CVD vs HPHT Lab Grown Diamonds: What are the Differences?

Difference between CVD vs HPHT Lab Grown Diamonds

The lab grown diamond has the same characteristics as the natural diamond. However, one is grown in the earth’s crust and the other in the lab. Natural diamonds take millions of years to become diamonds, whereas manmade or lab grown diamonds take much less time.

Diamond manufacturers have two kinds of manmade diamonds. HPHT and CVD Diamonds. You can find a wide range of both types of lab grown diamonds in USA.

What is the difference? HPHT and CVD are both lab grown diamonds. However, they have many similarities and differences. We shall start with the origin and meaning of the diamonds.

HPHT Diamonds

HPHT (High-Pressure High Temperature) is the process of creating lab grown diamonds within weeks compared to natural diamonds. It was first invented for industrial purposes in the 1950s. However, later, diamond manufacturers adopted it to make lab grown diamonds. The HPHT method is also used for treating mined diamonds to boost overall color and clarity.

CVD Diamonds

CVD (Chemical Vapour Deposition) is another procedure to create lab grown diamonds. It is a more advanced technique than HPHT diamonds. In the CVD process, diamonds are grown through a hydrocarbon gas mixture, like diamonds created in interstellar gas clouds. It was first invented and used to create CVD diamonds in the 1980s.

The Process of Making Both Lab Grown Diamonds

The significant difference between the HPHT and CVD diamonds is the process to make them. Let’s understand the process one after the other.

HPHT Method

  • The process starts with putting a small diamond seed in the carbon from which the diamond is made.
  • Similar to diamonds naturally grown in the earth, the seed is exposed to temperature and high pressure.
  • The temperature is kept at 2000 degrees Fahrenheit and pressure is maintained at 1.5 million PSI. (pounds per square inch)
  • The carbon melts and creates a diamond around the seed in the process.
  • It is cooled, and the process is completed. HPHT diamonds are ready.

CVD Method

  • The diamond seed is kept in a vacuum chamber in the CVD method.
  • The chamber is filled with carbon-rich gases and heated at 1500 degrees Fahrenheit.
  • Seeds turn into the plasma through these extreme temperatures, and carbon pieces are released.
  • These pieces are layered onto the seed that eventually grows in the diamonds.

The Characteristics of Both Lab Grown Diamonds

As you can see, both have a distinct procedure to grow as diamonds. Being lab grown diamonds, they have some similar characteristics along with some different ones. You can see a variety of both of these fancy cut diamonds for sale.

Let’s look at the characteristics.

HPHT Diamonds

  • HPHT diamonds grow in 14 directions and do not have strain patterns. However, they have graining patterns.
  • They have some unusual fluorescence along with occasional phosphorescence.
  • They have geometric color zoning; They are in cuboctahedron shape.

CVD Diamonds

  • CVD diamonds grow in a single direction and have banded strain patterns. However, they do not have graining patterns.
  • They also have some unusual fluorescence with occasional phosphorescence.
  • They are in a cubic shape.

To conclude, we cannot identify if the diamond is HPHT or CVD diamonds without professional help. Both methods create beautiful diamonds. They are identical to earth-grown diamonds in terms of chemical, optical, and physical.