What Is a Diamond Made in a Lab? A Straight Answer From Our LA Workshop

A diamond made in the lab is a real diamond. It's pure carbon, crystallized in the same face-centered cubic lattice as a mined stone, scoring 10 on the Mohs hardness scale, with the same refractive index of 2.42 and the same dispersion that throws fire and brilliance. The Federal Trade Commission settled the naming debate in 2018 when it dropped "natural" from the definition of a diamond. The Gemological Institute of America (GIA) and the International Gemological Institute (IGI) grade these stones on the exact same 4Cs scale used for mined diamonds. Same chemistry, same physics, same certificate. The only thing that changed is the address where it grew up.

What is a diamond made in lab?

A diamond made in a lab is a gem-quality crystal produced through a controlled industrial process instead of geological formation. You'll see it sold as a lab grown diamond, lab created diamond, man-made diamond, cultured diamond, or the older trade term synthetic diamond. They all mean the same product. What actually matters is whether the stone carries a current GIA or IGI certificate identifying it as laboratory-grown, with a report number that matches a laser inscription on the girdle.

A diamond made in lab is not a simulant. Cubic zirconia and moissanite are simulants, made of zirconium dioxide and silicon carbide respectively. They mimic the look of a diamond but aren't one. A lab grown diamond is carbon, full stop. That distinction is exactly what the FTC ruling protects.

How is a diamond made in the lab?

Two methods produce every gem-quality diamond made in lab: High Pressure High Temperature (HPHT) and Chemical Vapor Deposition (CVD).

HPHT was the original method, achieved by General Electric in 1954 under Project Superpressure, with Howard Tracy Hall and Herbert Strong credited as lead scientists. The Swedish company ASEA actually grew small crystals in 1953 but stayed quiet about it. A diamond seed sits in a chamber with graphite and a metal flux of iron, nickel, or cobalt, then gets squeezed to roughly 5 to 6 gigapascals and heated to 1,300 to 1,600 degrees Celsius. Carbon recrystallizes onto the seed layer by layer. HPHT stones often retain trace metallic inclusions from the flux.

CVD came later, in the 1980s, and now produces the majority of gem-quality stones. A diamond seed is sealed in a vacuum chamber filled with methane and hydrogen. Microwaves or lasers ionize the gas into plasma, breaking the methane so carbon atoms drift onto the seed. The diamond grows upward in a Type IIa structure, the purest classification, which accounts for only about 2 percent of natural diamonds. CVD runs at lower temperature and pressure, uses less energy, and scales better.

A gem-quality 1-carat diamond made in the lab takes roughly two to four weeks to grow. The largest synthetic uncut diamond on record is 150.42 carats, verified in Kyiv, Ukraine in November 2021. Most growers stop between 1 and 3 carats for commercial reasons, then cut and polish the rough using the same techniques applied to mined stones.

Is a diamond made in a lab a real diamond?

Yes. It passes standard thermal diamond testers, shows identical brilliance and fire, and can't be told apart from a mined diamond by the naked eye or a 10x jeweler's loupe. Verifying origin takes advanced gemological equipment: photoluminescence spectroscopy, FTIR analysis, and DiamondView imaging, which read growth zoning and trace impurity signatures. None of that affects how the stone looks on your hand. For more on what certificates capture and where they fall short, read the grade on the certificate is only half the story.

A short history of how we got here

The first proven synthesis came from GE in 1954, but those stones were industrial-grade and far too small for jewelry. Gem-quality crystals became possible in 1971. CVD breakthroughs through the 1980s and 1990s pushed quality up and costs down. The FTC recognized lab grown stones as diamonds in 2018. GIA started issuing full grade reports in 2020. Even De Beers, the world's largest mined diamond company, now sells lab grown through its Lightbox brand. That tells you where the industry landed.

How a diamond made in lab is graded and certified

GIA and IGI grade lab grown diamonds on the 4Cs: cut, color, clarity, and carat weight. Reports include type classification, spectroscopic detail, and a laser inscription matching the report number. IGI handles a larger share of lab grown volume right now. When you buy, three things should line up: the certificate number, the girdle inscription visible at 10x, and the lab's online lookup. Anything missing is a red flag worth walking away from.

