David Weaver
not necessarily limited to plastic laminate, but they go in deep in a softer substrate and some do roll around and shred and dent the substrate. The key for diamond use on steel or cast or laminate or whatever it may be is to give up a little bit of wanting the cutting media to feel like fresh sandpaper - when it embeds, it won't. when it's loose on the surface as it's settling in, it's definitely fast, but it's destroying everything and there's a temptation to keep loading it on to get that feel and speed.

I tried 100 grit diamonds on a kanaban (mild steel flattening plate from japan) and they are too big - they still work because they're rolling and they beat up everything, but the kanaban became hollow quickly. reflattening mild steel by hand then is something most of us would like to avoid (it's very rubbery compared to hardened steel and cast iron).

I wouldn't want to use any of these hand methods to flatten 1/8th or 1/4 off of a natural stone with a lot of sway, though.