Diamond Saw Wont Cut- If your blade still has diamond on it, and won’t cut, run a brick, concrete, old aluminum oxide grinding wheel, or Obsidian about 3″ thru the blade. This will strip off any alloy that is covering the diamond particles allowing them to cut. If you have no diamond left, you need a new blade.
Keeping the Oil Out -If you suspect that the rock you are about to cut will soak in oil, you should soak the rock in water for at least 24 hours before cutting. This fills the porous areas with water. Cutting oil can stain some stones. Denim Lapis is an example. Soaking in water really helps to minimize oil soak in.