CVD and HPHT are the most popular methods of forming diamonds in the laboratory. In this article, we are going to discuss both these methods and their feature, which one is the better method for diamond production.
High-Pressure High Temperature (HPHT) Method:
HPHT is abbreviated as high pressure and high temperature. It is a technique of administering HPHT to those diamonds that are not entirely crystallized, called premature diamonds, when diamonds are liberated from hot, exploding volcanic eruptions. The HPHT method is a meticulously regulated scientific approach.
The HPHT method completes the maturation of the immature diamonds that nature began by exerting 71,000 atmospheric pressures at temperatures up to 3,800°F, the similar conditions that nature applies to form natural diamonds.
A diamond will reach its entire fully grown state if these requirements are met. The HPHT procedure entails a highly experienced and reputable gemologist carefully placing a diamond within a confinement cube surrounded by heating devices to provide the required temperature.
The cube is then placed in a machine to simulate the pressure created by the Earth when diamonds are formed. The diamond is brought to its most mature, ideal, colorless condition via this procedure. The HPHT procedure merely completes what nature began.
Chemical Vapor Deposition (CVD) Method
Chemical vapor deposition is a technique for growing diamonds from a combination of hydrocarbon gases. This technique has been the focus of the extensive international investigation since the late 1970s. Preparing the substrate, introducing different quantities of gases into a chamber, and energizing them are all part of CVD development.
Choosing a suitable material and its crystallographic orientation is part of the substrate preparation process. Clearing the base or substrate, which is commonly done using diamond powder to melt down a non-diamond material, optimizes the substrate temperature to about 850 °C throughout the growth process through a series of experimental tests.
HPHT vs. CVD
With the naked eye, you won't be able to distinguish the difference between a CVD and an HPHT diamonds. Both procedures can produce a lovely, gleaming diamond. Both the CVD and HPHT methods will produce a genuine diamond that is visually, chemically, and physically similar to diamonds produced on the Earth. But the following facts and arguments help us to determine which method is more beneficial.
Chemical Vapor Deposition (CVD)-produced colorless lab grown diamonds , man-made synthetic diamonds are becoming more prevalent in the industry. Natural diamonds formed by geologic processes are very different from CVD-processed stones. They're also not the same as the High Pressure, High Temperature (HPHT) synthetic diamonds that have been around since 1955.
About ten years ago, CVD synthetic diamonds began to appear in the precious diamond industry. The procedure is placing a gas, such as methane, in a sealed vacuum chamber, then using radiation to activate and disintegrate the gas's molecules. This enables the carbon atoms to clump together on a substrate, much like snow does in a snowfall.
The high pressure and high-temperature method, originally used to produce diamonds effectively by standard electricity in 1955, basically mirrors the natural process of diamond formation.
Carbon crystallizes into diamonds under extreme heat and pressure deep below the Earth's surface. Given the amount of energy and equipment required, the HPHT process is costly and results in primarily brownish or yellowish diamonds in hue.
Because it operates at moderate temperatures and low pressure, the CVD technique is significantly less costly as it demands smaller and less expensive equipment. Colorless crystals may be produced in the vacuum chamber since it only includes carbon and some hydrogen.
The inventors of chemical vapor deposited diamonds first believed they would create diamonds fast and inexpensively. However, those expectations were not satisfied because the quality was uneven, and the standard brown colors were less than appealing.
CVD manufacturers have discovered that altering the gases in the growth chamber and utilizing a purer synthetic diamond as a seed crystal may enhance the color of the completed synthetic diamond while also speeding up growth rates during the last decade.
Because many early chemical vapors deposited diamonds had a brownish hue, manufacturers discovered that processing the material at high temperatures and pressures may eliminate the brown color, resulting in colorless crystals.
The other significant difference between CVD and HPHT is their morphology and growth patterns, and the HPHP has the octahedron morphology and grows in 14 different growth directions.
The CVD, on the other hand, has cubic morphology and has one growth direction, which is the weak point of the CVD method because the natural diamonds are also in the octahedron morphology, and this is the differentiating factor between different diamonds.
- The HPHT has octahedron morphology and numerous growth patterns, which is similar to real diamonds.
- The CVD has cubic morphology and a single growth pattern.
- The CVD is much less expensive than the HPHT because less pressure and temperature are required, and the equipment is also not as expensive as HPHT.
- The color of the CVD's diamonds matches closely to the real ones as they are colorless.
- The diamonds produced from the HPHT method are yellowish or brownish, which shows the artificialness.