Playing cards weren't just made of paper; they came in many other materials. There were cloisonné-plated gold playing cards, cards made of gold and silver foil, crystal playing cards, agate playing cards, ivory playing cards, elephant bone playing cards, ox horn and ox bone playing cards, bamboo playing cards, acrylic playing cards, fiberglass playing cards… These playing cards were mostly for collection and rarely used for playing. For example, agate, ivory, elephant bone, and ox horn and ox bone playing cards, although shaped like mahjong tiles, were still played like regular playing cards. There were also many irregularly shaped playing cards, such as round, Christmas tree-shaped, shoe-shaped, triangle-shaped, snowman-shaped…
One theory is that the four suits represented the four main professions of the time: spades represented spears, symbolizing soldiers; clubs represented clover, symbolizing agriculture; diamonds represented bricks and tiles used by craftsmen; and hearts represented the red heart, symbolizing priests.
Another theory suggests that the four suits originated from the patterns on artifacts used in ancient European divination. Spades represent olive leaves, symbolizing peace; clubs are clover, signifying luck; diamonds are diamond-shaped, symbolizing wealth; and hearts are heart-shaped, symbolizing wisdom and love.
