Causes of Diamond Color (7.07)
A perfect diamond of 100% carbon atoms with no structural defects will reflect all light. When defects in the diamond occur during the crystallization process, this causes light absorption. Not all of the spectral colors of white light are absorbed in these defects. The common impurity nitrogen when isolated among the carbon atoms, causes yellow-orange but when in an aggregate arrangement it will be a yellow hue. The percentage of nitrogen atoms will determine saturation of the yellow hue.
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Boron atoms absorb yellow light and some of the red and green causing a blue appearance. More boron will lead to higher saturation of the blue hue but very high concentration will cause greyish-blue to even black.
Carbon atom vacancies will cause colors also. A carbon atom vacancy next to a nitrogen-vacancy (NV), can cause pink. While carbon atom vacancies caused by natural radiation can result in green. It has also been found a single carbon atom vacancy in combination with other defects can cause blue.
In most natural diamonds the extreme pressure and heat in the will cause plastic deformation resulting in atomic vacancies and distorting the structure and creating glide planes resulting in pink, red and brown diamonds.
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