Every facet of fine line detailing and permanence is incorporated into this pen to execute writing in micro-spaces or on unusual and challenging surfaces. Microperm is used to make precise long-lasting marks on test tubes, circuit boards, diamonds, cellophane, wood and glass, plastic, metal, or wherever there is a need for waterproof ink that will write on non-porous surfaces. Diamond cutters can use Microperm to make minute markings on rough diamonds to insure exact cuts.