CVD Diamond is made in a laboratory from a seed. This seed can be a thin slice of graphite or a chunk of diamond. Specific gases are used in the process to grow the diamond atom by atom. The seed is placed in the chamber under a high vacuum, and then energy is applied to break down the chemical bonds between the gases. As the gases diffuse, the seed grows atom by atom.
A CVD diamond has the same chemical composition as a naturally grown diamond, but it is much cheaper to produce. While natural diamonds are mined from the earth, the production of CVD diamonds is less harmful to the environment, costs less, and produces less waste. Moreover, this type of diamond is not environmentally or socially damaging, since it is manufactured in a laboratory, rather than an open-pit mine. Besides, this technology is only available to a few companies globally, making it more economical for smaller-scale players.
The main difference between natural and CVD diamonds is their color. In natural diamonds, a single fluorescence band can be distinguished by its NV (near-colorless) color. The CVD process involves two main processes. First, the diamond substrate must be cleaned. Then, the gas mixture must be fed into the growth chamber. Once in the growth chamber, the gas molecules are ionized into chemically active radicals. These reactions occur in the growth chamber with the help of a welding torch or hot filament.
While diamonds are naturally colourless, CVD diamonds can contain metal or mineral inclusions. In addition to this, CVD diamonds are often surrounded by inclusions. These are called striations in the Gemological Institute of India classification system. They are a form of Type IIa diamond. They are considered to be the purest form of diamonds and are used in optical windows, laser components, and cutting tools. These types of synthetic diamonds are undergoing intense research to improve the growth process.
As compared to natural diamonds, CVD diamonds are often colored pink or purple. The color of the stone depends on the gas that was used during the process. Some varieties of CVD diamonds have a stepped or banded surface. In both cases, the center is a distinct, colored band. The striped banded graining is a characteristic of aCVD diamond. Various types of graining are caused by dislocations in the diamond lattice.
The fluorescence of a diamond is crucial for identifying it as a synthetic. A striated pattern indicates that a CVD Diamond is artificially colored. Hence, a striated CVD diamond is unlikely to be treated. Its color is more likely to show orange-to-red and red NV centers, which indicate it is a natural diamond. Nevertheless, it is important to note that a striated pattern does not necessarily indicate that a stone is a natural Diamond.
One example of a GIA-certified diamond is a diamond with a VS1 clarity grade. In the case of a Type II diamond, the diamond is nearly colorless and has a D-to-Z scale. It is rarer than natural diamonds, which are largely transparent. In addition to these differences, the GIA’s certification also notes that the CVD-certified stone is more stable than other types of crystal.
Another CVD diamond is a fancy-colored brown diamond. It is usually white or yellow, but some types of brown have been graded by manufacturers and clients. The GIA attributes the color of this diamond to its non-diamond carbon inclusions. Despite its obvious similarities to a natural diamond, however, a CVD diamond is more eco-friendly and requires less capital to create. It also takes less time to grow, making it more desirable.
Initially, CVD diamonds were brown and had brownish color. After the initial growth, the CVD producer changed the gas in the growth chamber, which accelerated the process and made it more uniform. By doing this, the diamonds grew at faster rates and were more consistent in quality and color. This new process can produce diamonds of any shape and size, but the cost of a CVD diamond is still higher than a natural diamond.