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Doubling but no doubled die

David S. Brenner of Delaware found what appeared to be a bona fide strong doubled die on a 2010 Grand Canyon 5-ounce silver bullion coin showing in images he sent to Numismatic News.  It wasn’t.

This article was originally printed in the latest issue of Numismatic News.
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David S. Brenner of Delaware found what appeared to be a bona fide strong doubled die on a 2010 Grand Canyon 5-ounce silver bullion coin showing in images he sent to Numismatic News. It wasn’t.


As I was talking to him and he reminded me that the inscriptions about the rim of the coin were incuse rather than raised, it set off alarm signals in my head, which turned out to be justified after I examined the actual coin.

In previous articles I’ve written over the years, I’ve explained that the most common form of Strike Doubling is generally accepted to be created by looseness in the press, which in turn causes vibrations to set up during the coining operation. This may cause the upper and/or lower die to bounce against the struck coin a split second after the coin is struck but just prior to ejection, resulting in an area of the field parallel to a design (on the die) smashing down a section of raised design(s) on the coin.

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Depending on the orientation of the coin on the lower die, (which may shift slightly during ejection) this flat shelf of doubling that borders one side of raised design elements may be found on the obverse and/or reverse and is usually what researchers point to as a diagnostic of strike doubling (also known as Machine Doubling Damage and Mechanical Doubling).

However, in other previous treatments of this subject I have examined variations from this flattened-to-the-field rule, including doubling formed as a design when smashed down a slope, how some design elements in the field that closely border a design may be raised up into another design area during die bounce, and the effect of a die that slides and pushes metal up the side of a design.

However, as much as Brenner’s coin appeared to exhibit a doubled die in his images, it is in fact regrettably not so. What many folks don’t know is that strike doubling that affects incuse designs results in split serifs and separation of elements that closely mimics true hub doubling. Due to the optical illusion of incuse designs appearing raised in photographs it is virtually impossible to tell the difference between this type of strike doubling and hub doubling when viewing images alone.

While Brenner found this effect to a greater or lesser degree on the reverses of all five coins in the 2010 5-ounce silver series, the one that was the strongest was on the Arizona Grand Canyon issue, so it is the one we will focus on here.

While it showed on every single character that bordered the rim, I shot photos of the date, PLURIBUS and the AN of CANYON. Notice the separation of images that is not typical to the more common forms of strike doubling. In particular, I have pointed out the obvious split serifs on the “1” of the date. Conspicuously absent is the flat shelf-like type of damage typical of strike doubling.

While the doubling on this coin seems to break all the rules of what we have learned to expect strike doubling to look like, the answer is simple and easy to understand.

Unlike the majority of coins that boast raised images, the affected elements noted above are incuse designs on this coin and are thus raised on the die. Since they are raised on the die, any bouncing of this portion of the die into the coin will be exactly like a hub or punch (which is generally raised) sinking images into a die blank. The result is an effect exactly like that found on a doubled die yet it is simply another manifestation of strike doubling, a form of damage that adds no value to a coin.

However, there is one catch and that is that we do know that on genuine doubled dies that might have an incuse area (such as Emanuel Hahn’s initials on the Canadian Voyageur nickel dollars) may also bear hub doubling. The trick is to first realize that a coin that shows absolutely no hub-like doubling anywhere other than in the incuse areas is highly suspect. Then study the raised areas of design and if they show strike doubling of the more commonly seen type, then you’ve nailed it 99.9 percent as being strike doubling on the entire coin’s obverse and/or reverse.

In this case we were able to find the flat shelf-like strike doubling on the base of the design but the clincher was in Designer/Engraver Phebe Hemphill’s initials within Grand Canyon just above the second “0” of the date. Here we can see that the coin was actually at least struck twice (as is typical for these large 3-inch diameter coins) and that strike doubling occurred right after the second strike to the east of the normal initials and then the strike doubling was flattened down even to the field by the second strike. This form of doubling (known as “flat field doubling” is a legitimate error since it occurred within the minting process but is largely ignored by collectors. It is pointed out by the black arrows. Additionally, we see that on the second strike our shelf-like type of doubling has also occurred on the west side of the initials as pointed out by the red arrows.

Since every one of Brenner’s coins in this five-piece set showed doubling or tripling to a greater or lesser degree in the recessed characters about the reverse rims, I expect that many of these coins will turn up in collector hands. The fact is, the larger the coin, the harder it is to eliminate strike doubling due to the higher pressures involved. So when you see one of these “fantastic” so-called doubled dies online, consider yourself warned. They are not errors or varieties but a mint-caused form of damage to the coin that occurred within a split second after the coin was struck, just prior to ejection.

E-mail Ken Potter at

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