Put the register's rarest lines in one place, the 264,000, the 208,000, the 18,780, and you have also written the counterfeiters' order book. Fakes are not distributed randomly across the record; they cluster on exactly the dates where a small official number meets a large public appetite, which is to say they cluster on this site's key pages. The frauds come in five shapes, each one an attack on a different part of what a mintage means, and knowing the shapes is most of the defense.
The added mintmark
The classic American coin fraud: take the common Philadelphia strike and solder, engrave, or glue the branch mint's letter onto it. The most attacked coin in the record is the 1916-D Mercury dime, 264,000 struck against eighteen million from Philadelphia the same year, a scarcity ratio that has made the added D a cottage industry for a century. The defense is beautiful and it is pure record-keeping: Denver used exactly four die pairs for the entire 1916 run, every genuine mintmark position and orientation is catalogued, and a D that sits anywhere else is a confession. The 1938-D half dollar draws the same attack for the same arithmetic, half a million struck beside four million from Philadelphia, with one twist the fraud never accounts for: genuine 1938-Ds were hoarded by the roll at issue, so certified examples are plentiful, and a raw one being offered as a treasure is answering its own question.
The removed mintmark
The same crime in reverse. The key of the Peace dollar series is the 1928 Philadelphia, 360,649 struck, the only sub-million circulation Peace dollar, while San Francisco made 1.6 million that year. So the fraud shaves the S off a 1928-S and sells silence as Philadelphia. The tell is the scar: metal does not forget, and the field where a mintmark lived shows disturbance under magnification, a flat spot, a polish halo, tooling lines. On any coin whose value depends on the absence of a letter, the empty space is the part to examine hardest.
The altered date
Why move a mintmark when you can move a year? Common-date Walkers become 1921s with a re-cut digit, which is why the 1921 trio's pages in this record all carry the same instruction: buy the trio certified, full stop. Canada's version is the register's neatest, because the fraud has a built-in lie detector: the 1948 dollar, 18,780 struck, gets faked from plentiful 1949s by reworking the last digit, but in 1948 the obverse legend still read ET IND IMP, King of India, and the 1949 legend does not. The counterfeiter alters the date and the coin's own words contradict him. The gray-zone cousin lives in the Buffalo series: acid applied to dateless nickels raises the ghost of the original date, and the coin is genuine, the date is genuine, but the market treats a restored date as a different, discounted thing, and a strong-dated key Buffalo at a bargain price deserves the acid question first.
The manufactured variety
The strangest genre: faking not a coin but an accident. The three-legged 1937-D exists because a Denver mint worker polished a damaged die hard enough to erase the bison's foreleg, a subtraction made at the mint, on the die, before striking. The counterfeit imitates the accident by grinding the leg off an ordinary coin afterward, a subtraction made on the coin, and the difference is readable: a genuine three-leg's missing leg was never struck, so the field beneath it is original mint surface, while a ground leg leaves scratches, flatness, and a hoof that stops wrong. The Walking Liberty series contributes the genre's subtlest case: because 1917's obverse-mintmark strikes are separately counted and two and a half times scarcer than the reverse strikes, reverse coins get their mark removed and a false one added up front, one coin, two frauds, promoted across an official boundary in the record.
The wholesale counterfeit
And then the fakes that skip alteration entirely: cast or struck from scratch. The 1893-S Morgan, 100,000 struck and the king of the series, meets these constantly, and here the record's defense is at its most elegant: every genuine 1893-S came from a single obverse die, whose date slant and mintmark position are published diagnostics, so the coin authenticates against a description written by its own die. Below that level of sophistication, the scale does the work, a Walking Liberty half weighs 12.50 grams and a Morgan 26.73, and casts run light, seamy, and soapy in the details.
The doctrine
Notice what every defense in this file has in common: it is documentation, not connoisseurship. Four die pairs, one obverse die, a legend that changed with a King's title, a mintmark's catalogued address, a mintage that predicts how many should exist. The record is the antidote to the fraud the record inspired, which is the closing argument of the varieties article run one step further: counted varieties fail by misattribution, uncounted ones fail by manufacture, and counterfeits attack both, so the buyer's answer covers both, attribution plus certification, the record plus the referee. The mintage is why they fake it. It is also, read closely enough, why they get caught.