Diamond is an allotrope of carbon like graphite. The carbon atoms in a diamond are arranged in a variation of the face-centered cubic crystal structure. Black Diamonds are polycrystalline diamonds found in alluvial deposits. These diamonds are made up of many tiny diamond crystals and are therefore porous.
Diamonds due to their extraordinary optical characteristic have very few impurities or inclusions. They are clear, colorless and mostly transparent. Black Diamonds have heavy inclusions mainly graphite that is blackish in color thus making them opaque.
Diamonds have high optical dispersion that is the ability to disperse light in different colors which in turn grants them the brilliance and sparkle. Black diamonds being porous and opaque do not disperse any light, rather the black inclusions absorb the light, and thus they do not sparkle like white diamonds.
Diamonds are the hardest materials existing, but this hardness also makes them very brittle. A harsh blow can cause the diamond to break. Black diamonds are fragile due to their porous composition and heavy inclusions. A harsh blow can cause the diamond to break or chip.
Diamonds are valued for their transparency that is clarity, color, size and cut for the brilliance. Brilliant cut in round diamonds is know to grant maximum brilliance to the diamond. Diamonds are usually cut in limited styles to maintain the brilliance. Black Diamonds are also valued for the color, clarity, size and cut. Black diamonds can be cut in any desired shape without bothering about the brilliance.
Diamonds are one of the most expensive gems, due to their rarity. They make a great investment as their value has witnessed a constant acceleration. Black diamonds are cheaper than white diamonds but their value has grown many folds over the last five years.
Diamond has look alikes like Cubic Zirconia, synthetic diamonds, crystals, silicon carbides or similar stones like White topaz and more expensive white sapphire. Onyx, Jet, Black crystals etc.
Diamonds are treated to improve the white diamond’s color grade color and clarity, including laser drilling to remove inclusions, application of sealants to fill cracks. Black diamonds are mostly treated to enhance the dark gray color to black, they may be irradiated or heat treated.