color check

Black/grays/white
00-00-00 33-33-33 66-66-66 99-99-99 CC-CC-CC FF-FF-FF

green/blue (no red)
00-99-33 00-99-66 00-99-99 00-99-CC 00-99-FF

red/blue (no green)
33-00-33 33-00-66 33-00-99 33-00-CC 33-00-FF CC-00-33

grayish greens & blues
66-66-99 66-99-66 66-99-99

66-CC-33 66-CC-66 66-CC-99 66-CC-CC 66-CC-ff

purples & lavenders
99-33-33 99-33-66 99-33-99 99-33-CC 99-33-FF

99-66-66 99-66-99 99-99-66

"yellow-greens"
CC-FF-33 CC-FF-66 CC-FF-99 CC-FF-CC CC-FF-FF

reds & pinks
FF-00-00 FF-66-33 FF-66-66 FF-66-99 FF-66-CC FF-66-FF

yellows
FF-FF-00 FF-FF-99 FF-FF-CC