Are Lab-Grown Diamonds "Real" Diamonds?

Consumers often wonder if lab-grown diamonds can be considered “real” diamonds, or if they ought to be classed with diamond simulants such as cubic zirconia. The difference is that diamond simulants (also called imitation diamonds) are not diamonds while a lab-grown diamond is identical in chemical structure to a mined diamond. Whether it was grown in a laboratory or deep below the surface of the Earth, a “real” diamond is characterized by its chemical composition of almost pure carbon. So the short answer is yes, lab-grown diamonds are real diamonds, chemically identical to mined diamonds. Read on to learn more.

How Are Diamonds Formed?

The diamonds extracted from mines grow 150 km (90 miles) deep, in the upper mantle. Most minerals are formed in the Earth’s crust, but two—the diamond and the peridot—are formed in the mantle and then carried upward by lava flows that burst through weak spots in the crust. In the upper mantle, temperatures can reach 1300°C (2400°F). The pressure is also immense down there, an incomprehensible 240 kbar, or 240,000 times the pressure of the atmosphere at sea level. This extreme heat and pressure crystallizes carbon atoms, rearranging them into a three-dimensional lattice-like structure.

During this process, other elements and minerals are sometimes captured within the crystal, which can affect the appearance of the diamond. Sometimes, these take the form of inclusions, which are minute quantities of liquid, gas, or even another crystal that get trapped inside the diamond while it is growing. Other times, the captured element will insert itself into the crystal and change the color of the diamond. Nitrogen can replace carbon in parts of the crystal lattice, for instance, producing a yellow diamond. Blue diamonds are created when as little as one atom of the element boron inserts itself into the carbon crystal. Other diamond colors, such as pink and red, are the result of deformations to the crystal lattice. The shape of the crystal changes, and only certain wavelengths of light are absorbed.

How Are Diamonds Grown in a Lab?

Discoveries pertaining to the formation of the Earth, the movements of tectonic plates, the chemical composition of minerals, and the interaction between heat and pressure have led to a deeper understanding of the conditions under which diamonds grow. Even though that knowledge is far from complete, as we cannot physically access the depths at which this process takes place, we now know enough to replicate the conditions found in the upper mantle in a laboratory setting.

This article goes into more depth on this topic, but briefly, diamonds grown using the High Pressure, High Temperature (HPHT) method replicate the conditions described above. A diamond seed, or some other form of carbon such as graphite, is placed in a medium, which itself is placed in a machine that presses on the container from all sides. The grower must take care to maintain a constant temperature and pressure so that the carbon atoms can uniformly recrystallize as diamond. If all goes well, in a matter of weeks, a perfectly clear diamond is formed. If the grower wants to grow different color diamonds, they can introduce different elements to the solution in the same way these elements enter the crystal growing process in the upper mantle. But while labs have a great deal of control over the outcome of this process, it’s not an exact science, and every diamond grown is unique.

In both the lab and the upper mantle, the same process is taking place: in the right conditions of heat and pressure, carbon atoms rearrange themselves into a crystal lattice and form a diamond. As a result, lab-grown diamonds are chemically identical to mined diamonds, unlike diamond simulants such as moissanite and cubic zirconia.

What is a Diamond Simulant?

Simply put, a diamond simulant is any gemstone that looks like a diamond but is not a diamond. They might have similar gemological characteristics: their color and clarity is similar to that of diamond, and it can be cut like a diamond to create similar optical effects (brightness, fire, and scintillation). Most diamond simulants are also lab-grown, but they have a different chemical structure, and thus different (and to most eyes, inferior) optical qualities. To the untrained eye and at a distance, a diamond simulant can easily be mistaken for a diamond, but under closer inspection even that untrained eye will notice that many diamond simulants lack the energetic and dynamic sparkle of a diamond. There is another difference you might not notice for many years: the tiny scratches that accumulate on a stone less hard than diamond, which make it appear duller over time.

Common Diamond Simulants

White topaz is the alternative to the traditional April birthstone, diamond, for a reason, as this gemstone can be as clear as a diamond. But it lacks diamond’s unmistakable sparkle and fire.

Moissanite was first discovered by Henri Moissan in a meteorite in 1893, and for a long time it was believed to only exist in extraterrestrial sources. It has since been discovered in a few terrestrial sources, though it is exceedingly rare. As a result, all moissanite gemstones are lab-grown. It is almost as hard as diamond and is often used as a diamond substitute in industrial applications. It may have a similar appearance and similar uses to diamond, but moissanite is silicon carbide, whereas diamond, whether mined or lab-grown, is pure carbon. Moissanite probably comes closest to imitating diamond’s distinct brilliance, but these stones are often tinted yellow rather than the dazzling white of a colorless diamond.

Cubic Zirconia is a mineral that occurs in nature only under rare circumstances. Gemstone-quality cubic zirconia is synthesized by mixing zirconium oxide powder with magnesium and calcium at high temperature. When it cools, it forms cubic zirconia crystals, the “cubic” in its name referring to the shape of the crystal lattice.

All of these are fine diamond alternatives, not none of them are truly diamonds. They all lack the hardness of diamond (moissanite comes close, rated 9-9.5 on the Mohs scale), and even the untrained eye can see that there’s something lacking—or, at least, something different—in their optical effects. That is what makes diamonds so special: not their rarity, but their unique beauty. And the only thing that can match, and even surpass, a mined diamond in clarity, color, and brilliance is a lab-grown diamond.