As discussed earlier, table salt is a quick way to remove grime from a loose diamond. This is especially helpful when a diamond comes straight out of the mounting and needs to be graded quickly.
Place the soiled diamond in the middle of the palm of your hand with about a half teaspoon of salt. Rub the stone against your hand, being careful not to cut yourself with the stone's edges. Also rub it between your fingers. Take your lint-free cleaning cloth and wipe.