Covered with a bloom or a pale powdery covering, regardless of colour.
Of a pale grey or bluish-green, especially when covered with a powdery residue.
Of a brilliant dark blue or slightly purplish colour like that of the pigment (noun sense 1).
In full ultramarine blue: a brilliant blue pigment that was traditionally made from ground-up lapis lazuli, and now usually either extracted from mineral deposits or made synthetically.
A brilliant dark blue or slightly purplish colour like that of the pigment.