Professional Supplier of Synthetic Stones
Free shipping on all orders placed on our website./ FAQ
Home / News / Lab Grown Diamond / Some things about colored lab diamonds

Some things about colored lab diamonds

Views: 125     Author: Site Editor     Publish Time: 2022-01-19      Origin: Site

Inquire

facebook sharing button
twitter sharing button
line sharing button
wechat sharing button
linkedin sharing button
pinterest sharing button
whatsapp sharing button
sharethis sharing button
Some things about colored lab diamonds

Fancy colored diamonds are made and marketed in a similar way to natural diamonds that are artificially re-colored, with diamonds of poor color and clarity that are not suitable for direct sale as white diamonds, i.e., poor quality. For example, diamonds with light to medium brown color and clarity that are cloudy or flawed, which are unsuitable for sale as white diamonds, are irradiated, autoclaved or heat treated to change them into various colors and then sold.

The causes of diamond color

I. Impurity elements: diamonds in the process of generation, there are other elements into, and caused by the point impurities.

 

1) Nitrogen: Nitrogen is the most common impurity element in diamonds, replacing carbon atoms and entering the lattice. Absorbed violet and blue light area, emitting yellow light, to its presence in the state is divided into Ib - single nitrogen, IaA - double nitrogen, IaB - three nitrogen, four nitrogen, sheet nitrogen.

 

2) Boron: Boron replaces the carbon atom and enters the lattice. Absorbs the yellow light region and emits blue light, type IIb.

 

(3) hydrogen: hydrogen atoms are very small and can enter the diamond interstices, natural diamonds contain a large amount of hydrogen, appearing gray tones; CVD diamonds have been driven out of the hydrogen in the high temperature and high pressure color change, and the gray color is not formed by hydrogen.

 blue diamond

Second, plastic deformation: after the generation of natural diamonds, by the action of high pressure, resulting in line or surface lattice dislocation or plastic deformation. The most common colors are: brown, pink, red, etc. CVD diamonds in the growth, because of the negative pressure, the entire diamond is filled with stress formed by plastic deformation, and produce different degrees of brown.

 

Third, point defects: diamonds are irradiated by radioactive substances, so that the proton, neutron or its outer ring of electrons in the nucleus of the carbon atom is knocked away, resulting in cavities, displacement, common colors are green, blue, black, and then after high temperature and pressure or heat treatment, will produce yellow, pink, red, etc.

The causes of the various colors of color-bred diamonds

I. Direct growth

 

(1) yellow: HPHT method of direct growth in the air assembly of raw materials,because the air contains 78% of nitrogen, will grow brownish yellow, if you add some metal elements can reduce the brown and get light yellow, medium yellow, golden yellow.

 

(2) Blue color: HPHT method of growth of raw materials by adding aluminum, titanium and other nitrogen removal agents, while adding boron, will produce a blue color; CVD method of growth by adding boron will also produce a blue color. These two kinds of blue are gray-blue, not bright enough, and not pleasing.

Second, irradiation color change, heat treatment

(1) Blue, green, black: all kinds of radiation sources can be used to change the color, but some of the effects are too poor, such as cobalt 60, and some irradiation residues are too strong, such as the fast neutrons emitted by nuclear reactors. Nowadays, when the gemstone industry needs irradiation, they use high-energy electrons produced by electron gas pedals with very short irradiation residual times, which are cheap in terms of equipment and irradiation cost.

Over-irradiation produces extremely dark blue and dark green, which looks black.

(2) yellow, pink, red: irradiation to get the blue, green, can be used again at high temperature and pressure, atmospheric pressure under hundreds to thousands of degrees Celsius low to high temperature heat treatment, depending on the original diamond contains different trace elements inside and get different colors. For example, a small amount of mono-nitrogen can give a pink color, and a large amount of mono-nitrogen can give a red to dark red color.

 

If a CVD diamond grows with brown color, the brown color must be reduced or eliminated by high temperature and pressure, and if the result is white, the owner will naturally sell it as a white diamond, and only if it produces gray color will it be sold as a fancy color diamond by irradiation. If a white diamond is irradiated to change its color, it will almost always be a vivid color.

 red diamond

When irradiating to change the color, the depth of the color entering from the diamond surface is about 1~3mm depending on the irradiation dose and time, and the normal irradiation can be done after the diamond is cut and polished, which basically does not hurt the diamond surface. High temperature and high pressure treatment will reduce or eliminate the brown color of the whole diamond, but will burn the surface of the diamond, usually after the rough grinding that is high temperature and high pressure color change, after the completion of the polishing needs to be re-polished.

 

The sales of natural fancy colored diamonds are about a few thousandths of white diamonds, and the sales of cultivated fancy colored diamonds are about a few percent of white diamonds. However, when the color is changed, a large part of the color is unattractive, such as pink with some brown or purple tones, which is not a nice positive pink. The blue color obtained by adding boron in growth is a grayish blue, or ink blue, which is not bright. A bad color, it will not sell at a high price point and will have a high percentage of stock.

 

De Beers sells blue, pink and white diamonds at the same price, and their color is good because the diamonds they use are originally white diamonds or very light brown or gray diamonds, so the color is good after the change.

 

Other manufacturers, especially CVD lab diamonds, can still sell very light brown and gray diamonds as white diamonds, and only change the color of darker brown and gray diamonds, so there is a high percentage of colored diamonds that are not good in color, so there are a lot of colored diamonds on hand. This situation, the industry to find ways to avoid.

 


Search for the products you need

Please Enter Your 
Information

Contact Us

  +86-158-7807-9646
 +86-774-3934000
 info@messigems.com - Linda
  B171-175, 2nd Floor, Gem Building, Wuzhou, China

Company info

Customer Service

Shipping

Copyright © Wuzhou Messi Gems Co.,LTD.