Norton offers a variety of stones with Fine, Medium, and Coarse grits. However, they don’t always tell us the exact grit size. We’ve done some digging to figure out what those grits actually are. Interestingly, Norton uses different grits for their Norton India Stones (made of aluminum oxide) and Norton Crystolon Stones (made of silicon carbide).
There isn’t one standard grit measurement used by everyone, but we usually go by the standard commonly used for Waterstones (JIS). Why? Well, for a few reasons. First, on the lower grits, it’s pretty similar to the USA standard (CAMI) for sandpaper and the European standard (FEPA). Second, the Waterstone standard covers a wide range from very coarse to extremely fine, unlike CAMI and FEPA. This makes it easier for us to use one standard for different stones. Lastly, using micron measurements allows for good comparisons of particle size, even though it might be hard to imagine what a 45-micron particle looks like. But if we say it’s roughly equivalent to a 325 grit, it gives you a better idea.
