A lab-grown diamond is not a facsimile of a natural diamond. Rather, it is an actual diamond, just produced via man-made technology rather than natural processes occurring in the earth over thousands of years.

Labs use either a process called HPHT (high pressure-high temperature) or CVD (chemical vapor deposition) to create diamonds.

As their name suggests, HPHT diamonds are made using high pressure and temperature to stimulate diamond growth. First, a tiny diamond seed is placed into carbon. Then, it is heated to about 1500 degrees Celsius (over 2700 degrees Fahrenheit) and simultaneously pressurized at around 1.5 million PSI (pounds per square inch). This heating and pressurizing process can be done with a belt press, a split-sphere “BARS” press, or a cubic press, depending on how the lab operates. After the diamond begins to form around the seed, the mixture is cooled down to create a diamond made from pure carbon.

CVD diamonds are also made from a small diamond seed but begin life as a much thinner slice, often a slice taken from a diamond already made from HPHT. First, the seed is sealed into a chamber before being heated to over 800 degrees Celsius (around 1500 degrees Fahrenheit). Then, gasses that are full of carbon, such as methane gas, are introduced into the chamber. Next, these gasses are converted into plasma via ionization. As this ionization breaks down bonds in the gas molecules, the carbon that comes out begins to bond to the diamond seed, crystalizing into a pure carbon diamond.