Coin Edge Detective | The Third Side Forensics Lab
THE THIRD SIDE FORENSICS LAB · FIELD GUIDE 01
Every coin has
a third side.
The face tells you who. The reverse tells you when. The edge holds the clues most people never think to look for.
A visual field guide to reeding, lettering, plain edges, and design details around a coin’s circumference. Observe first. Compare carefully. Keep the evidence in context.
01 / EDGE ATLAS
Read the surface, not the story you expect.
Coin edges can be plain, patterned, inscribed, or divided into alternating sections. The same broad category can look different by country, denomination, year, and production method.
Reeded
Closely spaced grooves run around the circumference. Count, spacing, and sharpness are observations to record, not proof of a mint or date.
Plain
A comparatively smooth edge may still show a seam, contact mark, or manufacturing detail under angled light.
Lettered
Words, numerals, or symbols may appear on the edge. Note orientation, spacing, interruptions, and whether the legend repeats.
Segmented
Different finishes or patterns appear in sections. Map the sequence around the coin before deciding a segment is missing or unusual.
02 / FIELD METHOD
A repeatable five-step examination.
Good documentation helps you compare specimens without overstating what a photograph can show.
- Orient
Record which face is up and where the edge inscription begins. - Illuminate
Use soft, angled light to reveal relief without crushing detail in glare. - Rotate
Capture overlapping views around the full circumference. - Describe
Write what is visible before assigning a cause or variety. - Compare
Check the same denomination, year, mint, and a reliable catalog reference.
| FIELD NOTE | RECORD | WHY IT HELPS |
|---|---|---|
| Edge type | Plain, reeded, lettered, segmented, or mixed | Sets a neutral starting category |
| Pattern details | Spacing, depth, sequence, legibility | Makes comparison specific |
| Condition | Wear, dents, corrosion, residue | Separates wear from design clues |
| Capture setup | Light direction, scale, camera angle | Explains changes between images |
Workbench note: this page is an educational guide. It does not upload photographs, measure coins, store observations, or authenticate a specimen.
03 / CASE FILE 001
The ridge that disappears.
A collector photographs a reeded coin. A short run of ridges looks flat in one image, and the collector wonders if it is a striking error.
Open the investigator’s notes
First check: repeat the image with light coming from another direction and rotate the coin. A flat-looking patch can come from glare, contact wear, a weak impression, or a genuine design transition.
Next record: whether the boundary is sharp or gradual; whether it repeats; and what the matching denomination and year show in a trusted reference.
Finding: one photograph is not enough to classify the feature. Preserve the observation and keep the cause open until independent evidence supports it.
04 / FREQUENT QUESTIONS
Before you draw a conclusion.
Can an edge pattern identify a coin by itself?
It can narrow a comparison, but denomination, date, mint mark, composition, dimensions, and trusted references also matter.
Does a missing reed prove an error?
No. Wear, damage, lighting, and intentional design transitions can look similar. Compare multiple views and references.
Can a photo confirm authenticity or value?
No. This field guide is educational and is not an appraisal, grading, or authentication service.
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