With its "PROFESSIONAL STONE" (new) / "CHOSERA" (old) brands Naniwa offers a high-tech line of sharpening stones. The Professional Stones are markedly harder than the Sharpening Stones from the same manufacturer. Naniwa designed these stones for professional woodworkers and carvers, who put the highest daily demands on their tools. Overall, these stones are best for those who don't have a lot of time to spend and need to quickly and cleanly sharpen their tools.
Professional Stones / Chosera stones are harder than the Naniwa Professional Stones and so take much longer to develop a hollow in use. These stones also cut faster, especially in the rougher stones -- 3000 grit and larger. The 400-grit Professional Stone, for instance, works faster than the 220-grit Sharpening Stone, and is only marginally slower than the Shapton 120-grit. Normally the Professional Stones only need to have their surfaces moistened a bit with water.
A flat stone is vital to a good sharpening job and flattening stones takes time. Have a look at the flattening blocks and supplies we offer.
A note on the packaging of the Chosera stones: The box is marked "with Stand", that is to say with a holder glued to the back of the stone. Normally these stones are delivered with a plastic holder. But we prefer, and most users of these stones agree, not to have a holder glued to the back of the stone because if one finds that the stone needs flattening in the middle of a job, one can simply flip the stone over to use the other side without interrupting work and then flatten the stone at one's leisure. So we asked Naniwa to deliver the stones without the holder, despite what the packaging says.
IMPORTANT NOTE on storage and lubrication: Professional Stones / Chosera sharpening stones are bound with magnesium and so have more cutting particles per unit of surface than resin-bound stones. But magnesium-bound stones are much more sensitive to prolonged exposure to water as other types of stones. So Professional Stones / Chosera stones should NOT be left to soak in water for prolonged periods and must be stored dry. If this advice is not followed the stones can develop hairline cracks or the binding material can be leached out of the stone. It is more than enough to pour a little water on the surface or briefly dip the stones in water, they do not need to be soaked. If you are not sure that you can keep this always in mind, perhaps because you have a number of different kinds of sharpening stones, it may be better to opt for the more tolerant Sharpening Stones.
Every Chosera sharpening stone is delivered with a special Nagura stone (67 x 49 x 25 mm) to put a fine sharpening paste on the surface of the Chosera stones during use.
View all Chosera Stones
Note on the Naniwa Name Change: The line Chosera is now Professional Stone. Besides the name change, the packaging has changed as well to a size that fits the stones better. Further the thickness of the stones changed from 25mm to 20mm and the Nagura stone is no longer included. We will be phasing out the Chosera over time and replacing them with Professional Stones. Both the old and new stones will be sold parallel as long as available. As the Professional Stones line is more expensive then its predecessor, purchasing the Chosera while they are still in stock is the better choice.