Usually , people use either USA or Japan diamond pad for lapping the stone. I have used Shapton diamond one for lapping whestone ,it is good but extremely expensive .In order to reduce the cost ,
1) use whestone makers lapping stone
2) use China made diamond disc [about USD8 to 10] for lapping or polishing the sharp edge of whestones.But the diamond grain is about #150. it is quite coarse . Then use waterproof fine grain sandpaper [USD$1] for further lapping.
I hope it is useful information .