They are finally up here on the website... this is the product description:
https://www.japaneseknifeimports.co...nes/products/800-grit-vitrified-diamond-stone
The Gesshin 800 grit vitrified Diamond stone is the most used stone in my personal collection. Since starting to use these a few years ago, they quickly became my favorite. I believe that most professional sharpeners are always on a quest for the best coarse stone they can find, but its always hard to find the perfect coarse stone. This one comes as close as any I have tried. While its not as fast as our Gesshin 220, it is as fast cutting as many 320-400 grit stones. However, being 800 grit, it fits within the medium grit range (naka toishi). The scratches it leaves are not as deep as those from the coarser stones I would normally start with. This allows me to jump directly from this stone to my finishing stones, cutting my sharpening time drastically. For example, a common 2 stone setup in our workshop might include this 800 grit stone and any one of our 3000-8000 grit stones (most often, it ends up being on of our 6000 grit stones).
Unlike other diamond stones found commonly in the market, this stone acts more like the traditional soaking stones many are used to. It is porous and actually soaks in water, while providing a more traditional whetstone feel. Because it is extremely thin, it soaks rather quickly (in just a few seconds), so despite not being technically splash-and-go, it is probably the closest one can get.
As you can see in the picture, the stone is mounted on a glass plate. The stone itself is only about 3mm thick. However, the stone is extremely slow wearing, and does not need flattening often. In fact, the stone is so wear resistant that I haven't been able to find an effective means for flattening the stone, which means that one must be good enough at sharpening to use the stone surface evenly while sharpening, as that is the most effective way of keeping the stone flat. Also, this stone is particularly aggressive on soft stainless cladding, and may leave deeper scratches when cutting on soft stainless cladding.
All in all, this is probably my favorite stone of all of the ones i own.