Are Lab-Grown Diamonds Real Diamonds, the FTC and Gemological Answer

Yes. A lab-grown diamond is a real diamond. Not a substitute, not a visual approximation. A diamond in the full chemical and physical sense, with the same carbon atoms, the same cubic crystal lattice, and the same optical behaviour as anything extracted from the earth.

If you want the broader market context, our analysis of the lab-grown vs natural price spread covers the economics across every major shape. This post stays focused on one question: is a lab-grown diamond a real diamond, and what do science, the FTC, and gemological testing actually confirm?

What the FTC ruled in 2018

The US Federal Trade Commission updated its Jewelry Guides in 2018. The change was specific. The FTC removed the word "natural" from its definition of a diamond.

The previous definition required a diamond to be a "natural mineral." The 2018 update removed that qualifier. The revised definition identifies a diamond as a mineral consisting essentially of pure carbon crystallised in the isometric system. Lab-grown diamonds satisfy that definition completely. The FTC confirmed explicitly that calling a lab-grown stone a "diamond" is accurate, not misleading, provided the seller also discloses the origin.

That disclosure requirement is the operative condition. A commercial listing cannot say "diamond" in isolation for a lab-grown stone. "Lab-grown diamond," "laboratory-created diamond," and "man made diamond" are all acceptable terms under the guides. The qualifier doesn't make the word "diamond" a stretch. It makes the description complete.

The FTC also observed that the word "synthetic" used alone as a descriptor might mislead buyers into thinking the stone is not genuine. That's a notable position: the regulator expressed more concern about sellers understating the authenticity of lab-grown stones than overstating it. The regulatory trajectory has been toward treating lab-grown diamonds as fully legitimate, not toward carving out a lesser category for them.

Every physical test, identical result

Run any standard gemological measurement on a lab-grown diamond and compare it to a natural equivalent. The numbers are the same. Not approximately the same. Identical.

Property	Lab-grown diamond	Natural diamond
Chemical composition	Pure carbon (C)	Pure carbon (C)
Crystal structure	Cubic (isometric)	Cubic (isometric)
Mohs hardness	10	10
Refractive index	2.42	2.42
Dispersion	0.044	0.044
Thermal conductivity	~2,200 W/mK	~2,200 W/mK
Density	3.52 g/cm3	3.52 g/cm3

Mohs 10 is the ceiling. Nothing scores higher. A refractive index of 2.42 is the reason diamonds look the way they do: light bends at that specific angle to produce the brilliance people pay for. Dispersion of 0.044 creates the fire, those coloured flashes from a well-cut stone. Thermal conductivity so high that diamonds feel cold against skin and transfer heat faster than almost any other solid material.

Every one of those values is identical regardless of whether the stone grew over a billion years in the earth's mantle or over a few weeks in a reactor chamber. The physics doesn't care about origin.

This also means that when a jeweller, gemologist, or sophisticated buyer holds a lab-grown diamond and a mined diamond side by side, there is nothing visible, tactile, or instrumentally detectable with standard retail equipment that distinguishes one from the other. The two stones are the same material.

Simulants are a separate category

Cubic zirconia and moissanite are not lab-grown diamonds. Both are diamond simulants: materials that visually resemble diamonds but fail the physical tests that a diamond passes.

Cubic zirconia (ZrO2) has a Mohs hardness of 8 to 8.5, not 10. Its refractive index falls between 2.15 and 2.18, not 2.42. Its thermal conductivity is a fraction of diamond's. A basic thermal conductivity probe, standard equipment in any jewellery store, distinguishes CZ from diamond in seconds. Lab-grown diamonds pass that test exactly as mined diamonds do. CZ does not.

Moissanite (silicon carbide, SiC) is a closer visual match but still physically distinct. Its refractive index of 2.65 to 2.69 is actually higher than diamond's, creating a subtly different optical appearance. Moissanite is doubly refractive: it splits incoming light into two rays, where diamond is singly refractive. Under magnification, this produces a characteristic doubling of facet junctions that any trained gemologist identifies immediately. Our moissanite vs lab-grown diamond comparison covers those differences in detail if you're weighing those options.

A lab-grown diamond passes every test a mined diamond passes. That simply isn't true of simulants. The category confusion is common, but it's also completely avoidable once you understand what each material actually is.

