Lab-grown diamonds are synthesized using two primary methods, drawing on advanced technology to replicate the natural conditions under which diamonds form:
- High Pressure High Temperature (HPHT): This technique uses a high-pressure, high-temperature environment to transform carbon material into diamonds. A machine subjects a carbon source to pressures above 870,000 pounds per square inch and temperatures between 1300 and 1600 degrees Celsius, closely imitating the Earth’s formation conditions.
- Chemical Vapor Deposition (CVD): In CVD, a seed diamond is placed in a vacuum chamber filled with carbon-rich gases heated to facilitate breakdown. The carbon atoms deposit on the seed, gradually crystallizing into diamond. Post-growth, some diamonds may undergo additional pressure and heat treatment to enhance quality.
|
Factor |
HPHT |
CVD |
|
Method |
High Pressure High Temperature |
Chemical Vapor Deposition |
|
Clarity |
Possible inclusions of metallic substances, may require more post-processing to remove imperfections. |
Tends to produce purer diamonds with fewer inclusions, closer to flawless clarity. |
|
Color Range |
Typically results in higher quality color grades, often achieving D-E color grade. |
Often produces colors from colorless to near-colorless, typically F-H color grade but can achieve higher with post-growth treatment |
|
Size Potential |
More suited for producing smaller diamonds, usually up to 2 carats. |
Capable of producing larger diamonds. |
Both methods produce diamonds that are visually indistinguishable from natural diamonds to the naked eye. Only specialized equipment and expertise can detect subtle differences in crystal structure and impurities, characteristic of their synthetic origin. As a consumer, you can distinguish the production method of a diamond from the GIA and IGI certificates. HPHT is also written as Type II, CVD is also written as Type llA.