One each of black and blue here.
Blue is the correct term for a solid grey cat - and the fur should have a bluish / slate tinge to it. Madam Pearl is noticeably toned towards the blue. Blue is the dilute of black.
If the "grey" is lighter and warm in tone (tending towards the brown / pink) then it is known as Lilac and it is the dilute of chocolate - a colour not found in genuine mogs.
Auferstehen, looking at the pic of Lirael in your sig, I'd say a cream Burmese.