#1501 is a super-pure asagi from one of the Okudo mine tunnels. This stone can be used with just clear water, a slurry made with the accompanying tomo-nagura, other tomo-nagura, or a diamond plate (diamond nagura).
 
Sized as a lifetime razor stone for a professional shop, this stone will provide you with Kezuroukai quality edges on a wide range of steels, be they straight razors, kanna, nomi, or whatever tools that require barber-type keenness.
 
A lifetime-size stone for a hobbyist or as a prime stone in a workshop. Three of the corners are perfect, one corner as seen in the photos has a mineralized volcanic area of alternate material called kawa. The miners decided that the corner would be cut this way. This edge of this end still allows for the use of a stone holder.
 
The back of the stone was hand-hewn, and is relatively but not perfectly flat. This could easily be amended with a diamond plate.
 
Size is 205x75x35mm=8x3x1 1/4 inches. Weight 1308grams=14oz