"figure on playing cards," 1598, probably from It.
spade, pl. of
spada "sword, spade," from L.
spatha "broad, flat weapon or tool," from Gk.
spathe "broad blade" (see
spade (1)). Phrase
in spades "in abundance" first recorded 1929 (Damon Runyon), probably from bridge, where spades are the highest-ranking suit.
"The invitations to the musicale came sliding in by pairs and threes and spade flushes." [O.Henry, "Cabbages & Kings," 1904]
Derogatory meaning "black person" is 1928, from the color of the playing card symbol.