Japanese Knife Steels Explained: Shirogami, Aogami, VG-10 and SG2
Researched. This guide is based on information published by the steelmakers, Proterial and Takefu Special Steel, plus a few knife retailers where the makers say nothing. We checked it on October 2, 2026. We have not tested these steels ourselves. This article contains no affiliate links.
When you shop for a Japanese knife, the listing usually names the steel: Shirogami, Aogami, VG-10, SG2. These names come from a small number of Japanese steelmakers. This guide explains what each one is, using the makers’ own figures wherever they publish them.
The short version
- Shirogami (White paper) and Aogami (Blue paper) are carbon steels made by Proterial at its Yasugi Works. They can rust, so they need drying after use.
- GIN3, VG-10 and SG2 are stainless steels. GIN3 is also made by Proterial; VG-10 and SG2 are made by Takefu Special Steel in Echizen, Fukui.
- A higher number in a name like Shirogami #1 or #2 does not mean “better”. In Proterial’s data, #1 has more carbon than #2 of the same color.
Steel by steel
The table uses the makers’ published figures. Proterial publishes composition ranges as typical values; Takefu publishes representative values. The hardness figures are what the makers state for standard heat treatment, not the hardness of any particular finished knife.
| Steel | Maker | Type | Carbon (%) | Other main elements (%) | Maker’s hardness figure |
|---|---|---|---|---|---|
| Shirogami #1 | Proterial | Carbon | 1.25–1.35 | Si 0.10–0.20, Mn 0.20–0.30 | HRC 60 or over |
| Shirogami #2 | Proterial | Carbon | 1.05–1.15 | Si 0.10–0.20, Mn 0.20–0.30 | HRC 60 or over |
| Aogami #1 | Proterial | Carbon, alloyed | 1.25–1.35 | Cr 0.30–0.50, W 1.50–2.00 | HRC 60 or over |
| Aogami #2 | Proterial | Carbon, alloyed | 1.05–1.15 | Cr 0.20–0.50, W 1.00–1.50 | HRC 60 or over |
| Aogami Super | Proterial | Carbon, alloyed | 1.40–1.50 | Cr 0.30–0.50, W 2.00–2.50, V 0.30–0.50 | HRC 60 or over |
| GIN3 | Proterial | Stainless | 0.95–1.10 | Cr 13.00–14.50, Mn 0.60–1.00 | HRC 59 or over |
| VG-10 | Takefu Special Steel | Stainless | 1.00 | Cr 15.00, Mo 1.00, V 0.25, Co 1.55 | HRC 60 or higher |
| SG2 (SPG2) | Takefu Special Steel | Powder stainless | Not published | Not published | HRC 62 or higher |
Shirogami (White paper)
Proterial describes Shirogami as carbon steel with minimal impurities. Shirogami #1 has more carbon than #2. Proterial lists #1 for uses needing the highest hardness, such as planes, chisels and razors, and #2 for chisels, razors and sickles. A lower-carbon Shirogami #3 (C 0.80–0.90) is listed by Proterial for uses that include kitchen knives; Proterial gives it a lower hardness figure when oil-quenched.
Aogami (Blue paper)
Aogami starts from a similar base but adds tungsten (W) and chromium (Cr). Proterial says these are added to improve heat-treatment properties and wear resistance. In a 2025 announcement, Proterial described Aogami as a high-carbon steel whose high hardness comes at the cost of corrosion resistance. KAI, a large Japanese knife maker, says Aogami gives excellent sharpness but is harder to sharpen.
Aogami Super
Aogami Super has the most carbon of the Aogami grades in Proterial’s data, and adds vanadium (V). Proterial notes that it is made with specialty melting. You may see slightly different carbon figures from retailers; we use Proterial’s own range.
GIN3 (often sold as Ginsan or Gingami #3)
GIN3 is Proterial’s stainless grade for blades. Proterial says it offers hardness and sharpness comparable to carbon steel, and lists kitchen knives and scissors among its uses. “Ginsan” and “Gingami” are trade nicknames; Proterial writes it as GIN3.
VG-10
VG-10 is a stainless steel from Takefu Special Steel. Takefu says it machines well, is easy to sharpen, and has excellent corrosion resistance and sharpness. Takefu also warns that imitation products have been sold under the VG-10 name, so buy from sellers who name the maker.
SG2 (SPG2)
Takefu calls this steel Super Gold 2 (SPG2); “SG2” is the common trade shorthand. It is Takefu’s powder-metallurgy stainless steel. Takefu says it combines high hardness, toughness, wear resistance and corrosion resistance. Takefu does not publish its composition.
What about R2?
Retailers describe R2 in different ways. Chef Knives To Go, for example, says SG2 and R2 are two names for the same steel. We could not confirm R2’s maker from a steelmaker’s own page, so we describe R2 only as a steel often sold as equivalent to SG2.
What the “paper” names mean
The color names are commonly said to come from the colored paper labels once used to tell the grades apart. Several Japanese knife makers and retailers repeat this, and one notes that the colors themselves carry no meaning. We did not find this explained on Proterial’s own pages, so treat it as industry tradition.
Carbon steel or stainless?
- Carbon steels (Shirogami, Aogami) rust if left wet. Wipe and dry the blade after each use. They may also discolor over time.
- Stainless steels (GIN3, VG-10, SG2) resist rust much better, which is why many home cooks start with them. “Stainless” means rust-resistant, not rust-proof.
- Clad knives can mix both. A common Japanese build wraps a carbon-steel core in stainless layers, so mainly the exposed edge needs carbon-steel care.
Who makes Shirogami and Aogami now?
Hitachi Metals, the original maker, renamed itself Proterial on January 4, 2023, following a tender offer by BCJ-52 Co., Ltd. On July 1, 2026, Proterial moved its magnetic materials and its wire and automotive components businesses into new subsidiaries; Proterial, Ltd. kept its other businesses. We found no announcement that the knife steels are being sold or discontinued. On December 9, 2025, Proterial began selling AIGAMI 2, the first grade of a new knife-steel series made at its Yasugi Works. Shirogami, Aogami and GIN are Proterial trademarks.
How to use this when you buy
- Check that the listing names the steel and, ideally, the steelmaker.
- Remember that the knifemaker’s heat treatment decides how hard the finished blade is. The makers’ hardness figures above are for standard heat treatment.
- If you do not want to dry your knife after every use, start with stainless or a stainless-clad blade.
Sources
- Proterial: Shirogami #1 (YSS)
- Proterial: Shirogami #2
- Proterial: Shirogami #3
- Proterial: Aogami #1
- Proterial: Aogami #2
- Proterial: Aogami Super
- Proterial: GIN3
- Proterial: AIGAMI launch (December 2025)
- Proterial: name change announcement (2022, Japanese)
- Proterial: reorganization in effect (July 1, 2026, Japanese)
- Takefu Special Steel: VG-10 (Japanese)
- Takefu Special Steel: SPG2
- KAI: carbon steel knives (Japanese)
- Jikko: carbon steel (Japanese)
- Chef Knives To Go: SG2 steel
We check facts against the sources above, as described in our Editorial & Accuracy Policy. If you spot an error, please tell us through our contact form.
