How to Identify the Keicho Oban

Start with the overall shape and scale. A genuine oban is a large, thin, oval plate of gold worked by hand — noticeably bigger than a normal coin and clearly not machine-round. The surface should be covered in fine, even horizontal striations running across the field. If the object is small, round, or perfectly regular, it is not an oban.

Next examine the stamped devices at the sides. Look for cartouches containing family crests (often paulownia-type marks) and small punch seals set into the striated field, with Japanese characters nearby. These stamps were applied by the Goto minting family as certification. Then focus on the center, where a vertical column of brush-inked characters should record the coin's value and certifying authority. This hand-applied sumi ink is the single most diagnostic feature of the type — struck-only "obans" with no trace of ink writing are a warning sign.

Assess the metal directly. Traditional oban gold is soft, high-karat, and warm yellow, without the paleness of low-purity alloys or the coldness of gilt base metal. Beware pieces that feel too light, ring like brass, show a plated edge, or have suspiciously crisp, uniform "ink" that looks printed rather than brushed. Because ink can genuinely fade with age, judge legibility together with wear on the gold, not in isolation.

Separate the oban from look-alikes. The smaller koban shares the oval striated look but is far smaller and simpler. Later oban (Genroku, Kyoho, Tenpo, Manen and others) differ in size, gold color, and inscription wording, so a Keicho attribution needs the specific era details confirmed. Modern replicas, tourist copies, and gold-plated fantasies are extremely common and are the default assumption until proven otherwise.

Finally, apply strong authentication caution. Given the high value and the flood of reproductions, do not rely on appearance alone: weight, dimensions, metal analysis, and the character of the ink and stamps should all be checked, ideally by a specialist in Japanese numismatics. Compare any candidate against documented Keicho oban and recent specialist auction records before treating it as genuine.