Last Updated: April 2026
TL;DR:
- Lab-grown and natural diamonds both score a 10 on the Mohs hardness scale — the highest rating that exists. Chemically and structurally, both are 100% crystallized carbon, and hardness is a property of that crystal structure, not where the stone was formed.
- The old claim that synthetic diamonds only reach 9.6 or 8.8 is outdated. Early HPHT batches from the 1980s-90s sometimes had structural flaws that softened the effective hardness, but today’s GIA-graded lab diamonds test identically to mined stones.
- Where the two types actually differ is price (lab diamonds run 60-85% cheaper), origin story, and resale value — not scratch resistance or durability.
I’ve cut, set, and graded thousands of stones for jewelry brands over the past two decades, and the question I get most from customers holding a lab-grown diamond ring is some version of “is this thing actually as tough as the real one?” The short answer is yes — synthetic diamonds are just as hard as real diamonds, both landing at 10 on the Mohs scale. If you’re comparing durability against a cubic zirconia stone or wondering how either type holds up to daily wear, the physics behind hardness explains everything.
What Exactly Is a Synthetic Diamond?
A synthetic diamond, also called a lab-grown diamond, is real crystallized carbon grown in a controlled lab environment instead of underground. It shares the same chemical formula, crystal lattice, and optical properties as a mined diamond — the only difference is where and how fast it formed.
This isn’t a diamond simulant like moissanite or cubic zirconia. Those are different minerals shaped to look like diamonds. A lab-grown stone is a diamond, full stop — the Federal Trade Commission updated its Jewelry Guides in 2018 specifically because “synthetic” and “lab-grown” diamonds are chemically identical to mined ones, just produced on a different timeline. If you set a natural and a lab-grown stone side by side, no jeweler’s loupe alone will tell you which is which. You need specialized equipment that detects trace growth patterns and inclusions, which is exactly why every reputable seller sends lab-grown stones out for GIA or IGI certification before selling them.
How Hard Are Synthetic Diamonds, Really?
Modern lab-grown diamonds test at 10 on the Mohs hardness scale — identical to natural diamonds. This is because hardness is determined entirely by the carbon atoms’ crystal structure, and both stone types share the exact same tetrahedral lattice.
The Mohs scale, developed by German mineralogist Friedrich Mohs in 1812, ranks minerals from 1 (talc) to 10 (diamond) based on scratch resistance rather than toughness or brittleness. According to GIA, both HPHT and CVD lab diamonds emerge from their growth chambers with the same continuous carbon lattice found in mined stones, which is why gemological labs no longer report a hardness gap between the two. The 9.6 or 8.8 figures you’ll still see floating around older blog posts trace back to early experimental synthetics from the 1970s and 80s — small industrial-grade crystals with more internal strain and defects, made for cutting tools rather than jewelry. Today’s gem-quality lab diamonds don’t have that problem.
How Synthetic Diamonds Are Actually Made
Natural diamonds form over 1 billion to 3.3 billion years, 90-125 miles below the earth’s surface, under roughly 725,000 pounds per square inch of pressure and temperatures around 2,200°F. Labs compress that timeline into weeks by recreating similar conditions with two different methods.
HPHT (High Pressure, High Temperature)
HPHT growth places a small diamond seed and a carbon source inside a press, then applies pressure above 870,000 psi and heat between 2,370°F and 2,900°F. A metal catalyst — usually nickel, cobalt, or iron — lowers the energy needed to bond carbon atoms onto the seed. The result is a cube-and-octahedron-shaped crystal that grows in a matter of days to a few weeks, depending on target size.
CVD (Chemical Vapor Deposition)
CVD works differently. A diamond seed plate sits in a vacuum chamber filled with methane and hydrogen gas. Microwaves ionize the gas into plasma, breaking the carbon-hydrogen bonds so pure carbon atoms deposit onto the seed layer by layer. Per AZoM, most CVD stones grow with a slight brown or yellow tint from nitrogen contamination and go through a follow-up HPHT treatment to strip the color before they’re cut and polished. This is also why lab diamonds frequently land in the VS1-VVS2 clarity range — tighter quality control at the growth stage means fewer inclusions to begin with.
Is a 10 on the Mohs Scale the Same as “Indestructible”?
No. A 10 on the Mohs scale only measures scratch resistance, not resistance to chipping or cracking. Both natural and synthetic diamonds can chip along their grain lines if struck at the wrong angle — hardness and toughness are two different properties.
This trips people up constantly. I’ve had customers drop a diamond ring on a tile floor and come back convinced it should be fine because “diamonds are the hardest thing on earth.” Hardness protects against everyday scuffs from keys, sand, and other jewelry — it doesn’t protect against a hard direct impact on a facet edge. If you’re worried about everyday wear rather than impact, diamonds resisting scratches is really the more useful question, and the answer there is the same for both stone types: practically never, from anything you’ll encounter in daily life except another diamond.
