Blue Diamond
Blue diamonds represent only 0.1% of all natural fancy coloured diamonds, making them extremely rare and valuable. Blue natural fancy colour diamonds generally have a slight hint of grey. Their colour is typically caused by the presence of boron. The higher the concentration of boron, the more intense and deeper the colour. Some greenish blue diamonds have been discovered that lack boron; it is thought that their blue colour is due to natural radiation that would have been present when they formed. Very rarely, a greyish blue colour is caused by the presence of hydrogen.
Please note that a significant amount of treated diamonds exist on the market. The purpose of the treatment is to increase the colour.
