How does a 3-way nail buffer work to make the nail shine the way it does?

You use the black (darkest or coarsest) side to shape up the edges and gently file out any ridges in the nail. Then the white (or lightest or medium coarseness) to go over what you just did - keep in mind GENTLY. Then the gray side or the smooth side to buff the nail all over. This gray smooth side will make the nail very very shiny if done correctly. I personally wouldnt reccomend doing all this very often being as it takes layers of nail off and makes mine thinner when i do it. Hope this helps.How does a 3-way nail buffer work to make the nail shine the way it does?
like sand paper corse,medium and fine polishing