This listing is for the asano stamped mikawa shiro nagura shown in the photos. This piece is koma layer and is a jumbo sized  that weighs 342 grams. I acquired my supply of nagura stones directly from Morio Sakomoto in Japan. He is the current holder and grader of the asano stamp. This red stamp is only given to stones verified as authentic and of excellent quality.

With the exception of the rubbing surface, I clear sealed the nagura for added protection of not only the preservation of the stamps but the nagura stone itself.

The mining of these stones ceased in the 1970s, and they are becoming increasingly scarce as time goes by. Eventually, whatever stock may be leftover will be completely depleted.

This listing comes with free domestic shipping