1. Jewelry Identifier
  2. Hallmarks
  3. SHAKUDO

* mixed-metal hallmark

The SHAKUDO hallmark: meaning, purity & value

Japanese copper-gold alloy (~4-10% gold). Develops a deep blue-black patina via traditional Niiro chemical treatment. Used in sword fittings and contemporary jewelry.

Published May 30, 2026

Quick facts

Metal
mixed-metal
Common regions
Japan

Stamps that mean the same thing

This purity may be struck into jewelry as any of: SHAKUDO / 赤銅. The mark differs by country and era, but the metal content is identical.

What SHAKUDO tells you

Japanese copper-gold alloy (~4-10% gold). Develops a deep blue-black patina via traditional Niiro chemical treatment. Used in sword fittings and contemporary jewelry.

How to check it yourself

  1. Examine the stamp under a 10× loupe — genuine marks are crisp and evenly struck, not doubled or smeared.
  2. Confirm the mark reads SHAKUDO or an equivalent such as 赤銅.
  3. Photograph it in the Jewelry Identifier app to read the metal, hallmark, and any gemstones from the image.
  4. For a binding result, have an assay office or gemological lab run an XRF purity test.

* Frequently asked

FAQ

Q. Is SHAKUDO the same as 赤銅?
A. Yes. SHAKUDO, 赤銅 all denote the same material — mixed-metal. Different markets and eras stamp it differently, but the purity is identical.
Q. How do I confirm a SHAKUDO stamp is genuine?
A. Look at the mark under 10× magnification for crisp, even strikes, cross-check the weight-to-volume ratio against the expected density, scan it with the Jewelry Identifier app, and — when it matters — have an XRF test done by an assay office or gemological lab.

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