Peru 1 C - Is This An Error?

Die crack + double die on date?
I don't have much experience, just guessing.

There were a few things going on with the die that struck this coin. First, keep in mind one simple fact, whatever you see on the coin was reversed on the die that made the coin. A raised line or area on the coin translates to a void of some sort in the die.

1. The surface of the die was slightly pitted - probably a little rust. A new die pair (in the modern coining era) is prepared for striking by polishing the high points of the die (the fields on the coin). This surfacing wears off as striking of coins proceeds. The longer the die stays in the press the more the die itself wears out. Sometimes, depending on the quality of the die steel small pits develop (usually rust) but at times due to voids or small bubbles in the die steel itself that were no originally visible. Sometimes after extended use a real large flaw (originally below the die surface) gets exposed. This starts as an apparent swelling of the coin - later the underlying defect can open up. The larger the die void the more there tends to be a weak spot on the opposite side of the coin at the same location. This is caused by a reduction in the cross section pressure.

2. There is a nice small die crack running through the date to the rim. Die cracks of this sort are the result of the failure of the die. The strike pressure fatigues the die metal and it simply gives up by splitting. Cracks if they progress too far will become terminal die flaws and the die has to be retired.

3. There are erosion flow lines (radial lines) near the rim of the coin. These are seen on older dies as the pressure of the coin metal flowing over the die surface wears groves in the die face. As these get deeper, raised lines start to appear on the coin. These are usually not a terminal defect and they can often be removed by resurfacing the die itself. This process, called "lapping the die" was far more common in the earlier days of coining and as dies become cheaper to produce the labor involved in lapping can be simply too costly to do. Coins made from eroded dies are usually considered a bit substandard by many collectors.

4. Beneath each digit of the date is a die erosion feature referred to as "a ghost image". It is formed in a manner similar to the erosion flow lines but it erodes the area next to digits resulting in the appearance of a false double date. The physics behind what happens to a die when struck by the master hub is fairly simple. The area directly under the pressure from the hub design HARDENS. It is a fact that pressure HARDENS steel as it does to most metals. A coin blank is softer than the coin after being struck. The metal adjacent to the feature remains just slightly softer. The softer metal is eroded more quickly by repeated striking and you get a ghost image just outside the original and SLIGHTLY LARGER. It is a radial feature.

5. The most impressive die feature is the diagonal raised line segment above the 7 in the date. That is due to damage to the die. Something like a "tool" hit the die surface for some reason making a hole in the die face. Every coin struck after that point in time will have the same raised lump. Sometimes these strange marks are caused by a hard object falling into the coining chamber. Usually a metal chip that got mixed in with blanks to be struck. Mints are FACTORIES no more no less. Lots of metal and metal chips get everywhere - when a hard object enters the coining chamber there will be damage of some kind.

These errors are all fairly common, but of the entire group the only one likely to attract attention and cause a small increase in value is #5. In fact, in some very popular series (especially earlier US) marks like this can result in a lot of collector interest (read higher prices). All you need is a very popular coin series and then a way to publicise this die variety. Only one die had the flaw so it is much rarer than the typical coin. I don't believe Peru has any such level of interest but if it did this would be a KEY die type.

Nice find.