Great Britain - Spade Guinea 1798 over 1792 or 1798, Gold, GEORGE III 1760–1820 Laureate head right. Rev. crowned spade-shaped arms, date below.S. 3729; Fr. 356 (221); KM. 609.Spink's entry in the SCBI merely acknowledges the existence of this rare overdate 1798/92 and omits any price guide. NGC only recognizes this variety as 1798 over 1798.8.39 g. RRR. Extremely rare overdate. NGC UNC Details. Obverse tooled