A new technique of clarity enhancement—similar to traditional laser drilling treatment—has been recently identified. The technique aims to improve of diamond clarity by the elimination of black inclusions. It is known as KM treatment, referring to ‘Kiduah Mayuhad,’ meaning ‘special drill’ in Hebrew.
The technique has not yet been officially introduced to the industry, but it is believed to have been used in Antwerp for nearly a year.
KM treatment, unlike traditional laser drilling, produces a continuous fracture that has an appearance resembling a feather more than a channel.
The KM treated diamonds can be identified in several ways. For example, the remnants of black coloration sporadically lines the surface of the laser-induced continuous fracture. The other means of identification is the use of a differential interference magnification to determine if the surface-reaching channel existed prior to polishing, according to the Journal. Evidence of the KM treatment lies in the consistency of surface characteristics on opposite sides of the fracture.
KM treatment is achieved when one ore more lasers heat the diamond’s inclusion, creating an internal fracture. The point of the beam is then directed on the shortest route to the surface of the stone, creating a channel through which—via a strong acid solution, heating and pressure—the black inclusion is bleached.
While identification methods are identified, the Journal warns that it may be difficult to distinguish a natural fracture from the feather-like one created the treatment.