BlackWatch may very well be the number two tartan in popularity - after Stewart Royal. It is a universal tartan and therefore for any man to wear. Women will wear it too, because it is very often used for kilted skirts or just skirts. You may also see it used in interior design.
The main colour may be green/blue but on many of the pictures below it was necessary to lighten up colours in Photoshop, or the kilt had appeared black. Hence the name Black Watch.
Two kilts are shown, one is an 11 oz. approx. 2.6 yard off-the-peg kilt made by O'Neill of Dublin, the other one a made to measure 16 oz. 5 yard James Morrison by Heritage of Scotland. You'll notice that the tartans are not 100% identical. That is due to the fact that seeral varieties of the Black Watch tartan exist.