Diamonds don't wear out! They are among the most abrasive resistant materials on the planet.
What happens is; first they "cap". This means that the very fine edges will chip due to excessive pressure or impact. This is the first 10 knives or so mentioned above.
Then what happens is the diamond is dislodged from the matrix holding it to the steel platform. The diamond is dislodged from the matrix by the user pressing too hard or "striking" the diamond. the diamond is pushed into the steel under it, which creates a cavity surrounding the diamond, permiting the diamond to move....back and forth....until it cuts its way out of the matrix.
The diamond requires almost no pressure to cut steel. drag a diamond hone very lightly across the blade of your most cherished collector pieces

I guarantee it will scratch the blade.
I continually hear about people that say their diamonds wore out. Not so. They wore them out by pressing too hard. Even the ones that say they are not pressing too hard, just don't know how lightly to use diamonds if you want them to last.
Diamonds are great, they'll cut the hardest steel. Pressing harder doesn't make them cut faster, it only dislodges the diamonds from the matrix. If you treat a diamond abrasive like a whetstone, you are pressing too hard.
I personally like to lube with a little water which I beleive reduces the cut but saves the diamond.
That is my opinion based on a background including: experience in Mil spec plating. 55 years of knife nut passion, manufacturing diamond hones, sharpening experience with just about all abrasives.
sal