Representative issue study
Showa 16 (1941) 1 Sen Aluminum
A reduced wartime aluminum specification demonstrates why year-specific mass matters.
昭和十六年一銭アルミニウム貨
- Date
- 昭和十六年 (1941)
- Denomination
- 1 Sen
- Material
- aluminum
- Issue class
- wartime-circulation
Context
Historical and monetary setting
The aluminum series underwent official weight and diameter reductions.
Identification
How to classify the object
Inspect oxidation, chalkiness, scratches, bends, stains, edge damage, mass, and diameter.
Evidence boundary
What this page does not claim
Do not use another aluminum year’s mass as this issue’s specification.
Issue evidence
Specifications, grading, and authentication
- Mass
- 0.65 g
- Diameter
- 16 mm
- Hole
- none
- Edge
- plain
- Production year
- 1941
- Legal issue year
- 1941
Material-specific grading
Aluminum: assess oxidation, chalky surfaces, scratches, bends, stains, and edge damage.
Authentication
Verify weight, diameter, thickness, alloy, magnetism, hole, edge, date and character style, die alignment, and evidence of casting, plating, altered dates, fake patina, or modern reproduction. Do not use destructive testing.
Continue
Related Taisho–Showa references
Evidence
Sources and scope
These links support the claims on this page. Source authority does not imply permission to republish source images.
Official specifications, first-issue years, legal-expiry dates, wartime and postwar regular types.
Open sourceImage identity and file-level reuse metadata only; historical claims are verified elsewhere.
Open source