The easiest way to figure out if your diamond blade is dulling is when it simply doesn’t do the job as well. The blade will cut slower than before, making it more difficult to make clean cuts as you would with a new stone blade. Visually, this will often look like the blade is becoming smooth. Closely inspect your blade (while the stone saw is not plugged in) to check to see if the diamonds have been smoothed over from wear. If the diamonds wear down, it’s time to buy a new blade.