Umajiyama Namito Asagi Whetstone 6" x 1"

Japanese name (Kanji): 馬路 並砥 浅黄

Name breakdown:

• 馬路 (Umaji) — the Umaji mine (abbreviated form of Umajiyama, without the "yama/mountain" suffix)
• 並砥 (Namito) — strata designation: the seventh working layer of the Hon-Kuchi Naori, located below Aisa and above Hon-Suita. Stones from this layer are known to be hard, very fine-grained, and highly consistent. Less prone to inclusions than other layers.
• 浅黄 (Asagi) — visual/color attribute: a pale grey-blue to steel-blue coloration. The actual color of Asagi stones can range from light silver-grey to deeper steel blue or even greenish. Color alone does not indicate hardness.

Mining region: Western mine (Nishi Mono), Kameoka district, Kyoto Prefecture. Umajiyama is located near Ohira and Mizukihara and produces stones of similar character, though typically softer than those from the eastern Kyoto mines. Production area: 京都府南桑田郡亀岡町馬路 (Kyoto Prefecture, Minamikuwada district, Kameoka town, Umaji). Mine is closed; stock held by wholesalers.

Grit rating (JIS equivalent): The Namito layer is known for very fine and hard stone due to high compression. For Hon-Kuchi Naori Namito stones at hard hardness, the approximate range is 8,000–12,000 JIS. For Umaji Namito Asagi specifically, given Umajiyama's generally softer character compared to eastern mines, the expected range is approximately 8,000–10,000 JIS. Individual examples may vary.

LV Hardness: Not confirmed for this specific combination in available sources. Based on Namito strata characteristics (hard, compressed, fine) balanced against Umajiyama's known tendency toward softer stone: estimated LV 3–4. A Namito from an eastern mine such as Aiiwatani would typically be LV 4.5–5; Umaji Namito is expected to fall lower on the scale.

Recommended progression: After a synthetic 5,000–8,000 JIS stone, or after a soft JNAT Tomae (LV 1–2). Best suited as a finishing stone for knives or as a razor pre-finishing stone. For razor use, follow with a Mikawa Shiro Nagura progression (Botan → Mejiro → Koma) on a harder finishing stone, or use this stone as the final step if hardness is appropriate.

Composition: Highly compressed siliceous shale from the Hon-Kuchi Naori geological formation. Namito is the seventh usable layer, known for very high compression resulting in fine grain structure and consistent performance. Stones from this strata are among the least likely to contain toxic inclusions.

Steels to sharpen: Universal. Well suited to high-carbon Japanese steels and traditional edge tools. The fineness and consistency of Namito make it particularly effective for knives requiring a refined edge with minimal aggressive scratch pattern.

Usage recommendations:

• No soaking required — surface wetting only
• Stone raises slurry with moderate ease given Umajiyama's softer character relative to eastern Namito examples
• Maintain slurry on the stone surface throughout sharpening
• For razor honing, use a Mikawa Shiro Nagura progression to develop slurry and refine the edge progressively
• Translates nagura feedback well, giving clear indication of edge progress
• Do not soak; water penetration between sedimentary layers can cause cracking over time
• Seal sides and base with cashew lacquer if not already done

Japanese name (Kanji): 中山 色物

Name breakdown:

• 中山 (Nakayama) — one of the most famous eastern Kyoto mines (Higashi Mono), located in the Umegahata district. Operated by the Honma family; the mine is now closed though limited reopening under Hatanaka has been authorized.
• 色物 (Iromono) — visual/color attribute meaning "colorful things": abstract splashes of color (red, pink, violet, and other tones) on the stone's base color. Most commonly seen on softer Kiita stones. Iromono is a color descriptor, not a strata name. When no strata is listed, the stone is most likely from the Tomae layer by default.

Mining region: Nakayama mine, Umegahata district, Kyoto city (京都市右京区梅ヶ畑). An eastern Kyoto mine (Higashi Mono), part of the Hon-Kuchi Naori geological seam connecting Nakayama, Ozuku, Okudo, Shoubudani, and Narutaki. Stones from this mine are among the most sought-after JNATs worldwide.

