The author of Collecting and Classifying Coloured Diamonds, gemologist Steven Hofer states, black diamonds are in “a transitional carbon state between graphite and pure diamond”. Hoffer continues, “The typical black diamond is composed of a mishmash of atoms rather than a regular, homogenous arrangement.” Black diamonds are both difficult and time consuming to cut. Surfacing pitting and areas with varying degrees of transparency are common problems.
One of the largest known black diamonds was cut from a 55.85 carat bort in 1972. The, end result, the “Star of Amsterdam” is a pear shaped diamond that weighs 33.74 carats.