Asano Stamped Mikawa Shiro Nagura
Botan, Tenjyou, Mejiro
Mikawa Shiro Nagura are often sold in sets of 3; Botan, Tenjyou and Mejiro. They’re also individually and as large bench stones. The most commonly seen pieces weigh around 80 g and are used to create abrasive slurry on a hard Honzan.
For razor honing, some users prefer to use all three in a Nagura progression. Some skip either Tenjyou or Mejiro. Those who are fortunate enough to own a Koma Nagura will use that as the final step before moving to Tomo Nagura.
Botan is the most coarse, and is followed by Tenjyou most often. Mejiro is not always finer than every Tenjyou though - so each has to be figured out and compared to each other. I’ve never seen a Botan that was finer than a Tenjyou or a Koma that was less fine than Mejiro, but anything is possible.
These stones are sold mostly by weight, but other factors apply too. Shape, color and size are the 3 most common characteristics that affect pricing. After that – Nagura mined long ago will also command a premium. The Asano stamps also affect pricing. There are Nagura without the Asano stamps on the market; some are good, some are not good. The theory is that any Nagura with the Asano stamps would be of good quality.