Diamond whetstones have been around for many years. The DMT stone consists of a steel base coated with electroplated diamond grit in a nickel matrix. The diamond bearing surface is supported by a strong glass fiber reinforced plastic base that keeps the plate rigid and flat. Unlike traditional bench stones, which can be used like a bar of soap, DMT stone has only one layer of abrasive and a limited lifespan. Like any product, diamond grinding systems have their pros and cons. They don't do well for sharpening steel, as even the hardest steel has a malleability that breaks down diamond abrasives the same way a fingertip breaks a sugar cube. Diamond grinding works very well despite this shortcoming. I've used them for years to keep my chisels and planes sharp and shockingly sharp. Restoring a blade with a DMT stone requires a specific technique, as detailed in the instructions for use that come with it. They are subject to mishandling and their surface may be free of abrasive if the grinding process is forced. I am now ready to replace one of my 5 year old DMT Stornes that has gone bald.