Yaginoshima Asagi Whetstone 6" x 1"

Yaginoshima Asagi whetstones are used for finishing knives on sharpening systems such as Hapstone, TSPROF, and other systems compatible with the Edge Pro form factor. Yaginoshima Asagi stones are highly effective for knives as a final finishing step. Produces a very even and consistent Kasumi finish. Well suited to high-carbon steels.

The stones are custom-cut from bench stones sourced from a reliable Japanese seller, with their working faces oriented parallel to the original working surfaces of the parent stones. They are then lapped, mounted on high-quality aluminum blanks, and laser-engraved. All operations are performed in-house at Gritomatic. Production run: 5 pcs.

Japanese name (Kanji): 八木ノ嶋 浅黄 (also written: 八木嶋, 八木の嶋)

Name breakdown:

• 八木ノ嶋 (Yaginoshima) — a western Kyoto mine (Nishi Mono) in the Tamba/Tanba region, located east of Ohira and north of Kouzaki. Historically controlled by Akechi Mitsuhide.
• 浅黄 (Asagi) — visual/color attribute: deep dark blue to grey-blue coloration, often with holographic Suminagashi-like patterns. Asagi is a color descriptor only; hardness is not implied by color. Strata is not explicitly named in this combination but Yaginoshima Asagi is associated with the Hon-Kuchi Naori seam.

Mining region: Western mine (Nishi Mono), Tamba/Tanba area, Kyoto Prefecture. Yaginoshima is connected to the main Hon-Kuchi Naori geological seam, which runs from Maruoyama/Ouchi/Yaginoshima eastward across the Katsura River toward Ohira, Ozuku, Okudo, Nakayama, and Narutaki. Suita from Yaginoshima is most famous, along with its Namito stones. The mine is permanently closed.

Grit rating (JIS equivalent): Yaginoshima stones span a wide range depending on hardness from softer Aoto-type to harder Asagi-type. The Asagi variant specifically is characterized as extremely dense and fine, at approximately 10,000–12,000 JIS.

Recommended progression: After a synthetic 5,000–8,000 JIS stone.

LV Hardness: LV 5 (very hard) for the dense Asagi type. Confirmed at hardness 5 across multiple vendor listings for Yaginoshima Asagi. On the 1–5 Tanaka Toishi scale: hardness 4.5, wear rate 1.5, self-slurry 1.5. Despite LV 5 hardness, demonstrates surprisingly smooth and manageable behavior even on heavier blades. Offers exceptional performance-to-price value in the super-hard stone category.

Composition: High-density siliceous shale, Hon-Kuchi Naori geological formation. Characteristic deep dark blue-grey base coloration with holographic Suminagashi-like patterning and Goma (sesame seed) inclusions. The very high density of the stone is responsible for both its hardness and exceptional fineness.

Usage recommendations:

• No soaking required — surface wetting only
• At LV 5, self-slurry production is low (rated 1.5/5); use a nagura to raise slurry.
• Stone translates nagura feedback exceptionally well, giving clear indication of edge development