Cerulean (/səˈruːliən/), also spelled caerulean, is a shade of blue that ranges from light blue to the darkest sky blue. The first recorded use of cerulean as a color name in English was in 1590. The word comes from the Latin word caeruleus, “dark blue, blue, or greenish blue”, which in turn probably comes from caerulum, diminutive of caelum. “Heaven, Heaven”. “Cerulean blue” is the name of a pigment. The pigment was discovered in the late 18th century and named cerulean blue in the 19th century.