1913-S Weak S

The 1913-S Weak S Indian Head Half Eagle is the version that turns up most often when San Francisco half eagles from this date appear for sale. The S mintmark above the arrow shafts is faint, soft, or shaped like a small blob with no defined curves, and on many pieces the area looks blank to the unaided eye. Roger Burdette's archival work traced the source: the upsetting machine at San Francisco failed to raise the planchet rim uniformly during the first weeks of 1913 production, leaving too little metal to flow into the deepest part of the die during striking. The mintmark sits closest to the rim, so its relief suffered first. Production ran in January and February only, totaling 408,000 pieces across two catalog entries, and the affected coins likely cover the bulk of the January output.

Attribution starts at the mintmark zone. The S can range from a barely readable shadow to a soft lump, and on the worst pieces the spot reads blank. A 10x loupe usually catches a faint trace of the original S geometry, a curve or ridge where one of the loops tried to fill, and that residual outline separates a genuine Weak S from a Philadelphia coin altered to pass as San Francisco. The standard 1913 issue from Philadelphia carries no mintmark, so a too-clean reverse on a coin offered as 1913-S deserves close inspection. The rest of the coin should pass standard type checks: the Indian portrait, headdress, and reverse eagle sit incuse below the field plane, and the piece weighs 8.359 grams at 21.6 millimeters in 90 percent gold.

For collectors the Weak S occupies the same odd spot as the 1912-S version. It is the more common of the two San Francisco varieties, but specialists track it separately and major grading services note the attribution on the holder. Circulated pieces in VF and EF turn up with some regularity, lower Mint State grades take patience, and anything above MS-63 is a real chase. Most date-set buyers acquire a Weak S first because that is what the market offers, and add a Strong S later if budget permits. For the broader story of Bela Lyon Pratt's incuse design, see the Indian Head Half Eagle series history.