The Colorado River versus Waterjet
Waterjet gives the best edge. The surface is unaltered, exhibiting no heat or stress damage. This outstanding edge quality it is created by supersonic erosion.
Erosion is an extremely gentle form of material removal, however it achieves amazing results.
For example: the Colorado river can erode the one mile deep Grand Canyon in 35 million years, and the abrasive waterjet can erode over one foot thick of granite at 0.2 inch per minute (5mm/min).