After you sharpened a knife on an extra fine stone, your knife will be razor sharp. For the fan of the truly ultimate sharpness there is the possibility to completely polish your knife by means of so-called stropping. This is done by using diamond paste you apply to a leather strop. Where most sharpeners perform the stropping on a stone after the sharpening, some of them also choose to use strops in order to maintain the sharpness of the knife. In case there is no leather strop available, also a piece of cardboard or, for example, MDF or balsa wood can be used.
You apply a very small amount of diamond paste and gently polish the edge of your knife. In principle you move away from the edge in order to prevent cutting your strop.