You're bound to have seen some purfling, but perhaps not known what it is.
Here's some, done by the man, Andrea Amati, who was possibly the inventor of it:
See the decorative dark line round the outside edge of the front of the violin? That's the purfling.
Here's some purfling in the process of being inserted onto a cello:
The purfling can be made of wood (sometimes dyed) or mother of pearl. It tends to make the edges of the violin more flexible, and this can change the sound of the instrument (not necessarily for the better).
Still, it looks jolly nice - so nice that in a cheap instrument the purfling may be made of plastic, or even just painted on.
And why not. It's enough to make the hours of practice worthwhile just to hold some purfling in your hands, isn't it.
Word To Use Today: purfling. This word comes from the Old French purfiler, to decorate with a border, from filer to spin, from the Latin fīlum, thread. English also has the lovely purfle, which is a decorative ruffled or curved band on a piece of fabric, or it can even mean to decorate something with such a band.