The Science Behind The Lab Grown Diamond
Diamonds started gaining popularity and have been heavily mined ever since the late 1800’s. Back then, no one could have imagined that one day we would have the technology to create diamonds in a lab that would be highly ethical and identical in every way to the diamonds coming from the earth. But that’s exactly what happened.
Starting in the mid-1900’s, companies began producing diamonds in labs for industrial purposes because of their thermal conductivity and hardness. NASA even recognized the value of lab grown diamonds and used them in their satellites because they could withstand the heat of the atmosphere. Over time, and thanks to the foresight of MiaDonna, we’ve seen the transition to using lab grown diamonds for fine jewelry, such as rings, earrings, necklaces and bracelets.
How are Lab Diamonds Created?
Through technological advances, there are now two primary methods for producing high quality lab grown diamonds:
the HPHT method and the CVD method.
Photo Credit: Diamond Foundry
The HPHT Diamond Creation Method
The HPHT method, which stands for high pressure and high temperature, is the original method of creating lab grown diamonds which recreates a diamond's natural growing environment found deep within the earth. Over time, this process was improved, and in the early 1950s this process started producing quality HPHT gem-grade diamonds. In addition to being a method for growing diamonds, the HPHT process is also used to enhance the color of lab grown diamonds to make them colorless, pink, green, blue, or yellow.
To grow an HPHT diamond, we start with a small diamond seed, highly refined graphite carbon and a catalyst consisting of a mixture of metals and powders. This is what earth mined diamonds are made of. The seed is then placed in the center of the HPHT chamber and is exposed to extreme heat and pressure which replicates the way diamonds are naturally grown underground by the earth. The diamond seed is then exposed to temperatures which exceed 2,000 degrees Fahrenheit and pressure of about 1.5 million PSI (pounds per square inch). The carbon melts, changing its atomic structure, and forms a diamond around the seed. It is then cooled and the diamond is formed.
Within the HPHT process there are primarily three press designs used. A Cubic Press is used to create diamond powder for industrial purposes. Cubic presses can also be very large and use 6 separate anvils that press onto a small cube to create the necessary pressure for crystal diamond growth. Belt Press is the founding technology behind growing diamonds. A Belt Press can be very large and can produce many diamonds in only one cycle by using two huge anvils that press together to create the necessary pressure. The Belt Press is capable of producing gem quality diamonds but is most commonly used to produce diamonds for industrial purposes, as well as diamond in powder form. Currently the Bars Press is the most effective tool used for producing gem quality diamonds. The Bars Press uses a combination of inner and outer anvils to apply hydraulic pressure to the growth cell within the unit.
The problem we found with this technology was it limited us in the size we could grow colorless diamonds. When MiaDonna pioneered the fine jewelry lab grown diamond industry in the early 2000’s, the diamonds being produced were under 0.25ct and were yellow in color. Enter CVD Technology…
The CVD Diamond Creation Method
Scientists started experimenting with the CVD method (Chemical Vapor Deposition) to grow diamonds in a lab in the 1980s, making it newer than the HPHT method. The CVD method imitates how diamonds form in interstellar gas clouds (outer-space). This method uses less pressure than the HPHT method, as well as smaller machines. This has become the go to production method for colorless diamonds in most laboratories.
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 rain down onto the diamond seed, causing the diamond to grow.
Perfecting the CVD method to grow diamonds in a lab has allowed us to grow much larger diamonds that are colorless. In 2016, MiaDonna proudly unveiled the largest colorless diamond, at the time, that had been grown in the United States. It is a stunning 6.28ct cushion cut Type II diamond and is a steal at $52,000. In the past, diamonds of this quality and size were reserved for celebrities and royalty, but with these advances in technology, they are now available to the general public.
Best Process for Type IIA Diamonds
The CVD process consistently produces the superior Type IIA Diamond quality (only some HPHT methods produce this quality of diamond), which are extremely rare for earth-mined diamonds. 97% of diamonds mined are the regular Type I diamond, which is what you will find in your local jewelry store. Type IIA diamonds are the most chemically pure diamonds, lacking nitrogen and or boron impurities, which makes them brighter and harder than Type I diamonds.
Which Lab Grown Diamond is Better? HPHT vs. CVD
If you are considering a lab grown diamond, you might be wondering if you should go with an HPHT diamond or a CVD diamond. Both technologies are fascinating, and both have their pros and cons. Fortunately, you don’t really have to worry about which process was used for your lab grown diamond. As with natural diamonds, the beauty of a lab grown diamond comes from its physical characteristics and not the precise method by which it was formed.
Just like earth-mined diamonds, the 4 Cs are used to grade and price lab grown diamonds. The type of inclusions and the shades of color will be slightly different with each kind of lab grown diamond, but the most important thing is the end result. Lab-grown diamonds, whether created via the HPHT or CVD method are far superior and more affordable than anything we will ever get out of the earth. Not to mention they are the most ethical option and are truly conflict free.
The majority of lab grown diamonds sold at MiaDonna are created using the CVD method. All come from SCS certified labs, and come with a 3rd party American grading certificate from either IGI or GCal.
Learn more about lab grown diamonds and browse our inventory.