What is CVD and HPHT diamond?

Not only does diamond has an important role in the jewel market, its property and sturdiness also make its usage an important one in different industries and technological fields. Still, generic application of diamond is difficult because of the high excavation cost. Lab grown diamond has led to many debates in the jewel market since a decade ago.


Many hope to create lab grown diamond, which share the same substance with natural diamond, in laboratory through artificial methods, so that the demand for natural diamond could be lowered and lab grown diamond can be more applicable in different fields.


However, due to the immature technologies in the early years, cultivating lab grown diamond was more costly than mining natural diamond, and the lab grown diamond at that time could not even be qualified as gem. That was why natural diamond still took up a large proportion in the jewel market.


As time passed, the technology for cultivating lab grown diamond has become more advance, while the cost has dropped. This has facilitated the launching of lab grown diamond on jewel market in the recent years.


For now, lab grown diamond can be mainly categorized into CVD and HPHT.



CVD diamond (lab grown diamond)

CVD technology refers to “Chemical Vapor Deposition”.


The technology involves putting a “diamond seed” (a tiny piece of natural diamond) in a specific vacuumed environment and exposing it to chemical gas containing carbon (which is the main component of diamond) atoms. With the use of microwave and heat, the carbon atoms within the gas will be vitalized and released, and the atoms will sediment on the diamond seed. The atoms will keep accumulating and grow into diamond crystals.


During the growth period, laboratory staffs will polish the diamond surface regularly and remove the non-carbon elements. Some by-product particles may be resulted during the process, but most will be blown away by air flow rather than remaining on the diamond seed.


Therefore, the purity of lab grown diamond is more controllable when cultivated through CVD technology.



HPHT diamond (lab grown diamond)

HPHT technology refers to “High Pressure High Temperature”.


To simulate the growth of natural diamond, the diamond seed will be placed inside a space with high pressure and temperature. Pure carbon substance (like graphite) will be melted and the carbon atoms within can be extracted. That, with the use of other metal flux, can loosen the requirement for diamond growth. The said carbon substance will move toward the diamond seed and crystallized.


Lab grown diamond cultivated through HPHT technology requires more advanced technology and more complex instruments than that of CVD cultivated diamond, though some HPHT cultivated diamonds created in the past may occasionally contain components from the metal flux.



With the technological breakthrough of lab grown diamond in the recent years, the processing cost has been lowered. The impurities problem of HPHT cultivated diamond has also been improved. CVD cultivated diamond is now more cost effective and can meet the demand of jewel market, which means sustainability for lab grown diamond business.


While lab grown diamond cultivated through CVD and HPHT technologies are different, the differences are only in the forms of production process and theories. Both type of them, in the end, are still diamonds which have the same diamond certificate and can be graded by the “4C grading of diamond”.


Nowadays, most of which that could be brought are lab grown diamonds, and they can already compete against high-grade-color and high-purity natural diamond.





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