Sugimoto Chuka (Chinese Cleaver) #7 (4007) Mid Weight White 2, Full Size

It depends on the blade thickness. A knife maker's guide sorts the chuka cleaver (中華包丁) into three thicknesses, each suited to different foods.

The thin kind (薄刃), the lightest, is for the everyday foods a supermarket sells; the medium-thick kind (中厚刃) can also cut hard foods such as bone-in chicken and fish bones; and the thick kind (厚刃), the heaviest and meant for experienced users, suits bone-in block meat and frozen food. Check the thickness of your blade before you cut any bone.

Shirogami 1 (White 1) has a higher carbon content than Shirogami 2 (White 2), roughly 1.3% vs 1.1%.

White 2 (Shirogami #2) has about 1.1% carbon and, per Proterial, a hardening hardness of over 60 HRC; White 1 sits around 1.3% carbon. That 0.2% difference is the core spec gap. More carbon generally means you can push hardness higher and hold a keener edge, but it also makes the steel more brittle and less forgiving. White 2 trades a bit of that potential peak sharpness for slightly better toughness and ease of sharpening.

Shirogami 1 carries a certain prestige. Sukenari's Nobuo Hanaki once told me directly that they only use White 1 for their mizu-honyaki because it is the pure form of carbon steel, it carries that halo. Among traditional smiths, White 1 is still spoken of as the benchmark.

They are Sugimoto's own production numbers, original to the company, its shop says, and its cleaver categories group them by thickness: numbers 1 and 6 thin (薄口), 2, 7 and 11 medium-thick (中厚口), 3 thick (厚口) and 22 extra-thick (極厚口).

Within that numbering system, #6 is in the thin group and #7 is in the medium-thick group.