Every die variety in the CopperCoins catalog has a unique die number. Collectors use it in search, on die pages, in My Coppercoins, and in forum posts. The number encodes the year, mint, denomination, variety type, and a sequential index within that group.
Display format
On the public site, die numbers are shown in three segments separated by a middle dot (•):
Year+Mint • Denom+Type • Index
Examples:
- 1955D•1DO•001 — 1955 Denver doubled-die obverse, first die in that group
- 1960D•1MM•042 — 1960 Denver repunched mint mark, 42nd in that group
- 1964P•1DR•001 — 1964 Philadelphia doubled-die reverse, first die in that group
URLs and database storage use a compact lowercase form without separators, e.g. 1960d1mm042. Search accepts either style — with or without dots, hyphens, or spaces.
Segment breakdown
| Segment | Meaning | Examples |
|---|---|---|
| Year + mint | Four-digit year immediately followed by mint mark letter. | 1955D, 1972P, 1968S |
| Denom + type | Denomination digit (1 = one cent in the Lincoln catalog) plus a two-letter die type code. |
1DO, 1MM, 1DR |
| Index | Three-digit sequence within the year + mint + denom + type group. Numbers are assigned in order as dies are verified distinct. | 001, 042, 226 |
Mint letters
- P — Philadelphia
- D — Denver
- S — San Francisco
- W — West Point (when cataloged)
Die type codes
| Code | Meaning |
|---|---|
| DO | Doubled Die Obverse |
| DR | Doubled Die Reverse |
| MM | Repunched Mint Mark |
| OM | Over Mint Mark |
Proof strikes
Proof dies add a trailing P on the index segment in display form, e.g. 1971S•1DO•001P. In storage the proof flag is a lowercase p appended to the compact number. Use the search form’s Strike type → Proof filter when you only want proof listings.
How index numbers are assigned
New dies receive the lowest available index in their group (year, mint, denomination, die type, and proof status). The sequence is kept gap-free over time; when a mistaken assignment is corrected, the old number may become a tombstone page that explains the merge and points to the canonical die. Released numbers can be reassigned later following catalog policy.
Public history of merges, releases, and reassignments is recorded in the catalog change log.
Also listed as
Some physical coins carry more than one catalogable variety (for example a repunched mint mark paired with a doubled die). CopperCoins may list these as separate die numbers linked to each other. On a die page, look for (also listed as …) under the main die number to jump to the partner listing.
Using die numbers in search
- Type all or part of the number in the Die number field on search.
- Partial prefixes work:
1960d1mmfinds all 1960-D RPM dies;1960d1mm042narrows to one. - Bullets, hyphens, and spaces are optional —
1960D-1MM-042and1960d1mm042both resolve.
See How to search the catalog for every filter.
Related help