The hamon on a T10 katana is produced through differential clay-tempering, a process where the bladesmith applies a thick layer of insulating clay along the spine before the final quench in water or oil. The exposed edge cools rapidly, hardening into martensite, while the clay-covered spine cools slowly and remains relatively soft and resilient. The boundary between these two crystalline zones — visible as a misty, undulating line along the blade — is the hamon. Because the clay is applied by hand, the pattern varies between individual blades, meaning no two T10 katana share an identical hamon. This natural variation is part of what makes each piece genuinely collectible.