Van de Graff Generator Method (7.33)
Depending on the original stone color, the Van de Graff generator method is capable of producing bluish hues. The common cape (yellow) diamonds used in this process, change to a bluish-green or greenish-blue. These treated diamonds are very common, so be aware of the likelihood of irradiation. To get the result of a straight blue diamond, a colorless stone must be used, and even then there are no guarantees. Obviously using the scarcer colorless category for irradiation purposes is not appropriate. To detect this color treatment, a lab checks a blue diamond for electrical conductivity. A natural blue diamond usually contains traces of boron, which causes it to conduct small electrical currents. On the other hand, a treated blue diamond incurs a structural change in its lattice, which renders it non-conductive. Very rarely do non-conductive, bluish-gray or greenish-blue, natural color diamonds appear in the market.
