Red, yellow, and green are considered the luckiest colors. Red bringing happiness and good fortune, yellow symbolizing power, and green bringing fortune with wealth and fertility.
These early plastic stacks, one for each lucky color, have three buttons each. The larger buttons in the red and yellow tested positive for Bakelite, but I think they are celluloid, along with the rest. Red set has a tigh top, yellow a buffed celluloid, and green a bubble and an unusual reverse bubble-like design on the bottom. These measure between 22-49mm / .87"-1.93". The green stack is the smallest of the stacks.
