Tool Review: DMT Dia-Sharp Diamond Stone By Jeff Fleisher There is a revolution going on in tool sharpening and it is being caused by the new DMT Dia-Sharp Diamond Stones . Although they work very well, I find that they require frequent flattening, and a soft touch, as they gouge and chip rather easily. I started woodworking … DMT DuoSharp Fine/Extra Fine Brand: DMT | Category: Sharpening Accessories Edit: I am leaving the original post below, and I will repeat this portion of the post below, where it makes sense with the rest … Recently I tested the DMT DuoSharp … At the same time I also ordered the special base that is available for these "stones", also made by DMT. After having used this stone for about 6 weeks now, I believe I have enough qualitative data and results to form this review, so let's get to it! Tool Review: I've been using Japanese waterstones for quite a few years. The DMT DuoSharp Diamond Stone. So I purchased the W250FNCB model DuoSharp stone from Amazon.com.