Diamonds never fail to turn heads with their utmost brilliance and appeal, and their charm is ultimate when it comes to colored diamonds. It is amazing that colored diamonds are found in almost every shade of a rainbow. However, according to the Gemological Institute of America (GIA), most of them are very rare. In fact, only one in ten thousand natural diamonds are colored.
How Colored Diamonds are Formed
A diamond is formed by bonding billions of carbon atoms. Any slightest change in the atom structure of a diamond will make it colored. For instance, the presence of boron atoms in the chemical structure a natural diamond will make it blue. Similarly, a yellow diamond is formed by the presence of nitrogen atoms. Other than that, irradiation can also turn a gemstone more blue, yellow, brown, red, pink, green, etc.
There are many laboratory treatments as well, which induce color in natural diamonds. In such cases, a light yellow diamond, for instance, is enhanced by coating it with blue color in order to offer an appeal of higher color grade stone. However, the GIA list entails 27 different shades of natural diamonds only.
Even though yellow colored diamonds are common, its vivid hues are somewhat rare. It is formed by the addition of nitrogen atoms. That is, a natural diamond will turn into yellow when its carbon atoms are replaced by nitrogen atoms.
The similarity between a carbon atom and nitrogen atom make it easier for the latter one to replace the former one in the formation process. Usually, the lighter hues of yellow diamonds are beautified using ‘blue coloring’ in order to categorize it as colorless diamonds.
Natural green diamonds are extremely rare. In fact, only ten natural green diamonds come to market every year. The cause of this green color in diamond is mainly the natural radiation process that occurs in the nearby rocks. During this process, the rocks will trap electrons that make it surface color green. In some cases, diamonds may lose its green hue during the polishing process, as the color is present only on the outer layer.
When it comes to the GIA issued colored grades, there are three ways to describe fancy colored diamonds: hue, tone, and saturation. The hue indicates the spectral color of a diamond, tone denotes the lightness and darkness of the color, and saturation is about the strength and purity of a color on a scale that ranges from neutral to vivid.