The title says it all, almost.

It's easy to understand that diamond is used as it is very
hard and will last very long.

Diamond powder is used on a flat(steel/aluminium) plate.
What I don't read about is how the diamond particles are kept in
place? I read some little info on fora about nickel plating, but I
don't get it. Is the nickel poured on the steel plate while liquid
and the diamonds are sprayed in the this liquid. When the nickel
gets hard again, the nickel is bonded with the steel plate underneath
and the diamond particles are kept in place in the nickel matrix?

Sintered diamond plates is when the diamonds are pressed in the
plate. That doesn't seem to be very difficult, just use a big hard object
to press the diamonds in a steel plate. Seems almost so easy
that I could do it myself.

Get a flat steel plate. Buy synthetic diamond powder, place/spread
the particles evenly on the plate and press it in the plate with a piece
of thick, hard(glass) surface.

And no I am not thinking about making my own diamond plate,lol.

Love to hear your knowledge on this guys.

Sharpman