When I went engagement ring shopping with my now husband I asked him: “How is it 2016 and we still haven’t figured out how to man-make diamonds?” Fast forward to 2024 where lab grown diamonds are dominating the industry, with couples everywhere choosing lab for its ethical and economical properties. But how can a lab grown diamond be made of the same chemical composition as a natural diamond, when they're created so differently? Let's break down how a lab grown diamond is made to better understand it's chemical structure.
History
In 1954, Utah native H. Tracy Hall, who worked for General Electric, invented the first reproducible way to make a lab grown diamond. At the time, these synthetic diamonds were primarily used for industrial purposes, and the method invented by Hall is still used to create industrial diamonds today. It wasn’t until the 1970's that these diamonds started to be produced as high quality gems for jewelry.
Today, there are two major ways lab grown diamonds are produced. High Pressure, High Temperature (HPHT) and Chemical Vapor Deposition (CVD).
High Pressure, High Temperature
HPHT, the method invented by Hall, creates diamonds using an environment that mimics the earth’s internal pressure and temperature. A small diamond seed, a form of pure carbon like graphite, and a small metal flux are placed into a press. In a calculated environment, the carbon is heated to temperatures up to 1,600 degrees celsius and pressed with atmospheric pressures up to 5,200 atm. The carbon is then dissolved and starts to crystalize through the metal flux and around the diamond seed, eventually creating a lab grown diamond. This process can take several weeks, as opposed to the earth’s natural cycle of a few billion years!
Once HPHT diamonds are formed, they often continue heat treatment to enhance their clarity and color, or even to create a fancy colored diamond. For example, adding boron to an HTHP diamond can turn the diamond blue, and adding nitrogen can turn a diamond yellow!
Chemical Vapor Deposition
The CVD process starts with a very thin sheet of diamond which is placed in a chamber along with carbon, hydrogen, and oxygen gasses. The chamber is then heated to a temperature up to 900 degrees Celsius, which causes the carbon to precipitate out of the gasses and eventually crystalize into a diamond.
CVD diamonds can be grown in larger quantities and even faster than HPHT diamonds, but 70% of CVD diamonds come out with a brownish yellow color. When this happens, the CVD diamonds will still need heat treatment to get the best quality stone. GIA and IGI will list this post growth treatment on a diamond grading certificate, but it isn’t meant to say that the stone is worth any less, just that they want to provide you with as much detail on the growing process as possible.
Grading
Whether HPHT or CVD, a rough diamond will be assessed for inclusions, and will be cut and polished just like a rough natural diamond would be. Reputable lab grown diamond graders include GIA, IGI and GCAL. Since IGI was the first to embrace lab grown diamonds, most lab grown diamonds you find are graded by them. Lab grown diamonds are also graded slightly differently than natural diamonds are, with some elements left out like phosphorescence, and some elements added like post growth treatment.
Once a diamond is grown, cut, polished and graded, it’s ready to go inside your custom engagement ring or other precious jewelry! You should always consult a diamond expert when choosing a stone to buy, and feel free to ask as many questions as you’d like. Buying a lab grown diamond can be a new and exciting process, so enjoy the learning curve and trust that you’re in good hands with a professional like those at SHANNON.
Ready to create your dream lab grown diamond engagement ring? We can’t wait to help you get started!