Grit rating (JIS equivalent): Approximately 6,000–10,000 JIS and above, suitable for finishing razor blades and high-carbon steel blades. A documented Nakayama Tomae Iromono Kiita Nashiji specimen measured grain size at 2.203 microns with hardness HS48, consistent with a high-end finishing stone. Nakayama stones at medium hardness (LV 3–4) correspond to approximately 8,000–10,000 JIS.

LV Hardness: Approximately LV 3–4 (medium to hard). Iromono coloration is most commonly found on softer Kiita stones, suggesting this particular specimen may lean toward the medium range, but Nakayama stones vary considerably. The stone described in collector listings as "kind of hard and condensed" with fast slurry production suggests LV 3.5–4.

Recommended progression: After a 6,000 JIS synthetic or a soft/medium JNAT Tomae. Suitable as a finishing stone for razors and high-quality kitchen knives. Does not require a tomo nagura or mechanical slurry-raising device in many cases, as the stone releases a good amount of black slurry on its own.

Composition: Siliceous shale, Hon-Kuchi Naori geological formation, Tomae strata (presumed). Iromono (色物) is a purely visual characteristic caused by mineral pigmentation during stone formation — red, pink, and violet color variations are due to iron oxide and other trace minerals embedded in the sedimentary matrix. It is not a mineralogical class of its own and does not inherently affect sharpening performance.

Steels to sharpen: Ideal for razors and fine cutlery requiring very high edge refinement. Effective on high-carbon steel (hagane) and stainless. Use with slurry and light pressure on soft iron cladding (jigane) to avoid scratching.

Usage recommendations:

• No soaking required — surface wetting only
• Stone produces a good quantity of black slurry relatively quickly; tomo nagura may not be needed
• Very smooth surface; maintain slurry throughout sharpening
• Not recommended for beginners — requires experience and controlled technique
• Before honing a razor, test for toxic inclusions (Kanesuji lines): run a soft metal or fingernail lightly across the surface and check for scratching; dark reflective lines warrant caution
• Iromono coloration with pink/violet patches should be checked individually — color variations may include harder mineral pockets
• Seal sides and base with cashew lacquer; do not soak

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. The mine has been closed for a long time.
• 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. Softer specimens (Aoto-type, LV 2–3) are documented at approximately 4,000–6,000 JIS. Hard Asagi specimens (LV 4.5–5) are extremely dense and fine, suitable for razor finishing, placing them at approximately 10,000–12,000 JIS. The Asagi variant specifically is characterized as extremely dense and fine.

LV Hardness: LV 5 (very hard) for the dense Asagi type. Confirmed at hardness 5 across multiple vendor listings for Yaginoshima Asagi. Some specimens rated LV 2–4 exist (the mine produces a range), but the Asagi type from this mine is specifically known for exceptional hardness and density. On the 1–5 Tanaka Toishi scale: hardness 4.5, wear rate 1.5, self-slurry 1.5.

Recommended progression: After a synthetic 5,000–8,000 JIS stone or a medium JNAT (LV 2–3). For razor use, a full Mikawa Shiro Nagura progression (Botan → Mejiro → Koma) is recommended before or on this stone. Also highly effective for knives and traditional carpentry tools as a final finishing step.

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.

Steels to sharpen: Universal, with particular strength in razor finishing. Despite LV 5 hardness, demonstrates smooth sharpening behavior and works well with heavier blades such as knives and woodworking tools. Produces a very even and consistent Kasumi finish. Respected in traditional Japanese carpentry for tool finishing. Well suited to high-carbon steels; use with slurry for soft iron cladding.

