HPHT Diamonds are diamonds that have been heated and treated to create a high-tech diamond. They are much more expensive than conventional mined diamonds because of their unique properties. These include: Banded “strain” pattern, Interference pattern, Physical properties, Color treatment, and more.
Color treatment
The hpht diamonds color treatment is a fairly new process to the jewelry trade. It was introduced in 1999 by General Electric and Lazare Kaplan International. However, some gemological laboratories had known about the technique as early as the mid-1990s.
The process is fairly simple and comparatively inexpensive. The result is an aesthetically pleasing diamond that retains its polish and other properties.
The process works by exposing the stone to high pressure and temperature. This promotes the growth of crystal structures. Depending on the type of diamond being treated, the color may be a subtle change or a dramatic one.
The most notable effect of this process is that it permanently alters the color of the diamond. In addition, the process can repair any defects that might be present.
Interference pattern
The interference pattern of hpht diamonds has been studied using microscopic observation. In this study, a series of HPHT diamonds were synthesized with nitrogen content varying from 50 to 600 ppm. These samples were examined for their first-order and second-order interference colors.
In general, the PL intensity of NV color centers in the HPHT diamonds decreased with increasing NS content. During standard HPHT synthesis, the nitrogen atom concentration is around 250 ppm. However, NS atoms in the diamond microcrystals are much lower than this. Thus, PL intensity of NV color centers is determined by the NS concentration.
For example, the FWHM of the 1332 cm-1 band was measured in the samples with lowest and highest NS concentrations. At the lowest NS concentration, the band had a FWHM of 3.4 cm-1. This value was higher than 3.6 cm-1 for the sample with the highest NS content.
Banded “strain” pattern
Banded “strain” patterns are often observed in CVD-Grown synthetic diamonds. However, this is not the only way to get a banded pattern. These are also present in HPHT-grown synthetic diamonds.
Using these methods, diamonds can be produced in a variety of shapes and sizes. In addition, this method requires a relatively low up-front cost. The process is a bit different than the natural process.
In the natural method, a diamond is created when hydrogen is combined with hydrocarbon gas. This is then heated to a high temperature. Once the diamond has crystallized, it is then treated with a chemical process. Generally, this process produces a colorless diamond.
As with a natural diamond, a number of crystals grow at the same time. These are called “seed” crystals. Each of the crystals carries a small number of neutrons.
Physical properties
Diamonds are the hardest naturally occurring substance known to man. These gemstones are formed by the crystallization of a tetrahedral structure of carbon atoms.
The internal structure of a diamond is a three-dimensional lattice with a large number of covalent bonds. This arrangement allows for great hardness and high thermal conductivity.
When a diamond is cut, the crystalline lattice is cleaved into octahedron planes. These planes contain a series of weak voids, or vacancies. Vacancies are responsible for the various colors of diamond. Colors vary from light to dark shades, depending on the presence of impurities.
In addition to the four valence electrons in a diamond, there are four single bonds. These bonds are joined to the atoms of four other carbon atoms by strong covalent bonds.
HPHT vs mined diamonds
The question of HPHT vs mined diamonds is not always easy to answer. However, it is important to keep in mind that both methods can produce a perfect diamond.
The two processes are similar. They both create a diamond by heating a carbon source, typically graphite or diamond powder, under high pressure. But they differ in one key way.
The HPHT process involves a lot more energy. Also, it can be expensive to operate. It has been around longer than the CVD method.
But if you have the money to invest in a high-quality diamond, the HPHT process can be a good choice. A diamond created by this method is a little more yellowish in color. There are a few reasons for this.
One is the inclusions. The inclusions are a sign that the lab-grown diamond is not as pure as its natural counterpart. Another reason is the lack of clarity.