What goes wrong when shoppers don't pay attention

This is the part most retailer guides skip, and it's what we see going sideways every week in our workshop.

Cut grade gets under-prioritized. People obsess over color and clarity and treat cut as an afterthought, so they end up with a VS clarity, F color stone that looks flat under daylight because the cut grade was quietly downgraded to "Good." Cut is the single biggest driver of how a diamond actually looks. Read it first, always.

Moissanite mislabeling happens more than the industry likes to admit. Some marketplaces ship stones labeled lab grown that test as moissanite, which violates FTC rules. Separately, some HPHT diamonds throw false moissanite readings on cheap testers because of trace metallic inclusions, which we break down in why some HPHT diamonds test as moissanite. The fix for both: a reputable seller and a multi-tester device.

Fluorescence catches people off guard. About 30 percent of diamonds fluoresce under UV light, and strong fluorescence in a lower-color stone can look milky in daylight. View any stone under daylight-equivalent lighting, not just showroom spotlights. To compare lab grown with its closest visual rival, see moissanite versus a lab grown diamond, and to tell the two stone types apart yourself, see how to tell a lab grown diamond from a natural one.

What we check in our LA workshop before approving a stone

Karaters runs a family workshop in downtown Los Angeles, second-generation jewelers with 25 years in the trade. Every diamond made in lab passes through a gemologist before it touches a setting. The checks, in order: cut grade and face-up performance under daylight lighting, certificate and girdle-inscription match, fluorescence behavior under UV, inclusion type and eye-visibility, and FTC-compliant origin disclosure on the certificate, the listing, and the receipt. That's the standard behind our lab grown engagement rings, tennis necklaces, and tennis bracelets. More on the workshop and the family on our story page.

Should you buy a diamond made in lab?

Buy lab grown if you want a real, certified diamond that lets your budget reach a larger stone, a higher cut grade, or a more elaborate setting, and if ethical sourcing and supply-chain transparency matter to you. Don't buy lab grown as a financial investment. The wholesale market has compressed sharply since 2020 as production scaled, and resale sits well below original retail. Honestly, most diamond purchases, mined or lab grown, don't appreciate. This is a category you wear and enjoy, not one you flip.

Frequently asked questions

Is a diamond made in lab a real diamond?

 Yes. It's chemically and physically identical to a mined diamond. The FTC classifies it as a diamond, and GIA and IGI issue full grade reports for lab grown stones.

How long does it take to grow a diamond made in lab? 

A gem-quality 1-carat stone takes roughly two to four weeks to grow, depending on the method and target size. Larger stones take longer.

Will a diamond made in the lab pass a diamond tester? 

Yes. Standard thermal diamond testers read them as diamonds. Verifying lab origin requires specialized equipment like photoluminescence spectroscopy.

How is a diamond made in lab graded? 

GIA and IGI grade them on the same 4Cs scale used for mined diamonds, with full reports and laser-inscribed report numbers on the girdle.

Do lab grown diamonds last forever? 

Yes. With a Mohs hardness of 10 and the same atomic structure as mined diamonds, they don't fade, cloud, or degrade under normal wear.

Are HPHT or CVD lab grown diamonds better? 

Neither is universally better. CVD dominates gem-quality production today. Cut grade and certificate quality matter far more than which growth method was used.

Final thoughts

A diamond made in the lab is a real diamond. The science settled that decades ago, the FTC ruling is on the books, and the grading framework matches what mined diamonds have always used. What separates a stone worth wearing for a lifetime from one that disappoints isn't where it grew. It's cut quality, certificate verification, fluorescence behavior, and honest origin disclosure. To see stones in person, book an appointment at our Los Angeles or Miami showroom, or browse lab grown engagement rings and tennis necklaces online. Every piece comes with a GIA or IGI certificate, a lifetime warranty, and the same standards we'd apply to a stone for our own family.