Natural diamonds require extreme natural environments to form. High-quality colored natural diamonds are rarer and come from the uncanny natural environment.
Compared with natural diamonds, the color of colored lab-grown diamonds is more controllable. Through various laboratory conditions, the color of lab-grown diamonds can be adjusted to make lab-grown diamonds more colorful.
The color of lab-grown diamonds is usually achieved using the following methods:
1. Additives:
The ideal diamond structure is composed of carbon elements, but in order to obtain other colored diamonds, other elements are added during the artificial synthesis process to replace carbon atoms into the diamond lattice or lattice gaps, resulting in point-like impurities, such as yellow diamonds: due to The nitrogen content in the air is very high, and diamonds synthesized by high temperature and high pressure methods will often appear yellowish brown. If some metal elements are added to them, the brownish color can be reduced and pleasant light yellow, golden and other colors can be obtained. If boron and some nitrogen scavengers (aluminum, titanium, etc.) are added to the synthesis, the diamonds produced will appear blue.
2. Pressure effect:
During the process of synthesizing diamonds using the high-temperature and high-pressure method, the crystal is plastically deformed under the action of high pressure, and dislocations occur inside the crystal, resulting in “defective color centers”, which makes the diamond appear brown, pink, red, etc. When diamonds are grown by the CVD method, the entire diamond will undergo plastic deformation due to stress, showing varying degrees of brown color.
3. Radiation and heat treatment:
For some cultivated diamonds with poor quality, many impurities and unattractive colors, artificial color-changing methods are often used. These diamonds with poor color and clarity are irradiated with radioactive substances to change the crystal structure, causing holes and displacement to appear. Green, blue and dark blue are then turned into yellow, pink or red through high temperature, high pressure or heat treatment.
4. Surface treatment:
Surface treatment mainly uses coloring and coating to improve yellowish diamonds. The coloring process is to apply a blue substance on the girdle of the diamond to improve the yellow tone. You can also apply a colored oxide film on the surface of the diamond to cover up the body color; the coating process is to use the CVD method to apply a layer of colored oxide on the surface of the diamond. A layer of diamond film is grown quickly. The diamond film is a polycrystalline material composed of carbon atoms with the structure, physical properties and chemical properties of diamond. The film thickness is generally tens to hundreds of microns, and the thickness can reach several millimeters.
5. Splicing process:
One is to glue two small diamonds into a larger diamond; the other is to use the diamond as the crown and colorless and transparent sapphire or glass as the pavilion, and glue the two together. At the same time, in order to adjust the color of the diamond, the bezel setting method is used to cover the spliced layer when setting.