How Are Lab-Grown Diamonds Made? Understanding HPHT vs. CVD
If you own a lab-grown diamond or are searching for the perfect lab-grown diamond engagement ring, you might be curious about how these diamonds are created. There are two primary methods used to produce lab-grown diamonds: the HPHT (High-Pressure High-Temperature) method and the CVD (Chemical Vapor Deposition) method. But what sets these two processes apart?
The HPHT Lab Diamond Growing Method
The HPHT method is the original technique for creating lab-grown diamonds, first introduced for gem-quality diamonds in the 1950s. In addition to growing diamonds, HPHT can also enhance a diamond’s color, producing vibrant hues like colorless, pink, green, blue, or yellow.
To grow an HPHT diamond, a small diamond seed is placed in carbon, the primary element of diamonds. This seed undergoes intense heat and pressure, simulating the natural conditions deep within the Earth. The diamond seed is exposed to temperatures exceeding 2,000°F and pressures of around 1.5 million PSI (pounds per square inch). As the carbon melts, it crystallizes around the seed, forming a diamond, which is then cooled to complete the growth process.
One key difference between HPHT and CVD diamonds is their growth shape. HPHT diamonds typically grow in a cub-octahedron form, while CVD diamonds develop into a more cube-like shape. Understanding these differences can help you appreciate the craftsmanship and technology behind each lab-grown diamond.
Are HPHT Diamonds Real?
Absolutely! HPHT diamonds are real diamonds and will test as such when using a diamond tester. Lab-grown through the High-Pressure High-Temperature method, these diamonds are chemically, physically, and optically identical to natural diamonds.
How Can I Tell If My Diamond Is an HPHT Lab-Grown Diamond?
To determine if your diamond was created using the HPHT method, check your diamond’s grading report. Most reports will specify how the diamond was grown under the Additional Information section. For example, a GIA report will clearly state if a diamond was formed using the HPHT process.
The CVD Lab Diamond Growing Method
The CVD (Chemical Vapor Deposition) method, developed in the 1980s, is a more recent innovation compared to the HPHT method. It replicates the natural formation of diamonds in interstellar gas clouds but uses lower pressure and smaller equipment than HPHT.
To grow a CVD diamond, a diamond seed is placed in a vacuum chamber filled with carbon-rich gases. The chamber is heated to around 1500°F, transforming the gas into plasma. This plasma releases carbon atoms that layer onto the seed, gradually forming a diamond.
One notable characteristic of CVD diamonds is that they are often Type IIA diamonds — a rare classification for natural diamonds. Type IIA diamonds are the purest form of diamonds, free of nitrogen or boron impurities. Unlike HPHT diamonds, which may contain nitrogen and sometimes exhibit magnetic properties, CVD diamonds are non-magnetic.
Are CVD Diamonds Real?
Yes! Diamonds created using the CVD method are real diamonds and will pass a diamond test. Lab-grown diamonds produced through CVD are identical to natural diamonds in their physical, optical, and chemical properties.
How to Know If You Have a CVD Lab-Grown Diamond
To find out if your diamond was grown using the CVD process, check your diamond’s grading report. The method of growth is usually specified in the “Additional Information” section. For instance, an IGI report will clearly state if the diamond was formed using CVD.
Which is Better: CVD or HPHT Diamonds?
With the naked eye, you won’t be able to distinguish between a CVD and an HPHT diamond. Both methods produce stunning, sparkling diamonds. Regardless of the process used, both CVD and HPHT diamonds are real diamonds — identical to natural ones in their optical, chemical, and physical properties.
