Cis-Dur
Although G-sharp major is usually notated as the enharmonic key of A-flat major, because A-flat major has only four flats as opposed to G-sharp major's eight sharps (including the F), it does appear as a secondary key area in several works in sharp keys, most notably in the Prelude and Fugue in C-sharp major from Johann Sebastian Bach's "The Well-Tempered Clavier", Book 1. The G-sharp minor prelude (and, in some editions, the fugue) from the same set ends with a Picardy third, on a G-sharp major chord.