Cerulean (/səˈruːliən/), also spelled caerulean, is a shade of blue ranging between azure and a darker sky blue. The first recorded use of cerulean as a colour name in English was in 1590. The word is derived from the Latin word caeruleus, "dark blue, blue, or blue-green", which in turn probably derives from caerulum, diminutive of caelum, "heaven, sky". "Cerulean blue" is the name of a pigment. The pigment was discovered in the late eighteenth century and designated as cerulean blue in the nineteenth century. From Wikipedia
