The way it works is that it creates a hole is that the drill bit is actually hollow from the center and hence when you drill it will create a hole which the size of the drill. The size varies from 5/64″ to 4″.
The size of the shaft has to be a standard is 3/8″ so that it can be used in the drill.

However, if you are looking for some special purpose diamond drill bit for example say drilling hole into glass then the diamond drill bit needs to be a bit blunt from the front. The other thing is that they
will operate more slowly than the regular diamond core drill bit. The blunt diamond drill bits have diamonds on the tip and on the side whereas in a core drill the diamonds are at the sides since they do not have a tip.
The way the diamonds are attached to the tip is in two ways one is sintered and the other is bonding. In bonding the diamonds are attached to the drill tip using the electroplating bonding process.

The diamond drill bits as a matter of precaution or rather rule should only be used with very slow drills so that the impact of high drills does not destroy the drill bit or the material. The other important thing to know is that the drill pressure has to be very low too when
using the diamond drill bits.