The 1876-CC twenty-cent piece, known as the “Duke of Carson City coins” owing to its remarkable scarcity, was struck with a single pair of dies and the obverse includes an easily identifiable diagnostic: significant doubling on all the letters of “LIBERTY” on the banner across the shield on the obverse.
Our Coin Resource Center listing describes the doubling: “The most prominent diagnostic of this die marriage is bold doubling to the word LIBERTY and stars 2 through 9 on the obverse. Patches of raised die lines are seen at Liberty’s foot and at both sides of the date, and the top of an errant 8 is seen in the denticles below the primary digit 8 in the date. On the reverse, the mintmark is widely spaced with the first C centered over the letter Y in TWENTY and the second C centered over the extreme left edge of the letter C in CENTS. A faint vertical die line extends up from the left foot of the letter E in CENTS.”
The upside, at least for collectors, of this doubling is that it is impossible to forge an 1876-CC twenty-cent piece by adding a mintmark to one of its more common Philadelphia Mint siblings.
Considering how rare 1876-CC twenty-cent pieces are, most if not all known examples are certified, rendering the diagnostic, for the purposes of authentication, unnecessary. Granted, collectors should always be on the lookout for fake third-party slabs containing fake coins, so if a slab’s authenticity cannot be confirmed, the diagnostic might come in handy.
The sale of any 1876-CC is a notable event, and the existing confirmed examples are well known enough that it is highly unlikely that a certified example will appear on the market unannounced. In sum, if you’re looking at an authentic 1876-CC twenty-cent piece, it’s likely well-documented and already in a third-party holder.
In his magisterial 2020 The Confident Carson City Coin Collector, Carson City coinage expert Rusty Goe estimates that 14 to 17 examples survive across all grades. PCGS and NGC report a combined total of 23 grading events, suggesting that a number have been broken out of third-party holders and either resubmitted or submitted to another grading service.
Any collector who needs to evaluate a raw piece, hoping to identify the next known example of this significant U.S. rarity, however, would do well to keep this diagnostic, and others, in mind.
