slate blue

a moderate to dark grayish blue.

Origin of slate blue

First recorded in 1790–1800

slate-blue, adjective

He was shown with a crown of peacock's feathers, clad in a golden dhoti and in every case his skin was mauve or slate-blue.

The Loves of Krishna in Indian Painting and Poetry |W. G. Archer
The night fell very cold, with an empty heaven overhead, but its lower arcs set with slate-blue cloud.

Through the Heart of Patagonia |H. Hesketh Prichard
A petrel it is, about the size of a house pigeon, and of a slate-blue colour.

The Land of Fire |Mayne Reid
There was a smile on her lips, but there was fiery challenge in her slate-blue eyes.

The Drums Of Jeopardy |Harold MacGrath

Slate-blue eyes, two books with endless pages, the soul of this wife of his.

The Drums Of Jeopardy |Harold MacGrath