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 — Mikawa Shiro Nagura progression is strongly recommended for razors
• Stone translates nagura feedback exceptionally well, giving clear indication of edge development
• Despite high hardness, demonstrates surprisingly smooth and manageable behavior even on heavier blades
• Goma (black sesame-seed dots) present — test for toxicity before honing fine edges; hard Goma can scratch soft jigane if used without slurry, but are safe with slurry in place
• Seal sides and base with cashew lacquer; do not soak
• Offers exceptional performance-to-price value in the super-hard stone category

Japanese name (Kanji): 大平 烏

Name breakdown:

• 大平 (Ohira) — a western Kyoto mine (Nishi Mono) located near Mt. Atago. One of the few mines still occasionally active. Full designation: 大平山合砥石 (Ohira-kōzan gō-toishi = Ohira mine finishing/polishing stone).
• 烏 (Karasu) — visual/color attribute meaning "crow": a dark blue-black-and-white pattern within the stone resembling crows in flight against a darkening sky. Karasu indicates origin from the Aisa layer (合さ) of the Hon-Kuchi Naori strata. Karasu stones almost exclusively come from the Aisa layer, which sits at the boundary between Tomae and Namito. The Aisa layer has only four seams and is known for high hardness and abrasive force, but also for a higher probability of impurities.

Mining region: Ohira mine (大平山), western Kyoto (Nishi Mono), near Mt. Atago. One of the few Kyoto whetstone mines that is still occasionally active (along with Maruoyama). Stock is also available from material stored by major wholesalers (Tanaka, Imanishi, Hatanaka, Asano). The Hon-Kuchi Naori seam at Ohira connects westward to Yaginoshima and eastward toward Atagoyama, Ozuku, Okudo, and Nakayama.

Grit rating (JIS equivalent): Fine, 8,000 JIS and above. For Hon-Kuchi Naori stones at hard hardness (LV 4–5), the approximate range is 10,000–12,000 JIS. Ohira stones in general are described as approximately 9,000–10,000 JIS. Karasu/Aisa origin implies harder, denser material which tends toward the upper end of the fineness range.

LV Hardness: LV 4–5 (hard to very hard). Ohira Karasu is documented as "comparatively hard" and requires nagura. The Aisa layer from which Karasu originates is known for hardness. Individual specimens on the market have been noted at hardness 3.5–5 depending on the specific seam, but Karasu from Aisa is typically on the harder end. Not recommended for beginners.

Recommended progression: After a soft or medium JNAT Tomae (LV 2–3) or a synthetic 6,000–8,000 JIS stone. Intended for final finishing of razors, woodworking tools, and high-quality knives. Nagura is required.

Composition: Siliceous shale, Aisa layer (合さ) of the Hon-Kuchi Naori geological formation. The Aisa layer sits below Tomae and above Namito, with only four seams. Karasu patterning (dark blue-black areas) is caused by carbonaceous or organic material concentrated during sediment compression. Aisa stones are noted for high abrasive force but also for a higher incidence of impurities compared to Tomae or Namito. The Ohira mine specifically produces a rare variant with Karasu layers distributed from the surface through to the bottom of the stone.

Steels to sharpen: Well suited for hammered blades (tsuchime), traditional carpentry tools, and high-carbon Japanese steels including Honyaki and traditionally forged blades. Effective for razors at LV 4+. Use with slurry on soft iron cladding (jigane) — without slurry, the hard Aisa abrasive can scratch softer steel. Stones with very dark Karasu spots should be tested before use on fine edges.

Usage recommendations:

• No soaking required — surface wetting only
• Nagura is required — the stone is hard and does not raise slurry easily on its own; use Mikawa Shiro Nagura (Botan or Mejiro) to develop working slurry
• Not recommended for beginners; requires experience and controlled pressure
• Before use on a razor, test all dark Karasu spots and any visible lines for toxicity: drag a soft metal across the surface and inspect for unexpected scratches; dark reflective Kanesuji lines are a common risk in Aisa-origin stones and must be avoided
• Light Karasu stones free of Kanesuji lines are the most prized and safest to use
• Maintain slurry on the surface throughout sharpening; do not allow the stone to run dry
• Seal sides and base with cashew lacquer; do not soak
• Rare — Karasu from Ohira is uncommon on the market; Karasu from eastern mines (Nakayama, Ozuku) is more frequently encountered