercial term and “synthetic” was deliberately de-emphasised.

My advice to a buyer caught in the crossfire is deflating: all three terms describe the same object. Synthetic, laboratory-grown and laboratory-created are one product. The argument is about connotation, not chemistry, and you should not read a seller’s word choice as a statement about quality in either direction. Read the growth method and the treatment line instead.

Australia: the Consumer Law and the ACCC

Under the Australian Consumer Law, selling a lab-created stone as natural is misleading or deceptive conduct, full stop.

The ACCC’s guidance to the jewellery industry adds usable detail. “Laboratory created” is unlikely to mislead. Trade names can mislead, however, where they imply natural origin — the ACCC’s own example is “Biron Emerald” — and describing a cubic zirconia as any kind of “diamond” risks breaching the Act. That trade-name point is worth carrying into a showroom: a proprietary-sounding name is not a disclosure, and if the only origin word on the ticket is a brand, ask the plain question.

The ACCC does enforce against jewellery sellers. In July 2008 the Federal Court in Brisbane fined Carrerabenz Diamond Industries Pty Ltd A$220,000 on 27 charges for advertising diamonds against fake inflated “usual” prices 42 to 233 per cent above reality, with the court describing two-price jewellery advertising in terms of criminal conduct warranting deterrence. That case was about pricing rather than synthetics, but the principle transfers cleanly: in this industry, the representation is the offence.

One practical note on remedies, scoped carefully because the scope matters. Consumer guarantees under the Australian Consumer Law apply to consumer purchases, and they cannot be contracted away by a term in a receipt. If a stone is not as described, that is a consumer-law matter and not merely a matter of a shop’s goodwill. Business-to-business and investment-style transactions sit under different rules, so if you are buying in a trade capacity, take your own advice.

AUSTRAC: the obligations that arrived in 2026

The newest change affects us directly. Under Australia’s Tranche 2 anti-money-laundering and counter-terrorism-financing reforms, dealers in precious metals and stones became regulated entities: enrolment by 31 March 2026, full compliance from 1 July 2026. The trigger is accepting physical currency, or virtual assets, of A$10,000 or more in a transaction. The obligations include an AML/CTF program, customer due diligence, sanctions screening, suspicious matter reporting and seven-year record keeping.

For a buyer, the visible consequence is simple: a gem dealer asking for identification on a substantial cash purchase is not being nosy, and a dealer who cheerfully takes a large cash sum with no questions asked in the second half of 2026 is telling you something about how they run the rest of their business.

Finally, a disclosure point specific to grown stones that most people miss. GIA requires growth-method and treatment disclosure on its lab-grown reports, noting whether a CVD stone shows indications of post-growth treatment. Treatment status is material information within the lab-grown category too. If you are buying a grown stone, the report should tell you not just that it was made, but how, and what happened to it afterwards.

Everything above was context. This is the part to screenshot and take shopping.

The four questions, in order

One: is this stone natural or laboratory-grown? Ask it exactly like that, and ask for the answer in writing on the invoice rather than in conversation. A good seller answers in four words without flinching. Hesitation, a pivot to how beautiful the stone is, or a brand name offered in place of an origin word are all the same answer, and it is not a good one.

Two: how was it grown, or where was it mined? For a grown stone, HPHT or CVD for diamond; flame fusion, flux, hydrothermal, Czochralski for coloured. For a mined stone, the country at minimum and the field if the seller genuinely knows. Be sceptical of origin claims that arrive with more confidence than evidence — origin determination for coloured stones is a laboratory discipline, not a matter of opinion.

Three: what was done to it after it formed or grew? This is the treatment question, and it applies to both categories. Heat, flux healing, fracture filling, diffusion and irradiation on the natural side; post-growth HPHT annealing of CVD diamond on the grown side. Treatments are entirely legitimate when they are disclosed and priced accordingly. Non-disclosure is the only actual sin here, and it is the one that costs buyers money.

Four: who says so, and on what document? A report from a recognised laboratory, with a date and a number you can verify with the issuing lab. Check that the report describes the stone in front of you — weight and measurements should match. And check the date: reports issued before a stone was recut or reset describe a stone that no longer exists in that form.

If you are buying laboratory-grown

Buy it as jewellery, not as an asset. That is the whole strategy, and Chapter V is why.

Beyond that: get the growth method and any post-growth treatment on the report, not just the word “lab-grown”. Understand that a GIA report saying “premium” and an IGI report showing full 4Cs are not comparable documents, so compare like with like or not at all. Do not pay a natural-adjacent premium for a manufactured product on the strength of a brand story. And do not let anyone sell you a grown stone as an investment — the Jewellers Association of Australia has been explicit that they must not be marketed that way.

If you buy well on those terms, you will get an enormous amount of visible stone for your money and there is no reason on earth to feel defensive about it.

If you are buying natural

Buy the individual stone, not the category. “Natural” is not a quality grade; there is a very great deal of dull, poorly cut, heavily treated natural material in the market, and a well-made grown stone beats it comprehensively on looks and on price.

What natural buys, when you buy it carefully, is a specific object that cannot be reordered — and, in the rare categories, a functioning secondary market. Notice that both halves of that sentence depend on rarity rather than on the word “natural”. Insist on treatment disclosure in writing. For anything significant, insist on a laboratory report. And if unheated material is what you are after, understand what the premium is for: our unheated sapphires and the wider Ceylon and Australian collections exist precisely so the comparison can be made stone by stone rather than in the abstract.

What we do, and what we do not do

Ministry of Gems sells only natural, earth-mined stones. We do not sell laboratory-grown material in any category. That is a positioning decision rooted in three generations of family work in the Ceylon gem fields since the 1960s, and it is not a claim that the other product is illegitimate.

Every stone we sell is assessed in-house by our FGAA-qualified gemmologist — that is me — and carries full treatment disclosure in writing, whether the answer is flattering or not. Each stone receives a Digital Gemstone Passport recording what it is, what was done to it and what we know about where it came from; you can see how that works on our gemstone passport page. We offer free lifetime re-authentication, which in plain terms means you can send a stone back to us at any point in the future and we will re-examine it and confirm what it is, without charge, for as long as we are trading.

If you want to test any of this, the fastest route is to ask a hard question and see how quickly a plain answer comes back. Talk to our gemmologist — bring the awkward one.