How Are Industrial Diamonds Affixed To Nail Files?

[AndiFlatland]

About 20 years ago I bought a very smart nail file from the local branch of Boots. Instead of the usual textured metal surface, it was covered on both sides with a layer of tiny, almost microscopic industrial diamonds. One side was covered with rather coarser diamonds than the other, giving a choice of abrasiveness, depending on whether you were filing your nails, or just buffing the rough edges off them.
What has always intrigued me, though, is how they get the diamonds to stay stuck to the metal blade. The file has never lost its abrasiveness in all these years, and is still just as effective as when I first bought it.
I suspect the answer might be something like when the file is first stamped out, it may be heated to a very high temperature, and the diamond particles are then rolled hard on to the surface, so that when the metal cools, the diamonds are bound very tightly to the surface.
Does anybody know if this is the process, or what it is if not?

[tamborine]

Maybe affixed with industrial glue? Wish I still had mine but a mizzo 'friend' nicked it!

[EDDIE51]

Information here, a nail file is just a 'tool' scroll down to the paragraph about production methods.
http://en.wikipedia.org/wiki/Diamond_tool
I would think the 'resin bonded' method would be the one for a nail file.