The process of creating grown diamonds (also called synthetic or lab-created diamonds) from carbon is almost magical.
The technology needed to create grown diamonds was discovered in the 1950s. After nearly seven decades, scientists can recreate conditions to grow diamonds inside machines. Today, there are two trusted methods of creating grown diamonds in laboratory – the Chemical Vapor Deposition or CVD method and the High-Pressure High-Temperature or the HPHT method.
In both these methods, the raw material used is a carbon seed (which is technically a thin slice of diamond and diamonds are pure carbon).
What’s the High Pressure High Temperature Method?
As the name suggests, this diamond growth process includes subjecting carbon to extreme temperatures and pressures to replicate the extreme heat and pressure conditions deep within the earth where natural diamonds form.
According to the GIA, the process starts inside specifically designed HPHT presses (machine) whose chamber is heated to 1300-1600°C with pressures above 870,000 pounds per square inch. Within this growth chamber, a carbon starting material, such as graphite, dissolves in a molten flux consisting of metals such as iron (Fe), nickel (Ni) or cobalt (Co), which lowers the temperature and pressure needed for diamond growth. The carbon material then migrates through the flux towards the cooler diamond seed and crystallizes on it to form a diamond crystal. Crystallization occurs over a period of several days to weeks to grow one or several crystals.GIA
HPHT is a popular method used to grow diamonds for many important industrial applications. (Diamond’s amazing properties like hardness, thermal conductivity, etc. are important in mechanical tools and equipment).
Using HPHT, it is difficult to create grown diamonds that are truly colorless, especially of quality grades that will make them acceptable in fine jewelry applications. This is because even the smallest presence of nitrogen or boron during the process can result in a yellow or blue color diamonds respectively.
While colored grown diamonds are considered quite rare but they are still a small percentage of the diamond jewelry market.
Using the CVD technology enables to grow diamonds inside a vacuum chamber from a hydrocarbon gas mixture. (CH4 or methane gas)
A thin slice of diamond seed (often an HPHT produced diamond) is placed within the chamber and then heated to high temperature of around 800 degrees Celsius. This is the ideal atmosphere designed for a lab grown diamond to be born. The gas is then ionized into plasma using microwaves, lasers, or other techniques and in the process of ionization breaks the molecular bonds in CH4 and the pure carbon rains on to the diamond seed, layer by layer.
The CVD process, even though complex, has a few advantages over the HPHT process. High pressures are not needed, and temperatures, and while still high they are nowhere as high as that of the HPHT. Also, the CVD process being a more recent technical advancement, allows for a finer control over the diamond growth environment inside the chamber which in turns can improve the yield quality.
At the same time, CVD diamonds are a result of a technically complex method where equipment, raw materials come at a hefty cost. The technical manpower needed to apply this technology in real-time is also a major limiting factor why high quality diamonds worthy of being set in jewelry remain difficult to grow in laboratories.
A diamond is the hardest stone known to mankind and a lab-created diamond or synthetic diamond one is no different. They share the same chemical and physical properties as naturally mined diamonds.
Both are born from the same element called carbon and endure similar atmospheric conditions to result in a crystal that’s unmatched in its sparkle and beauty.
The great thing about the man-made process is that it is now possible for consumers to choose colorless grown diamonds or fancy colored grown diamond which were ‘out-priced’ for most consumers.
Unlike stimulants such as cubic zirconia, moissanite, or white sapphire, lab grown diamonds are 100% diamonds and will pass all diamond tests. The only difference is their origin.
The one major reason that millennial and celebrities too are shifting to lab created diamonds is because of origin assurance which is an important aspect for consumers today.
Lab grown diamonds are graded (or certified) by the same diamond grading agencies and governing bodies that grade all the mined diamonds (GIA, IGI, GCAL among others)