Three materials that get called the same word
In casual conversation everything white and sparkly is "a diamond." In practice the market offers three materials that behave very differently, and the price gap between them is not a quality gradient — it is three different substances.
Lab-grown diamond is diamond. Carbon in the diamond cubic lattice, identical hardness, identical thermal conductivity, identical refractive index. It is made rather than mined, which is a difference in origin and nothing else.
Moissanite is silicon carbide. A real and durable gemstone in its own right, with optics that differ noticeably from diamond, sold honestly under its own name by most vendors.
Cubic zirconia is zirconium dioxide in cubic crystal form. It is inexpensive, it is attractive for the first few months, and it does not survive daily wear in a ring.
None of the three is fake. Each is what it is. The problems come from one being presented as another, and from buyers choosing based on price without knowing what they bought.
How a lab diamond is actually made
There are two commercial routes, and they leave different signatures.
HPHT reproduces the conditions under which diamond forms in the earth: roughly 5–6 gigapascals of pressure and temperatures in the 1300–1600 °C range, applied to a carbon source with a metal solvent. It is fast relative to geological time and relatively efficient. Typical traces can include metallic flux inclusions — occasional tiny dark particles — and in some stones a measurable response to a magnet.
CVD grows diamond from a carbon-bearing gas, usually methane diluted in hydrogen, in a low-pressure chamber energised into plasma. Carbon deposits layer by layer onto a seed plate. CVD is easier to scale in area and can produce high clarity, but early material was often brown and had to be treated afterwards; modern processes produce genuinely colourless stones directly. The telling characteristics tend toward different growth stratigraphy and strain patterns, which is why identification relies on spectroscopy rather than visible inspection.
Both processes yield diamond. A jeweller's thermal probe cannot tell either from a mined stone, because there is nothing to detect — thermal conductivity is a property of the material, not its origin. Distinguishing lab-grown from natural requires laboratory equipment looking at growth features, fluorescence patterns and phosphorescence.
Reports, inscriptions and why both matter
A report from IGI, GIA, GCAL or a comparable laboratory will state plainly laboratory-grown or lab-created, along with the 4Cs. There is no ambiguity in the wording of a proper report.
There is a second checkpoint that people skip: the girdle inscription. Reputable lab-grown diamonds carry a laser inscription on the girdle — typically the report number plus "LABORATORY GROWN." A ten-times loupe will show it. This is what ties the physical stone to the paper, and it is worth checking that they match. If a stone is offered with a report but no inscription, you are trusting the pairing rather than verifying it.
Be more careful with the phrase "certified" when no issuing laboratory is named. A "certificate" printed by the seller, without a report number you can check against the issuer's own database, verifies nothing.
Moissanite: not a substitute, a different stone
Moissanite deserves to be evaluated on its merits, because for many buyers it is genuinely the better purchase.
Its refractive index is around 2.65 against diamond's 2.42, and its dispersion is roughly double. The practical consequence is that it produces more fire than a diamond — more visible rainbow flashes, in a way that reads as slightly different rather than better or worse. Look at it under daylight or a downlight and the effect is obvious once you know what you are seeing.
It is also doubly refractive, meaning light splits into two paths inside the stone. Through the table you can often see doubling along the facet edges — each back facet appearing as two parallel lines. To many untrained eyes the extra fire reads as "sparkly" rather than wrong; the doubling is the more reliable giveaway.
Hardness is about 9.25, below diamond but above essentially anything it would encounter in daily life, so it holds a polish well for years.
One trap worth knowing: older thermal-conductivity testers were developed before moissanite was commercial, and moissanite conducts heat too, so a basic diamond tester can pass it as diamond. Testers that also measure electrical conductivity separate the two. This is a reason to deal with vendors who are explicit about material rather than relying on a quick probe result.
Cubic zirconia: fine for the right job, wrong for a daily ring
CZ scores around 8 to 8.5 on the Mohs scale. That sounds close to durable until you consider what actually abrades jewellery: not diamond, but household dust, which is largely quartz at 7. Add skin contact, lotions and fabric, and a CZ's facet edges round off and the surface hazes within months of continuous wear in a ring. It also attracts grease film, so it goes dull between cleanings.
That is not a reason to avoid it. For earrings, occasional-wear pieces, and designs where the stone is large and the price is the point, it does its job. It is the wrong material for something you never take off, and it is the material most often substituted dishonestly.
What each one actually costs now
Prices for lab-grown diamonds have fallen steeply and consistently as CVD capacity expanded. That has two consequences buyers should absorb before paying.
The first is good: you get substantially more stone for the same money than a few years ago.
The second is the one nobody likes hearing: there is effectively no resale market. Whatever you pay is for wearing, not holding. Anyone pricing a lab-grown stone today against what similar stones sold for two years ago will be disappointed, and that is normal for a technology-driven cost curve, not a defect in your purchase.
Moissanite sits at a small fraction of lab-grown diamond pricing and has been relatively stable. CZ is priced essentially as a consumable.
If you are buying something to wear for years, pay for the material whose properties you want and stop thinking about what it will be worth later.
Choosing without getting sold to
A short sequence covers most situations.
First, decide the material explicitly and say it out loud when buying. "Lab-grown diamond," not "diamond"; moissanite, not "diamond alternative." Any hesitation here is the actual warning sign.
Second, for a lab-grown diamond, get a report from a named laboratory and check that the girdle inscription matches it.
Third, match material to how it will be worn. Daily wear on a hand that meets door handles, gym equipment and dishes calls for diamond or moissanite. Occasional wear in protected settings can use anything.
Fourth, set the stone appropriately. Hardness above 9 resists scratching, but all three materials have cleavage-like directions and a sharp girdle can chip under a focused blow. A bezel or well-made prongs with protected corners matter more than the name on the report for anything worn daily.
And fifth, clean it boringly. Warm water, mild soap, a soft brush. Ultrasonic cleaners are fine for undamaged diamond and moissanite, and a bad idea for anything with fractures or filling. Jeweller's torches near a stone during resizing damage fillings and can affect some treated stones — say so before work begins.
The short version
Lab-grown diamond is diamond, and the only honest distinction to make is between it and a mined one. Moissanite is a different, durable, very fiery stone that should be bought under its own name at its own price. Cubic zirconia is a short-life material for occasional wear. They are not three grades of one thing, and paying for one while receiving another is the only real failure mode here.
Maison Elara works with lab-grown diamond rings, lab-grown sapphire rings and freshwater pearl necklaces. See Maison Elara for current pieces and specifications.
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