玉鋼

Tamahagane

Jewel Steel

The legendary steel produced by smelting iron sand (satetsu) in a traditional tatara furnace over three days. The bloom contains steel at varying carbon levels, which a swordsmiths then separates by eye. For tool use, the finest pieces are laminated into a hard hagane cutting edge. Represents the absolute summit of Japanese metallurgical tradition — both material and art object.

Performance Characteristics

Sharpness10/10

Edge Retention8/10

Ease of Sharpening9/10

Rust Resistance2/10

Chemical Composition

carbon0.60–1.50% (varies through bloom)

Technical Data

Hardness58–65 HRC (varies by section) HRC

Heat TreatmentTraditional — charcoal fire, water quench, tatara process

Primary UseJapanese swords (katana), ultimate collector's blades and tools

ManufacturerNittokyo Nittosha Foundry (Shimane Prefecture, sole surviving tatara operator)