A commercial size ultra-grade asagi from the Hoard collection that I bought about 10 years ago of Meiji era tennen toishi natural Japanese sharpening stones. All of the Hoard stones were formed as rectangles at the mine site entrance where the miners always had a wooden shelter for scaling and hand sawing and trimming waste from the raw stones while shaping them into useable shapes and sizes. 
 
This flawless asagi-type stone has tones of yellow & green which tend to create a blue blush on the surface. The dried slurry is cloud-white.
It is;
9 1/2 x 4 x 2 1/4 inch thick (24.3 x 10.4 x 5.8 mm). It weighs 122 ounces (3621 grams).
 
I have tested this stone on Swedish, vintage British, all kinds of Japanese, commercial, and boutique steels, and American steel, and this stone managed pretty much every blade leaving barber sharpness to each.
All of my base stones come with a tested tomo-nagura slurry stone of an appropriately sized (to the base stone) and a money-back guarantee minus the shipping costs.
 
Below is a video of mine working on a similar stone.
 
https://www.youtube.com/watch?v=YXqynvbS3Vc&list=UUf_A5qQ4SZZmGiPLJ61eR_g