Lab-Grown Diamonds

The CVD method was created in the 1980s, making it newer than the HPHT method. The CVD method imitates how diamonds form in interstellar gas clouds. The CVD method uses less pressure than the HPHT method as well as smaller machines.

The CVD method places a diamond seed in a vacuum chamber. This chamber becomes filled with carbon rich gases and is heated to nearly 1500 degrees fahrenheit. The gas turns into plasma from these extremely high temperatures, causing the release of carbon pieces. These carbon pieces become layered onto the diamond seed, which grows the diamond.

The HPHT growth method is the original method of creating lab-grown diamonds. Gem quality HPHT diamonds were introduced in the 1950s. Outside of growing diamonds, post-HPHT treatment can also be used to enhance the color of diamonds (whether natural or lab-grown) to make them colorless, pink, green, blue, or yellow.

To grow an HPHT diamond, a small diamond seed is placed in carbon, the element that diamonds are made of. The diamond seed is exposed to extreme heat and pressure, replicating the way diamonds are naturally grown underground by the earth. The diamond seed is exposed to temperatures of over 2,000 degrees Fahrenheit and pressure of about 1.5 million PSI (pounds per square inch). The carbon melts and forms a diamond around the seed. It is then cooled and the diamond is formed.

Growth Process	Typical Growth Morphology	Photo Example of Rough
Natural	Shape: Octahedron Growth: 8 directions
High Pressure, High Temperature (HPHT)	Shape: Cuboctohedron Growth: 14 directions
Chemical Vapor Deposition (CVD)	Shape: Cube Growth: 1 direction

Due to exposure to trace amounts of boron or nitrogen gases, as well as impure lab conditions, lab-grown diamonds may grow with a pinkish, greenish or blueish cast/color. This is more often associated with HPHT growth method, but it has also been seen with diamonds grown through the CVD method. As a result they may undergo post-HPHT treatment to correct these color irregularities. In fact, larger lab grown diamonds (2ct or larger) frequently undergo this treatment due to the extreme difficulty of growing perfect diamonds of this size. These diamonds are not any less desirable. Some laboratories do not disclose whether this treatment is present. However, at Toner Jewelers we choose not to carry diamonds that do not indicate whether post-HPHT treatment has been detected on their certificate.

It is important to note the major distinction between lab grown diamonds and diamond simulants. Diamond simulants, such as cubic zirconia and moissanite, appear similar to diamonds but are not true carbon crystals. Simulants do not have the same chemical and physical properties as natural diamonds and therefore sell at much lower prices than lab-grown diamonds. Simulants can be distinguished from natural or lab grown diamonds using only the naked eye because they reflect light differently, and are less durable because they are softer than natural and lab grown diamonds.

Unlike earth mined diamonds which have a proven market value based on appreciation that has accumulated over hundreds of years, lab grown diamonds are so new to the market that their market value continues to be unpredictable. As a result, we are unable to promise that we will be able to give you a full trade value towards an upgrade in the future as we would with an earth mined diamond. We will always be able to offer an amount, but that amount will be based on whatever the current market value for your lab grown diamond at the time of trade.

Lab Grown Diamonds:
What You Should Know

What are the benefits of lab grown diamonds?

How are lab grown diamonds grown?

The CVD Method

The HPHT Method

Post-HPHT Treatment:

Lab Grown Diamonds vs. Diamond Simulants

Lab Grown Diamond Trade Policy

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Lab Grown Diamonds:What You Should Know