A new laser treatment for diamonds, which typically does not have a surface-reaching drill hole, recently entered the trade. For a better understanding of this new technique, observations were made on several round-brilliant-cut diamonds before and after treatment. Diamonds with dark inclusions near the surface are favored for this new method, which causes small cleavages to develop or expand around an inclusion. Once the cleavage reaches the surface, it serves as a conduit for the solution that is used to bleach the dark inclusion. Irregular, wormhole-like channels are used to widen the cleavage to facilitate entry of the bleaching solution.