Novaculite is a type of stone that can only be found in North America and in a limited geographical region of Texas, Oklahoma and Arkansas. The novacula stone formation in the Ouachitas of Central Arkansas is geologically considered, without a doubt, to be the purest and finest quality.  Its extremely high-purity silica content exceeds 99 percent. This Ouachita Mountain Novaculite is the only Novaculite we use in producing the FINEST whetstone sharpeners you can buy.
Actually, the company contacted me to make sure I received the stones and that I was happy with them. Excellent service. The stones are great! I'm pretty much a novice so the clear instructions that came with the stones and the eBook instructions were wonderful. The eBook had quality pictures demonstrating the use of the stones and the written instructions were clear and to the point. Within minutes of opening the box I had the stones figured out and sharpening my AF survival knife, my pocket knife and a couple of my wife's kitchen knives...which included a very expensive chef's knife. Very satisfied with this product and highly recommend it.
We begin our whetstone sharpening process with a 400 grit stone to shape the edge of the blade and develop a burr along the edge of the knife. Once the shape is set and we have a burr along the full length of the knife we move on to the 1000 grit stone to refine the edge and begin removing the burr, followed by the 5000 grit fine stone stone to give a beautiful sharp edge on the blade. We finish off each knife on a leather stropping block which removes the final remnants of the burr and gives a strong and lasting edge.
Medieval people typically used a whetstone to sharpen their knives for use either in cooking or in their craft. Whetstones were not necessarily used by an individual looking for superior quality, but were instead used mostly as a convenient tool for a quick sharpening. This is exemplified by the hole present near the top of the whetstone through which craftsmen could string some sort of cord to tie the whetstone to their clothing, which makes carrying this tool relatively simple. The guilds of London likely used whetstones regularly, as many crafts such as curriers or cooks relied on the rigorous use of blades, which could thus become dull and unusable. However, using a whetstone to finish a freshly made blade was considered inappropriate, as it would not provide the same edge as a proper grindstone would. The grindstone was a much larger instrument, capable of sharpening a blade much more quickly and effectively than a whetstone because of the speed at which one could use it. It was used more in the initial crafting of a blade, but the whetstone was used for regular upkeep. As mentioned, some crafts were displeased with the use of whetstones to finish their products. The Bladesmiths, for instance, of fifteenth-century London were particularly careful about ensuring that their blades were not ruined by others using a whetstone rather than a grindstone. They raised an official complaint about this issue at one point, which suggests that the people in charge of ensuring the sharpness of their blades were slacking off. 

I did a lot of research and bought this along with a diamond flat stone... and the henckles steel. The sharpest I got my knife (using a microscope to see the edge at 1000x) was using the diamonds stone up to 1000 grit, then straighten it with the steel, then use this stone to basically polish the knife. You are basically making the very very edge smooth and what this does is makes your blade last much longer before it needs sharpening. The edge of a knife looks like a hacksaw under a microscope so just picture making the teeth smaller. I will tell you if you use your knife on anything hard you just need a steel to realign the edge. You can do that about 5-10x before you need to sharpen it again. I learned a lot using a microscope to see the edge.