CVD vs HPHT Methods of Creating Lab Diamonds

Lab-grown diamonds are diamonds that were grown by scientists in a lab. They share the same chemical makeup as an earth made diamond and are optically identical.

In this post we will look at two main methods of creating lab grown diamonds: Chemical Vapor Deposition (CVD) and High Pressure High Temperature (HPHT)

Both methods are able to create real diamonds that are visually, chemically, and physically indistinguishable from diamonds grown on earth in terms of their full range and quality. So let's review each one more closely and underline main differences between two.

High Pressure High Temperature (HPHT)

The process was designed to mimic the pressure and temperatures found within the earth where natural diamond crystals are formed over millions of years. The HPHT process manages to recreate this environment, but allows a diamond to form in a matter of weeks compared to the roughly 150 million years it took to form the world’s natural diamonds! It is also sometimes used as a finish touch for CVD made diamonds, to enhance color and clarity. 

Chemical Vapor Deposition (CVD)

CVD diamonds are produced through a process known as Chemical Vapour Deposition. This technique involves placing a small diamond seed in a sealed chamber and heating it to approximately 800 degrees celsius. Carbon-rich gases, such as methane, are then introduced into the chamber and ionised into plasma using various methods like microwaves and lasers. This ionisation breaks down the gases and allows the carbon to combine with the diamond seed, gradually forming the diamond layer by layer. The CVD process is generally understood to be the less costly method of creating diamonds out of the two as it requires much less energy.

Differences

Both methods are capable of producing high quality diamonds. As a result, we do not favor one over the other when sourcing our lab grown diamonds.

In the end, the main distinction between an HPHT diamond and a CVD diamond lies in their unique diamond growth patterns. By closely examining the crystal structure under magnification, a lab diamond specialist may potentially be able to differentiate between the two.

HPHT diamonds typically grow in a cuboctahedron shape with 14 distinct growth directions, while CVD diamonds have a cubic shape with just one growth direction. Occasionally, a CVD diamond may exhibit signs of strains, but this is a rare occurrence that can only be observed under extreme magnification, to a naked eye there is no difference. 

With all that being said we do believe that choice between HPHT or CVD is strictly a personal preference rather than something that will have affect on visible differences of your stone. All lab grown diamonds that we source undergo a thorough assessment making sure you get a beautiful quality diamond. 

We are here to support you and help you make a choice that would suit your needs best, if you need any further assistance you can always email us at hello@arajewelry.ca