The present invention involves a system and method for grinding herbs, tobacco, marijuana and the like. The herb grinder system herein includes interchangeable and replaceable lower grinder plates that are secured in place with threading, bayonet mounts or the like. The upper and lower grinding plates are provided with blades having a modified diamond shape which provides extremely sharp leading edges regardless of which direction the grip assembly of the grinder housing is rotated. The lower plates are also provided with variations in the size, shape and arrangement of hole sizes through which the ground material is allowed to pass through. This construction provides the user with the ability to control his/her grind size mixture, which may be consistent sized grinds or a mixture of different sized grinds.