The science behind lab grown diamonds is very complex and interesting.
There are two methods of creating a lab grown diamond. One is CVD and one is HPHT. HPHT was the original method of creating lab grown diamonds so we will begin with that.
To grow an HPHT diamond, a small diamond seed (a minuscule part of a diamond) is placed in carbon, the element that diamonds are made of. The diamond seed is exposed to extreme heat and pressure, replicating the way diamonds are naturally grown underground by the earth. The diamond seed is exposed to temperatures of over 2,000 degrees Fahrenheit and pressure of about 1.5 million PSI (pounds per square inch). The carbon melts and forms a diamond around the seed. It is then cooled and the rough diamond is formed, ready to be cut and polished.
HPHT rough diamonds do form differently than CVD diamonds.
The newer CVD method places a diamond seed in a vacuum chamber. This chamber becomes filled with carbon-rich gases and is heated to nearly 1500 degrees Fahrenheit. The gas turns into plasma from these extremely high temperatures, causing the release of carbon pieces. These carbon pieces become layered onto the diamond seed, which then grows the diamond.
There is no visible difference between the two final stones.