This is a beautiful Mizukihara Aomi Suita (Bluish Suita) from Kyoto, Japan. The sharpening surface features a pale bluish-gray to creamy white base, accented by delicate yellowish-brown and reddish lines that create a distinctive and naturally beautiful pattern.

Mizukihara is one of the notable natural whetstone-producing areas in Kyoto's Nishimono (Western Mine) region, belonging to a different geological area from the Higashimono (Eastern Mine) quarries centered around Umegahata. Mizukihara stones are appreciated for combining the refined finishing qualities expected of Kyoto natural whetstones with pleasant tactile feedback and excellent abrasive performance. These characteristics make them particularly appealing for sharpening traditional Japanese kitchen knives and other precision edged tools.

We rate this particular stone at approximately Hardness Lv. 4.0−. Although it is not an extremely hard stone, it is neither excessively soft nor overly muddy. Instead, it offers a firm, well-balanced, and controlled sharpening feel, providing clear feedback from the blade without the sensation of the edge sinking into the stone's surface.

One of the most distinctive characteristics of this stone is the rich, dark slurry that develops during sharpening, becoming almost black in appearance. As the stone releases fine abrasive particles and the slurry incorporates metal removed from the blade, it quickly darkens, creating a striking contrast against the pale bluish sharpening surface.

The stone is not so hard that slurry formation becomes difficult. Rather, it offers an excellent balance between the direct abrasive action of the stone itself and the smoother, more refined polishing effect produced by the slurry.

In terms of finishing characteristics, this stone is particularly well suited for achieving a delicate, natural Kasumi finish rather than a highly reflective mirror polish. On traditional Japanese kitchen knives, it can finely refine the soft iron cladding (Jigane) while imparting a tighter, brighter appearance to the harder steel core (Hagane), creating a beautiful and natural contrast between the two.

Thanks to its moderate hardness and firm, compact structure, this stone offers more than simply a soft, slurry-driven Kasumi finish.

The user can first work directly on the stone's surface, taking advantage of its clear tactile feedback to precisely refine the bevel and cutting edge. As the slurry develops, it can then be used to soften and unify the surface texture, producing a more even and harmonious finish.

Its subtle bluish coloration, delicate natural lines, firm and responsive sharpening feel, and characteristic dark slurry give this stone both excellent practical performance and the unique individuality that makes Japanese natural whetstones so highly appreciated.

A particularly attractive Mizukihara Aomi Suita from Kyoto's Nishimono region, combining distinctive natural beauty with reliable sharpening performance.

Highly recommended for Kasumi finishing and final sharpening of traditional Japanese kitchen knives.