Spotting Fakes — An Introduction to Authenticating Japanese Swords

Unfortunately, forgeries exist in the Japanese sword world. Basic authentication knowledge is essential for collectors.

Gimei (false signature): Forged signatures of famous smiths. Detected by examining calligraphy style, file marks (yasurime), and consistency with the blade's era.

Atomei (later signature): Signatures added after the original creation. Watch for unnatural color or patina on the nakago.

O-suriage mumei: Blades whose tang has been greatly shortened, removing the original signature. These aren't forgeries, but require expertise to evaluate based on workmanship.

Key points for detection: 1. Does the jihada and hamon match the claimed era and school? 2. Is the nakago patina natural? 3. Do the file marks match the attributed smith? 4. Is the overall balance and form consistent?

Why NBTHK matters: Amateur judgment is risky. Always purchase swords with NBTHK certification. All swords at DATEKATANA come with papers.