never heard of a black Charolais but I would think it wouldn't have a lot of Charolais in it to be truly black in color. Charolais carry 2 genes for dilution so that is why when you breed a Charolais and black Angus you get a smokey color similar to Murray Grey. So if you would have to then breed that F1 to a homozygous black to maybe not have a dilution factor. Charolais are red but because they carry 2 dominant dilution genes it removes all the pigment. At minimum you would have to have an F2 or F3 to start not having a dilution coloration but then you have diluted the Charolais so much its not really a Charolais but more Angus... so idk