noun
blue-black
A very dark blue that appears almost black; used for colors of ink, hair, fabrics, etc.
この万年筆のインクはブルーブラックです。
This fountain pen ink is blue-black.
彼女の髪は自然なブルーブラックだ。
Her hair is a natural blue-black.
Loanword from English 'blue-black', combining 'blue' and 'black'.