How are HPHT and CVD diamonds made?
Imagine. A stunning diamond composed of pure carbon molecules arranged in the signature crystalline formation. A diamond that is in every physical, chemical, and optical aspect identical to an Earth-mined diamond. Only this diamond did not require the sacrifice of the planet’s natural resources and the sweat of forced labor to produce the gem. Imagine an eco-friendly shimmering diamond that costs about 30 percent less than a natural diamond.
No longer is this vision a far-fetched dream, but a reality made possible with modern technology. Synthetic diamonds, also known as laboratory-grown diamonds, are equal to natural diamonds in terms of physical and chemical properties. The only difference is that you can purchase or own a laboratory-grown diamond guilt-free, knowing the process used to create it did not inflict damage to the environment or humanity. This is why many in the industry also refer to them as “conflict-free” diamonds.
How are synthetic diamonds created? Two main processes are used to grow the synthetic diamonds available on the market today. Below you will find an overview of the high-pressure high-temperature (HPHT) process and the chemical vapor deposition (CVD) process.
How are HPHT diamonds made?
Short for “high-pressure high-temperature”, HPHT diamonds are referred to as such because of the laboratory process used to create them. Carbon is the element all diamonds are composed of. As such, the diamond creation process first starts with a sample of carbon. Carbon can be extracted from cremated ashes or hair and turned into a diamond. The sample of cremains or hair is subjected to extremely high temperatures in order to extract the carbon that will be used for the diamond-growing foundation.
The HPHT process is the closest method to the natural diamond-creation process that occurs deep within Earth’s mantle. An HPHT machine creates an environment with extremely high pressure (in excess of 70,000 atmospheres) and incredibly high temperatures (in excess of 1400 degrees Celsius). The application of these conditions causes a diamond to grow from the crystalline foundation. Once a diamond has grown to the desired size, it is then sent to industry experts that cut and polish the synthetic diamond, in the same manner they would treat natural diamonds.
How are CVD diamonds made?
CVD is short for chemical vapor deposition, a process in which carbon atoms are deposited onto a substrate to create a diamond. Various materials can withstand the deposition of diamond, including diamond, silicon, tungsten, quartz glass, molybdenum, silicon carbide, and silicon nitride. As long as the substance is able to withstand high temperatures and the activated gas process – and it does not dissolve carbon – it should be a suitable substrate for the CVD creation process. This material must be thoroughly cleaned and is often brushed with a diamond powder, and usually ran through test runs to optimize the temperature (around 800 degrees Celsius).
Once the substrate is prepared, different amounts of gases are fed into the chamber of the machine and energized. Gases used include a carbon source which is typically methane, as well as hydrogen. Microwave power creates ionization which activates radicals in the growth chamber. Just as with the HPHT method, once the diamond has been grown, it is cut and polished by experts according to the same standards used for natural diamonds.