Black diamonds are a polycrystalline diamond generally found in Central Africa and Brazil. They are different from other diamonds in that they are more porous and have high luminescence.
Black diamonds result when the carbon was not properly pressurized during the formation of the diamond. Instead, a minute speck of carbon remained and as the diamond rough continued to form, the new growth of diamond took on the black color of the carbon speck.
The basic white color we see in white diamonds is due to scattering of white light by particles of matter in the path of the light, very similar to the visible beam or cloud resulting from a ray of light illuminating particles of dust floating in the air of a room.
In general, gray variety diamonds acquire their inherent color in one of two ways: scattering of light by minute gray particles inside a translucent diamond, or through absorption of light at various wavelengths.
Avid collectors understand that pure blue diamonds are extremely scarce in nature and the mention of blue conjures images of the sky or a sapphire blue color.
The main causes of color in diamonds are the presence of natural irradiation or structural defects. Blue is caused by the presence of boron. The new Australian diamonds are most likely colored by trace elements of hydrogen, which causes a blue-gray color, whereas the pure blue diamonds in high intensities of color tend to come from South Africa.
The Adamas Collection contains a rare sky intense blue diamond, as well as a large, jet black diamond. The cloud white diamond and the slate gray diamond are two very interesting pieces included in the collection.