Review (4/5): Great glass files
These files are fantastic. I really like the fact that they're not etched like any other glass file. They do a great job at filing natural nails without all that ear splitting, teeth hurting, grinding noise other glass files make.
As far as buffing/polishing goes, yes, they do make a naked, natural nail shiny. But unless your nail is free of bumps, humps, divots, etc., it's going to take a long time to shine the nail evenly. What you end up doing is making thin/weak spots in the nail which will cause breaks or cracks as the nail grows out because these files take off a lot of nail. You can get shinier nails quicker with a base coat.