Blundered Obverse Die with an extra 8 punched in Liberty's drapery left of the pendant.
Surfaces are fully original and slightly toned in faint yellow, peach and violet.
Strike is a little shallow, most notable at Liberty's hairline, characteristic of this issue. Scattered light contact marks are visible under a glass, but do not remove this coin from the Gem category. 1866-S is a rare date half dime in Gem Uncirculated condition, with this coin tied with one other as the Finest Certified by PCGS, trailed by 3 MS65s.