The genesis of the dreamy world of naturally colored diamonds
Posted by Hari Krishna
March 22, 2021
The dreamy world of naturally colored diamonds is surprisingly large. You might be surprised to know that natural diamonds come in all the colors of the rainbow spectrum.
The natural diamonds have 12 primary colors and 27 base colors. However, the original color of diamonds is noticeable only through face-up view.
Besides, very few diamonds have a pure hue (single color). Most of the diamonds have varying gradients of the intermediate modifying hue of colors that form over 200 color combinations.
For example, yellow diamonds might exhibit hints of green (which are called greenish-yellow) or orange (which are called orangy yellow).
After knowing that the natural diamonds have more color shade options than your pair of jeans, you must have understood that the process of diamonds naturally getting colored is very complex.
Even multiple causes of color can exist behind the single naturally colored diamond. So, let see how your favorite naturally colored diamond has got its color:
Natural diamonds are nothing but a rare form of crystalline carbon. The perfect diamonds are made of 100% carbon and end up being colorless.
But as we all know, perfection rarely exists!
Diamonds, during their formation process, accumulate different kinds of defects. Such defects exhibit in the form of a vibrant spectrum of colors from the diamonds.
These formation-defects modify the direction of the light entering the diamond or selectively absorb/refract the particular wavelengths of light from the visible light spectrum.
As each wavelength of light corresponds to a distinct color, selective transmission/absorption or alteration in the direction of light induces apparent color to the diamonds.
Examples of such defects:
• Inclusion of other elements such as boron, nitrogen,
• Uncommonly high temperature or pressure during the formation process,
• Vacant sites between carbon atom bonds,
• Minute deformations due to radiation,
• Higher than normal concentration of carbon,
• Inclusion of tiny particles of non-carbon mineral materials, etc.
Let us see them in detail:
One of the most common causes of diamonds getting particular color is the substitution of carbon particles in the diamond crystal lattice (molecular structure) by any other atoms.
However, there are very few elements whose atom size is nearly similar to carbon atoms and can substitute them in the diamond crystal in a way that can produce any color.
These elements are – Boron, Hydrogen, Nitrogen, and their isotopes. They produce colors:
❖ Yellow:
Yellow-colored natural diamonds become Fancy colored natural diamonds when they are beyond fall outside the traditional D-Z color-range (colorless to light-yellow) of diamond grading.
Natural diamonds get fancy yellow color when nitrogen atoms substitute for carbon atoms in the diamond crystal lattice (mineral structure).
The intensity of the yellow color varies according to the concentration of nitrogen.
❖ Blue:
The blue color in the diamond is due to the substitution of carbon atoms by boron atoms in the diamond lattice.
❖ Violet:
Violet color in the natural diamonds is either due to the radiation effect or the hydrogen atom substitution in the diamond lattice.
During their formation process, if a diamond is near to the radioactive mineral grains, the high-velocity radioactive particles throw out/displaces the position of some carbon atoms in the lattice.
It creates the vacant space in the crystalline structure of the diamond and deviates the usual path of entering visible light to the diamonds.
Radiation often produces green color in natural diamonds.
❖ Green:
Green-colored natural diamonds are rare.
Besides the high-energy radiation, the presence of nitrogen, hydrogen, or nickel atoms in diamond lattices is the other possible reason behind the naturally green colored diamonds.
Sometimes, diamonds get exposed to extremely high pressure/temperature for millions of years during their formation process within the earth-surface.
Due to this, they experience some lateral forces of plate-tectonics, causing the change in the alignment of the diamond structure lattice known as glide planes/slip planes.
These glide planes are not like fractures. They are microscopic planes (visible under 10X magnification) within the diamond along which carbon atoms shifting takes place.
However, the glide planes do alter the way that light passes through the diamond crystal. Some diamonds have multiple parallel glide planes, which increases the intensity of the diamond-color.
Most graining displays are brown, and in rare instances, pink or red.
❖ Pink & Red:
Red & Pink are rare natural colors in diamonds.
It occurs due to the extra high pressure/temperature during the diamond formation process causes glide planes within the diamond crystal lattice.
When light passes through these glide planes, red light from the visible spectrum is selectively transmitted.
The red light appears pink when this selective transmission is weak.
❖ Brown:
Brown color develops in the natural diamonds when plastic deformation creates planes of displaced carbon atoms (also known as internal parallel glide planes) in the diamond lattice.
When the uniformly distributed tiny diamond-inclusions, they can render the diamond opaque black color or a highly reflective translucent milky white color.
❖ Milky White:
Milky white natural diamonds occur when the diamond has dense clouds of fine-grained & reflective/translucent mineral inclusions.
These inclusions interfere in the passage of entering & reflecting the visible light spectrum.
❖ Black:
Naturally black colored diamonds contain such a high density of mineral inclusions like graphite, pyrite, hematite that allows very little light to pass through the crystal.
Some heavily fractured diamonds also induce naturally black color due to graphitization of the fracture surfaces.
[Please note: The above-listed causes of the color in natural diamonds are just a few of the many. There are many causes of color in diamonds by combinations of multiple treatments, such as coating, heating, irradiation, etc.]
Naturally colored diamonds are the perfect living example of having defects/irregularities within yourself, do not decrease your work or make you weaker.
However, these irregularities make you more alluring and desirable. The structural deformities in naturally colored diamonds are just limited to a color change. They do not cause any durability issues.
The rarity & desirability of naturally colored diamonds increases their demand in a way that makes them steal the spotlight!
Well, you don’t have to go anywhere else to own this natural allure!
HK also has some incredibly alluring pieces of naturally colored diamonds, which you can explore and buy from the Fancy option on HK.CO website/app after registering yourself!
