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CVD Diamonds Compared with Natural Diamonds

CVD diamond is one type of lab-grown diamond, the other is HPHT diamond.

A CVD diamond has the same crystal structure and chemical composition as a natural diamond. Therefore, they look just like the natural gemstone. They sparkle the same. They have the same hardness.

The differences between a natural and a CVD diamond stem from how they were made. CVD diamonds are man-made in a lab while natural diamonds are created in the earth. Nature is not a controlled, sterile environment, and natural processes vary abundantly. Therefore, the results are not perfect. There are many types of inclusions and structural signs that nature made a given gem.

CVD diamonds, on the other hand, are made in a controlled environment.

What are CVD Diamonds

Chemical Vapor Deposition (CVD) is a more recently developed technique by which diamonds can be grown from a hydrocarbon gas mixture. In the CVD process, a thin slice of diamond seed (often a natural diamond) is placed in a sealed chamber and heated to around 800 degrees Celsius. The chamber is then filled with a carbon rich gas (usually methane) along with other gases. Then, the gases are ionized into plasma using microwaves, lasers, or other techniques. The ionization breaks the molecular bonds in the gases and the pure carbon adheres to the diamond seed and slowly builds up into a crystal, atom by atom, layer by layer.

What are the differences between CVD and HPHT diamonds

The CVD process has a few advantages over the HPHT process.

1.High pressures are not needed, and temperatures, while high, do not need to be anywhere near as high as with HPHT.

2.Also, CVD diamonds can be grown over larger areas by starting with a larger diamond seed plate.

3.Finally, the CVD process allows for a finer control over the environment in the growth chamber and thus the properties of the finished diamond.

4.With HPHT diamonds, it is very difficult to create truly colorless gems. This is because even the smallest presence of nitrogen or boron during the process can result in a yellow or blue color respectively. On the contrary, intense research is ongoing in our company into the field of Chemical Vapor Deposition, and every day the technology is improving. The company pioneers a major breakthrough in industry.

Microwave Plasma Chemical Vapor Deposition (MPCVD) advancing and enhanced the quality, output and accuracy. Meanwhile, energy consumption reduced and increased functionality at the same time.Thus, only ZS technology can grow the finest CVD diamonds without any color enhancement/treatment all over the world, which, in year 2019, were identified and certified by IGI as the world-only pure CVD.

Measurement of lab-grown diamond

Just like natural diamonds, the 4Cs are used to grade and price lab grown diamonds. The type of inclusions and the shades of color may be slightly different with each kind of lab grown diamond, but the most important thing is the end result. A G color, SI1 clarity CVD diamond will sparkle just as brilliantly as a G color, SI1 HPHT diamond (assuming they were cut to the same proportions of course).

Nowadays, quite a few authorities are introducing the new standards “5Cs+2T” to measure the CVD diamonds, 2T is representative of transparency and treatment, thus, only the CVD diamonds from ZS tech are without any treatment and certified by IGI.

INTERNATIONAL GEMOLOGICAL INSTITUTE