Last month, a 1.29 carat colorless “E” synthetic with almost no inclusions (the largest of its kind in history) hit the polished diamond market. While synthetics have been produced since the 1950s, the technology has been primarily used to supply the market with industrial grade stones, not gem-quality diamonds.

In 1954, General Electric successfully implemented a super high-pressure, high-temperature (HPHT) technology that was capable of producing a diamond in a laboratory that was chemically identical to that of a natural one. The process involved exposing carbon and graphite to extreme pressure and temperature, mimicking the natural diamond creation process. More than 50 years later, versions of this process are still used to supply 98% of the world’s industrial grade diamonds. The downside of HPHT is that most of the diamonds produced are in shades of yellow and brown because of the presence of nitrogen in the manufacturing process. There have been successful attempts creating colorless diamonds using HPHT, however the cost of doing so renders the method uneconomic. More significant to the jewelry market is the use of HPHT to upgrade or “treat” natural stones improving the color and clarity.

About a decade ago Chemical Vapor Deposition (CVD) diamonds began to appear in the gem diamond market. The CVD method can produce diamonds in a lower pressure environment than HPHT, using a gas such as methane and a substrate to grow diamonds. Diamond composition can be controlled to create a single crystal form allowing the production of very clean colorless diamonds over a carat in size much more economically than HPHT.

While HPHT has the advantage of using fewer ingredients and producing more diamonds more quickly, making the process most suitable for producing industrial grade diamonds, CVD is more suitable for manufacturing higher quality diamonds because the process permits more refined control over the chemical properties.

The record breaking 1.29 carat stone mentioned above was created using CVD, and is currently on the market for $7,633, about 38% cheaper than a natural equivalent which can currently be found on the market for around $10,500.