Types of Gimei and Authentication: The Sword Industry's Approach to Detecting False Signatures
* Image is for illustrative purposes only.Table of Contents
What is Gimei? — A History of "Lies" Hidden in Signed Blades
In the valuation of Japanese swords, the signature (mei) of the swordsmith carved into the tang (nakago) is one of the most critical factors in assessment. Blades bearing the signatures of master smiths often command prices of millions to tens of millions of yen on the market, and this significant economic value has become a breeding ground for fake signatures. A fake signature (gimei) refers to a signature that is not authentic—one carved or altered by someone other than the original swordsmith after the blade was made.
The history of fake signatures runs parallel to the history of Japanese swords themselves. Already in the Edo period, a "famous blade boom" occurred, and swords bearing the names of renowned smiths such as Masamune, Nagamitsu, and Yoshihiro circulated in the market. The custom that arose whereby a blade could not be recognized as famous without a certificate of authentication called "orisashi" issued by the Honami family was itself a countermeasure against the prevalence of fake signatures. Even today, signed blades that do not pass the scrutiny of the NBTHK or the Nihontō Preservation Society contain fake signatures at a certain rate, and the frontline of authentication focuses considerable energy on their exclusion. With the expansion of internet auctions and overseas markets, awareness of gimei risk has become more important than ever.
Major Classifications of Gimei — Five Patterns
Gimei can be broadly classified into five types based on fabrication methods and motives.
| Classification | Characteristics |
|---|---|
| ①Nochi-mei | A signature added later to an unsigned blade. The blade itself is often an authentic antique or famous sword, and the typical example is adding a false signature to an unsigned work by a master smith to increase its value. A discrepancy easily arises between the age character of the tang and the newness of the signature, making this type relatively easy for authenticators to detect. |
| ②Kaisan-mei | An authentic signature from a relatively unknown smith altered by recarving into the name of a renowned smith. For example, changing "Nobufusa" to "Nobuhide"—alterations between smiths with similar character forms are common. When performed with old rust already present, distinction becomes difficult. |
| ③Togidashi-mei | A technique of polishing the tang whose signature has become illegible due to rust or dirt, creating the appearance of discovering a previously unknown brushstroke. If the polishing traces are too uniform, suspicion increases. |
| ④Daitsuke-mei | The substitution of a tang from a different blade, with a different blade body attached. The age and style characteristics of the tang and blade body often do not match, and the position of the peg holes and the degree of tang corrosion become important assessment factors. |
| ⑤Keizu-shasho-mei | Assuming the identity of a historically documented smith from an established lineage but with few surviving works, and inscribing a false signature on an unsigned blade with similar stylistic characteristics. Cases often target provincial smiths with limited historical records. |
How Authenticators Distinguish Gimei
Assessment of gimei by authenticators is conducted along two axes: examination of the blade's stylistic characteristics and examination of the signature's calligraphic style and carving technique.
- Consistency Check with the Blade: This is fundamental. For example, if a blade with the characteristic jigane of the Bizen tradition (itame skin and choji-midare hamon) bears a signature of Masamune, a renowned master of the Soshu tradition, suspicion arises immediately. Masamune's blades are characterized by nie-worked jigane and distinctive gunome-midare hamon, which are physically impossible on a Bizen-style blade.
- Signature Calligraphic Analysis: Comparison is made against a database of each smith's distinctive character forms, chisel angle, carving depth, and spacing. References include oshigata documents dating back to the Honami family, as well as accumulated authentication data held by the NBTHK. Reference characteristics are relatively abundant for smiths from the mid-Edo period onward, but fewer reference materials exist for smiths of the ko-to (ancient blade) period, making assessment difficult. Recently, digitization of oshigata data has progressed, and more precise comparison is becoming possible.
- Observation of Chisel Marks: This is an important clue. Chisels used by smiths before the Edo period were often wide, chisel-shaped implements that tend to produce U-shaped cross-sections in the carved grooves. Forgeries made after the modern period typically exhibit V-shaped cross-sections, which can often be distinguished by magnified observation.
- Rust Formation Patterns: This cannot be overlooked. On authentic ancient signatures, rust of similar age accumulates within the grooves of the signature and on the tang surface; with later forgeries, rust within the grooves is uniformly thin or retains an artificially colored unnaturalness. The application of non-destructive testing techniques such as fluorescent X-ray analysis to authentication is also being discussed at the research level.
Economic and Legal Issues of Gimei in the Industry
Gimei causes serious economic losses to the sword industry. Signed blades often command prices several to dozens of times higher than unsigned blades, and buyers suffer substantial losses in transactions involving gimei. Particularly in modern times with increasing overseas buyers, fraudulent transactions targeting purchasers unfamiliar with Japanese authentication culture have become problematic.
Legally, selling a gimei as an "authentic signed blade" may constitute fraud (Penal Code Article 246). In fact, there have been cases in the past where dealers selling gimei at high prices were prosecuted. However, many cases are difficult to judge—such as signatures added in good faith during restoration in earlier times—and legal determinations are influenced by individual circumstances.
The Japanese Sword Dealers Association and industry organizations recommend that members present authentication certificates in sword transactions and unofficially encourage trading signed blades that have not passed NBTHK examination as "equivalent to unsigned." This is an industry effort at self-regulation to ensure transparency, but it lacks legal force and has limitations in its enforcement.
Reducing Gimei Risk — Practical Measures for Buyers
Taking the following stepwise precautions when purchasing a signed blade can help mitigate risk.
- Verify the Presence of an Authentication Certificate from the NBTHK or Nihontō Preservation Society: Both organizations conduct comprehensive examination including verification of the authenticity of signatures on signed blades, and swords awarded grades such as "Specially Important Sword" or "Important Sword" are virtually certain not to have gimei. However, since counterfeit certificates themselves can exist, it is desirable to verify the certificate number by contacting the issuing organization.
- Consult Multiple Authenticators: It is not uncommon for different experts to hold differing opinions even if one appraiser judges a signature to be authentic. For high-value transactions, obtaining second opinions from multiple specialists is becoming established as industry practice.
- Assess Value as an Unsigned Blade: Even if the authenticity of a signature is questionable, if the blade quality is excellent, it will be recognized as having a certain value as an unsigned sword. Purchasing with awareness of gimei risk and trading at a price based on "blade assessment ignoring the signature" is one option chosen by experienced collectors.
Swords listed in TOUKENZA's online catalog can be viewed along with seller information. Authentication certificate presence and condition can be confirmed on the product detail page, and inquiries about unclear points are recommended through the contact form.
