I have tried to get a black royal icing and the best I get is a deep charcoal gray can anyone help with this I know others do it.  Any help is appreciated. Thanks 

mix a bunch of other colours first, it's easier to get black from a dark bluey/redy/green/brown mix than from white

I just use Americolor Super Black and get a true black with no problem.  You've got to let the color develop for a little while.  It will develop from a deep charcoal to black if you've used enough color.  If you try to get jet black immediately, you'll use way too much color.

I let it set over night and it was still charcoal should I just add more black and wait?

Yes, if it's sat overnight and is still not black, add more color.  :)

Thanks so much 

My blacks  and greys sometimes look a little purple, I add a touch of yellow to balance the blue tones and make it black or grey.

Thank you