CVD (Kemisk dampaflejring) diamonds are created in a laboratory environment and their color is usually controlled during the growth process. Most CVD diamonds are nearly colorless or yellowish in color, similar to traditional diamonds found in nature. Imidlertid, it is theoretically possible to introduce color during the growth process, but this is not common.
For some manufacturers there is the ability to customize growth conditions to produce diamonds with the desired color. Availability of colored CVD diamanter may be limited compared to traditional colorless or near-colorless diamonds.
There are several main ways to color diamonds:
Traditional diamond color optimization method: An ancient treatment method is to apply a thin layer of bluish substance with a high refractive index on the surface of the diamond, which can improve the color of colorless diamonds by 1-2 levels. Some even apply colorless nail polish directly.
HPHT high-pressure high-temperature method: Diamonds are annealed under high-temperature and high-pressure conditions to repair yellow-brown, tan, and brown type IIa diamond crystal defects, causing the diamonds to fade and form high-color diamonds; or this method can also be used Turn colorless diamonds into visually “colored diamonds”, such as pink diamonds, blue diamonds, green diamonds, yellow diamonds or blue, etc.
Coating method for colorless diamonds: CVD coating is a new technology for optimizing the color of diamonds. Generelt, the crown of type Ia faceted diamond is coated with a layer of synthetic sky blue with a thickness of several to dozens of microns using chemical vapor deposition. Diamond film to imitate natural blue diamonds; this color treatment can only be identified in professional laboratories.
Radiation color changing method: Radiation color changing uses radiation irradiation to change the color of the stone, which can be called a permanent color changing method. Irradiation can produce different color centers, thereby changing the color of diamonds. Irradiated diamonds can appear in almost any color, such as blue diamonds and green. Imidlertid, this radiation color-changing method is only suitable for colored diamonds with poor color. For diamonds above K color grade, it is impossible to use this method to improve the color grade.