How Are Lab Grown Diamonds Made? A Comprehensive Guide

Lab grown diamonds are real diamonds, chemically and physically identical to those pulled from the earth. The only difference is origin: instead of forming over billions of years deep in the mantle, they are grown in a matter of weeks inside advanced reactors that recreate the same conditions. Understanding how that happens makes it clear why lab grown diamonds have become a mainstream choice for engagement rings and fine jewelry.

In short: Lab grown diamonds are made by two proven methods. High Pressure High Temperature (HPHT) mimics the earth by squeezing a tiny diamond seed under roughly 1.5 million pounds per square inch at about 1,400 to 1,600 degrees Celsius. Chemical Vapor Deposition (CVD) grows a diamond layer by layer from a carbon-rich gas inside a vacuum chamber. Both produce genuine diamonds with the same hardness (10 on the Mohs scale), brilliance, and chemistry as mined stones, and both are graded by the same labs using the same 4Cs. Growth takes roughly two to four weeks depending on size and method.

What a diamond actually is

Every diamond, mined or grown, is pure carbon arranged in a rigid cubic crystal lattice. That structure is what gives diamond its unmatched hardness and its ability to bend and return light as fire and brilliance. Because a lab grown diamond has the exact same atomic arrangement, it behaves identically to a mined diamond in every optical and physical test. This is why major grading laboratories certify both, and why the term "real" applies to both. To see how the two compare on price, our natural vs lab grown price comparison lays out the difference clearly.

Method 1: High Pressure High Temperature (HPHT)

HPHT was the original method for growing gem-quality diamonds and it recreates the natural formation environment directly. A small diamond seed crystal is placed alongside a source of pure carbon, usually graphite, and surrounded by a metal flux. A specialized press then applies immense pressure, around 5 to 6 gigapascals, while heating the chamber to roughly 1,400 to 1,600 degrees Celsius.

Under these conditions the carbon dissolves and migrates onto the cooler seed, crystallizing atom by atom into a larger diamond. There are three common press designs used to generate the pressure: the cubic press, the belt press, and the split-sphere (BARS) press. HPHT is particularly effective for producing yellow and near-colorless diamonds and is also used to improve the color of some stones after growth.

Method 2: Chemical Vapor Deposition (CVD)

CVD is the newer and now dominant technique for gem-quality growth. A thin diamond seed slice is placed in a sealed vacuum chamber, which is then filled with a carbon-rich gas such as methane along with hydrogen. Microwave energy heats the gas into a plasma, breaking the molecules apart so that carbon atoms rain down and bond to the seed, building the diamond up in extremely thin layers.

CVD runs at much lower pressure than HPHT and gives growers fine control over the diamond's purity and type, which is why it is favored for high-clarity, near-colorless stones. Grown crystals are often treated with a brief HPHT step afterward to optimize color. The result is a rough diamond that is then cut and polished exactly like a mined stone.

How long does it take?

Growth time depends on the size and method, but a one-carat CVD diamond typically takes around two to four weeks, while larger stones take longer. Compare that to the one to three billion years a mined diamond spends forming, and the efficiency of the lab process becomes obvious. Faster, controlled production is a major reason lab grown stones cost significantly less for comparable quality.

Are they graded and certified?

Yes. Reputable lab grown diamonds are assessed against the same 4Cs (cut, color, clarity, and carat) as mined diamonds, and independent laboratories such as IGI and GIA issue certificates that clearly state the stone is laboratory grown. Every diamond we supply is certified, so you know exactly what you are buying. If you are new to grading, start with our diamond education guides.

Lab grown vs mined: what changes and what does not

• Chemistry and hardness: identical. Both are pure carbon at 10 on the Mohs scale. More on this in are lab grown diamonds chemically the same as natural diamonds.
• Durability: identical, and a lab grown diamond lasts a lifetime just like a mined one. See durability of lab grown diamonds.
• Price: lab grown typically costs far less for the same size and quality, letting you size up or save.
• Origin: the only real difference. Lab grown offers a traceable, conflict-free origin.

Frequently asked questions

Can a jeweler tell the difference by eye? No. A lab grown diamond is visually and optically identical to a mined one. Distinguishing them requires specialized equipment that detects tiny differences in trace elements and growth patterns.

Do lab grown diamonds test as real? Yes, they pass a standard diamond tester because they are genuine diamond, not a simulant like cubic zirconia or moissanite.

Which method is better, HPHT or CVD? Neither is universally better. Both produce beautiful, certified diamonds. Quality depends on the individual stone and its grading, not the method alone.

Explore our engagement rings set with certified lab grown diamonds, or talk to our team about designing a piece around the exact stone you want.