What is the difference between CVD and HPHT Lab Grown Diamonds?

What is the difference between CVD and HPHT Lab Grown Diamonds?

Lab-Grown Diamonds are created via two methods – Chemical Vapor Deposition (CVD) and High Pressure High Temperature (HPHT). 

What is the difference between CVD and HPHT Lab Grown Diamonds?

While HPHT diamonds are more closely connected to the typical growth patterns of mined diamonds, CVD growing is known to produce finer stones, as it is a newer growth method.

Colorless Diamond created by Syntechno LTD by Igor Stratichuk via Wikimedia Commons

What are CVD Diamonds?

CVD stands for Chemical Vapor Deposition – a process where machines use a vacuum method to compile atoms and form solid materials. Researchers discovered they could use this process, which was popular in the semiconductor industry, to grow diamonds, as diamonds are made purely of carbon atoms.

CVD Lab Grown Diamonds have just one growth plane, whereas the older HPHT method grows diamonds with 14 growth planes.

CVD was introduced as a method to grow gem-quality diamonds in 2003, and quickly became an attractive alternative to the HPHT growth method because it did not require the extreme pressure and heat that HPHT does – leading to diamonds with more luster and creating fewer chemical emissions.  

What about HPHT?

HPHT (High Pressure High Temperature) was the original growth method for synthetic diamonds. A tiny diamond seed is treated with extreme temperatures and pressures, meant to replicate the extreme conditions deep within the earth where natural diamonds form. 

HPHT Lab Grown Diamonds typically have 14 growth planes, in comparison to just one for CVD Lab Grown Diamonds.

General Electric became the first to grow synthetic diamonds in the 1950s using this method, and in 1970 presented the first gem-quality lab-grown diamond to the world.

Are the prices different?

Prices for both types of lab grown diamonds are typically the same if the stone's quality is otherwise even. 

 How can I tell them apart?

While not easy to discern to the naked eye, lower-quality diamonds do have unique differences. HPHT Lab Grown Diamonds, for instance, may look less brilliant than comparable mined diamonds, as growing the stones oftentimes reduces luster.

As for CVD Lab Grown Diamonds, lower-quality stones may be slightly brown or gray in color if they are grown too rapidly. Fine CVD Diamonds typically take weeks to grow, though some manufacturers aim to grow diamonds within a few days – at the expense of the diamond's quality.