The pipe intruded rocks of the Transvaal Supergroup as well as igneous rocks of the Bushveld Igneous Complex. The kimberlite has been radiometrically dated at 1179 ± 36 Ma using Rb–Sr in clinopyroxene and 1202 ± 72 Ma using U–Pb in perovskite. The pipe is itself intruded by a gabbro sill of 1150 Ma.

The internal geology of the pipe was first described by Wagner who noted the presence of a “floating reef” of Waterberg quartzite which occurred in the middle of the pipe and was associated with a considerable rubble zone of rounded quartzite and sandstone boulders. These Waterberg quartzite inclusions indicated the presence of this formation at the time of emplacement, but which has since been eroded from the area. Later geological work identified the presence of a number of discrete kimberlite varieties that included two major types of TKB, named the “Brown” and “Grey” kimberlites. The large floating reef referred to above occurred within the Grey Kimberlite along the boundary with the Brown. In addition, a central complex that consisted of several phases of kimberlite occurred within the Grey. This was referred to as the Black Kimberlite, which has an associated variety called the Piebald Kimberlite. The last phase of magmatism was the intrusion of carbonate-rich dykes.

- autogenous (AG) milling – a gentler recovery process that breaks down ore via attrition rather than crushing, thereby better protecting the large, high-value stones for which the Cullinan mine is known;

- high pressure grinding rolls (HPGR) technology – a gentler liberation technique incorporating inter-particle crushing, thereby moving away from high impact cone crushing; and

- enhanced utilisation of XRF X-ray technology to replace conventional Dense Media Separation (DMS) plants to treat coarser +12mm material.