Naniwa Diamond Pro stone with grit #400 is a premium diamond plate of lower granulation that is excellent for knife sharpening even when we are dealing with very hard steel and ceramics, for which regular whetstones prove ineffective or too slow. It is suitable for all types of steel. The low grit makes it especially suitable for repairing damaged blades and flattening other whetstones.

🚩 Must be wet when in use! This is a splash-and-go stone, so it is not necessary to soak it before sharpening, just splash some water on the top side of the stone and ... action! As with all water stones, keep Naniwa Diamond Pro stones wet when sharpening but allow them to dry between uses.

A diamond stone is a great alternative for anyone who likes to save time on sharpening, as it removes material very quickly (both from whetstones and when repairing/sharpening knives), and works very well with all types of steel. One of the main arguments why a diamond sharpening stone works so well is that it is completely flat and does not wear/dish when used. 

The Naniwa Diamond Pro stone series differs from other diamond stones you may be familiar with. Naniwa Diamond Pro stones have a resin-bound diamond matrix layer bonded to a metal plate. Whereas many other diamond stones have only a single thin layer of diamond abrasive, the Naniwa Diamond Pro stones have several abrasive layers that form an impressive 1mm thick layer. This allows the stone to effectively "shed" worn layers, offering a fresh diamond grit.

Each Naniwa Diamond Pro stone comes with an additional dressing stone for keeping the diamond layer clean and functional. The dressing stone should be soaked before use.

The #400 grit is suitable for resetting, flattening, or altering bevels without leaving deep scratches and also excels at starting edges on very hard knives.

It sets a good flat foundation for knife thinning and removes deep stratches quickly, priming your knife for finer stones.

USAGE INSTRUCTIONS:

• For stone flattening - secure the whetstone that needs to be flattened with a stone holder. Placing the diamond stone on top of the whetstone, use circular and up-and-down movements to begin flattening process. For better results, draw a grid on the whetstone with a ballpoint pen or a pencil (do not use markers, those can be absorbed into the surface of the stone). When the grid is no longer visible, the stone is flattened. Thoroughly rinse both stones to remove any excess material. Flattening whetstones to up to #5000 grit will get you good results by only using the Naniwa diamond stone, while for higher granulations we recommend finishing with the (included) dressing stone to get a smoother/finer surface on the whetstone. 
• For knife repairs - place the diamond stone on a flat surface and make sure it won't move around (use a stone holder for the most secure position). Proceed with the same movement/sharpening technique as with whetstones to fix a damaged blade (see our Knife Sharpening Guide for details).
• For knife sharpening - place the diamond stone on a flat surface and make sure it won't move around (use a stone holder for the most secure position). Proceed with the same movement/sharpening technique as with whetstones to sharpen the blade (see our Knife Sharpening Guide for details). A lower granulation (#140 - #600 grit) is recommended for initial sharpening, followed by a #1000 grit diamond stone and, if desired, even finer grits. The final result will still be quite rough, so we recommend finishing with a leather strop. Make sure to splash some water on the diamond stone before sharpening.

Advantages of diamond sharpening stones:

• quickly removes material when repairing or changing the blade's geometry
  quick sanding and straightening
• can be used for sharpening very hard powder steels (ZDP-189, HAP-40, R2) and ceramics
• it retains its shape and does not wear/dish with use
• lower granulations (such as this #400 grit) are excellent for flattening whetstones and repairing damaged blades.

Disadvantages of diamond sharpening stones:

• for a really fine/smooth edge and very precise sharpening, whetstones are a better choice - diamond stones are too rough
• not suitable for making "kasumi (mirror) finish" on the blade

This is a splash-and-go stone, so it is not necessary to soak it before sharpening, just splash some water on the top side of the stone and ... action! As with all water stones, keep Naniwa Diamond Pro stones wet when sharpening but allow them to dry between uses.

For easier sharpening, we recommend purchasing a Stone Holder (Sink Bridge) to ensure mess-free and a stable position of the stone during sharpening.

Specifications:

*Sidenote: Due to market expansion, Naniwa often changes product names and their packaging, so use the model specification for reference.