So what types are available?

Emery boards: These are made of cardboard with a glued-on coating of emery, a type of very hard rock. It is ground down to make an abrasive powder - an emery board is a bit like sandpaper stuck on cardboard.

Emery boards are cheap. They come with a choice of surfaces or 'grits'. They work by 'tearing' your nails. This abrasive action can weaken the nail, which is why it's important to file in one direction only.

Unfortunately, emery boards don't last very long. They are also impossible to clean, so you risk getting an infection, especially if you don't replace them regularly or if you share them with someone else.

Metal files: These are more durable than emery boards. They can be sterilised, but be sure to dry them quickly, as they can rust if left to soak in water.

Metal files can be rough on nails, causing them to flake if not used gently. They are best for hard, strong nails.

Glass files: These are smoother than emery boards and metal files, so are less likely to splinter or tear nails. Glass files are expensive but are easy to clean and sterilise.

Unlike metal files and emery boards which lose their abrasiveness over time, glass files never go dull and so are more durable - as long as you don't drop them! They're worth investing in if you have delicate, easily broken nails.

Crystal file: These give nails an even smoother finish, and are so hard-wearing they can be used to remove hard skin on the feet. They don't tear the nail like an emery board or metal file, plus you can file nails in both directions without weakening them.

Crystal files are more expensive than emery boards and metal files, but if handled properly can last for a lifetime - they are much harder to break than glass files.

Crystal files are hygienic because they are non-porous, which means that bacteria can't grow or get trapped on the rough surface.

Dos and don'ts to filing nails

Dos

1 Replace emery boards regularly, even if it's only you using them. A lot of bacteria can build up between uses, especially if you have cuts on your fingers when you use the emery board.

2 Do sterilise metal, glass and ceramic nail files every time you use them.

3 Do use nail scissors or clippers to shorten nails before filing if you have more than a couple of millimetres to trim.

4 Do trim or file a broken nail straightaway to avoid it splitting down to the nail bed.

Don'ts

1 Don't file nails when they are wet, as softened nails are more prone to damage than dry.

2 Don't file nails back and forth if you're using an emery board or metal file; file in one direction from the edge to the middle to prevent tearing.

3 Don't file the corners of your nails as this can weaken them and make them more likely to break. File them straight across to make an oval shape. Pointed nails tend to break more easily.