Dark haired people, ranging from dark chestnut and deep brown to black, with either dark or light colored eyes, can also be seen among the Indo-European and non-Indo-European ethnic groups in Iran, the Caucasus, Central Asia, Afghanistan and India. Hair is naturally reflective, so black hair isn’t completely dark in bright light. However, the darkest shade is deep enough that it doesn’t give the reflection a warm, neutral tone. Instead, the sheen can seem almost blue, like the iridescence of a raven’s wing. Thus, it’s known as raven-black.  It’s found in people of African, Latin American, South Asian and Southeast Asian descent. Black hair overwhelmingly predominates in almost all parts of Asia, although areas in Northwestern Asia (mainly Turkey, Cyprus, Lebanon, Israel, Georgia, and Armenia) have significant non-black haired populations.
Sky blue is the name of a colour that resembles the colour of the unclouded sky at noon (azure) reflecting off of a metallic surface. The entry for “sky-blue” in Murray’s New English Dictionary (1919) reports a first sighting of the term in the article on “silver” in Ephraim Chambers’s Cyclopaedia of 1728. However, many writers had used the term “sky blue” to name a colour before Chambers. For example, we find “sky blue” in A Collection of Voyages and Travels (London: Awnsham and John Churchill, 1704), vol. 2, p. 322, where John Nieuhoff describes certain flowers: “they are of a lovely sky blue colour, and yellow in the middle”.
The sense of this colour may have been first used in 1585 in a book by Nicolas de Nicolay where he stated “the tulbant of the merchant must be skie coloured”.