You may have seen them in the health and beauty section of the store and passed them by. They look pretty, but doesn't a glass nail file equal glass shards in your purse?
Not so. Glass nail files, sometimes referred to as crystal nail files, are made of treated glass that's tempered to be more endurable. (They have more in common with your glass pans for the oven than your drinking glasses, in that regard.) They're incredibly sturdy. Because they're made of non-porous glass, they can also easily be sterilized. For example, if you're thinking about switching to glass files for your nail salon, they can be sterilized in an autoclave, among other options. They are also washable with soap and water, and more enduring than your standard emery board file.
They're also a lot better for your nails, actually. You may not realize this, but emery boards are designed to be used only in one direction. If you saw your nail back and forth on it, you can actually do more damage to the end of the nail than you realize, making your nail tip vulnerable to chipping and splitting. Glass files, because of their design, sturdiness, and finer grit, can improve your nail health. This is because you can use them in any direction, and also because using them seals the tip of your nail, joining the keratin edges together. This prevents splitting and chipping, as well as preventing water, dirt, and bacteria from getting into your nail through the damage a typical emery board might do.
In addition to all this, many are painted in the Czech Republic, an area of the world renowned for their glass work. (You may be familiar with Czech beads, if nothing else, which are a staple of the craft world.) They can also be bought and customized in bulk for business ventures. A savvy salon owner may buy Czech painted nail files online and get their logo printed on some really beautiful nail files for their customers.
So they are actually better for you, they're not as fragile as they seem, and often they're really pretty. And while they're more expensive than your standard emery boards (which can be found cheaply and by the dozens) they are still not a hugely expensive outlay, most costing between 5-10 dollars per file. (They often come in sets of two or more, designed for different uses.) Many come with sturdy little carrying cases, if you are worried that you're a little more rough with your purse than most people are.