Cerulean blue is a deep medium blue color based on a 19th century blue pigment. The word cerulean originates with the Latin caeruleus meaning blue. As such, the term was used for ancient blue pigments particularly mixes of copper and cobalt compounds that were thought to capture the color of the sky. The modern color cerulean blue is based on the color of cobalt stannate, an expensive 19th century pigment that produced a deep blue. It is currently common for another compound, cobalt chromate, to be marketed under the same name. The latter pigment is darker and greener. The following are common types of cerulean blue with a few related colors.
Cerulean Blue #3
#0040ff
Cerulean Blue #2
#007ba7
Deep Cerulean
#007bbb
Vivid Cerulean
#00aaee
Deep sky blue
#00bfff
Cobalt
#030aa7
Bright Cerulean
#1dacd6
Cerulean Blue #4
#2a52be
Cerulean Blue #4
#2a52be
Dark Cobalt
#2e2d88
Saturated Sky Blue
#4b4cfc
Cerulean
#55aaee
Cerulean Frost
#6d9bc3
Pale Cerulean
#9bc4e2
Notes
The photo above is illustrative. Please don't put cerulean blue pigment on your skin. The color of the original 19th century cerulean blue pigment can be prominently seen in the following artwork by Berthe Morisot entitled Summer's Day.