Many final products are made by Gritomatic. We buy sharpening stones from manufacturing companies. We cut stones if needed, perform flattening and lapping, and mount the stones to blanks. We keep the names of the original sharpening stones in the names of the finished products, as well as the countries of origin of these stones.
We don't sell sharpening stones without blanks.
Grit terminology is not applicable to natural sharpening stones, including those composed of novaculite. The behavior of a natural stone depends on its density and how good it was lapped. You can find Arkansas stones in a Grit Chart, but they are there for reference only.
All stones wear as they are used and thicker stones have longer life cycles as a result. However, it's easier to use thinner stones on Edge Pro sharpeners because of their lower weight. The 6 mm thickness offers a perfect balance between life cycle and weight, and has become the community standard for Edge Pro format sharpening stones When made of hard material, 3 mm stones are good as ultra-fine sharpening stones, for example alumina ceramic or natural stones.
Courtesy of Mr. Wizard. Please read chart explanation in README.