I have been working on a method to grind valve seats using diamond powder and so far I have the powder. The actual process involves a slurry of ceramic clay mixed with diamond grit that is poured into a mold and fired in a kiln used for ceramics. The diamond grit I bought is synthetic diamond so that the stone I produced could be dressed by a real diamond or maybe carbide, but it is all theory at this point. You can buy diamond paste for polishing. I just wanted a tool to chamfer small valve seats at various angles. It is doable but you need a kiln or know an art studio for clay throwers.