CVD Vs HPHT – What’s the Difference?
CVD and HPHT are the two primary methods used to create lab-created diamonds. It’s essential to be aware of the distinctions between them so you can make an informed decision when purchasing a diamond.
Both processes can produce diamonds that appear optically, chemically and physically identical to earth-mined gems. However, there may be subtle distinctions that require the use of a microscope for identification.
Cost
Laboratory-grown diamonds are created using two main processes: cvd vs hpht. Both of these techniques produce stunning gems with similar color, clarity, and morphology to naturally occurring diamonds.
Both processes involve placing a small diamond seed inside an enclosed chamber and exposing it to carbon gases like methane or hydrogen. Once heated to temperatures that cause them to break down, these gases deposit thin layers of carbon onto the diamond seed.
Carbon layers build up inside diamonds as temperatures increase, creating higher-quality stones with lower energy consumption than naturally mined diamonds.
However, it’s essential to remember that the HPHT process can be expensive due to its high power and machinery requirements. Furthermore, diamonds created through this technique often exhibit yellow or brown hues.
Color
When it comes to lab grown diamonds, there’s often misinformation surrounding the topic. Although they’re synthetic (not like cubic zirconia or moissanite), they look very similar to natural diamonds and there are so many varieties that it can be difficult to tell which ones are real.
Chemical vapor deposition (CVD) is a more recent process than HPHT and replicates diamond formation in interstellar gas clouds. CVD utilizes a vacuum chamber filled with methane gases to recreate this natural phenomenon.
Once the gas has vaporized, it leaves behind a layer of carbon which traps onto the diamond seed crystal. This results in yellow and brown man made diamonds.
Recent advances have allowed for the production of colorless CVD lab-grown diamonds. These are created using a type IIa diamond seed crystal, which is rare.
Clarity
Laboratory-grown diamonds can be created using two primary techniques: high pressure, high temperature (HPHT) and chemical vapor deposition (CVD). Both produce optically, chemically, and physically identical diamonds.
The HPHT process replicates the natural creation of diamonds in the earth’s mantle, using extreme temperatures and high pressure to crystallize carbon into a diamond. Although more expensive due to required equipment and energy requirements, this method typically produces yellowish or brownish colored diamonds.
General Electric first used the CVD method of growing diamonds in 1954, which is more cost-effective due to its working at moderate temperatures and low pressure. Furthermore, this requires less equipment and produces diamonds with an array of colors.
The primary distinction between lab-grown diamonds produced through hpht vs cvd methods lies in their growth patterns. An HPHT diamond grows into a cuboctahedron shape with 14 unique growth directions, while the CVD diamond develops into an upright cubic form with one growth direction.
Weight
When it comes to lab-grown diamonds, two processes are employed: HPHT and CVD. Both processes produce an exquisite synthetic diamond that is optically, chemically and physically identical to a natural gemstone.
Lab-created diamonds, however, are more eco-friendly as they use less energy and leave smaller carbon footprints on the earth. Plus, these gems tend to be nearly 40% less expensive than naturally mined gems.
In the HPHT method, a small diamond seed is embedded in carbon and heated and pressured until it melts and forms a diamond around itself.
Conclusion
After that, the pressure is relieved and carbon is cooled. Finally, a diamond is cut and polished like a natural gemstone.
HPHT diamonds may show strain lines, similar to the whitish graining found in natural diamonds. While this does not affect a diamond’s clarity grade, it’s something to be aware of nonetheless.
