Deep in the earth during long periods of geological
time, certain diamonds have been subjected to plastic deformation
(i.e., "strain") resulting in a brownish appearance.
Diamonds subjected to the HPHT process results
in a "healing" of the plastic deformation mentioned above, thereby
removing the cause of the brownish coloration.
Xanthic Collection diamonds are all natural, as
the HPHT process does not add anything to the diamond nor remove
anything from the diamond.
In fact, the process that restores Xanthic Collection
Diamonds to their original natural state is permanent.
HPHT stands for High Pressure High Temperature