Which term describes graphite formation around a diamond's mineral inclusions and feathers that results from the extreme conditions of HPHT processing?

Which term describes graphite formation around a diamond's mineral inclusions and feathers that results from the extreme conditions of HPHT processing?

• A. Gravity sorting
• B. Grease belt
• C. Girdle thickness percentage
• D. Graphitization

Answer: (D)

Graphitization is the process at play here. Under the extreme conditions of HPHT processing, the carbon in a diamond can reorganize from the diamond’s sp3 lattice to the more stable sp2 structure of graphite. This transformation tends to occur along weaknesses such as mineral inclusions and feather tracks, producing a graphite-forming halo around those features. In other words, the carbon around inclusions and along feathers reconfigures into graphite as a result of HPHT treatment. Other terms don’t describe this chemical/structural change. Gravity sorting relates to separating stones by density, girdle thickness percentage measures a cut dimension, and grease belt isn’t the concept used to describe HPHT-induced graphitization.

Graphitization is the process at play here. Under the extreme conditions of HPHT processing, the carbon in a diamond can reorganize from the diamond’s sp3 lattice to the more stable sp2 structure of graphite. This transformation tends to occur along weaknesses such as mineral inclusions and feather tracks, producing a graphite-forming halo around those features. In other words, the carbon around inclusions and along feathers reconfigures into graphite as a result of HPHT treatment.

Other terms don’t describe this chemical/structural change. Gravity sorting relates to separating stones by density, girdle thickness percentage measures a cut dimension, and grease belt isn’t the concept used to describe HPHT-induced graphitization.