NSK Kyokuha Diamond 400 Stone

The Kyokuha Diamond 400 is a solid coarse stone.  Unlike diamond plates, these stones are constructed in a manner more similar to normal waterstones.  The top ~5mm of the stone is composed of a hard binding agent with diamond abrasive mixed in.  This is then attached to a taller base, such that the whole item together is about the same size as many of the other stones we sell.  Unlike some diamond stones that use metal or aluminum bases, this base is a lightweight, water-resistant plastic, which I have found to be lighter and more convenient to use and care for than other bases.
With regard to the stone, we've been using it for years here.  The 400 has decent tactile feedback and the scratch pattern it leaves is very consistent and even. And, again, unlike diamond plates with the abrasives plated onto the surface, these stones leave scratches with a depth more similar to regular sharpening stones.  Thanks to their diamond abrasive, they work well on all steel types, including some of the hardest and wear-resistant steel.  They can even be used to sharpen ceramic knives.  As the binding agent is not porous, these stones are true splash and go stones.
When it comes to flattening, we recommend our Gesshin 100 Grit XL stone fixer.  Diamond flattening plates will not work well on this, and you are likely to cause damage to the diamond plate.