There are three main factors to consider when buying a CVD diamond. These are the SiV-doublet, the Nitrogen content and the Color range. If you want to buy the best diamond for the lowest price, you should first understand what CVD stands for. Then, you can make a more informed decision. Let’s take a look at how CVD diamonds are made. What makes them so special?
Vacancy is created
CVD diamonds that contain a silicon atom have a unique doublet (SiV-doublet) at 736.6 nanometres. This vacancy is created by substituting one silicon atom for two carbon atoms in the diamond matrix. The result is a doublet with a single spin-1/2 electron and a high-quality crystal. The diamonds’ high-quality crystals are also known as SiV-doublet CVD diamonds.
The characteristic fluorescence pattern of a SiV-doublet CVD diamond can be used to detect CVDs. These diamonds are often identified using the DiamondView imaging instrument. Photoluminescence spectroscopy (PLS) is another technique that can be used to detect the silicon-vacancy defect. Other visual gemological characteristics are also helpful for identifying CVDs, but they are not definitive.
Nitrogen concentration
One of the hottest topics in research on CVD diamonds is the incorporation of impurities. For example, nitrogen can enhance the dosimetric properties of diamonds and make them better radiation detectors. Similarly, nitrogen incorporation in single crystal diamonds can create high-density NV centres. This article will review several studies on the topic. Let’s start with a review of the current literature.
To understand the chemical reactions involved in the process, we first consider the role of nitrogen. Nitrogen is used to accelerate the growth of single-crystal diamonds. It can also improve the bonding properties of the formed adamantine substrate. Furthermore, nitrogen has two important purposes: to increase the growth rate of single-crystal diamonds, and to prevent lattice defects. Here, we look at two such applications.
Color range
The color range of CVD vs HPHT diamonds is broad, and there is considerable variety within it. In as-grown samples, the broad bands typically occur together. The 510 nm band can contain isolated substitutional nitrogen, resulting in hues ranging from pink to orange brown. A CVD diamond with a single crystal of brown color could show a broad band centred in the NIR region of the spectrum. In contrast, the short wavelength side of the band could show significant absorption at the red end of the visible spectrum, creating a blue hue.
The brown color of CVD diamonds is due to a defect called vacancy. The process of creating CVD diamonds involves growing layers of material layer by layer, and this leaves small voids. The high growth temperature allows incorporated vacancies to become mobile, and these voids dissolve into vacancy disks, resulting in energy reduction. The brown hue of CVD diamonds is generally very pronounced, and this characteristic can be minimized by increasing the color grade.
Size of a single diamond
CVD diamonds are man-made and, as a result, the cost of these stones is comparable to that of natural diamonds. This process involves a number of steps, including using more than one seed, which leads to smaller diamonds. However, it is worth noting that the size of a single diamond is limited by the amount of carbon in the iron-based melt. This makes the production of CVD diamonds more expensive than traditional methods.
CVD diamonds cost less than HPHT diamonds. The two diamond-making processes are almost similar, but the differences between them are the quality of the stone, the type of jewelry setting, and the design of the stone itself. While CVD diamonds are generally of lower quality, they are still priced similarly to mined diamonds. Whether or not you decide to buy a synthetic diamond is a personal choice. For many people, the cost difference between HPHT and CVD diamonds comes down to the choice of the stone.
Conclusion
In CVD, the process of diamond synthesis is characterized by the presence of defects. The earliest type of CVD diamonds are known as Type Ia, while the later type is referred to as Type IIa. The difference between the two is that Type Ia diamonds have an abundance of C defects, while Type IIb diamonds have a low concentration of C defects. However, type IIa diamonds are much rarer.
