Do You Know The Difference Between CVD and HPHT Lab-Grown Diamonds?

We are here to help you with the basics!

As synthetic diamonds (also known as “Lab-grown diamonds”) are more available in today’s jewelry marketplace, both jewelers and consumers are showing interest and want to learn more about the material’s nature and whether it can be identified by the gemological labs.

Lab-grown diamonds have enjoyed growing sales from millennials attracted by the prospect of a cheaper alternative to natural diamonds, that are guaranteed to be conflict-free.

As the GIA laboratory (Gemological Institute of America) indicates, synthetic diamonds should not be confused with imitations or simulants diamonds. Imitations that only looks like a diamond (like cubic zirconia or synthetic moissanite) have very different chemical and physical properties than a natural diamond. However, lab-grown diamonds are so similar to natural diamonds, which makes them harder to detect.

The International Diamond Council defines synthetic diamonds as a “Man-made product that has the same chemical composition, crystal structure, optical and physical properties as a diamond.”

While both natural diamonds and lab-grown are made of carbon, have the same density and hardness, the main and core difference is their origin. natural diamonds are created deep within the earth and are mostly more than one billion years old. on the other hand, synthetic diamonds are produced in a lab in a matter of days.

There are two methods to produce lab-grown diamonds: HPHT and CVD

HPHT stands for “High-Pressure, High Temperature”.
This technique replicates the formation conditions of the diamonds deep in the earth, by applying high pressure and high temperature to a carbon source.

CVD stands for “Chemical Vapour Deposition”.
In this process, a diamond is produced by heating gas to a very high temperature, where the atomic compounds are then broken down and the carbon atoms are deposited onto the surface. then, a single crystal is formed layer by layer.

The main difference between CVD and HPHT lab-grown diamonds is that CVD diamonds are usually light brown, which is less attractive than the HPHT diamonds, and so they usually go through an additional process of HPHT to remove the brown tint (this additional treatment can only be applied to diamonds with clarity of VS1 or higher). 

There is a big price difference between natural diamonds and lab-grown diamonds. one main reason is that the production cost of a lab-grown diamond is very low and keeps going down. while in the past the production cost of a lab-grown diamond was about $3000-$4000, now the cost is about $300-$400.

Depending on the size, color and clarity, a lab-grown diamond can be up to 30-50% less expensive than a natural diamond.