Sky blue is the name of a color, first recorded in English in the 1728 Cyclopӕdia of Ephraim Chambers. Prior to the Chambers reference, the color had first been used in 1585 in a book by Nicolas De Nicolay where he stated "the tulbant of the merchant must be skie coloured." Displayed at left is the web color sky blue.

Deep sky blue is an azure-cyan color associated with deep sky blue. Deep sky blue is a web color. This color is the color on the color wheel halfway between azure and cyan. The traditional name for this colour is Capri. The first use of Capri as a color name in English was in 1920.

The color Capri in general is named for the azure-cyan colour of the Mediterranean sea around the island of Capri off Italy, the site of several villas belonging to the Roman Emperor Tiberius, including his Imperial residence in his later years, the Villa Jovis.

The color name deep sky blue for this color did not come into use until the promulgation of the X11 colour list in 1987. The name Capri is still used for this color as well as the name deep sky blue.