The Laser Micro Jet (LMJ) is a precision cutting machine in which the laser pulses are directed down a very fine jet of water.As a result the laser pulses are taken to the bottom of the cut and the sides of the cut remain parallel.The water jet follows the contour of the work piece so no focussing is required and the water cools the material as it is being cut.Diamond manufacturers and toolmakers can use the wet laser to cut, slice, dice and drill materials such as natural and synthetic single crystal diamond, polycrystalline diamond, polycrystalline PCBN and CVD diamond.Cuts up to 25 mm deep have been achieved with a width of only 50 microns.As the water jet cannot bend, the cuts are perfectly straight.Wet lasers are already replacing dry lasers for the cutting of high value gem diamond stones as thermal shock breakage is reduced by 50% and the parallel sided cut improves yields and reduces polishing times.With industrial natural and synthetic diamond, the wet laser can significantly reduce the time taken for shaping the profiles of tools and, as with gem quality diamond, the cutting is cool and much cleaner than with dry laser cutting.Low CBN content PCBN is thermally shock sensitive and dry lasers can cause cracking.The wet laser prevents local overheating and hence cracking can be reduced or eliminated.This paper looks at the many advantages water can make to the laser cutting process