Komon - Natural Stone - Premium Pick - Koma Nagura
Komon Stone 003
One of our most trusted sources handpicks these stones from the famed Imanishi in Kyoto for us, spending hours testing dozens and dozens and selecting only the best of the best at a variety of price points. These tennen toishi represent some of the best value you will find on the market for natural stones.
These stones are so impressive that they often make you feel like you are "cheating", so to speak - they provide outstanding results at a speed seemingly found only in stones that cost many times more, all while being fun and easy to use - they make it seem as if you have learned years of polishing in a matter of minutes. Combining these gems with the correct steel, you will come to understand the beautiful harmony skilled polishers sometimes have difficulty describing - working on natural stones with well-made knives truly ties the whole subject together.
We are proud to provide such wonderful pieces to you!
Brand: Komon-picked Imanishi
Producing Area:
Appearance: Near-pure white with the faintest tint of green; a few goma speckled in
Size: 205mm x 60mm x 38mm
Weight: 901g
~Grit Range: 1500-3000
1-5 Scale: 1 = Less, 5 = More
Hardness Level: 3.5
Scratch Depth: 2.5
Speed: 4
Wear Rate: 2
Self Slurry: 2
Thirst: 2
Consistency: 4.5
Feedback: 2.5
Ease of Use: 3.5
Notes: Koma Nagura stones are a staple in traditional sword polishing progressions—and are often used in razor and fine tool sharpening as well. Pure, high-quality examples like this are increasingly rare, and we’re fortunate to have sourced one. Typically used after Chu Nagura and before Uchigumori, Koma plays a crucial role in refining the foundation polish, allowing Uchigumori stones to fully express their potential. This particular stone is fast-cutting, with black slurry forming in seconds, and it effortlessly removes scratches even from stones more than half its grit level–a polisher dream!
It finishes with a warm, frosty kasumi that’s both beautiful and distinct. Working the jigane for just a few minutes can start to reveal banding, offering exceptional visual depth. Initial feedback has a bit of texture and grip, which quickly smooths out as slurry builds. It’s also hard enough to handle push-cut tools and even Ura on single bevel knives. Obviously effective on knife edges, but given its rarity it is advised that it be mostly reserved for polishing or wide bevel applications. For faster cutting and more even feedback, using a nagura, preferably a tomo nagura, could help.
Simply put, this is an incredible find for anyone building a premium polishing progression—or a collector seeking something truly special.
Recommended Usage: Pre polisher, frosty kasumi, gnarly edges, push cut tools
Disclaimer: Given the natural aspect of these stones, all graded characteristics are our own subjective thoughts which may vary from your expectations and assessment. The images shown and characteristics described may be from a previous, random example, or when first measured before being tested numerous times. If purchased, yours may differ slightly in appearance and qualities. All stone sales are final.
Tanaka Toishi - Natural Stone - Mikawa Chu Shima Nagura - #019
LBEBA-019
Brand: Tanaka Toishi 田中砥石工業所
Dimensions: 225mm x 86mm x 44mm
Weight: 1615g
Notes: Really nice specimen from the famous Mikawa mine in Aichi Prefecture via the famous Tanaka Toishi brand. They are firm to hard, and quality specimens are fast and give good polishing results. Generally easy to use depending on the hardness.
Suggested Use: pre or final polisher for knives and push-cut tools.
Background Info: Nagura is made of lithified tuff, which is silica-rich stratified volcanic ash that has been compacted into a solid over many, many years. They contain very fine particles of silica (and other which are often more friable than other sedimentary stones, and thus are ideal for polishing. They are used as one of the last stones before Uchigumori in a traditional sword polishing sequence. The word "Nagura" is the named after the individual who discovered the utility of the lithified tuff as a whetstone, Sakon Nagura, over 700 years ago.
Please Note: Given the natural aspect of these stones, all subjective qualities are our estimates and may vary slightly from your exact expectations and assessment. The images shown and characteristics described may be from a previous example. If purchased, yours may differ slightly in appearance and qualities. Dimensions, weight, and stamps may be different from listed if it has been tested.
Tanaka Toishi - Natural Stone - Mikawa Shima Chu Nagura - #018
LBEBA-018
Brand: Tanaka Toishi 田中砥石工業所
Producing Area: Mikawa Mountain Range, Kitashitara, Aichi - Japan
Mine: Kada Mountain or unspecified Junmikawa stratum
Strata: N/A
Appearance: "Striped" (shima) lines running linearly down the length of the stone, a mix of off-white and orange. Beautiful chalky block!
Size: 220mm x 82mm x 45mm
Weight: 1573g
~Grit Range: 2500-4000
1-5 Scale: 1 = Less, 5 = More
Hardness Level: 3.5
Scratch Depth: 2.5
Speed: 2 (4 with tomo nagura)
Wear Rate: 2
Self Slurry: 2 (4 with tomo nagura)
Thirst: 3
Consistency: 3.5
Feedback: 2.5
Ease of Use: 2.5
Notes: A large, pure nagura that will last many years.
Suggested Use: pre or final polisher for knives and push-cut tools.
Background Info: Nagura are made of lithified tuff, which is silica-rich stratified volcanic ash that has been compacted into a solid over many, many years, and this composition yields unique sharpening and polishing properties. Much of their use has been centered around blades other than knives: swords, razors, woodworking tools and so on. Nagura can come from several locations in Japan, the most famous being the Junmikawa (Mikawa) mine located within the Mikawa Mountain range in Aichi Prefecture.
Chu Nagura are used as one of the last stones before Uchigumori in a traditional sword polishing sequence. Such "proper" Chu Nagura are mined at Kada Mountain, not from the Mikawa mine-proper, both of which are in the same mountain range. Chu Nagura can also be somewhat of a catch-all term for stones from the Mikawa mine that do not fit cleanly into the known classified strata. Within swords, "chu" is often used to roughly mean "medium" (medium grit, medium size, etc.)
Please Note: Given the natural aspect of these stones, all subjective qualities are our estimates and may vary slightly from your exact expectations and assessment. The images shown and characteristics described may be from a previous example. If purchased, yours may differ slightly in appearance and qualities. Dimensions, weight, and stamps may be different from listed if it has been tested.