Why the Hardness Myth Still Circulates
Plenty of older jewelry blogs — including earlier versions of posts on this exact topic — repeat the 9.6-versus-10 figure because it got copied forward from outdated trade literature without anyone re-checking it against current gemological research. The confusion likely started from conflating hardness with color grade or clarity treatments, which genuinely can vary between individual stones regardless of origin. Brilliant Earth and other major retailers now state plainly that lab-grown and mined diamonds are durability-equivalent, and GIA grades both using identical scales for cut, color, clarity, and carat.
Where lab-grown diamonds genuinely lose ground to natural ones isn’t in the showroom — it’s in the resale market. If you’re weighing that trade-off, it’s worth reading about the advantages natural diamonds still hold alongside the well-documented drawbacks of lab-grown stones before you buy — pricing power and long-term value retention still favor mined diamonds, even though hardness doesn’t.
How Do Diamonds Compare to Other Hard Materials?
Diamond outranks every other gem-quality material on the Mohs scale. Corundum (sapphire and ruby) sits at 9, moissanite at 9.25, cubic zirconia at 8-8.5, and platinum — a common setting metal — falls around 4-4.5.
That gap matters when you’re choosing a setting metal or picking a simulant. A platinum band will slowly develop a soft patina from daily contact with a diamond you wear next to it, which is a normal, cosmetic effect rather than damage — you can see the full breakdown in the platinum versus diamond hardness comparison. If budget is the real constraint and you’re considering a diamond alternative altogether, cubic zirconia’s lower hardness means it scratches and loses its shine faster, which is exactly why it costs a fraction of what a diamond does regardless of origin.
Environmental and Ethical Differences Worth Knowing
Hardness aside, buyers increasingly choose between natural and lab-grown diamonds based on sourcing rather than physical properties. Lab-grown production sidesteps large-scale mining but still consumes significant energy — some CVD reactors run for weeks per batch. If sourcing matters to your decision as much as durability does, the deeper comparison in natural versus synthetic diamonds and their environmental impact lays out the tradeoffs, and the wider case for lab-grown stones is covered in the positive impacts of synthetic diamonds.
The Bottom Line
Synthetic diamonds are exactly as hard as real diamonds — both score a 10 on the Mohs scale because both are the same material: pure crystallized carbon. The 9.6-versus-10 gap you might have read elsewhere is a leftover figure from decades-old industrial diamond production, not a reflection of what’s on jewelry counters today. Buy a lab-grown stone with confidence on durability; make your decision on price, resale value, and sourcing instead, since that’s where the real differences live.
Frequently Asked Questions
Can a jeweler tell a synthetic diamond from a natural one by scratch testing?
No. Since both score 10 on the Mohs scale, a scratch test can’t distinguish them — only specialized equipment that detects growth patterns, trace elements, or fluorescence under specific lighting can identify origin. Standard jewelers rely on gemological lab certificates from GIA or IGI rather than any physical test.
Do lab-grown diamonds chip more easily than natural diamonds?
No, chip resistance is comparable between the two because it depends on the crystal’s cleavage planes, which form the same way regardless of growth method. Poor cutting or a weak setting causes most chipping incidents, not the stone’s origin.
Is a lab-grown diamond considered a “real” diamond?
Yes. The FTC classifies lab-grown diamonds as real diamonds with identical chemical, physical, and optical properties to mined stones. The only distinction the FTC requires disclosed is the method of origin, not any difference in the material itself.
Why do some lab-grown diamonds look more “perfect” than natural ones?
Lab-grown stones typically form with fewer inclusions because growers control the environment tightly, which is why so many land in the VS1-VVS2 clarity range. Natural diamonds form under unpredictable geological conditions over millions of years, so inclusions and minor flaws are more common.
Does hardness affect how a diamond is priced?
No, since both natural and lab-grown diamonds share identical hardness, it isn’t a pricing factor at all. Price differences of 60-85% between the two come down to production cost, scarcity, and resale market demand — not durability.
What should I check before buying a synthetic diamond?
Confirm it comes with a GIA or IGI grading report that states “laboratory-grown” clearly, and compare the cut, color, and clarity grades the same way you would for a natural stone. Hardness will be identical either way, so focus your comparison on the 4Cs and the seller’s return policy instead.
Tiger is a fashion&jewelry lover. He is also a fashion jewelry manufacturer that help thousands of small business to grow and also do business with some big fashion jewelry brands. He is a truly metal expert and he will share some information you are looking for.