How grading laboratories identify origin

If lab-grown diamonds are chemically identical to mined diamonds, how does a grading lab tell which is which? Identical composition doesn't mean identical formation history, and that history leaves measurable physical signatures.

Two methods dominate laboratory screening.

Photoluminescence spectroscopy exposes a stone to a specific wavelength of laser light and reads the resulting fluorescence pattern. Diamonds grown via CVD (Chemical Vapour Deposition) show a characteristic emission peak at 737 nanometres, produced by silicon vacancy centres that form during the growth process. This spectral signature appears frequently in CVD stones and rarely in natural diamonds. GIA's iD100 instrument screens stones using this principle and produces a preliminary result in seconds. A positive screen prompts further analysis; it isn't a full grading determination, but it reliably flags origin for review.

Are CVD diamonds real? Yes, by exactly the same logic that applies to any other lab-grown stone. CVD is a growth method. The stone that emerges is still pure carbon in cubic crystal form, still Mohs 10, still a diamond by every definition the FTC and the gemological community apply.

The second detection tool is diamond type classification. Diamonds are categorised by nitrogen and boron content into Types Ia, Ib, IIa, and IIb. Around 98% of natural diamonds are Type Ia, containing nitrogen aggregated into clusters through long geological processes. CVD grown diamonds are typically Type IIa, meaning very low nitrogen. Type IIa stones do occur naturally, but they're rare: somewhere between 1 and 2% of all natural diamonds. A parcel of matched specification stones skewing heavily toward Type IIa is a reliable origin indicator.

HPHT grown diamonds (produced by high pressure, high temperature processes) carry different signatures: metallic flux inclusions from the growth medium, distinct strain patterns under polarised light, and sector zoning visible under ultraviolet illumination. Our CVD vs HPHT post covers what each growth process produces and why those physical differences exist.

None of these signatures affect performance. A Type IIa stone cuts, polishes, and wears identically to any other diamond. Detection methods exist for disclosure and certification purposes, not because lab-grown stones are lesser material.

The price spread is real, and the stone still is too

Lab-grown diamonds are chemically identical to natural diamonds and cost dramatically less. Across our index of active listings from more than 110 retailers, the median lab-grown round sells at $329 per carat against $1,980 per carat for a natural round. That's an 83.4% discount on the same material.

Shape	Natural $/ct	Lab-grown $/ct	Discount
Round	$1,980	$329	83.4%
Oval	$2,270	$378	83.3%
Cushion	$2,683	$449	83.3%
Emerald	$1,997	$368	81.6%
Radiant	$2,555	$438	82.9%
Baguette	$2,801	$291	89.6%

The baguette figure stands out. An 89.6% discount on a specialist cut with lower lab-grown supply relative to natural is notable. Even in categories where lab-grown production is thinner, the price gap against natural remains overwhelming.

The spread reflects one variable: rarity. Natural diamonds are scarce because geology made them scarce over billions of years. Lab-grown diamonds aren't scarce because modern production infrastructure can produce more of them. The physical result at the end of either process is identical. The economics of getting there are not.

What every reputable listing must state

Disclosure isn't optional and hasn't been since the FTC clarified its position. Every major grading laboratory enforces this on every certificate it issues. An IGI grading report for a lab-grown diamond states "laboratory-grown diamond" on the face of the document. GIA reports carry the same qualifier. There is no graded lab-grown stone without its origin stated explicitly.

Retailers in our index comply with this standard. If you encounter a listing elsewhere describing a stone as a "diamond" at a surprisingly low price with no origin qualifier, treat that as a warning. Either the seller is operating outside FTC guidance, or the stone is a simulant being described deceptively.

For buyers weighing what this means for future value, lab-grown and natural diamonds behave very differently in secondary markets. Our lab-grown diamond resale value post addresses that directly before you commit to a decision.

The question the chemistry can't settle

Every gemological test confirms lab-grown diamonds are real. What chemistry cannot tell you is whether geological rarity is something you're buying.

Some buyers want a stone that the earth spent a billion years creating. That's a coherent preference, and natural diamonds carry a premium because of it. Other buyers want the best stone their budget allows and aren't paying for geology. Lab-grown diamonds serve that second preference as well as anything on the market.

Both buyers get a real diamond. The distinction is origin and the supply economics that follow from it. The chemistry is not in question, and it hasn't been since 2018.